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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.43 by root, Sun Aug 9 16:08:16 2009 UTC vs.
Revision 1.63 by root, Thu Aug 27 21:29:37 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		44	AnyEvent::MP::Intro - outdated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 will not be queued.
67	will not be queued.
68		74
69	=item port id - C<noderef#portname>	75	=item port ID - C<noderef#portname>
70		76
71	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	77	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	78	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	79	exception is the the node port, whose ID is identical to its node
74	reference.	80	reference.
75		81
76	=item node	82	=item node
77		83
78	A node is a single process containing at least one port - the node	84	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	85	which provides nodes to manage each other remotely, and to create new
80	create new ports, among other things.	86	ports.
81		87
82	Nodes are either private (single-process only), slaves (connected to a	88	Nodes are either private (single-process only), slaves (can only talk to
83	master node only) or public nodes (connectable from unrelated nodes).	89	public nodes, but do not need an open port) or public nodes (connectable
		90	from any other node).
84		91
85	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	92	=item node ID - C<[a-za-Z0-9_\-.:]+>
86		93
87	A node reference is a string that either simply identifies the node (for	94	A node ID is a string that either simply identifies the node (for
88	private and slave nodes), or contains a recipe on how to reach a given	95	private and slave nodes), or contains a recipe on how to reach a given
89	node (for public nodes).	96	node (for public nodes).
90		97
91	This recipe is simply a comma-separated list of C<address:port> pairs (for	98	This recipe is simply a comma-separated list of C<address:port> pairs (for
92	TCP/IP, other protocols might look different).	99	TCP/IP, other protocols might look different).
…		…
105		112
106	=cut	113	=cut
107		114
108	package AnyEvent::MP;	115	package AnyEvent::MP;
109		116
110	use AnyEvent::MP::Base;	117	use AnyEvent::MP::Kernel;
111		118
112	use common::sense;	119	use common::sense;
113		120
114	use Carp ();	121	use Carp ();
115		122
116	use AE ();	123	use AE ();
117		124
118	use base "Exporter";	125	use base "Exporter";
119		126
120	our $VERSION = $AnyEvent::MP::Base::VERSION;	127	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
121		128
122	our @EXPORT = qw(	129	our @EXPORT = qw(
123	NODE $NODE *SELF node_of _any_	130	NODE $NODE *SELF node_of after
124	resolve_node initialise_node	131	resolve_node initialise_node
125	snd rcv mon kil reg psub spawn	132	snd rcv mon mon_guard kil reg psub spawn
126	port	133	port
127	);	134	);
128		135
129	our $SELF;	136	our $SELF;
130		137
…		…
134	kil $SELF, die => $msg;	141	kil $SELF, die => $msg;
135	}	142	}
136		143
137	=item $thisnode = NODE / $NODE	144	=item $thisnode = NODE / $NODE
138		145
139	The C<NODE> function returns, and the C<$NODE> variable contains	146	The C<NODE> function returns, and the C<$NODE> variable contains the
140	the noderef of the local node. The value is initialised by a call	147	node id of the local node. The value is initialised by a call to
141	to C<become_public> or C<become_slave>, after which all local port	148	C<initialise_node>.
142	identifiers become invalid.
143		149
144	=item $noderef = node_of $port	150	=item $nodeid = node_of $port
145		151
146	Extracts and returns the noderef from a portid or a noderef.	152	Extracts and returns the noderef from a port ID or a node ID.
147		153
148	=item initialise_node $noderef, $seednode, $seednode...	154	=item initialise_node $profile_name
149
150	=item initialise_node "slave/", $master, $master...
151		155
152	Before a node can talk to other nodes on the network it has to initialise	156	Before a node can talk to other nodes on the network it has to initialise
153	itself - the minimum a node needs to know is it's own name, and optionally	157	itself - the minimum a node needs to know is it's own name, and optionally
154	it should know the noderefs of some other nodes in the network.	158	it should know the noderefs of some other nodes in the network.
155		159
156	This function initialises a node - it must be called exactly once (or	160	This function initialises a node - it must be called exactly once (or
157	never) before calling other AnyEvent::MP functions.	161	never) before calling other AnyEvent::MP functions.
158		162
159	All arguments are noderefs, which can be either resolved or unresolved.	163	All arguments (optionally except for the first) are noderefs, which can be
		164	either resolved or unresolved.
		165
		166	The first argument will be looked up in the configuration database first
		167	(if it is C<undef> then the current nodename will be used instead) to find
		168	the relevant configuration profile (see L<aemp>). If none is found then
		169	the default configuration is used. The configuration supplies additional
		170	seed/master nodes and can override the actual noderef.
160		171
161	There are two types of networked nodes, public nodes and slave nodes:	172	There are two types of networked nodes, public nodes and slave nodes:
162		173
163	=over 4	174	=over 4
164		175
165	=item public nodes	176	=item public nodes
166		177
167	For public nodes, C<$noderef> must either be a (possibly unresolved)	178	For public nodes, C<$noderef> (supplied either directly to
168	noderef, in which case it will be resolved, or C<undef> (or missing), in	179	C<initialise_node> or indirectly via a profile or the nodename) must be a
169	which case the noderef will be guessed.	180	noderef (possibly unresolved, in which case it will be resolved).
170		181
171	Afterwards, the node will bind itself on all endpoints and try to connect	182	After resolving, the node will bind itself on all endpoints.
172	to all additional C<$seednodes> that are specified. Seednodes are optional
173	and can be used to quickly bootstrap the node into an existing network.
174		183
175	=item slave nodes	184	=item slave nodes
176		185
177	When the C<$noderef> is the special string C<slave/>, then the node will	186	When the C<$noderef> (either as given or overriden by the config file)
		187	is the special string C<slave/>, then the node will become a slave
178	become a slave node. Slave nodes cannot be contacted from outside and will	188	node. Slave nodes cannot be contacted from outside, and cannot talk to
179	route most of their traffic to the master node that they attach to.	189	each other (at least in this version of AnyEvent::MP).
180		190
181	At least one additional noderef is required: The node will try to connect	191	Slave nodes work by creating connections to all public nodes, using the
182	to all of them and will become a slave attached to the first node it can	192	L<AnyEvent::MP::Global> service.
183	successfully connect to.
184		193
185	=back	194	=back
186		195
187	This function will block until all nodes have been resolved and, for slave	196	After initialising itself, the node will connect to all additional
188	nodes, until it has successfully established a connection to a master	197	C<$seednodes> that are specified diretcly or via a profile. Seednodes are
189	server.	198	optional and can be used to quickly bootstrap the node into an existing
		199	network.
190		200
		201	All the seednodes will also be specially marked to automatically retry
		202	connecting to them indefinitely, so make sure that seednodes are really
		203	reliable and up (this might also change in the future).
		204
191	Example: become a public node listening on the default node.	205	Example: become a public node listening on the guessed noderef, or the one
		206	specified via C<aemp> for the current node. This should be the most common
		207	form of invocation for "daemon"-type nodes.
192		208
193	initialise_node;	209	initialise_node;
		210
		211	Example: become a slave node to any of the the seednodes specified via
		212	C<aemp>. This form is often used for commandline clients.
		213
		214	initialise_node "slave/";
194		215
195	Example: become a public node, and try to contact some well-known master	216	Example: become a public node, and try to contact some well-known master
196	servers to become part of the network.	217	servers to become part of the network.
197		218
198	initialise_node undef, "master1", "master2";	219	initialise_node undef, "master1", "master2";
…		…
201		222
202	initialise_node 4041;	223	initialise_node 4041;
203		224
204	Example: become a public node, only visible on localhost port 4044.	225	Example: become a public node, only visible on localhost port 4044.
205		226
206	initialise_node "locahost:4044";	227	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		228
212	=item $cv = resolve_node $noderef	229	=item $cv = resolve_node $noderef
213		230
214	Takes an unresolved node reference that may contain hostnames and	231	Takes an unresolved node reference that may contain hostnames and
215	abbreviated IDs, resolves all of them and returns a resolved node	232	abbreviated IDs, resolves all of them and returns a resolved node
…		…
252	=item snd $port, type => @data	269	=item snd $port, type => @data
253		270
254	=item snd $port, @msg	271	=item snd $port, @msg
255		272
256	Send the given message to the given port ID, which can identify either	273	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	274	a local or a remote port, and must be a port ID.
258	stringifies a sa port ID (such as a port object :).
259		275
260	While the message can be about anything, it is highly recommended to use a	276	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	277	string as first element (a port ID, or some word that indicates a request
262	type etc.).	278	type etc.).
263		279
264	The message data effectively becomes read-only after a call to this	280	The message data effectively becomes read-only after a call to this
265	function: modifying any argument is not allowed and can cause many	281	function: modifying any argument is not allowed and can cause many
266	problems.	282	problems.
…		…
271	that Storable can serialise and deserialise is allowed, and for the local	287	that Storable can serialise and deserialise is allowed, and for the local
272	node, anything can be passed.	288	node, anything can be passed.
273		289
274	=item $local_port = port	290	=item $local_port = port
275		291
276	Create a new local port object that can be used either as a pattern	292	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"),	293	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		294
280	=item $port = port { my @msg = @_; $finished }	295	=item $local_port = port { my @msg = @_ }
281		296
282	Creates a "miniport", that is, a very lightweight port without any pattern	297	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.	298	creating a port and calling C<rcv $port, $callback> on it.
285		299
286	The block will be called for every message received on the port. When the	300	The block will be called for every message received on the port, with the
287	callback returns a true value its job is considered "done" and the port	301	global variable C<$SELF> set to the port ID. Runtime errors will cause the
288	will be destroyed. Otherwise it will stay alive.	302	port to be C<kil>ed. The message will be passed as-is, no extra argument
		303	(i.e. no port ID) will be passed to the callback.
289		304
290	The message will be passed as-is, no extra argument (i.e. no port id) will	305	If you want to stop/destroy the port, simply C<kil> it:
291	be passed to the callback.
292		306
293	If you need the local port id in the callback, this works nicely:	307	my $port = port {
294		308	my @msg = @_;
295	my $port; $port = port {	309	...
296	snd $otherport, reply => $port;	310	kil $SELF;
297	};	311	};
298		312
299	=cut	313	=cut
300		314
301	sub rcv($@);	315	sub rcv($@);
		316
		317	sub _kilme {
		318	die "received message on port without callback";
		319	}
302		320
303	sub port(;&) {	321	sub port(;&) {
304	my $id = "$UNIQ." . $ID++;	322	my $id = "$UNIQ." . $ID++;
305	my $port = "$NODE#$id";	323	my $port = "$NODE#$id";
306		324
307	if (@_) {	325	rcv $port, shift \|\| \&_kilme;
308	rcv $port, shift;
309	} else {
310	$PORT{$id} = sub { }; # nop
311	}
312		326
313	$port	327	$port
314	}	328	}
315		329
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)	330	=item rcv $local_port, $callback->(@msg)
336		331
337	Replaces the callback on the specified miniport (after converting it to	332	Replaces the default callback on the specified port. There is no way to
338	one if required).	333	remove the default callback: use C<sub { }> to disable it, or better
339		334	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...] => $callback->(@msg), ...
345
346	Register callbacks to be called on matching messages on the given full
347	port (after converting it to one if required) and return the port.
348
349	The callback has to return a true value when its work is done, after
350	which is will be removed, or a false value in which case it will stay
351	registered.
352		335
353	The global C<$SELF> (exported by this module) contains C<$port> while	336	The global C<$SELF> (exported by this module) contains C<$port> while
354	executing the callback.	337	executing the callback. Runtime errors during callback execution will
		338	result in the port being C<kil>ed.
355		339
356	Runtime errors during callback execution will result in the port being	340	The default callback received all messages not matched by a more specific
357	C<kil>ed.	341	C<tag> match.
358		342
359	If the match is an array reference, then it will be matched against the	343	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
360	first elements of the message, otherwise only the first element is being
361	matched.
362		344
363	Any element in the match that is specified as C<_any_> (a function	345	Register (or replace) callbacks to be called on messages starting with the
364	exported by this module) matches any single element of the message.	346	given tag on the given port (and return the port), or unregister it (when
		347	C<$callback> is C<$undef> or missing). There can only be one callback
		348	registered for each tag.
365		349
366	While not required, it is highly recommended that the first matching	350	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	351	element (the tag) has been removed. The callback will use the same
368	also the most efficient match (by far).	352	environment as the default callback (see above).
369		353
370	Example: create a port and bind receivers on it in one go.	354	Example: create a port and bind receivers on it in one go.
371		355
372	my $port = rcv port,	356	my $port = rcv port,
373	msg1 => sub { ...; 0 },	357	msg1 => sub { ... },
374	msg2 => sub { ...; 0 },	358	msg2 => sub { ... },
375	;	359	;
376		360
377	Example: create a port, bind receivers and send it in a message elsewhere	361	Example: create a port, bind receivers and send it in a message elsewhere
378	in one go:	362	in one go:
379		363
380	snd $otherport, reply =>	364	snd $otherport, reply =>
381	rcv port,	365	rcv port,
382	msg1 => sub { ...; 0 },	366	msg1 => sub { ... },
383	...	367	...
384	;	368	;
		369
		370	Example: temporarily register a rcv callback for a tag matching some port
		371	(e.g. for a rpc reply) and unregister it after a message was received.
		372
		373	rcv $port, $otherport => sub {
		374	my @reply = @_;
		375
		376	rcv $SELF, $otherport;
		377	};
385		378
386	=cut	379	=cut
387		380
388	sub rcv($@) {	381	sub rcv($@) {
389	my $port = shift;	382	my $port = shift;
390	my ($noderef, $portid) = split /#/, $port, 2;	383	my ($noderef, $portid) = split /#/, $port, 2;
391		384
392	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	385	$NODE{$noderef} == $NODE{""}
393	or Carp::croak "$port: rcv can only be called on local ports, caught";	386	or Carp::croak "$port: rcv can only be called on local ports, caught";
394		387
395	if (@_ == 1) {	388	while (@_) {
		389	if (ref $_[0]) {
		390	if (my $self = $PORT_DATA{$portid}) {
		391	"AnyEvent::MP::Port" eq ref $self
		392	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		393
		394	$self->[2] = shift;
		395	} else {
396	my $cb = shift;	396	my $cb = shift;
397	delete $PORT_DATA{$portid};
398	$PORT{$portid} = sub {	397	$PORT{$portid} = sub {
399	local $SELF = $port;	398	local $SELF = $port;
400	eval {	399	eval { &$cb }; _self_die if $@;
401	&$cb	400	};
402	and kil $port;
403	};	401	}
404	_self_die if $@;	402	} elsif (defined $_[0]) {
405	};
406	} else {
407	my $self = $PORT_DATA{$portid} \|\|= do {	403	my $self = $PORT_DATA{$portid} \|\|= do {
408	my $self = bless {	404	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
409	id => $port,
410	}, "AnyEvent::MP::Port";
411		405
412	$PORT{$portid} = sub {	406	$PORT{$portid} = sub {
413	local $SELF = $port;	407	local $SELF = $port;
414		408
415	eval {
416	for (@{ $self->{rc0}{$_[0]} }) {	409	if (my $cb = $self->[1]{$_[0]}) {
417	$_ && &{$_->[0]}	410	shift;
418	&& undef $_;	411	eval { &$cb }; _self_die if $@;
419	}	412	} else {
420
421	for (@{ $self->{rcv}{$_[0]} }) {
422	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
423	&& &{$_->[0]}	413	&{ $self->[0] };
424	&& undef $_;
425	}
426
427	for (@{ $self->{any} }) {
428	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
429	&& &{$_->[0]}
430	&& undef $_;
431	}	414	}
432	};	415	};
433	_self_die if $@;	416
		417	$self
434	};	418	};
435		419
436	$self
437	};
438
439	"AnyEvent::MP::Port" eq ref $self	420	"AnyEvent::MP::Port" eq ref $self
440	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	421	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
441		422
442	while (@_) {
443	my ($match, $cb) = splice @_, 0, 2;	423	my ($tag, $cb) = splice @_, 0, 2;
444		424
445	if (!ref $match) {	425	if (defined $cb) {
446	push @{ $self->{rc0}{$match} }, [$cb];	426	$self->[1]{$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 {	427	} else {
453	push @{ $self->{any} }, [$cb, $match];	428	delete $self->[1]{$tag};
454	}	429	}
455	}	430	}
456	}	431	}
457		432
458	$port	433	$port
…		…
513	will arrive, or the monitoring action will be invoked after possible	488	will arrive, or the monitoring action will be invoked after possible
514	message loss has been detected. No messages will be lost "in between"	489	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	490	(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	491	port). After the monitoring action was invoked, further messages might get
517	delivered again.	492	delivered again.
		493
		494	Note that monitoring-actions are one-shot: once released, they are removed
		495	and will not trigger again.
518		496
519	In the first form (callback), the callback is simply called with any	497	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	498	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	499	"normally"). Note also that I<< the callback B<must> never die >>, so use
522	C<eval> if unsure.	500	C<eval> if unsure.
…		…
683	my $id = "$RUNIQ." . $ID++;	661	my $id = "$RUNIQ." . $ID++;
684		662
685	$_[0] =~ /::/	663	$_[0] =~ /::/
686	or Carp::croak "spawn init function must be a fully-qualified name, caught";	664	or Carp::croak "spawn init function must be a fully-qualified name, caught";
687		665
688	($NODE{$noderef} \|\| add_node $noderef)	666	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
689	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
690		667
691	"$noderef#$id"	668	"$noderef#$id"
692	}	669	}
693		670
694	=back	671	=item after $timeout, @msg
695		672
696	=head1 NODE MESSAGES	673	=item after $timeout, $callback
697		674
698	Nodes understand the following messages sent to them. Many of them take	675	Either sends the given message, or call the given callback, after the
699	arguments called C<@reply>, which will simply be used to compose a reply	676	specified number of seconds.
700	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
701	the remaining arguments are simply the message data.
702		677
703	While other messages exist, they are not public and subject to change.	678	This is simply a utility function that come sin handy at times.
704		679
705	=over 4
706
707	=cut	680	=cut
708		681
709	=item lookup => $name, @reply	682	sub after($@) {
		683	my ($timeout, @action) = @_;
710		684
711	Replies with the port ID of the specified well-known port, or C<undef>.	685	my $t; $t = AE::timer $timeout, 0, sub {
712		686	undef $t;
713	=item devnull => ...	687	ref $action[0]
714		688	? $action[0]()
715	Generic data sink/CPU heat conversion.	689	: snd @action;
716		690	};
717	=item relay => $port, @msg	691	}
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		692
740	=back	693	=back
741		694
742	=head1 AnyEvent::MP vs. Distributed Erlang	695	=head1 AnyEvent::MP vs. Distributed Erlang
743		696
…		…
762	convenience functionality.	715	convenience functionality.
763		716
764	This means that AEMP requires a less tightly controlled environment at the	717	This means that AEMP requires a less tightly controlled environment at the
765	cost of longer node references and a slightly higher management overhead.	718	cost of longer node references and a slightly higher management overhead.
766		719
		720	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
		721	uses "local ports are like remote ports".
		722
		723	The failure modes for local ports are quite different (runtime errors
		724	only) then for remote ports - when a local port dies, you I<know> it dies,
		725	when a connection to another node dies, you know nothing about the other
		726	port.
		727
		728	Erlang pretends remote ports are as reliable as local ports, even when
		729	they are not.
		730
		731	AEMP encourages a "treat remote ports differently" philosophy, with local
		732	ports being the special case/exception, where transport errors cannot
		733	occur.
		734
767	=item * Erlang uses processes and a mailbox, AEMP does not queue.	735	=item * Erlang uses processes and a mailbox, AEMP does not queue.
768		736
769	Erlang uses processes that selctively receive messages, and therefore	737	Erlang uses processes that selectively receive messages, and therefore
770	needs a queue. AEMP is event based, queuing messages would serve no useful	738	needs a queue. AEMP is event based, queuing messages would serve no
771	purpose.	739	useful purpose. For the same reason the pattern-matching abilities of
		740	AnyEvent::MP are more limited, as there is little need to be able to
		741	filter messages without dequeing them.
772		742
773	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	743	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
774		744
775	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	745	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
776		746
777	Sending messages in Erlang is synchronous and blocks the process. AEMP	747	Sending messages in Erlang is synchronous and blocks the process (and
778	sends are immediate, connection establishment is handled in the	748	so does not need a queue that can overflow). AEMP sends are immediate,
779	background.	749	connection establishment is handled in the background.
780		750
781	=item * Erlang can silently lose messages, AEMP cannot.	751	=item * Erlang suffers from silent message loss, AEMP does not.
782		752
783	Erlang makes few guarantees on messages delivery - messages can get lost	753	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,	754	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).	755	and c, and the other side only receives messages a and c).
786		756
…		…
798	eventually be killed - it cannot happen that a node detects a port as dead	768	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.	769	and then later sends messages to it, finding it is still alive.
800		770
801	=item * Erlang can send messages to the wrong port, AEMP does not.	771	=item * Erlang can send messages to the wrong port, AEMP does not.
802		772
803	In Erlang it is quite possible that a node that restarts reuses a process	773	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	774	known to other nodes for a completely different process, causing messages
805	messages destined for that process to end up in an unrelated process.	775	destined for that process to end up in an unrelated process.
806		776
807	AEMP never reuses port IDs, so old messages or old port IDs floating	777	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.	778	around in the network will not be sent to an unrelated port.
809		779
810	=item * Erlang uses unprotected connections, AEMP uses secure	780	=item * Erlang uses unprotected connections, AEMP uses secure
…		…
846	This also saves round-trips and avoids sending messages to the wrong port	816	This also saves round-trips and avoids sending messages to the wrong port
847	(hard to do in Erlang).	817	(hard to do in Erlang).
848		818
849	=back	819	=back
850		820
		821	=head1 RATIONALE
		822
		823	=over 4
		824
		825	=item Why strings for ports and noderefs, why not objects?
		826
		827	We considered "objects", but found that the actual number of methods
		828	thatc an be called are very low. Since port IDs and noderefs travel over
		829	the network frequently, the serialising/deserialising would add lots of
		830	overhead, as well as having to keep a proxy object.
		831
		832	Strings can easily be printed, easily serialised etc. and need no special
		833	procedures to be "valid".
		834
		835	And a a miniport consists of a single closure stored in a global hash - it
		836	can't become much cheaper.
		837
		838	=item Why favour JSON, why not real serialising format such as Storable?
		839
		840	In fact, any AnyEvent::MP node will happily accept Storable as framing
		841	format, but currently there is no way to make a node use Storable by
		842	default.
		843
		844	The default framing protocol is JSON because a) JSON::XS is many times
		845	faster for small messages and b) most importantly, after years of
		846	experience we found that object serialisation is causing more problems
		847	than it gains: Just like function calls, objects simply do not travel
		848	easily over the network, mostly because they will always be a copy, so you
		849	always have to re-think your design.
		850
		851	Keeping your messages simple, concentrating on data structures rather than
		852	objects, will keep your messages clean, tidy and efficient.
		853
		854	=back
		855
851	=head1 SEE ALSO	856	=head1 SEE ALSO
852		857
853	L<AnyEvent>.	858	L<AnyEvent>.
854		859
855	=head1 AUTHOR	860	=head1 AUTHOR

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.43 by root, Sun Aug 9 16:08:16 2009 UTC vs.
Revision 1.63 by root, Thu Aug 27 21:29:37 2009 UTC