[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 1.55 by root, Fri Aug 14 23:17:17 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		46	AnyEvent::MP::Intro - outdated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 _any_
113	resolve_node initialise_node	132	resolve_node initialise_node
114	snd rcv mon kil reg psub	133	snd rcv mon 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.
173		201
174	=back	202	=back
175		203
176	This function will block until all nodes have been resolved and, for slave	204	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	205	nodes, until it has successfully established a connection to a master
178	server.	206	server.
179		207
180	Example: become a public node listening on the default node.	208	Example: become a public node listening on the guessed noderef, or the one
		209	specified via C<aemp> for the current node. This should be the most common
		210	form of invocation for "daemon"-type nodes.
181		211
182	initialise_node;	212	initialise_node;
		213
		214	Example: become a slave node to any of the the seednodes specified via
		215	C<aemp>. This form is often used for commandline clients.
		216
		217	initialise_node "slave/";
		218
		219	Example: become a slave node to any of the specified master servers. This
		220	form is also often used for commandline clients.
		221
		222	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
183		223
184	Example: become a public node, and try to contact some well-known master	224	Example: become a public node, and try to contact some well-known master
185	servers to become part of the network.	225	servers to become part of the network.
186		226
187	initialise_node undef, "master1", "master2";	227	initialise_node undef, "master1", "master2";
…		…
190		230
191	initialise_node 4041;	231	initialise_node 4041;
192		232
193	Example: become a public node, only visible on localhost port 4044.	233	Example: become a public node, only visible on localhost port 4044.
194		234
195	initialise_node "locahost:4044";	235	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		236
201	=item $cv = resolve_node $noderef	237	=item $cv = resolve_node $noderef
202		238
203	Takes an unresolved node reference that may contain hostnames and	239	Takes an unresolved node reference that may contain hostnames and
204	abbreviated IDs, resolves all of them and returns a resolved node	240	abbreviated IDs, resolves all of them and returns a resolved node
…		…
241	=item snd $port, type => @data	277	=item snd $port, type => @data
242		278
243	=item snd $port, @msg	279	=item snd $port, @msg
244		280
245	Send the given message to the given port ID, which can identify either	281	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	282	a local or a remote port, and must be a port ID.
247	stringifies a sa port ID (such as a port object :).
248		283
249	While the message can be about anything, it is highly recommended to use a	284	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	285	string as first element (a port ID, or some word that indicates a request
251	type etc.).	286	type etc.).
252		287
253	The message data effectively becomes read-only after a call to this	288	The message data effectively becomes read-only after a call to this
254	function: modifying any argument is not allowed and can cause many	289	function: modifying any argument is not allowed and can cause many
255	problems.	290	problems.
…		…
260	that Storable can serialise and deserialise is allowed, and for the local	295	that Storable can serialise and deserialise is allowed, and for the local
261	node, anything can be passed.	296	node, anything can be passed.
262		297
263	=item $local_port = port	298	=item $local_port = port
264		299
265	Create a new local port object that can be used either as a pattern	300	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"),	301	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		302
269	=item $port = port { my @msg = @_; $finished }	303	=item $local_port = port { my @msg = @_ }
270		304
271	Creates a "miniport", that is, a very lightweight port without any pattern	305	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.	306	creating a port and calling C<rcv $port, $callback> on it.
274		307
275	The block will be called for every message received on the port. When the	308	The block will be called for every message received on the port, with the
276	callback returns a true value its job is considered "done" and the port	309	global variable C<$SELF> set to the port ID. Runtime errors will cause the
277	will be destroyed. Otherwise it will stay alive.	310	port to be C<kil>ed. The message will be passed as-is, no extra argument
		311	(i.e. no port ID) will be passed to the callback.
278		312
279	The message will be passed as-is, no extra argument (i.e. no port id) will	313	If you want to stop/destroy the port, simply C<kil> it:
280	be passed to the callback.
281		314
282	If you need the local port id in the callback, this works nicely:	315	my $port = port {
283		316	my @msg = @_;
284	my $port; $port = port {	317	...
285	snd $otherport, reply => $port;	318	kil $SELF;
286	};	319	};
287		320
288	=cut	321	=cut
289		322
290	sub rcv($@);	323	sub rcv($@);
		324
		325	sub _kilme {
		326	die "received message on port without callback";
		327	}
291		328
292	sub port(;&) {	329	sub port(;&) {
293	my $id = "$UNIQ." . $ID++;	330	my $id = "$UNIQ." . $ID++;
294	my $port = "$NODE#$id";	331	my $port = "$NODE#$id";
295		332
296	if (@_) {	333	rcv $port, shift \|\| \&_kilme;
297	rcv $port, shift;
298	} else {
299	$PORT{$id} = sub { }; # nop
300	}
301		334
302	$port	335	$port
303	}	336	}
304		337
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)	338	=item rcv $local_port, $callback->(@msg)
325		339
326	Replaces the callback on the specified miniport (after converting it to	340	Replaces the default callback on the specified port. There is no way to
327	one if required).	341	remove the default callback: use C<sub { }> to disable it, or better
328		342	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...] => $callback->(@msg), ...
334
335	Register callbacks to be called on matching messages on the given full
336	port (after converting it to one if required) and return the port.
337
338	The callback has to return a true value when its work is done, after
339	which is will be removed, or a false value in which case it will stay
340	registered.
341		343
342	The global C<$SELF> (exported by this module) contains C<$port> while	344	The global C<$SELF> (exported by this module) contains C<$port> while
343	executing the callback.	345	executing the callback. Runtime errors during callback execution will
		346	result in the port being C<kil>ed.
344		347
345	Runtime errors wdurign callback execution will result in the port being	348	The default callback received all messages not matched by a more specific
346	C<kil>ed.	349	C<tag> match.
347		350
348	If the match is an array reference, then it will be matched against the	351	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
349	first elements of the message, otherwise only the first element is being
350	matched.
351		352
352	Any element in the match that is specified as C<_any_> (a function	353	Register (or replace) callbacks to be called on messages starting with the
353	exported by this module) matches any single element of the message.	354	given tag on the given port (and return the port), or unregister it (when
		355	C<$callback> is C<$undef> or missing). There can only be one callback
		356	registered for each tag.
354		357
355	While not required, it is highly recommended that the first matching	358	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	359	element (the tag) has been removed. The callback will use the same
357	also the most efficient match (by far).	360	environment as the default callback (see above).
358		361
359	Example: create a port and bind receivers on it in one go.	362	Example: create a port and bind receivers on it in one go.
360		363
361	my $port = rcv port,	364	my $port = rcv port,
362	msg1 => sub { ...; 0 },	365	msg1 => sub { ... },
363	msg2 => sub { ...; 0 },	366	msg2 => sub { ... },
364	;	367	;
365		368
366	Example: create a port, bind receivers and send it in a message elsewhere	369	Example: create a port, bind receivers and send it in a message elsewhere
367	in one go:	370	in one go:
368		371
369	snd $otherport, reply =>	372	snd $otherport, reply =>
370	rcv port,	373	rcv port,
371	msg1 => sub { ...; 0 },	374	msg1 => sub { ... },
372	...	375	...
373	;	376	;
		377
		378	Example: temporarily register a rcv callback for a tag matching some port
		379	(e.g. for a rpc reply) and unregister it after a message was received.
		380
		381	rcv $port, $otherport => sub {
		382	my @reply = @_;
		383
		384	rcv $SELF, $otherport;
		385	};
374		386
375	=cut	387	=cut
376		388
377	sub rcv($@) {	389	sub rcv($@) {
378	my $port = shift;	390	my $port = shift;
379	my ($noderef, $portid) = split /#/, $port, 2;	391	my ($noderef, $portid) = split /#/, $port, 2;
380		392
381	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	393	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
382	or Carp::croak "$port: rcv can only be called on local ports, caught";	394	or Carp::croak "$port: rcv can only be called on local ports, caught";
383		395
384	if (@_ == 1) {	396	while (@_) {
		397	if (ref $_[0]) {
		398	if (my $self = $PORT_DATA{$portid}) {
		399	"AnyEvent::MP::Port" eq ref $self
		400	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		401
		402	$self->[2] = shift;
		403	} else {
385	my $cb = shift;	404	my $cb = shift;
386	delete $PORT_DATA{$portid};
387	$PORT{$portid} = sub {	405	$PORT{$portid} = sub {
388	local $SELF = $port;	406	local $SELF = $port;
389	eval {	407	eval { &$cb }; _self_die if $@;
390	&$cb	408	};
391	and kil $port;
392	};	409	}
393	_self_die if $@;	410	} elsif (defined $_[0]) {
394	};
395	} else {
396	my $self = $PORT_DATA{$portid} \|\|= do {	411	my $self = $PORT_DATA{$portid} \|\|= do {
397	my $self = bless {	412	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
398	id => $port,
399	}, "AnyEvent::MP::Port";
400		413
401	$PORT{$portid} = sub {	414	$PORT{$portid} = sub {
402	local $SELF = $port;	415	local $SELF = $port;
403		416
404	eval {
405	for (@{ $self->{rc0}{$_[0]} }) {	417	if (my $cb = $self->[1]{$_[0]}) {
406	$_ && &{$_->[0]}	418	shift;
407	&& undef $_;	419	eval { &$cb }; _self_die if $@;
408	}	420	} else {
409
410	for (@{ $self->{rcv}{$_[0]} }) {
411	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
412	&& &{$_->[0]}	421	&{ $self->[0] };
413	&& undef $_;
414	}
415
416	for (@{ $self->{any} }) {
417	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
418	&& &{$_->[0]}
419	&& undef $_;
420	}	422	}
421	};	423	};
422	_self_die if $@;	424
		425	$self
423	};	426	};
424		427
425	$self
426	};
427
428	"AnyEvent::MP::Port" eq ref $self	428	"AnyEvent::MP::Port" eq ref $self
429	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	429	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
430		430
431	while (@_) {
432	my ($match, $cb) = splice @_, 0, 2;	431	my ($tag, $cb) = splice @_, 0, 2;
433		432
434	if (!ref $match) {	433	if (defined $cb) {
435	push @{ $self->{rc0}{$match} }, [$cb];	434	$self->[1]{$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 {	435	} else {
442	push @{ $self->{any} }, [$cb, $match];	436	delete $self->[1]{$tag};
443	}	437	}
444	}	438	}
445	}	439	}
446		440
447	$port	441	$port
…		…
491		485
492	=item $guard = mon $port	486	=item $guard = mon $port
493		487
494	=item $guard = mon $port, $rcvport, @msg	488	=item $guard = mon $port, $rcvport, @msg
495		489
496	Monitor the given port and do something when the port is killed, and	490	Monitor the given port and do something when the port is killed or
497	optionally return a guard that can be used to stop monitoring again.	491	messages to it were lost, and optionally return a guard that can be used
		492	to stop monitoring again.
		493
		494	C<mon> effectively guarantees that, in the absence of hardware failures,
		495	that after starting the monitor, either all messages sent to the port
		496	will arrive, or the monitoring action will be invoked after possible
		497	message loss has been detected. No messages will be lost "in between"
		498	(after the first lost message no further messages will be received by the
		499	port). After the monitoring action was invoked, further messages might get
		500	delivered again.
498		501
499	In the first form (callback), the callback is simply called with any	502	In the first form (callback), the callback is simply called with any
500	number of C<@reason> elements (no @reason means that the port was deleted	503	number of C<@reason> elements (no @reason means that the port was deleted
501	"normally"). Note also that I<< the callback B<must> never die >>, so use	504	"normally"). Note also that I<< the callback B<must> never die >>, so use
502	C<eval> if unsure.	505	C<eval> if unsure.
503		506
504	In the second form (another port given), the other port (C<$rcvport)	507	In the second form (another port given), the other port (C<$rcvport>)
505	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on	508	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
506	"normal" kils nothing happens, while under all other conditions, the other	509	"normal" kils nothing happens, while under all other conditions, the other
507	port is killed with the same reason.	510	port is killed with the same reason.
508		511
509	The third form (kill self) is the same as the second form, except that	512	The third form (kill self) is the same as the second form, except that
…		…
536	sub mon {	539	sub mon {
537	my ($noderef, $port) = split /#/, shift, 2;	540	my ($noderef, $port) = split /#/, shift, 2;
538		541
539	my $node = $NODE{$noderef} \|\| add_node $noderef;	542	my $node = $NODE{$noderef} \|\| add_node $noderef;
540		543
541	my $cb = @_ ? $_[0] : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	544	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
542		545
543	unless (ref $cb) {	546	unless (ref $cb) {
544	if (@_) {	547	if (@_) {
545	# send a kill info message	548	# send a kill info message
546	my (@msg) = @_;	549	my (@msg) = ($cb, @_);
547	$cb = sub { snd @msg, @_ };	550	$cb = sub { snd @msg, @_ };
548	} else {	551	} else {
549	# simply kill other port	552	# simply kill other port
550	my $port = $cb;	553	my $port = $cb;
551	$cb = sub { kil $port, @_ if @_ };	554	$cb = sub { kil $port, @_ if @_ };
…		…
598	will be reported as reason C<< die => $@ >>.	601	will be reported as reason C<< die => $@ >>.
599		602
600	Transport/communication errors are reported as C<< transport_error =>	603	Transport/communication errors are reported as C<< transport_error =>
601	$message >>.	604	$message >>.
602		605
		606	=cut
		607
		608	=item $port = spawn $node, $initfunc[, @initdata]
		609
		610	Creates a port on the node C<$node> (which can also be a port ID, in which
		611	case it's the node where that port resides).
		612
		613	The port ID of the newly created port is return immediately, and it is
		614	permissible to immediately start sending messages or monitor the port.
		615
		616	After the port has been created, the init function is
		617	called. This function must be a fully-qualified function name
		618	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		619	program, use C<::name>.
		620
		621	If the function doesn't exist, then the node tries to C<require>
		622	the package, then the package above the package and so on (e.g.
		623	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		624	exists or it runs out of package names.
		625
		626	The init function is then called with the newly-created port as context
		627	object (C<$SELF>) and the C<@initdata> values as arguments.
		628
		629	A common idiom is to pass your own port, monitor the spawned port, and
		630	in the init function, monitor the original port. This two-way monitoring
		631	ensures that both ports get cleaned up when there is a problem.
		632
		633	Example: spawn a chat server port on C<$othernode>.
		634
		635	# this node, executed from within a port context:
		636	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		637	mon $server;
		638
		639	# init function on C<$othernode>
		640	sub connect {
		641	my ($srcport) = @_;
		642
		643	mon $srcport;
		644
		645	rcv $SELF, sub {
		646	...
		647	};
		648	}
		649
		650	=cut
		651
		652	sub _spawn {
		653	my $port = shift;
		654	my $init = shift;
		655
		656	local $SELF = "$NODE#$port";
		657	eval {
		658	&{ load_func $init }
		659	};
		660	_self_die if $@;
		661	}
		662
		663	sub spawn(@) {
		664	my ($noderef, undef) = split /#/, shift, 2;
		665
		666	my $id = "$RUNIQ." . $ID++;
		667
		668	$_[0] =~ /::/
		669	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		670
		671	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
		672
		673	"$noderef#$id"
		674	}
		675
603	=back	676	=back
604		677
605	=head1 NODE MESSAGES	678	=head1 NODE MESSAGES
606		679
607	Nodes understand the following messages sent to them. Many of them take	680	Nodes understand the following messages sent to them. Many of them take
…		…
671	convenience functionality.	744	convenience functionality.
672		745
673	This means that AEMP requires a less tightly controlled environment at the	746	This means that AEMP requires a less tightly controlled environment at the
674	cost of longer node references and a slightly higher management overhead.	747	cost of longer node references and a slightly higher management overhead.
675		748
		749	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
		750	uses "local ports are like remote ports".
		751
		752	The failure modes for local ports are quite different (runtime errors
		753	only) then for remote ports - when a local port dies, you I<know> it dies,
		754	when a connection to another node dies, you know nothing about the other
		755	port.
		756
		757	Erlang pretends remote ports are as reliable as local ports, even when
		758	they are not.
		759
		760	AEMP encourages a "treat remote ports differently" philosophy, with local
		761	ports being the special case/exception, where transport errors cannot
		762	occur.
		763
676	=item * Erlang uses processes and a mailbox, AEMP does not queue.	764	=item * Erlang uses processes and a mailbox, AEMP does not queue.
677		765
678	Erlang uses processes that selctively receive messages, and therefore	766	Erlang uses processes that selectively receive messages, and therefore
679	needs a queue. AEMP is event based, queuing messages would serve no useful	767	needs a queue. AEMP is event based, queuing messages would serve no
680	purpose.	768	useful purpose. For the same reason the pattern-matching abilities of
		769	AnyEvent::MP are more limited, as there is little need to be able to
		770	filter messages without dequeing them.
681		771
682	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	772	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
683		773
684	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	774	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
685		775
686	Sending messages in Erlang is synchronous and blocks the process. AEMP	776	Sending messages in Erlang is synchronous and blocks the process (and
687	sends are immediate, connection establishment is handled in the	777	so does not need a queue that can overflow). AEMP sends are immediate,
688	background.	778	connection establishment is handled in the background.
689		779
690	=item * Erlang can silently lose messages, AEMP cannot.	780	=item * Erlang suffers from silent message loss, AEMP does not.
691		781
692	Erlang makes few guarantees on messages delivery - messages can get lost	782	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,	783	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).	784	and c, and the other side only receives messages a and c).
695		785
…		…
707	eventually be killed - it cannot happen that a node detects a port as dead	797	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.	798	and then later sends messages to it, finding it is still alive.
709		799
710	=item * Erlang can send messages to the wrong port, AEMP does not.	800	=item * Erlang can send messages to the wrong port, AEMP does not.
711		801
712	In Erlang it is quite possible that a node that restarts reuses a process	802	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	803	known to other nodes for a completely different process, causing messages
714	messages destined for that process to end up in an unrelated process.	804	destined for that process to end up in an unrelated process.
715		805
716	AEMP never reuses port IDs, so old messages or old port IDs floating	806	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.	807	around in the network will not be sent to an unrelated port.
718		808
719	=item * Erlang uses unprotected connections, AEMP uses secure	809	=item * Erlang uses unprotected connections, AEMP uses secure
…		…
755	This also saves round-trips and avoids sending messages to the wrong port	845	This also saves round-trips and avoids sending messages to the wrong port
756	(hard to do in Erlang).	846	(hard to do in Erlang).
757		847
758	=back	848	=back
759		849
		850	=head1 RATIONALE
		851
		852	=over 4
		853
		854	=item Why strings for ports and noderefs, why not objects?
		855
		856	We considered "objects", but found that the actual number of methods
		857	thatc an be called are very low. Since port IDs and noderefs travel over
		858	the network frequently, the serialising/deserialising would add lots of
		859	overhead, as well as having to keep a proxy object.
		860
		861	Strings can easily be printed, easily serialised etc. and need no special
		862	procedures to be "valid".
		863
		864	And a a miniport consists of a single closure stored in a global hash - it
		865	can't become much cheaper.
		866
		867	=item Why favour JSON, why not real serialising format such as Storable?
		868
		869	In fact, any AnyEvent::MP node will happily accept Storable as framing
		870	format, but currently there is no way to make a node use Storable by
		871	default.
		872
		873	The default framing protocol is JSON because a) JSON::XS is many times
		874	faster for small messages and b) most importantly, after years of
		875	experience we found that object serialisation is causing more problems
		876	than it gains: Just like function calls, objects simply do not travel
		877	easily over the network, mostly because they will always be a copy, so you
		878	always have to re-think your design.
		879
		880	Keeping your messages simple, concentrating on data structures rather than
		881	objects, will keep your messages clean, tidy and efficient.
		882
		883	=back
		884
760	=head1 SEE ALSO	885	=head1 SEE ALSO
761		886
762	L<AnyEvent>.	887	L<AnyEvent>.
763		888
764	=head1 AUTHOR	889	=head1 AUTHOR

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Revision 1.37 by root, Fri Aug 7 16:47:23 2009 UTC vs.
Revision 1.55 by root, Fri Aug 14 23:17:17 2009 UTC