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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.37 by root, Fri Aug 7 16:47:23 2009 UTC vs.
Revision 1.61 by root, Mon Aug 24 08:06:49 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		46	AnyEvent::MP::Intro - outdated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 (connected to a
73	master node only) or public nodes (connectable from unrelated nodes).	91	master node only) or public nodes (connectable from unrelated nodes).
74		92
75	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	93	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>
…		…
95		113
96	=cut	114	=cut
97		115
98	package AnyEvent::MP;	116	package AnyEvent::MP;
99		117
100	use AnyEvent::MP::Base;	118	use AnyEvent::MP::Kernel;
101		119
102	use common::sense;	120	use common::sense;
103		121
104	use Carp ();	122	use Carp ();
105		123
106	use AE ();	124	use AE ();
107		125
108	use base "Exporter";	126	use base "Exporter";
109		127
110	our $VERSION = '0.1';	128	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		129
111	our @EXPORT = qw(	130	our @EXPORT = qw(
112	NODE $NODE *SELF node_of _any_	131	NODE $NODE *SELF node_of after
113	resolve_node initialise_node	132	resolve_node initialise_node
114	snd rcv mon kil reg psub	133	snd rcv mon mon_guard kil reg psub spawn
115	port	134	port
116	);	135	);
117		136
118	our $SELF;	137	our $SELF;
119		138
…		…
123	kil $SELF, die => $msg;	142	kil $SELF, die => $msg;
124	}	143	}
125		144
126	=item $thisnode = NODE / $NODE	145	=item $thisnode = NODE / $NODE
127		146
128	The C<NODE> function returns, and the C<$NODE> variable contains	147	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	148	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	149	C<initialise_node>.
131	identifiers become invalid.
132		150
133	=item $noderef = node_of $port	151	=item $noderef = node_of $port
134		152
135	Extracts and returns the noderef from a portid or a noderef.	153	Extracts and returns the noderef from a port ID or a noderef.
136		154
137	=item initialise_node $noderef, $seednode, $seednode...	155	=item initialise_node $noderef, $seednode, $seednode...
138		156
139	=item initialise_node "slave/", $master, $master...	157	=item initialise_node "slave/", $master, $master...
140		158
…		…
143	it should know the noderefs of some other nodes in the network.	161	it should know the noderefs of some other nodes in the network.
144		162
145	This function initialises a node - it must be called exactly once (or	163	This function initialises a node - it must be called exactly once (or
146	never) before calling other AnyEvent::MP functions.	164	never) before calling other AnyEvent::MP functions.
147		165
148	All arguments are noderefs, which can be either resolved or unresolved.	166	All arguments (optionally except for the first) are noderefs, which can be
		167	either resolved or unresolved.
		168
		169	The first argument will be looked up in the configuration database first
		170	(if it is C<undef> then the current nodename will be used instead) to find
		171	the relevant configuration profile (see L<aemp>). If none is found then
		172	the default configuration is used. The configuration supplies additional
		173	seed/master nodes and can override the actual noderef.
149		174
150	There are two types of networked nodes, public nodes and slave nodes:	175	There are two types of networked nodes, public nodes and slave nodes:
151		176
152	=over 4	177	=over 4
153		178
154	=item public nodes	179	=item public nodes
155		180
156	For public nodes, C<$noderef> must either be a (possibly unresolved)	181	For public nodes, C<$noderef> (supplied either directly to
157	noderef, in which case it will be resolved, or C<undef> (or missing), in	182	C<initialise_node> or indirectly via a profile or the nodename) must be a
158	which case the noderef will be guessed.	183	noderef (possibly unresolved, in which case it will be resolved).
159		184
160	Afterwards, the node will bind itself on all endpoints and try to connect	185	After resolving, the node will bind itself on all endpoints and try to
161	to all additional C<$seednodes> that are specified. Seednodes are optional	186	connect to all additional C<$seednodes> that are specified. Seednodes are
162	and can be used to quickly bootstrap the node into an existing network.	187	optional and can be used to quickly bootstrap the node into an existing
		188	network.
163		189
164	=item slave nodes	190	=item slave nodes
165		191
166	When the C<$noderef> is the special string C<slave/>, then the node will	192	When the C<$noderef> (either as given or overriden by the config file)
		193	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	194	node. Slave nodes cannot be contacted from outside and will route most of
168	route most of their traffic to the master node that they attach to.	195	their traffic to the master node that they attach to.
169		196
170	At least one additional noderef is required: The node will try to connect	197	At least one additional noderef is required (either by specifying it
171	to all of them and will become a slave attached to the first node it can	198	directly or because it is part of the configuration profile): The node
172	successfully connect to.	199	will try to connect to all of them and will become a slave attached to the
		200	first node it can successfully connect to.
		201
		202	Note that slave nodes cannot change their name, and consequently, their
		203	master, so if the master goes down, the slave node will not function well
		204	anymore until it can re-establish conenciton to its master. This makes
		205	slave nodes unsuitable for long-term nodes or fault-tolerant networks.
173		206
174	=back	207	=back
175		208
176	This function will block until all nodes have been resolved and, for slave	209	This function will block until all nodes have been resolved and, for slave
177	nodes, until it has successfully established a connection to a master	210	nodes, until it has successfully established a connection to a master
178	server.	211	server.
179		212
		213	All the seednodes will also be specially marked to automatically retry
		214	connecting to them infinitely.
		215
180	Example: become a public node listening on the default node.	216	Example: become a public node listening on the guessed noderef, or the one
		217	specified via C<aemp> for the current node. This should be the most common
		218	form of invocation for "daemon"-type nodes.
181		219
182	initialise_node;	220	initialise_node;
		221
		222	Example: become a slave node to any of the the seednodes specified via
		223	C<aemp>. This form is often used for commandline clients.
		224
		225	initialise_node "slave/";
		226
		227	Example: become a slave node to any of the specified master servers. This
		228	form is also often used for commandline clients.
		229
		230	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
183		231
184	Example: become a public node, and try to contact some well-known master	232	Example: become a public node, and try to contact some well-known master
185	servers to become part of the network.	233	servers to become part of the network.
186		234
187	initialise_node undef, "master1", "master2";	235	initialise_node undef, "master1", "master2";
…		…
190		238
191	initialise_node 4041;	239	initialise_node 4041;
192		240
193	Example: become a public node, only visible on localhost port 4044.	241	Example: become a public node, only visible on localhost port 4044.
194		242
195	initialise_node "locahost:4044";	243	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		244
201	=item $cv = resolve_node $noderef	245	=item $cv = resolve_node $noderef
202		246
203	Takes an unresolved node reference that may contain hostnames and	247	Takes an unresolved node reference that may contain hostnames and
204	abbreviated IDs, resolves all of them and returns a resolved node	248	abbreviated IDs, resolves all of them and returns a resolved node
…		…
241	=item snd $port, type => @data	285	=item snd $port, type => @data
242		286
243	=item snd $port, @msg	287	=item snd $port, @msg
244		288
245	Send the given message to the given port ID, which can identify either	289	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	290	a local or a remote port, and must be a port ID.
247	stringifies a sa port ID (such as a port object :).
248		291
249	While the message can be about anything, it is highly recommended to use a	292	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	293	string as first element (a port ID, or some word that indicates a request
251	type etc.).	294	type etc.).
252		295
253	The message data effectively becomes read-only after a call to this	296	The message data effectively becomes read-only after a call to this
254	function: modifying any argument is not allowed and can cause many	297	function: modifying any argument is not allowed and can cause many
255	problems.	298	problems.
…		…
260	that Storable can serialise and deserialise is allowed, and for the local	303	that Storable can serialise and deserialise is allowed, and for the local
261	node, anything can be passed.	304	node, anything can be passed.
262		305
263	=item $local_port = port	306	=item $local_port = port
264		307
265	Create a new local port object that can be used either as a pattern	308	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"),	309	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		310
269	=item $port = port { my @msg = @_; $finished }	311	=item $local_port = port { my @msg = @_ }
270		312
271	Creates a "miniport", that is, a very lightweight port without any pattern	313	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.	314	creating a port and calling C<rcv $port, $callback> on it.
274		315
275	The block will be called for every message received on the port. When the	316	The block will be called for every message received on the port, with the
276	callback returns a true value its job is considered "done" and the port	317	global variable C<$SELF> set to the port ID. Runtime errors will cause the
277	will be destroyed. Otherwise it will stay alive.	318	port to be C<kil>ed. The message will be passed as-is, no extra argument
		319	(i.e. no port ID) will be passed to the callback.
278		320
279	The message will be passed as-is, no extra argument (i.e. no port id) will	321	If you want to stop/destroy the port, simply C<kil> it:
280	be passed to the callback.
281		322
282	If you need the local port id in the callback, this works nicely:	323	my $port = port {
283		324	my @msg = @_;
284	my $port; $port = port {	325	...
285	snd $otherport, reply => $port;	326	kil $SELF;
286	};	327	};
287		328
288	=cut	329	=cut
289		330
290	sub rcv($@);	331	sub rcv($@);
		332
		333	sub _kilme {
		334	die "received message on port without callback";
		335	}
291		336
292	sub port(;&) {	337	sub port(;&) {
293	my $id = "$UNIQ." . $ID++;	338	my $id = "$UNIQ." . $ID++;
294	my $port = "$NODE#$id";	339	my $port = "$NODE#$id";
295		340
296	if (@_) {	341	rcv $port, shift \|\| \&_kilme;
297	rcv $port, shift;
298	} else {
299	$PORT{$id} = sub { }; # nop
300	}
301		342
302	$port	343	$port
303	}	344	}
304		345
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)	346	=item rcv $local_port, $callback->(@msg)
325		347
326	Replaces the callback on the specified miniport (after converting it to	348	Replaces the default callback on the specified port. There is no way to
327	one if required).	349	remove the default callback: use C<sub { }> to disable it, or better
328		350	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...] => $callback->(@msg), ...
334
335	Register callbacks to be called on matching messages on the given full
336	port (after converting it to one if required) and return the port.
337
338	The callback has to return a true value when its work is done, after
339	which is will be removed, or a false value in which case it will stay
340	registered.
341		351
342	The global C<$SELF> (exported by this module) contains C<$port> while	352	The global C<$SELF> (exported by this module) contains C<$port> while
343	executing the callback.	353	executing the callback. Runtime errors during callback execution will
		354	result in the port being C<kil>ed.
344		355
345	Runtime errors wdurign callback execution will result in the port being	356	The default callback received all messages not matched by a more specific
346	C<kil>ed.	357	C<tag> match.
347		358
348	If the match is an array reference, then it will be matched against the	359	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
349	first elements of the message, otherwise only the first element is being
350	matched.
351		360
352	Any element in the match that is specified as C<_any_> (a function	361	Register (or replace) callbacks to be called on messages starting with the
353	exported by this module) matches any single element of the message.	362	given tag on the given port (and return the port), or unregister it (when
		363	C<$callback> is C<$undef> or missing). There can only be one callback
		364	registered for each tag.
354		365
355	While not required, it is highly recommended that the first matching	366	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	367	element (the tag) has been removed. The callback will use the same
357	also the most efficient match (by far).	368	environment as the default callback (see above).
358		369
359	Example: create a port and bind receivers on it in one go.	370	Example: create a port and bind receivers on it in one go.
360		371
361	my $port = rcv port,	372	my $port = rcv port,
362	msg1 => sub { ...; 0 },	373	msg1 => sub { ... },
363	msg2 => sub { ...; 0 },	374	msg2 => sub { ... },
364	;	375	;
365		376
366	Example: create a port, bind receivers and send it in a message elsewhere	377	Example: create a port, bind receivers and send it in a message elsewhere
367	in one go:	378	in one go:
368		379
369	snd $otherport, reply =>	380	snd $otherport, reply =>
370	rcv port,	381	rcv port,
371	msg1 => sub { ...; 0 },	382	msg1 => sub { ... },
372	...	383	...
373	;	384	;
		385
		386	Example: temporarily register a rcv callback for a tag matching some port
		387	(e.g. for a rpc reply) and unregister it after a message was received.
		388
		389	rcv $port, $otherport => sub {
		390	my @reply = @_;
		391
		392	rcv $SELF, $otherport;
		393	};
374		394
375	=cut	395	=cut
376		396
377	sub rcv($@) {	397	sub rcv($@) {
378	my $port = shift;	398	my $port = shift;
379	my ($noderef, $portid) = split /#/, $port, 2;	399	my ($noderef, $portid) = split /#/, $port, 2;
380		400
381	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	401	$NODE{$noderef} == $NODE{""}
382	or Carp::croak "$port: rcv can only be called on local ports, caught";	402	or Carp::croak "$port: rcv can only be called on local ports, caught";
383		403
384	if (@_ == 1) {	404	while (@_) {
		405	if (ref $_[0]) {
		406	if (my $self = $PORT_DATA{$portid}) {
		407	"AnyEvent::MP::Port" eq ref $self
		408	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		409
		410	$self->[2] = shift;
		411	} else {
385	my $cb = shift;	412	my $cb = shift;
386	delete $PORT_DATA{$portid};
387	$PORT{$portid} = sub {	413	$PORT{$portid} = sub {
388	local $SELF = $port;	414	local $SELF = $port;
389	eval {	415	eval { &$cb }; _self_die if $@;
390	&$cb	416	};
391	and kil $port;
392	};	417	}
393	_self_die if $@;	418	} elsif (defined $_[0]) {
394	};
395	} else {
396	my $self = $PORT_DATA{$portid} \|\|= do {	419	my $self = $PORT_DATA{$portid} \|\|= do {
397	my $self = bless {	420	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
398	id => $port,
399	}, "AnyEvent::MP::Port";
400		421
401	$PORT{$portid} = sub {	422	$PORT{$portid} = sub {
402	local $SELF = $port;	423	local $SELF = $port;
403		424
404	eval {
405	for (@{ $self->{rc0}{$_[0]} }) {	425	if (my $cb = $self->[1]{$_[0]}) {
406	$_ && &{$_->[0]}	426	shift;
407	&& undef $_;	427	eval { &$cb }; _self_die if $@;
408	}	428	} else {
409
410	for (@{ $self->{rcv}{$_[0]} }) {
411	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
412	&& &{$_->[0]}	429	&{ $self->[0] };
413	&& undef $_;
414	}
415
416	for (@{ $self->{any} }) {
417	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
418	&& &{$_->[0]}
419	&& undef $_;
420	}	430	}
421	};	431	};
422	_self_die if $@;	432
		433	$self
423	};	434	};
424		435
425	$self
426	};
427
428	"AnyEvent::MP::Port" eq ref $self	436	"AnyEvent::MP::Port" eq ref $self
429	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	437	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
430		438
431	while (@_) {
432	my ($match, $cb) = splice @_, 0, 2;	439	my ($tag, $cb) = splice @_, 0, 2;
433		440
434	if (!ref $match) {	441	if (defined $cb) {
435	push @{ $self->{rc0}{$match} }, [$cb];	442	$self->[1]{$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 {	443	} else {
442	push @{ $self->{any} }, [$cb, $match];	444	delete $self->[1]{$tag};
443	}	445	}
444	}	446	}
445	}	447	}
446		448
447	$port	449	$port
…		…
491		493
492	=item $guard = mon $port	494	=item $guard = mon $port
493		495
494	=item $guard = mon $port, $rcvport, @msg	496	=item $guard = mon $port, $rcvport, @msg
495		497
496	Monitor the given port and do something when the port is killed, and	498	Monitor the given port and do something when the port is killed or
497	optionally return a guard that can be used to stop monitoring again.	499	messages to it were lost, and optionally return a guard that can be used
		500	to stop monitoring again.
		501
		502	C<mon> effectively guarantees that, in the absence of hardware failures,
		503	that after starting the monitor, either all messages sent to the port
		504	will arrive, or the monitoring action will be invoked after possible
		505	message loss has been detected. No messages will be lost "in between"
		506	(after the first lost message no further messages will be received by the
		507	port). After the monitoring action was invoked, further messages might get
		508	delivered again.
		509
		510	Note that monitoring-actions are one-shot: once released, they are removed
		511	and will not trigger again.
498		512
499	In the first form (callback), the callback is simply called with any	513	In the first form (callback), the callback is simply called with any
500	number of C<@reason> elements (no @reason means that the port was deleted	514	number of C<@reason> elements (no @reason means that the port was deleted
501	"normally"). Note also that I<< the callback B<must> never die >>, so use	515	"normally"). Note also that I<< the callback B<must> never die >>, so use
502	C<eval> if unsure.	516	C<eval> if unsure.
503		517
504	In the second form (another port given), the other port (C<$rcvport)	518	In the second form (another port given), the other port (C<$rcvport>)
505	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on	519	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
506	"normal" kils nothing happens, while under all other conditions, the other	520	"normal" kils nothing happens, while under all other conditions, the other
507	port is killed with the same reason.	521	port is killed with the same reason.
508		522
509	The third form (kill self) is the same as the second form, except that	523	The third form (kill self) is the same as the second form, except that
…		…
536	sub mon {	550	sub mon {
537	my ($noderef, $port) = split /#/, shift, 2;	551	my ($noderef, $port) = split /#/, shift, 2;
538		552
539	my $node = $NODE{$noderef} \|\| add_node $noderef;	553	my $node = $NODE{$noderef} \|\| add_node $noderef;
540		554
541	my $cb = @_ ? $_[0] : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	555	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
542		556
543	unless (ref $cb) {	557	unless (ref $cb) {
544	if (@_) {	558	if (@_) {
545	# send a kill info message	559	# send a kill info message
546	my (@msg) = @_;	560	my (@msg) = ($cb, @_);
547	$cb = sub { snd @msg, @_ };	561	$cb = sub { snd @msg, @_ };
548	} else {	562	} else {
549	# simply kill other port	563	# simply kill other port
550	my $port = $cb;	564	my $port = $cb;
551	$cb = sub { kil $port, @_ if @_ };	565	$cb = sub { kil $port, @_ if @_ };
…		…
598	will be reported as reason C<< die => $@ >>.	612	will be reported as reason C<< die => $@ >>.
599		613
600	Transport/communication errors are reported as C<< transport_error =>	614	Transport/communication errors are reported as C<< transport_error =>
601	$message >>.	615	$message >>.
602		616
603	=back
604
605	=head1 NODE MESSAGES
606
607	Nodes understand the following messages sent to them. Many of them take
608	arguments called C<@reply>, which will simply be used to compose a reply
609	message - C<$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	617	=cut
617		618
618	=item lookup => $name, @reply	619	=item $port = spawn $node, $initfunc[, @initdata]
619		620
620	Replies with the port ID of the specified well-known port, or C<undef>.	621	Creates a port on the node C<$node> (which can also be a port ID, in which
		622	case it's the node where that port resides).
621		623
622	=item devnull => ...	624	The port ID of the newly created port is return immediately, and it is
		625	permissible to immediately start sending messages or monitor the port.
623		626
624	Generic data sink/CPU heat conversion.	627	After the port has been created, the init function is
		628	called. This function must be a fully-qualified function name
		629	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		630	program, use C<::name>.
625		631
626	=item relay => $port, @msg	632	If the function doesn't exist, then the node tries to C<require>
		633	the package, then the package above the package and so on (e.g.
		634	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		635	exists or it runs out of package names.
627		636
628	Simply forwards the message to the given port.	637	The init function is then called with the newly-created port as context
		638	object (C<$SELF>) and the C<@initdata> values as arguments.
629		639
630	=item eval => $string[ @reply]	640	A common idiom is to pass your own port, monitor the spawned port, and
		641	in the init function, monitor the original port. This two-way monitoring
		642	ensures that both ports get cleaned up when there is a problem.
631		643
632	Evaluates the given string. If C<@reply> is given, then a message of the	644	Example: spawn a chat server port on C<$othernode>.
633	form C<@reply, $@, @evalres> is sent.
634		645
635	Example: crash another node.	646	# this node, executed from within a port context:
		647	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		648	mon $server;
636		649
637	snd $othernode, eval => "exit";	650	# init function on C<$othernode>
		651	sub connect {
		652	my ($srcport) = @_;
638		653
639	=item time => @reply	654	mon $srcport;
640		655
641	Replies the the current node time to C<@reply>.	656	rcv $SELF, sub {
		657	...
		658	};
		659	}
642		660
643	Example: tell the current node to send the current time to C<$myport> in a	661	=cut
644	C<timereply> message.
645		662
646	snd $NODE, time => $myport, timereply => 1, 2;	663	sub _spawn {
647	# => snd $myport, timereply => 1, 2, <time>	664	my $port = shift;
		665	my $init = shift;
		666
		667	local $SELF = "$NODE#$port";
		668	eval {
		669	&{ load_func $init }
		670	};
		671	_self_die if $@;
		672	}
		673
		674	sub spawn(@) {
		675	my ($noderef, undef) = split /#/, shift, 2;
		676
		677	my $id = "$RUNIQ." . $ID++;
		678
		679	$_[0] =~ /::/
		680	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		681
		682	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
		683
		684	"$noderef#$id"
		685	}
		686
		687	=item after $timeout, @msg
		688
		689	=item after $timeout, $callback
		690
		691	Either sends the given message, or call the given callback, after the
		692	specified number of seconds.
		693
		694	This is simply a utility function that come sin handy at times.
		695
		696	=cut
		697
		698	sub after($@) {
		699	my ($timeout, @action) = @_;
		700
		701	my $t; $t = AE::timer $timeout, 0, sub {
		702	undef $t;
		703	ref $action[0]
		704	? $action[0]()
		705	: snd @action;
		706	};
		707	}
648		708
649	=back	709	=back
650		710
651	=head1 AnyEvent::MP vs. Distributed Erlang	711	=head1 AnyEvent::MP vs. Distributed Erlang
652		712
…		…
671	convenience functionality.	731	convenience functionality.
672		732
673	This means that AEMP requires a less tightly controlled environment at the	733	This means that AEMP requires a less tightly controlled environment at the
674	cost of longer node references and a slightly higher management overhead.	734	cost of longer node references and a slightly higher management overhead.
675		735
		736	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
		737	uses "local ports are like remote ports".
		738
		739	The failure modes for local ports are quite different (runtime errors
		740	only) then for remote ports - when a local port dies, you I<know> it dies,
		741	when a connection to another node dies, you know nothing about the other
		742	port.
		743
		744	Erlang pretends remote ports are as reliable as local ports, even when
		745	they are not.
		746
		747	AEMP encourages a "treat remote ports differently" philosophy, with local
		748	ports being the special case/exception, where transport errors cannot
		749	occur.
		750
676	=item * Erlang uses processes and a mailbox, AEMP does not queue.	751	=item * Erlang uses processes and a mailbox, AEMP does not queue.
677		752
678	Erlang uses processes that selctively receive messages, and therefore	753	Erlang uses processes that selectively receive messages, and therefore
679	needs a queue. AEMP is event based, queuing messages would serve no useful	754	needs a queue. AEMP is event based, queuing messages would serve no
680	purpose.	755	useful purpose. For the same reason the pattern-matching abilities of
		756	AnyEvent::MP are more limited, as there is little need to be able to
		757	filter messages without dequeing them.
681		758
682	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	759	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
683		760
684	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	761	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
685		762
686	Sending messages in Erlang is synchronous and blocks the process. AEMP	763	Sending messages in Erlang is synchronous and blocks the process (and
687	sends are immediate, connection establishment is handled in the	764	so does not need a queue that can overflow). AEMP sends are immediate,
688	background.	765	connection establishment is handled in the background.
689		766
690	=item * Erlang can silently lose messages, AEMP cannot.	767	=item * Erlang suffers from silent message loss, AEMP does not.
691		768
692	Erlang makes few guarantees on messages delivery - messages can get lost	769	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,	770	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).	771	and c, and the other side only receives messages a and c).
695		772
…		…
707	eventually be killed - it cannot happen that a node detects a port as dead	784	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.	785	and then later sends messages to it, finding it is still alive.
709		786
710	=item * Erlang can send messages to the wrong port, AEMP does not.	787	=item * Erlang can send messages to the wrong port, AEMP does not.
711		788
712	In Erlang it is quite possible that a node that restarts reuses a process	789	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	790	known to other nodes for a completely different process, causing messages
714	messages destined for that process to end up in an unrelated process.	791	destined for that process to end up in an unrelated process.
715		792
716	AEMP never reuses port IDs, so old messages or old port IDs floating	793	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.	794	around in the network will not be sent to an unrelated port.
718		795
719	=item * Erlang uses unprotected connections, AEMP uses secure	796	=item * Erlang uses unprotected connections, AEMP uses secure
…		…
755	This also saves round-trips and avoids sending messages to the wrong port	832	This also saves round-trips and avoids sending messages to the wrong port
756	(hard to do in Erlang).	833	(hard to do in Erlang).
757		834
758	=back	835	=back
759		836
		837	=head1 RATIONALE
		838
		839	=over 4
		840
		841	=item Why strings for ports and noderefs, why not objects?
		842
		843	We considered "objects", but found that the actual number of methods
		844	thatc an be called are very low. Since port IDs and noderefs travel over
		845	the network frequently, the serialising/deserialising would add lots of
		846	overhead, as well as having to keep a proxy object.
		847
		848	Strings can easily be printed, easily serialised etc. and need no special
		849	procedures to be "valid".
		850
		851	And a a miniport consists of a single closure stored in a global hash - it
		852	can't become much cheaper.
		853
		854	=item Why favour JSON, why not real serialising format such as Storable?
		855
		856	In fact, any AnyEvent::MP node will happily accept Storable as framing
		857	format, but currently there is no way to make a node use Storable by
		858	default.
		859
		860	The default framing protocol is JSON because a) JSON::XS is many times
		861	faster for small messages and b) most importantly, after years of
		862	experience we found that object serialisation is causing more problems
		863	than it gains: Just like function calls, objects simply do not travel
		864	easily over the network, mostly because they will always be a copy, so you
		865	always have to re-think your design.
		866
		867	Keeping your messages simple, concentrating on data structures rather than
		868	objects, will keep your messages clean, tidy and efficient.
		869
		870	=back
		871
760	=head1 SEE ALSO	872	=head1 SEE ALSO
761		873
762	L<AnyEvent>.	874	L<AnyEvent>.
763		875
764	=head1 AUTHOR	876	=head1 AUTHOR

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Revision 1.37 by root, Fri Aug 7 16:47:23 2009 UTC vs.
Revision 1.61 by root, Mon Aug 24 08:06:49 2009 UTC