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

Comparing cvsroot/AnyEvent-MP/MP.pm (file contents):
Revision 1.37 by root, Fri Aug 7 16:47:23 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
27		37
28	# monitoring	38	# monitoring
29	mon $port, $cb->(@msg) # callback is invoked on death	39	mon $port, $cb->(@msg) # callback is invoked on death
30	mon $port, $otherport # kill otherport on abnormal death	40	mon $port, $otherport # kill otherport on abnormal death
31	mon $port, $otherport, @msg # send message on death	41	mon $port, $otherport, @msg # send message on death
32		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		46	AnyEvent::MP::Intro - outdated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.
		51
33	=head1 DESCRIPTION	52	=head1 DESCRIPTION
34		53
35	This module (-family) implements a simple message passing framework.	54	This module (-family) implements a simple message passing framework.
36		55
37	Despite its simplicity, you can securely message other processes running	56	Despite its simplicity, you can securely message other processes running
…		…
40	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>
41	manual page.	60	manual page.
42		61
43	At the moment, this module family is severly broken and underdocumented,	62	At the moment, this module family is severly broken and underdocumented,
44	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 -
45	stay tuned! The basic API should be finished, however.	64	stay tuned!
46		65
47	=head1 CONCEPTS	66	=head1 CONCEPTS
48		67
49	=over 4	68	=over 4
50		69
51	=item port	70	=item port
52		71
53	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).
54		73
55	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
56	messages. All C<rcv> handlers will receive messages they match, messages	75	some messages. Messages will not be queued.
57	will not be queued.
58		76
59	=item port id - C<noderef#portname>	77	=item port id - C<noderef#portname>
60		78
61	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
62	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
63	exception is the the node port, whose ID is identical to its node	81	exception is the the node port, whose ID is identical to its node
64	reference.	82	reference.
65		83
66	=item node	84	=item node
67		85
68	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,
69	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
70	create new ports, among other things.	88	ports.
71		89
72	Nodes are either private (single-process only), slaves (connected to a	90	Nodes are either private (single-process only), slaves (can only talk to
73	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).
74		93
75	=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>
76		95
77	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
78	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
…		…
95		114
96	=cut	115	=cut
97		116
98	package AnyEvent::MP;	117	package AnyEvent::MP;
99		118
100	use AnyEvent::MP::Base;	119	use AnyEvent::MP::Kernel;
101		120
102	use common::sense;	121	use common::sense;
103		122
104	use Carp ();	123	use Carp ();
105		124
106	use AE ();	125	use AE ();
107		126
108	use base "Exporter";	127	use base "Exporter";
109		128
110	our $VERSION = '0.1';	129	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		130
111	our @EXPORT = qw(	131	our @EXPORT = qw(
112	NODE $NODE *SELF node_of _any_	132	NODE $NODE *SELF node_of after
113	resolve_node initialise_node	133	resolve_node initialise_node
114	snd rcv mon kil reg psub	134	snd rcv mon mon_guard kil reg psub spawn
115	port	135	port
116	);	136	);
117		137
118	our $SELF;	138	our $SELF;
119		139
…		…
123	kil $SELF, die => $msg;	143	kil $SELF, die => $msg;
124	}	144	}
125		145
126	=item $thisnode = NODE / $NODE	146	=item $thisnode = NODE / $NODE
127		147
128	The C<NODE> function returns, and the C<$NODE> variable contains	148	The C<NODE> function returns, and the C<$NODE> variable contains the
129	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
130	to C<become_public> or C<become_slave>, after which all local port	150	C<initialise_node>.
131	identifiers become invalid.
132		151
133	=item $noderef = node_of $port	152	=item $noderef = node_of $port
134		153
135	Extracts and returns the noderef from a portid or a noderef.	154	Extracts and returns the noderef from a port ID or a noderef.
136		155
137	=item initialise_node $noderef, $seednode, $seednode...	156	=item initialise_node $noderef, $seednode, $seednode...
138		157
139	=item initialise_node "slave/", $master, $master...	158	=item initialise_node "slave/", $master, $master...
140		159
…		…
143	it should know the noderefs of some other nodes in the network.	162	it should know the noderefs of some other nodes in the network.
144		163
145	This function initialises a node - it must be called exactly once (or	164	This function initialises a node - it must be called exactly once (or
146	never) before calling other AnyEvent::MP functions.	165	never) before calling other AnyEvent::MP functions.
147		166
148	All arguments are noderefs, which can be either resolved or unresolved.	167	All arguments (optionally except for the first) are noderefs, which can be
		168	either resolved or unresolved.
		169
		170	The first argument will be looked up in the configuration database first
		171	(if it is C<undef> then the current nodename will be used instead) to find
		172	the relevant configuration profile (see L<aemp>). If none is found then
		173	the default configuration is used. The configuration supplies additional
		174	seed/master nodes and can override the actual noderef.
149		175
150	There are two types of networked nodes, public nodes and slave nodes:	176	There are two types of networked nodes, public nodes and slave nodes:
151		177
152	=over 4	178	=over 4
153		179
154	=item public nodes	180	=item public nodes
155		181
156	For public nodes, C<$noderef> must either be a (possibly unresolved)	182	For public nodes, C<$noderef> (supplied either directly to
157	noderef, in which case it will be resolved, or C<undef> (or missing), in	183	C<initialise_node> or indirectly via a profile or the nodename) must be a
158	which case the noderef will be guessed.	184	noderef (possibly unresolved, in which case it will be resolved).
159		185
160	Afterwards, the node will bind itself on all endpoints and try to connect	186	After resolving, the node will bind itself on all endpoints.
161	to all additional C<$seednodes> that are specified. Seednodes are optional
162	and can be used to quickly bootstrap the node into an existing network.
163		187
164	=item slave nodes	188	=item slave nodes
165		189
166	When the C<$noderef> is the special string C<slave/>, then the node will	190	When the C<$noderef> (either as given or overriden by the config file)
		191	is the special string C<slave/>, then the node will become a slave
167	become a slave node. Slave nodes cannot be contacted from outside and will	192	node. Slave nodes cannot be contacted from outside, and cannot talk to
168	route most of their traffic to the master node that they attach to.	193	each other (at least in this version of AnyEvent::MP).
169		194
170	At least one additional noderef is required: The node will try to connect	195	Slave nodes work by creating connections to all public nodes, using the
171	to all of them and will become a slave attached to the first node it can	196	L<AnyEvent::MP::Global> service.
172	successfully connect to.
173		197
174	=back	198	=back
175		199
176	This function will block until all nodes have been resolved and, for slave	200	After initialising itself, the node will connect to all additional
177	nodes, until it has successfully established a connection to a master	201	C<$seednodes> that are specified diretcly or via a profile. Seednodes are
178	server.	202	optional and can be used to quickly bootstrap the node into an existing
		203	network.
179		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
180	Example: become a public node listening on the default node.	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.
181		212
182	initialise_node;	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/";
183		219
184	Example: become a public node, and try to contact some well-known master	220	Example: become a public node, and try to contact some well-known master
185	servers to become part of the network.	221	servers to become part of the network.
186		222
187	initialise_node undef, "master1", "master2";	223	initialise_node undef, "master1", "master2";
…		…
190		226
191	initialise_node 4041;	227	initialise_node 4041;
192		228
193	Example: become a public node, only visible on localhost port 4044.	229	Example: become a public node, only visible on localhost port 4044.
194		230
195	initialise_node "locahost:4044";	231	initialise_node "localhost:4044";
196
197	Example: become a slave node to any of the specified master servers.
198
199	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
200		232
201	=item $cv = resolve_node $noderef	233	=item $cv = resolve_node $noderef
202		234
203	Takes an unresolved node reference that may contain hostnames and	235	Takes an unresolved node reference that may contain hostnames and
204	abbreviated IDs, resolves all of them and returns a resolved node	236	abbreviated IDs, resolves all of them and returns a resolved node
…		…
241	=item snd $port, type => @data	273	=item snd $port, type => @data
242		274
243	=item snd $port, @msg	275	=item snd $port, @msg
244		276
245	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
246	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.
247	stringifies a sa port ID (such as a port object :).
248		279
249	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
250	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
251	type etc.).	282	type etc.).
252		283
253	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
254	function: modifying any argument is not allowed and can cause many	285	function: modifying any argument is not allowed and can cause many
255	problems.	286	problems.
…		…
260	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
261	node, anything can be passed.	292	node, anything can be passed.
262		293
263	=item $local_port = port	294	=item $local_port = port
264		295
265	Create a new local port object that can be used either as a pattern	296	Create a new local port object and returns its port ID. Initially it has
266	matching port ("full port") or a single-callback port ("miniport"),	297	no callbacks set and will throw an error when it receives messages.
267	depending on how C<rcv> callbacks are bound to the object.
268		298
269	=item $port = port { my @msg = @_; $finished }	299	=item $local_port = port { my @msg = @_ }
270		300
271	Creates a "miniport", that is, a very lightweight port without any pattern	301	Creates a new local port, and returns its ID. Semantically the same as
272	matching behind it, and returns its ID. Semantically the same as creating
273	a port and calling C<rcv $port, $callback> on it.	302	creating a port and calling C<rcv $port, $callback> on it.
274		303
275	The block will be called for every message received on the port. When the	304	The block will be called for every message received on the port, with the
276	callback returns a true value its job is considered "done" and the port	305	global variable C<$SELF> set to the port ID. Runtime errors will cause the
277	will be destroyed. Otherwise it will stay alive.	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.
278		308
279	The message will be passed as-is, no extra argument (i.e. no port id) will	309	If you want to stop/destroy the port, simply C<kil> it:
280	be passed to the callback.
281		310
282	If you need the local port id in the callback, this works nicely:	311	my $port = port {
283		312	my @msg = @_;
284	my $port; $port = port {	313	...
285	snd $otherport, reply => $port;	314	kil $SELF;
286	};	315	};
287		316
288	=cut	317	=cut
289		318
290	sub rcv($@);	319	sub rcv($@);
		320
		321	sub _kilme {
		322	die "received message on port without callback";
		323	}
291		324
292	sub port(;&) {	325	sub port(;&) {
293	my $id = "$UNIQ." . $ID++;	326	my $id = "$UNIQ." . $ID++;
294	my $port = "$NODE#$id";	327	my $port = "$NODE#$id";
295		328
296	if (@_) {	329	rcv $port, shift \|\| \&_kilme;
297	rcv $port, shift;
298	} else {
299	$PORT{$id} = sub { }; # nop
300	}
301		330
302	$port	331	$port
303	}	332	}
304		333
305	=item reg $port, $name
306
307	=item reg $name
308
309	Registers the given port (or C<$SELF><<< if missing) under the name
310	C<$name>. If the name already exists it is replaced.
311
312	A port can only be registered under one well known name.
313
314	A port automatically becomes unregistered when it is killed.
315
316	=cut
317
318	sub reg(@) {
319	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
320
321	$REG{$_[0]} = $port;
322	}
323
324	=item rcv $port, $callback->(@msg)	334	=item rcv $local_port, $callback->(@msg)
325		335
326	Replaces the callback on the specified miniport (after converting it to	336	Replaces the default callback on the specified port. There is no way to
327	one if required).	337	remove the default callback: use C<sub { }> to disable it, or better
328		338	C<kil> the port when it is no longer needed.
329	=item rcv $port, tagstring => $callback->(@msg), ...
330
331	=item rcv $port, $smartmatch => $callback->(@msg), ...
332
333	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
334
335	Register callbacks to be called on matching messages on the given full
336	port (after converting it to one if required) and return the port.
337
338	The callback has to return a true value when its work is done, after
339	which is will be removed, or a false value in which case it will stay
340	registered.
341		339
342	The global C<$SELF> (exported by this module) contains C<$port> while	340	The global C<$SELF> (exported by this module) contains C<$port> while
343	executing the callback.	341	executing the callback. Runtime errors during callback execution will
		342	result in the port being C<kil>ed.
344		343
345	Runtime errors wdurign callback execution will result in the port being	344	The default callback received all messages not matched by a more specific
346	C<kil>ed.	345	C<tag> match.
347		346
348	If the match is an array reference, then it will be matched against the	347	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
349	first elements of the message, otherwise only the first element is being
350	matched.
351		348
352	Any element in the match that is specified as C<_any_> (a function	349	Register (or replace) callbacks to be called on messages starting with the
353	exported by this module) matches any single element of the message.	350	given tag on the given port (and return the port), or unregister it (when
		351	C<$callback> is C<$undef> or missing). There can only be one callback
		352	registered for each tag.
354		353
355	While not required, it is highly recommended that the first matching	354	The original message will be passed to the callback, after the first
356	element is a string identifying the message. The one-string-only match is	355	element (the tag) has been removed. The callback will use the same
357	also the most efficient match (by far).	356	environment as the default callback (see above).
358		357
359	Example: create a port and bind receivers on it in one go.	358	Example: create a port and bind receivers on it in one go.
360		359
361	my $port = rcv port,	360	my $port = rcv port,
362	msg1 => sub { ...; 0 },	361	msg1 => sub { ... },
363	msg2 => sub { ...; 0 },	362	msg2 => sub { ... },
364	;	363	;
365		364
366	Example: create a port, bind receivers and send it in a message elsewhere	365	Example: create a port, bind receivers and send it in a message elsewhere
367	in one go:	366	in one go:
368		367
369	snd $otherport, reply =>	368	snd $otherport, reply =>
370	rcv port,	369	rcv port,
371	msg1 => sub { ...; 0 },	370	msg1 => sub { ... },
372	...	371	...
373	;	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, $otherport;
		381	};
374		382
375	=cut	383	=cut
376		384
377	sub rcv($@) {	385	sub rcv($@) {
378	my $port = shift;	386	my $port = shift;
379	my ($noderef, $portid) = split /#/, $port, 2;	387	my ($noderef, $portid) = split /#/, $port, 2;
380		388
381	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	389	$NODE{$noderef} == $NODE{""}
382	or Carp::croak "$port: rcv can only be called on local ports, caught";	390	or Carp::croak "$port: rcv can only be called on local ports, caught";
383		391
384	if (@_ == 1) {	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 {
385	my $cb = shift;	400	my $cb = shift;
386	delete $PORT_DATA{$portid};
387	$PORT{$portid} = sub {	401	$PORT{$portid} = sub {
388	local $SELF = $port;	402	local $SELF = $port;
389	eval {	403	eval { &$cb }; _self_die if $@;
390	&$cb	404	};
391	and kil $port;
392	};	405	}
393	_self_die if $@;	406	} elsif (defined $_[0]) {
394	};
395	} else {
396	my $self = $PORT_DATA{$portid} \|\|= do {	407	my $self = $PORT_DATA{$portid} \|\|= do {
397	my $self = bless {	408	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
398	id => $port,
399	}, "AnyEvent::MP::Port";
400		409
401	$PORT{$portid} = sub {	410	$PORT{$portid} = sub {
402	local $SELF = $port;	411	local $SELF = $port;
403		412
404	eval {
405	for (@{ $self->{rc0}{$_[0]} }) {	413	if (my $cb = $self->[1]{$_[0]}) {
406	$_ && &{$_->[0]}	414	shift;
407	&& undef $_;	415	eval { &$cb }; _self_die if $@;
408	}	416	} else {
409
410	for (@{ $self->{rcv}{$_[0]} }) {
411	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
412	&& &{$_->[0]}	417	&{ $self->[0] };
413	&& undef $_;
414	}
415
416	for (@{ $self->{any} }) {
417	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
418	&& &{$_->[0]}
419	&& undef $_;
420	}	418	}
421	};	419	};
422	_self_die if $@;	420
		421	$self
423	};	422	};
424		423
425	$self
426	};
427
428	"AnyEvent::MP::Port" eq ref $self	424	"AnyEvent::MP::Port" eq ref $self
429	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	425	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
430		426
431	while (@_) {
432	my ($match, $cb) = splice @_, 0, 2;	427	my ($tag, $cb) = splice @_, 0, 2;
433		428
434	if (!ref $match) {	429	if (defined $cb) {
435	push @{ $self->{rc0}{$match} }, [$cb];	430	$self->[1]{$tag} = $cb;
436	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
437	my ($type, @match) = @$match;
438	@match
439	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
440	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
441	} else {	431	} else {
442	push @{ $self->{any} }, [$cb, $match];	432	delete $self->[1]{$tag};
443	}	433	}
444	}	434	}
445	}	435	}
446		436
447	$port	437	$port
…		…
491		481
492	=item $guard = mon $port	482	=item $guard = mon $port
493		483
494	=item $guard = mon $port, $rcvport, @msg	484	=item $guard = mon $port, $rcvport, @msg
495		485
496	Monitor the given port and do something when the port is killed, and	486	Monitor the given port and do something when the port is killed or
497	optionally return a guard that can be used to stop monitoring again.	487	messages to it were lost, and optionally return a guard that can be used
		488	to stop monitoring again.
		489
		490	C<mon> effectively guarantees that, in the absence of hardware failures,
		491	that after starting the monitor, either all messages sent to the port
		492	will arrive, or the monitoring action will be invoked after possible
		493	message loss has been detected. No messages will be lost "in between"
		494	(after the first lost message no further messages will be received by the
		495	port). After the monitoring action was invoked, further messages might get
		496	delivered again.
		497
		498	Note that monitoring-actions are one-shot: once released, they are removed
		499	and will not trigger again.
498		500
499	In the first form (callback), the callback is simply called with any	501	In the first form (callback), the callback is simply called with any
500	number of C<@reason> elements (no @reason means that the port was deleted	502	number of C<@reason> elements (no @reason means that the port was deleted
501	"normally"). Note also that I<< the callback B<must> never die >>, so use	503	"normally"). Note also that I<< the callback B<must> never die >>, so use
502	C<eval> if unsure.	504	C<eval> if unsure.
503		505
504	In the second form (another port given), the other port (C<$rcvport)	506	In the second form (another port given), the other port (C<$rcvport>)
505	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on	507	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
506	"normal" kils nothing happens, while under all other conditions, the other	508	"normal" kils nothing happens, while under all other conditions, the other
507	port is killed with the same reason.	509	port is killed with the same reason.
508		510
509	The third form (kill self) is the same as the second form, except that	511	The third form (kill self) is the same as the second form, except that
…		…
536	sub mon {	538	sub mon {
537	my ($noderef, $port) = split /#/, shift, 2;	539	my ($noderef, $port) = split /#/, shift, 2;
538		540
539	my $node = $NODE{$noderef} \|\| add_node $noderef;	541	my $node = $NODE{$noderef} \|\| add_node $noderef;
540		542
541	my $cb = @_ ? $_[0] : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	543	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
542		544
543	unless (ref $cb) {	545	unless (ref $cb) {
544	if (@_) {	546	if (@_) {
545	# send a kill info message	547	# send a kill info message
546	my (@msg) = @_;	548	my (@msg) = ($cb, @_);
547	$cb = sub { snd @msg, @_ };	549	$cb = sub { snd @msg, @_ };
548	} else {	550	} else {
549	# simply kill other port	551	# simply kill other port
550	my $port = $cb;	552	my $port = $cb;
551	$cb = sub { kil $port, @_ if @_ };	553	$cb = sub { kil $port, @_ if @_ };
…		…
598	will be reported as reason C<< die => $@ >>.	600	will be reported as reason C<< die => $@ >>.
599		601
600	Transport/communication errors are reported as C<< transport_error =>	602	Transport/communication errors are reported as C<< transport_error =>
601	$message >>.	603	$message >>.
602		604
603	=back
604
605	=head1 NODE MESSAGES
606
607	Nodes understand the following messages sent to them. Many of them take
608	arguments called C<@reply>, which will simply be used to compose a reply
609	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
610	the remaining arguments are simply the message data.
611
612	While other messages exist, they are not public and subject to change.
613
614	=over 4
615
616	=cut	605	=cut
617		606
618	=item lookup => $name, @reply	607	=item $port = spawn $node, $initfunc[, @initdata]
619		608
620	Replies with the port ID of the specified well-known port, or C<undef>.	609	Creates a port on the node C<$node> (which can also be a port ID, in which
		610	case it's the node where that port resides).
621		611
622	=item devnull => ...	612	The port ID of the newly created port is return immediately, and it is
		613	permissible to immediately start sending messages or monitor the port.
623		614
624	Generic data sink/CPU heat conversion.	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>.
625		619
626	=item relay => $port, @msg	620	If the function doesn't exist, then the node tries to C<require>
		621	the package, then the package above the package and so on (e.g.
		622	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		623	exists or it runs out of package names.
627		624
628	Simply forwards the message to the given port.	625	The init function is then called with the newly-created port as context
		626	object (C<$SELF>) and the C<@initdata> values as arguments.
629		627
630	=item eval => $string[ @reply]	628	A common idiom is to pass your own port, monitor the spawned port, and
		629	in the init function, monitor the original port. This two-way monitoring
		630	ensures that both ports get cleaned up when there is a problem.
631		631
632	Evaluates the given string. If C<@reply> is given, then a message of the	632	Example: spawn a chat server port on C<$othernode>.
633	form C<@reply, $@, @evalres> is sent.
634		633
635	Example: crash another node.	634	# this node, executed from within a port context:
		635	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		636	mon $server;
636		637
637	snd $othernode, eval => "exit";	638	# init function on C<$othernode>
		639	sub connect {
		640	my ($srcport) = @_;
638		641
639	=item time => @reply	642	mon $srcport;
640		643
641	Replies the the current node time to C<@reply>.	644	rcv $SELF, sub {
		645	...
		646	};
		647	}
642		648
643	Example: tell the current node to send the current time to C<$myport> in a	649	=cut
644	C<timereply> message.
645		650
646	snd $NODE, time => $myport, timereply => 1, 2;	651	sub _spawn {
647	# => snd $myport, timereply => 1, 2, <time>	652	my $port = shift;
		653	my $init = shift;
		654
		655	local $SELF = "$NODE#$port";
		656	eval {
		657	&{ load_func $init }
		658	};
		659	_self_die if $@;
		660	}
		661
		662	sub spawn(@) {
		663	my ($noderef, undef) = split /#/, shift, 2;
		664
		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;
		694	};
		695	}
648		696
649	=back	697	=back
650		698
651	=head1 AnyEvent::MP vs. Distributed Erlang	699	=head1 AnyEvent::MP vs. Distributed Erlang
652		700
…		…
671	convenience functionality.	719	convenience functionality.
672		720
673	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
674	cost of longer node references and a slightly higher management overhead.	722	cost of longer node references and a slightly higher management overhead.
675		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
676	=item * Erlang uses processes and a mailbox, AEMP does not queue.	739	=item * Erlang uses processes and a mailbox, AEMP does not queue.
677		740
678	Erlang uses processes that selctively receive messages, and therefore	741	Erlang uses processes that selectively receive messages, and therefore
679	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
680	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.
681		746
682	(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).
683		748
684	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	749	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
685		750
686	Sending messages in Erlang is synchronous and blocks the process. AEMP	751	Sending messages in Erlang is synchronous and blocks the process (and
687	sends are immediate, connection establishment is handled in the	752	so does not need a queue that can overflow). AEMP sends are immediate,
688	background.	753	connection establishment is handled in the background.
689		754
690	=item * Erlang can silently lose messages, AEMP cannot.	755	=item * Erlang suffers from silent message loss, AEMP does not.
691		756
692	Erlang makes few guarantees on messages delivery - messages can get lost	757	Erlang makes few guarantees on messages delivery - messages can get lost
693	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,
694	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).
695		760
…		…
707	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
708	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.
709		774
710	=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.
711		776
712	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
713	ID known to other nodes for a completely different process, causing	778	known to other nodes for a completely different process, causing messages
714	messages destined for that process to end up in an unrelated process.	779	destined for that process to end up in an unrelated process.
715		780
716	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
717	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.
718		783
719	=item * Erlang uses unprotected connections, AEMP uses secure	784	=item * Erlang uses unprotected connections, AEMP uses secure
…		…
755	This also saves round-trips and avoids sending messages to the wrong port	820	This also saves round-trips and avoids sending messages to the wrong port
756	(hard to do in Erlang).	821	(hard to do in Erlang).
757		822
758	=back	823	=back
759		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
		858	=back
		859
760	=head1 SEE ALSO	860	=head1 SEE ALSO
761		861
762	L<AnyEvent>.	862	L<AnyEvent>.
763		863
764	=head1 AUTHOR	864	=head1 AUTHOR

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