[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 1.63 by root, Thu Aug 27 21:29:37 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;
		17
		18	# ports are message endpoints
		19
		20	# sending messages
13	snd $port, type => data...;	21	snd $port, type => data...;
		22	snd $port, @msg;
		23	snd @msg_with_first_element_being_a_port;
14		24
15	$SELF # receiving/own port id in rcv callbacks	25	# creating/using ports, the simple way
		26	my $simple_port = port { my @msg = @_; 0 };
16		27
17	rcv $port, smartmatch => $cb->($port, @msg);	28	# creating/using ports, tagged message matching
18		29	my $port = port;
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	30	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
21	rcv $port1, pong => sub { warn "pong received\n" };	31	rcv $port, pong => sub { warn "pong received\n"; 0 };
22	snd $port2, ping => $port1;
23		32
24	# more, smarter, matches (_any_ is exported by this module)	33	# create a port on another node
25	rcv $port, [child_died => $pid] => sub { ...	34	my $port = spawn $node, $initfunc, @initdata;
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
27		35
28	# monitoring	36	# monitoring
29	mon $port, $cb->(@msg) # callback is invoked on death	37	mon $port, $cb->(@msg) # callback is invoked on death
30	mon $port, $otherport # kill otherport on abnormal death	38	mon $port, $otherport # kill otherport on abnormal death
31	mon $port, $otherport, @msg # send message on death	39	mon $port, $otherport, @msg # send message on death
32		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		44	AnyEvent::MP::Intro - outdated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
33	=head1 DESCRIPTION	50	=head1 DESCRIPTION
34		51
35	This module (-family) implements a simple message passing framework.	52	This module (-family) implements a simple message passing framework.
36		53
37	Despite its simplicity, you can securely message other processes running	54	Despite its simplicity, you can securely message other processes running
…		…
40	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>
41	manual page.	58	manual page.
42		59
43	At the moment, this module family is severly broken and underdocumented,	60	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 -	61	so do not use. This was uploaded mainly to reserve the CPAN namespace -
45	stay tuned! The basic API should be finished, however.	62	stay tuned!
46		63
47	=head1 CONCEPTS	64	=head1 CONCEPTS
48		65
49	=over 4	66	=over 4
50		67
51	=item port	68	=item port
52		69
53	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).
54		71
55	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
56	messages. All C<rcv> handlers will receive messages they match, messages	73	some messages. Messages will not be queued.
57	will not be queued.
58		74
59	=item port id - C<noderef#portname>	75	=item port ID - C<noderef#portname>
60		76
61	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
62	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
63	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
64	reference.	80	reference.
65		81
66	=item node	82	=item node
67		83
68	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,
69	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
70	create new ports, among other things.	86	ports.
71		87
72	Nodes are either private (single-process only), slaves (connected to a	88	Nodes are either private (single-process only), slaves (can only talk to
73	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).
74		91
75	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	92	=item node ID - C<[a-za-Z0-9_\-.:]+>
76		93
77	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
78	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
79	node (for public nodes).	96	node (for public nodes).
80		97
81	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
82	TCP/IP, other protocols might look different).	99	TCP/IP, other protocols might look different).
…		…
95		112
96	=cut	113	=cut
97		114
98	package AnyEvent::MP;	115	package AnyEvent::MP;
99		116
100	use AnyEvent::MP::Base;	117	use AnyEvent::MP::Kernel;
101		118
102	use common::sense;	119	use common::sense;
103		120
104	use Carp ();	121	use Carp ();
105		122
106	use AE ();	123	use AE ();
107		124
108	use base "Exporter";	125	use base "Exporter";
109		126
110	our $VERSION = '0.1';	127	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		128
111	our @EXPORT = qw(	129	our @EXPORT = qw(
112	NODE $NODE *SELF node_of _any_	130	NODE $NODE *SELF node_of after
113	resolve_node initialise_node	131	resolve_node initialise_node
114	snd rcv mon kil reg psub	132	snd rcv mon mon_guard kil reg psub spawn
115	port	133	port
116	);	134	);
117		135
118	our $SELF;	136	our $SELF;
119		137
…		…
123	kil $SELF, die => $msg;	141	kil $SELF, die => $msg;
124	}	142	}
125		143
126	=item $thisnode = NODE / $NODE	144	=item $thisnode = NODE / $NODE
127		145
128	The C<NODE> function returns, and the C<$NODE> variable contains	146	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	147	node id 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	148	C<initialise_node>.
131	identifiers become invalid.
132		149
133	=item $noderef = node_of $port	150	=item $nodeid = node_of $port
134		151
135	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.
136		153
137	=item initialise_node $noderef, $seednode, $seednode...	154	=item initialise_node $profile_name
138
139	=item initialise_node "slave/", $master, $master...
140		155
141	Before a node can talk to other nodes on the network it has to initialise	156	Before a node can talk to other nodes on the network it has to initialise
142	itself - the minimum a node needs to know is it's own name, and optionally	157	itself - the minimum a node needs to know is it's own name, and optionally
143	it should know the noderefs of some other nodes in the network.	158	it should know the noderefs of some other nodes in the network.
144		159
145	This function initialises a node - it must be called exactly once (or	160	This function initialises a node - it must be called exactly once (or
146	never) before calling other AnyEvent::MP functions.	161	never) before calling other AnyEvent::MP functions.
147		162
148	All arguments are noderefs, which can be either resolved or unresolved.	163	All arguments (optionally except for the first) are noderefs, which can be
		164	either resolved or unresolved.
		165
		166	The first argument will be looked up in the configuration database first
		167	(if it is C<undef> then the current nodename will be used instead) to find
		168	the relevant configuration profile (see L<aemp>). If none is found then
		169	the default configuration is used. The configuration supplies additional
		170	seed/master nodes and can override the actual noderef.
149		171
150	There are two types of networked nodes, public nodes and slave nodes:	172	There are two types of networked nodes, public nodes and slave nodes:
151		173
152	=over 4	174	=over 4
153		175
154	=item public nodes	176	=item public nodes
155		177
156	For public nodes, C<$noderef> must either be a (possibly unresolved)	178	For public nodes, C<$noderef> (supplied either directly to
157	noderef, in which case it will be resolved, or C<undef> (or missing), in	179	C<initialise_node> or indirectly via a profile or the nodename) must be a
158	which case the noderef will be guessed.	180	noderef (possibly unresolved, in which case it will be resolved).
159		181
160	Afterwards, the node will bind itself on all endpoints and try to connect	182	After resolving, the node will bind itself on all endpoints.
161	to all additional C<$seednodes> that are specified. Seednodes are optional
162	and can be used to quickly bootstrap the node into an existing network.
163		183
164	=item slave nodes	184	=item slave nodes
165		185
166	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
167	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
168	route most of their traffic to the master node that they attach to.	189	each other (at least in this version of AnyEvent::MP).
169		190
170	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
171	to all of them and will become a slave attached to the first node it can	192	L<AnyEvent::MP::Global> service.
172	successfully connect to.
173		193
174	=back	194	=back
175		195
176	This function will block until all nodes have been resolved and, for slave	196	After initialising itself, the node will connect to all additional
177	nodes, until it has successfully established a connection to a master	197	C<$seednodes> that are specified diretcly or via a profile. Seednodes are
178	server.	198	optional and can be used to quickly bootstrap the node into an existing
		199	network.
179		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
180	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.
181		208
182	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/";
183		215
184	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
185	servers to become part of the network.	217	servers to become part of the network.
186		218
187	initialise_node undef, "master1", "master2";	219	initialise_node undef, "master1", "master2";
…		…
190		222
191	initialise_node 4041;	223	initialise_node 4041;
192		224
193	Example: become a public node, only visible on localhost port 4044.	225	Example: become a public node, only visible on localhost port 4044.
194		226
195	initialise_node "locahost:4044";	227	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		228
201	=item $cv = resolve_node $noderef	229	=item $cv = resolve_node $noderef
202		230
203	Takes an unresolved node reference that may contain hostnames and	231	Takes an unresolved node reference that may contain hostnames and
204	abbreviated IDs, resolves all of them and returns a resolved node	232	abbreviated IDs, resolves all of them and returns a resolved node
…		…
241	=item snd $port, type => @data	269	=item snd $port, type => @data
242		270
243	=item snd $port, @msg	271	=item snd $port, @msg
244		272
245	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
246	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.
247	stringifies a sa port ID (such as a port object :).
248		275
249	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
250	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
251	type etc.).	278	type etc.).
252		279
253	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
254	function: modifying any argument is not allowed and can cause many	281	function: modifying any argument is not allowed and can cause many
255	problems.	282	problems.
…		…
260	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
261	node, anything can be passed.	288	node, anything can be passed.
262		289
263	=item $local_port = port	290	=item $local_port = port
264		291
265	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
266	matching port ("full port") or a single-callback port ("miniport"),	293	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		294
269	=item $port = port { my @msg = @_; $finished }	295	=item $local_port = port { my @msg = @_ }
270		296
271	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
272	matching behind it, and returns its ID. Semantically the same as creating
273	a port and calling C<rcv $port, $callback> on it.	298	creating a port and calling C<rcv $port, $callback> on it.
274		299
275	The block will be called for every message received on the port. When the	300	The block will be called for every message received on the port, with the
276	callback returns a true value its job is considered "done" and the port	301	global variable C<$SELF> set to the port ID. Runtime errors will cause the
277	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.
278		304
279	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:
280	be passed to the callback.
281		306
282	If you need the local port id in the callback, this works nicely:	307	my $port = port {
283		308	my @msg = @_;
284	my $port; $port = port {	309	...
285	snd $otherport, reply => $port;	310	kil $SELF;
286	};	311	};
287		312
288	=cut	313	=cut
289		314
290	sub rcv($@);	315	sub rcv($@);
		316
		317	sub _kilme {
		318	die "received message on port without callback";
		319	}
291		320
292	sub port(;&) {	321	sub port(;&) {
293	my $id = "$UNIQ." . $ID++;	322	my $id = "$UNIQ." . $ID++;
294	my $port = "$NODE#$id";	323	my $port = "$NODE#$id";
295		324
296	if (@_) {	325	rcv $port, shift \|\| \&_kilme;
297	rcv $port, shift;
298	} else {
299	$PORT{$id} = sub { }; # nop
300	}
301		326
302	$port	327	$port
303	}	328	}
304		329
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)	330	=item rcv $local_port, $callback->(@msg)
325		331
326	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
327	one if required).	333	remove the default callback: use C<sub { }> to disable it, or better
328		334	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...] => $callback->(@msg), ...
334
335	Register callbacks to be called on matching messages on the given full
336	port (after converting it to one if required) and return the port.
337
338	The callback has to return a true value when its work is done, after
339	which is will be removed, or a false value in which case it will stay
340	registered.
341		335
342	The global C<$SELF> (exported by this module) contains C<$port> while	336	The global C<$SELF> (exported by this module) contains C<$port> while
343	executing the callback.	337	executing the callback. Runtime errors during callback execution will
		338	result in the port being C<kil>ed.
344		339
345	Runtime errors wdurign callback execution will result in the port being	340	The default callback received all messages not matched by a more specific
346	C<kil>ed.	341	C<tag> match.
347		342
348	If the match is an array reference, then it will be matched against the	343	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
349	first elements of the message, otherwise only the first element is being
350	matched.
351		344
352	Any element in the match that is specified as C<_any_> (a function	345	Register (or replace) callbacks to be called on messages starting with the
353	exported by this module) matches any single element of the message.	346	given tag on the given port (and return the port), or unregister it (when
		347	C<$callback> is C<$undef> or missing). There can only be one callback
		348	registered for each tag.
354		349
355	While not required, it is highly recommended that the first matching	350	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	351	element (the tag) has been removed. The callback will use the same
357	also the most efficient match (by far).	352	environment as the default callback (see above).
358		353
359	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.
360		355
361	my $port = rcv port,	356	my $port = rcv port,
362	msg1 => sub { ...; 0 },	357	msg1 => sub { ... },
363	msg2 => sub { ...; 0 },	358	msg2 => sub { ... },
364	;	359	;
365		360
366	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
367	in one go:	362	in one go:
368		363
369	snd $otherport, reply =>	364	snd $otherport, reply =>
370	rcv port,	365	rcv port,
371	msg1 => sub { ...; 0 },	366	msg1 => sub { ... },
372	...	367	...
373	;	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, $otherport;
		377	};
374		378
375	=cut	379	=cut
376		380
377	sub rcv($@) {	381	sub rcv($@) {
378	my $port = shift;	382	my $port = shift;
379	my ($noderef, $portid) = split /#/, $port, 2;	383	my ($noderef, $portid) = split /#/, $port, 2;
380		384
381	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	385	$NODE{$noderef} == $NODE{""}
382	or Carp::croak "$port: rcv can only be called on local ports, caught";	386	or Carp::croak "$port: rcv can only be called on local ports, caught";
383		387
384	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 {
385	my $cb = shift;	396	my $cb = shift;
386	delete $PORT_DATA{$portid};
387	$PORT{$portid} = sub {	397	$PORT{$portid} = sub {
388	local $SELF = $port;	398	local $SELF = $port;
389	eval {	399	eval { &$cb }; _self_die if $@;
390	&$cb	400	};
391	and kil $port;
392	};	401	}
393	_self_die if $@;	402	} elsif (defined $_[0]) {
394	};
395	} else {
396	my $self = $PORT_DATA{$portid} \|\|= do {	403	my $self = $PORT_DATA{$portid} \|\|= do {
397	my $self = bless {	404	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
398	id => $port,
399	}, "AnyEvent::MP::Port";
400		405
401	$PORT{$portid} = sub {	406	$PORT{$portid} = sub {
402	local $SELF = $port;	407	local $SELF = $port;
403		408
404	eval {
405	for (@{ $self->{rc0}{$_[0]} }) {	409	if (my $cb = $self->[1]{$_[0]}) {
406	$_ && &{$_->[0]}	410	shift;
407	&& undef $_;	411	eval { &$cb }; _self_die if $@;
408	}	412	} else {
409
410	for (@{ $self->{rcv}{$_[0]} }) {
411	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
412	&& &{$_->[0]}	413	&{ $self->[0] };
413	&& undef $_;
414	}
415
416	for (@{ $self->{any} }) {
417	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
418	&& &{$_->[0]}
419	&& undef $_;
420	}	414	}
421	};	415	};
422	_self_die if $@;	416
		417	$self
423	};	418	};
424		419
425	$self
426	};
427
428	"AnyEvent::MP::Port" eq ref $self	420	"AnyEvent::MP::Port" eq ref $self
429	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	421	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
430		422
431	while (@_) {
432	my ($match, $cb) = splice @_, 0, 2;	423	my ($tag, $cb) = splice @_, 0, 2;
433		424
434	if (!ref $match) {	425	if (defined $cb) {
435	push @{ $self->{rc0}{$match} }, [$cb];	426	$self->[1]{$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 {	427	} else {
442	push @{ $self->{any} }, [$cb, $match];	428	delete $self->[1]{$tag};
443	}	429	}
444	}	430	}
445	}	431	}
446		432
447	$port	433	$port
…		…
491		477
492	=item $guard = mon $port	478	=item $guard = mon $port
493		479
494	=item $guard = mon $port, $rcvport, @msg	480	=item $guard = mon $port, $rcvport, @msg
495		481
496	Monitor the given port and do something when the port is killed, and	482	Monitor the given port and do something when the port is killed or
497	optionally return a guard that can be used to stop monitoring again.	483	messages to it were lost, and optionally return a guard that can be used
		484	to stop monitoring again.
		485
		486	C<mon> effectively guarantees that, in the absence of hardware failures,
		487	that after starting the monitor, either all messages sent to the port
		488	will arrive, or the monitoring action will be invoked after possible
		489	message loss has been detected. No messages will be lost "in between"
		490	(after the first lost message no further messages will be received by the
		491	port). After the monitoring action was invoked, further messages might get
		492	delivered again.
		493
		494	Note that monitoring-actions are one-shot: once released, they are removed
		495	and will not trigger again.
498		496
499	In the first form (callback), the callback is simply called with any	497	In the first form (callback), the callback is simply called with any
500	number of C<@reason> elements (no @reason means that the port was deleted	498	number of C<@reason> elements (no @reason means that the port was deleted
501	"normally"). Note also that I<< the callback B<must> never die >>, so use	499	"normally"). Note also that I<< the callback B<must> never die >>, so use
502	C<eval> if unsure.	500	C<eval> if unsure.
503		501
504	In the second form (another port given), the other port (C<$rcvport)	502	In the second form (another port given), the other port (C<$rcvport>)
505	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on	503	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
506	"normal" kils nothing happens, while under all other conditions, the other	504	"normal" kils nothing happens, while under all other conditions, the other
507	port is killed with the same reason.	505	port is killed with the same reason.
508		506
509	The third form (kill self) is the same as the second form, except that	507	The third form (kill self) is the same as the second form, except that
…		…
536	sub mon {	534	sub mon {
537	my ($noderef, $port) = split /#/, shift, 2;	535	my ($noderef, $port) = split /#/, shift, 2;
538		536
539	my $node = $NODE{$noderef} \|\| add_node $noderef;	537	my $node = $NODE{$noderef} \|\| add_node $noderef;
540		538
541	my $cb = @_ ? $_[0] : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	539	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
542		540
543	unless (ref $cb) {	541	unless (ref $cb) {
544	if (@_) {	542	if (@_) {
545	# send a kill info message	543	# send a kill info message
546	my (@msg) = @_;	544	my (@msg) = ($cb, @_);
547	$cb = sub { snd @msg, @_ };	545	$cb = sub { snd @msg, @_ };
548	} else {	546	} else {
549	# simply kill other port	547	# simply kill other port
550	my $port = $cb;	548	my $port = $cb;
551	$cb = sub { kil $port, @_ if @_ };	549	$cb = sub { kil $port, @_ if @_ };
…		…
598	will be reported as reason C<< die => $@ >>.	596	will be reported as reason C<< die => $@ >>.
599		597
600	Transport/communication errors are reported as C<< transport_error =>	598	Transport/communication errors are reported as C<< transport_error =>
601	$message >>.	599	$message >>.
602		600
603	=back
604
605	=head1 NODE MESSAGES
606
607	Nodes understand the following messages sent to them. Many of them take
608	arguments called C<@reply>, which will simply be used to compose a reply
609	message - C<$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	601	=cut
617		602
618	=item lookup => $name, @reply	603	=item $port = spawn $node, $initfunc[, @initdata]
619		604
620	Replies with the port ID of the specified well-known port, or C<undef>.	605	Creates a port on the node C<$node> (which can also be a port ID, in which
		606	case it's the node where that port resides).
621		607
622	=item devnull => ...	608	The port ID of the newly created port is return immediately, and it is
		609	permissible to immediately start sending messages or monitor the port.
623		610
624	Generic data sink/CPU heat conversion.	611	After the port has been created, the init function is
		612	called. This function must be a fully-qualified function name
		613	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		614	program, use C<::name>.
625		615
626	=item relay => $port, @msg	616	If the function doesn't exist, then the node tries to C<require>
		617	the package, then the package above the package and so on (e.g.
		618	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		619	exists or it runs out of package names.
627		620
628	Simply forwards the message to the given port.	621	The init function is then called with the newly-created port as context
		622	object (C<$SELF>) and the C<@initdata> values as arguments.
629		623
630	=item eval => $string[ @reply]	624	A common idiom is to pass your own port, monitor the spawned port, and
		625	in the init function, monitor the original port. This two-way monitoring
		626	ensures that both ports get cleaned up when there is a problem.
631		627
632	Evaluates the given string. If C<@reply> is given, then a message of the	628	Example: spawn a chat server port on C<$othernode>.
633	form C<@reply, $@, @evalres> is sent.
634		629
635	Example: crash another node.	630	# this node, executed from within a port context:
		631	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		632	mon $server;
636		633
637	snd $othernode, eval => "exit";	634	# init function on C<$othernode>
		635	sub connect {
		636	my ($srcport) = @_;
638		637
639	=item time => @reply	638	mon $srcport;
640		639
641	Replies the the current node time to C<@reply>.	640	rcv $SELF, sub {
		641	...
		642	};
		643	}
642		644
643	Example: tell the current node to send the current time to C<$myport> in a	645	=cut
644	C<timereply> message.
645		646
646	snd $NODE, time => $myport, timereply => 1, 2;	647	sub _spawn {
647	# => snd $myport, timereply => 1, 2, <time>	648	my $port = shift;
		649	my $init = shift;
		650
		651	local $SELF = "$NODE#$port";
		652	eval {
		653	&{ load_func $init }
		654	};
		655	_self_die if $@;
		656	}
		657
		658	sub spawn(@) {
		659	my ($noderef, undef) = split /#/, shift, 2;
		660
		661	my $id = "$RUNIQ." . $ID++;
		662
		663	$_[0] =~ /::/
		664	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		665
		666	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
		667
		668	"$noderef#$id"
		669	}
		670
		671	=item after $timeout, @msg
		672
		673	=item after $timeout, $callback
		674
		675	Either sends the given message, or call the given callback, after the
		676	specified number of seconds.
		677
		678	This is simply a utility function that come sin handy at times.
		679
		680	=cut
		681
		682	sub after($@) {
		683	my ($timeout, @action) = @_;
		684
		685	my $t; $t = AE::timer $timeout, 0, sub {
		686	undef $t;
		687	ref $action[0]
		688	? $action[0]()
		689	: snd @action;
		690	};
		691	}
648		692
649	=back	693	=back
650		694
651	=head1 AnyEvent::MP vs. Distributed Erlang	695	=head1 AnyEvent::MP vs. Distributed Erlang
652		696
…		…
671	convenience functionality.	715	convenience functionality.
672		716
673	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
674	cost of longer node references and a slightly higher management overhead.	718	cost of longer node references and a slightly higher management overhead.
675		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
676	=item * Erlang uses processes and a mailbox, AEMP does not queue.	735	=item * Erlang uses processes and a mailbox, AEMP does not queue.
677		736
678	Erlang uses processes that selctively receive messages, and therefore	737	Erlang uses processes that selectively receive messages, and therefore
679	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
680	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.
681		742
682	(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).
683		744
684	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	745	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
685		746
686	Sending messages in Erlang is synchronous and blocks the process. AEMP	747	Sending messages in Erlang is synchronous and blocks the process (and
687	sends are immediate, connection establishment is handled in the	748	so does not need a queue that can overflow). AEMP sends are immediate,
688	background.	749	connection establishment is handled in the background.
689		750
690	=item * Erlang can silently lose messages, AEMP cannot.	751	=item * Erlang suffers from silent message loss, AEMP does not.
691		752
692	Erlang makes few guarantees on messages delivery - messages can get lost	753	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,	754	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).	755	and c, and the other side only receives messages a and c).
695		756
…		…
707	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
708	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.
709		770
710	=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.
711		772
712	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
713	ID known to other nodes for a completely different process, causing	774	known to other nodes for a completely different process, causing messages
714	messages destined for that process to end up in an unrelated process.	775	destined for that process to end up in an unrelated process.
715		776
716	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
717	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.
718		779
719	=item * Erlang uses unprotected connections, AEMP uses secure	780	=item * Erlang uses unprotected connections, AEMP uses secure
…		…
755	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
756	(hard to do in Erlang).	817	(hard to do in Erlang).
757		818
758	=back	819	=back
759		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
760	=head1 SEE ALSO	856	=head1 SEE ALSO
761		857
762	L<AnyEvent>.	858	L<AnyEvent>.
763		859
764	=head1 AUTHOR	860	=head1 AUTHOR

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Revision 1.63 by root, Thu Aug 27 21:29:37 2009 UTC