[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 1.52 by root, Fri Aug 14 15:13:20 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 $somple_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		46	AnyEvent::MP::Intro - outdated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
…		…
95		114
96	=cut	115	=cut
97		116
98	package AnyEvent::MP;	117	package AnyEvent::MP;
99		118
100	use AnyEvent::MP::Base;	119	use AnyEvent::MP::Kernel;
101		120
102	use common::sense;	121	use common::sense;
103		122
104	use Carp ();	123	use Carp ();
105		124
106	use AE ();	125	use AE ();
107		126
108	use base "Exporter";	127	use base "Exporter";
109		128
110	our $VERSION = '0.1';	129	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		130
111	our @EXPORT = qw(	131	our @EXPORT = qw(
112	NODE $NODE *SELF node_of _any_	132	NODE $NODE *SELF node_of _any_
113	resolve_node initialise_node	133	resolve_node initialise_node
114	snd rcv mon kil reg psub	134	snd rcv mon kil reg psub spawn
115	port	135	port
116	);	136	);
117		137
118	our $SELF;	138	our $SELF;
119		139
…		…
123	kil $SELF, die => $msg;	143	kil $SELF, die => $msg;
124	}	144	}
125		145
126	=item $thisnode = NODE / $NODE	146	=item $thisnode = NODE / $NODE
127		147
128	The C<NODE> function returns, and the C<$NODE> variable contains	148	The C<NODE> function returns, and the C<$NODE> variable contains the
129	the noderef of the local node. The value is initialised by a call	149	noderef of the local node. The value is initialised by a call to
130	to C<become_public> or C<become_slave>, after which all local port	150	C<initialise_node>.
131	identifiers become invalid.
132		151
133	=item $noderef = node_of $port	152	=item $noderef = node_of $port
134		153
135	Extracts and returns the noderef from a portid or a noderef.	154	Extracts and returns the noderef from a port ID or a noderef.
136		155
137	=item initialise_node $noderef, $seednode, $seednode...	156	=item initialise_node $noderef, $seednode, $seednode...
138		157
139	=item initialise_node "slave/", $master, $master...	158	=item initialise_node "slave/", $master, $master...
140		159
…		…
143	it should know the noderefs of some other nodes in the network.	162	it should know the noderefs of some other nodes in the network.
144		163
145	This function initialises a node - it must be called exactly once (or	164	This function initialises a node - it must be called exactly once (or
146	never) before calling other AnyEvent::MP functions.	165	never) before calling other AnyEvent::MP functions.
147		166
148	All arguments are noderefs, which can be either resolved or unresolved.	167	All arguments (optionally except for the first) are noderefs, which can be
		168	either resolved or unresolved.
		169
		170	The first argument will be looked up in the configuration database first
		171	(if it is C<undef> then the current nodename will be used instead) to find
		172	the relevant configuration profile (see L<aemp>). If none is found then
		173	the default configuration is used. The configuration supplies additional
		174	seed/master nodes and can override the actual noderef.
149		175
150	There are two types of networked nodes, public nodes and slave nodes:	176	There are two types of networked nodes, public nodes and slave nodes:
151		177
152	=over 4	178	=over 4
153		179
154	=item public nodes	180	=item public nodes
155		181
156	For public nodes, C<$noderef> must either be a (possibly unresolved)	182	For public nodes, C<$noderef> (supplied either directly to
157	noderef, in which case it will be resolved, or C<undef> (or missing), in	183	C<initialise_node> or indirectly via a profile or the nodename) must be a
158	which case the noderef will be guessed.	184	noderef (possibly unresolved, in which case it will be resolved).
159		185
160	Afterwards, the node will bind itself on all endpoints and try to connect	186	After resolving, the node will bind itself on all endpoints and try to
161	to all additional C<$seednodes> that are specified. Seednodes are optional	187	connect to all additional C<$seednodes> that are specified. Seednodes are
162	and can be used to quickly bootstrap the node into an existing network.	188	optional and can be used to quickly bootstrap the node into an existing
		189	network.
163		190
164	=item slave nodes	191	=item slave nodes
165		192
166	When the C<$noderef> is the special string C<slave/>, then the node will	193	When the C<$noderef> (either as given or overriden by the config file)
		194	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	195	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.	196	their traffic to the master node that they attach to.
169		197
170	At least one additional noderef is required: The node will try to connect	198	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	199	directly or because it is part of the configuration profile): The node
172	successfully connect to.	200	will try to connect to all of them and will become a slave attached to the
		201	first node it can successfully connect to.
173		202
174	=back	203	=back
175		204
176	This function will block until all nodes have been resolved and, for slave	205	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	206	nodes, until it has successfully established a connection to a master
178	server.	207	server.
179		208
180	Example: become a public node listening on the default node.	209	Example: become a public node listening on the guessed noderef, or the one
		210	specified via C<aemp> for the current node. This should be the most common
		211	form of invocation for "daemon"-type nodes.
181		212
182	initialise_node;	213	initialise_node;
		214
		215	Example: become a slave node to any of the the seednodes specified via
		216	C<aemp>. This form is often used for commandline clients.
		217
		218	initialise_node "slave/";
		219
		220	Example: become a slave node to any of the specified master servers. This
		221	form is also often used for commandline clients.
		222
		223	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
183		224
184	Example: become a public node, and try to contact some well-known master	225	Example: become a public node, and try to contact some well-known master
185	servers to become part of the network.	226	servers to become part of the network.
186		227
187	initialise_node undef, "master1", "master2";	228	initialise_node undef, "master1", "master2";
…		…
190		231
191	initialise_node 4041;	232	initialise_node 4041;
192		233
193	Example: become a public node, only visible on localhost port 4044.	234	Example: become a public node, only visible on localhost port 4044.
194		235
195	initialise_node "locahost:4044";	236	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		237
201	=item $cv = resolve_node $noderef	238	=item $cv = resolve_node $noderef
202		239
203	Takes an unresolved node reference that may contain hostnames and	240	Takes an unresolved node reference that may contain hostnames and
204	abbreviated IDs, resolves all of them and returns a resolved node	241	abbreviated IDs, resolves all of them and returns a resolved node
…		…
241	=item snd $port, type => @data	278	=item snd $port, type => @data
242		279
243	=item snd $port, @msg	280	=item snd $port, @msg
244		281
245	Send the given message to the given port ID, which can identify either	282	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	283	a local or a remote port, and must be a port ID.
247	stringifies a sa port ID (such as a port object :).
248		284
249	While the message can be about anything, it is highly recommended to use a	285	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	286	string as first element (a port ID, or some word that indicates a request
251	type etc.).	287	type etc.).
252		288
253	The message data effectively becomes read-only after a call to this	289	The message data effectively becomes read-only after a call to this
254	function: modifying any argument is not allowed and can cause many	290	function: modifying any argument is not allowed and can cause many
255	problems.	291	problems.
…		…
260	that Storable can serialise and deserialise is allowed, and for the local	296	that Storable can serialise and deserialise is allowed, and for the local
261	node, anything can be passed.	297	node, anything can be passed.
262		298
263	=item $local_port = port	299	=item $local_port = port
264		300
265	Create a new local port object that can be used either as a pattern	301	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"),	302	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		303
269	=item $port = port { my @msg = @_; $finished }	304	=item $local_port = port { my @msg = @_ }
270		305
271	Creates a "miniport", that is, a very lightweight port without any pattern	306	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.	307	creating a port and calling C<rcv $port, $callback> on it.
274		308
275	The block will be called for every message received on the port. When the	309	The block will be called for every message received on the port, with the
276	callback returns a true value its job is considered "done" and the port	310	global variable C<$SELF> set to the port ID. Runtime errors will cause the
277	will be destroyed. Otherwise it will stay alive.	311	port to be C<kil>ed. The message will be passed as-is, no extra argument
		312	(i.e. no port ID) will be passed to the callback.
278		313
279	The message will be passed as-is, no extra argument (i.e. no port id) will	314	If you want to stop/destroy the port, simply C<kil> it:
280	be passed to the callback.
281		315
282	If you need the local port id in the callback, this works nicely:	316	my $port = port {
283		317	my @msg = @_;
284	my $port; $port = port {	318	...
285	snd $otherport, reply => $port;	319	kil $SELF;
286	};	320	};
287		321
288	=cut	322	=cut
289		323
290	sub rcv($@);	324	sub rcv($@);
		325
		326	sub _kilme {
		327	die "received message on port without callback";
		328	}
291		329
292	sub port(;&) {	330	sub port(;&) {
293	my $id = "$UNIQ." . $ID++;	331	my $id = "$UNIQ." . $ID++;
294	my $port = "$NODE#$id";	332	my $port = "$NODE#$id";
295		333
296	if (@_) {	334	rcv $port, shift \|\| \&_kilme;
297	rcv $port, shift;
298	} else {
299	$PORT{$id} = sub { }; # nop
300	}
301		335
302	$port	336	$port
303	}	337	}
304		338
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)	339	=item rcv $local_port, $callback->(@msg)
325		340
326	Replaces the callback on the specified miniport (after converting it to	341	Replaces the default callback on the specified port. There is no way to
327	one if required).	342	remove the default callback: use C<sub { }> to disable it, or better
328		343	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...] => $callback->(@msg), ...
334
335	Register callbacks to be called on matching messages on the given full
336	port (after converting it to one if required) and return the port.
337
338	The callback has to return a true value when its work is done, after
339	which is will be removed, or a false value in which case it will stay
340	registered.
341		344
342	The global C<$SELF> (exported by this module) contains C<$port> while	345	The global C<$SELF> (exported by this module) contains C<$port> while
343	executing the callback.	346	executing the callback. Runtime errors during callback execution will
		347	result in the port being C<kil>ed.
344		348
345	Runtime errors wdurign callback execution will result in the port being	349	The default callback received all messages not matched by a more specific
346	C<kil>ed.	350	C<tag> match.
347		351
348	If the match is an array reference, then it will be matched against the	352	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
349	first elements of the message, otherwise only the first element is being
350	matched.
351		353
352	Any element in the match that is specified as C<_any_> (a function	354	Register callbacks to be called on messages starting with the given tag on
353	exported by this module) matches any single element of the message.	355	the given port (and return the port), or unregister it (when C<$callback>
		356	is C<$undef>).
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 $otherport, reply =>
370	rcv port,	373	rcv port,
371	msg1 => sub { ...; 0 },	374	msg1 => sub { ... },
372	...	375	...
373	;	376	;
374		377
375	=cut	378	=cut
376		379
…		…
379	my ($noderef, $portid) = split /#/, $port, 2;	382	my ($noderef, $portid) = split /#/, $port, 2;
380		383
381	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	384	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
382	or Carp::croak "$port: rcv can only be called on local ports, caught";	385	or Carp::croak "$port: rcv can only be called on local ports, caught";
383		386
384	if (@_ == 1) {	387	while (@_) {
		388	if (ref $_[0]) {
		389	if (my $self = $PORT_DATA{$portid}) {
		390	"AnyEvent::MP::Port" eq ref $self
		391	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		392
		393	$self->[2] = shift;
		394	} else {
385	my $cb = shift;	395	my $cb = shift;
386	delete $PORT_DATA{$portid};
387	$PORT{$portid} = sub {	396	$PORT{$portid} = sub {
388	local $SELF = $port;	397	local $SELF = $port;
389	eval {	398	eval { &$cb }; _self_die if $@;
390	&$cb	399	};
391	and kil $port;
392	};	400	}
393	_self_die if $@;	401	} elsif (defined $_[0]) {
394	};
395	} else {
396	my $self = $PORT_DATA{$portid} \|\|= do {	402	my $self = $PORT_DATA{$portid} \|\|= do {
397	my $self = bless {	403	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
398	id => $port,
399	}, "AnyEvent::MP::Port";
400		404
401	$PORT{$portid} = sub {	405	$PORT{$portid} = sub {
402	local $SELF = $port;	406	local $SELF = $port;
403		407
404	eval {
405	for (@{ $self->{rc0}{$_[0]} }) {	408	if (my $cb = $self->[1]{$_[0]}) {
406	$_ && &{$_->[0]}	409	shift;
407	&& undef $_;	410	eval { &$cb }; _self_die if $@;
408	}	411	} else {
409
410	for (@{ $self->{rcv}{$_[0]} }) {
411	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
412	&& &{$_->[0]}	412	&{ $self->[0] };
413	&& undef $_;
414	}
415
416	for (@{ $self->{any} }) {
417	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
418	&& &{$_->[0]}
419	&& undef $_;
420	}	413	}
421	};	414	};
422	_self_die if $@;	415
		416	$self
423	};	417	};
424		418
425	$self
426	};
427
428	"AnyEvent::MP::Port" eq ref $self	419	"AnyEvent::MP::Port" eq ref $self
429	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	420	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
430		421
431	while (@_) {
432	my ($match, $cb) = splice @_, 0, 2;	422	my ($tag, $cb) = splice @_, 0, 2;
433		423
434	if (!ref $match) {	424	if (defined $cb) {
435	push @{ $self->{rc0}{$match} }, [$cb];	425	$self->[1]{$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 {	426	} else {
442	push @{ $self->{any} }, [$cb, $match];	427	delete $self->[1]{$tag};
443	}	428	}
444	}	429	}
445	}	430	}
446		431
447	$port	432	$port
…		…
491		476
492	=item $guard = mon $port	477	=item $guard = mon $port
493		478
494	=item $guard = mon $port, $rcvport, @msg	479	=item $guard = mon $port, $rcvport, @msg
495		480
496	Monitor the given port and do something when the port is killed, and	481	Monitor the given port and do something when the port is killed or
497	optionally return a guard that can be used to stop monitoring again.	482	messages to it were lost, and optionally return a guard that can be used
		483	to stop monitoring again.
		484
		485	C<mon> effectively guarantees that, in the absence of hardware failures,
		486	that after starting the monitor, either all messages sent to the port
		487	will arrive, or the monitoring action will be invoked after possible
		488	message loss has been detected. No messages will be lost "in between"
		489	(after the first lost message no further messages will be received by the
		490	port). After the monitoring action was invoked, further messages might get
		491	delivered again.
498		492
499	In the first form (callback), the callback is simply called with any	493	In the first form (callback), the callback is simply called with any
500	number of C<@reason> elements (no @reason means that the port was deleted	494	number of C<@reason> elements (no @reason means that the port was deleted
501	"normally"). Note also that I<< the callback B<must> never die >>, so use	495	"normally"). Note also that I<< the callback B<must> never die >>, so use
502	C<eval> if unsure.	496	C<eval> if unsure.
503		497
504	In the second form (another port given), the other port (C<$rcvport)	498	In the second form (another port given), the other port (C<$rcvport>)
505	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on	499	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
506	"normal" kils nothing happens, while under all other conditions, the other	500	"normal" kils nothing happens, while under all other conditions, the other
507	port is killed with the same reason.	501	port is killed with the same reason.
508		502
509	The third form (kill self) is the same as the second form, except that	503	The third form (kill self) is the same as the second form, except that
…		…
536	sub mon {	530	sub mon {
537	my ($noderef, $port) = split /#/, shift, 2;	531	my ($noderef, $port) = split /#/, shift, 2;
538		532
539	my $node = $NODE{$noderef} \|\| add_node $noderef;	533	my $node = $NODE{$noderef} \|\| add_node $noderef;
540		534
541	my $cb = @_ ? $_[0] : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	535	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
542		536
543	unless (ref $cb) {	537	unless (ref $cb) {
544	if (@_) {	538	if (@_) {
545	# send a kill info message	539	# send a kill info message
546	my (@msg) = @_;	540	my (@msg) = ($cb, @_);
547	$cb = sub { snd @msg, @_ };	541	$cb = sub { snd @msg, @_ };
548	} else {	542	} else {
549	# simply kill other port	543	# simply kill other port
550	my $port = $cb;	544	my $port = $cb;
551	$cb = sub { kil $port, @_ if @_ };	545	$cb = sub { kil $port, @_ if @_ };
…		…
598	will be reported as reason C<< die => $@ >>.	592	will be reported as reason C<< die => $@ >>.
599		593
600	Transport/communication errors are reported as C<< transport_error =>	594	Transport/communication errors are reported as C<< transport_error =>
601	$message >>.	595	$message >>.
602		596
		597	=cut
		598
		599	=item $port = spawn $node, $initfunc[, @initdata]
		600
		601	Creates a port on the node C<$node> (which can also be a port ID, in which
		602	case it's the node where that port resides).
		603
		604	The port ID of the newly created port is return immediately, and it is
		605	permissible to immediately start sending messages or monitor the port.
		606
		607	After the port has been created, the init function is
		608	called. This function must be a fully-qualified function name
		609	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		610	program, use C<::name>.
		611
		612	If the function doesn't exist, then the node tries to C<require>
		613	the package, then the package above the package and so on (e.g.
		614	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		615	exists or it runs out of package names.
		616
		617	The init function is then called with the newly-created port as context
		618	object (C<$SELF>) and the C<@initdata> values as arguments.
		619
		620	A common idiom is to pass your own port, monitor the spawned port, and
		621	in the init function, monitor the original port. This two-way monitoring
		622	ensures that both ports get cleaned up when there is a problem.
		623
		624	Example: spawn a chat server port on C<$othernode>.
		625
		626	# this node, executed from within a port context:
		627	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		628	mon $server;
		629
		630	# init function on C<$othernode>
		631	sub connect {
		632	my ($srcport) = @_;
		633
		634	mon $srcport;
		635
		636	rcv $SELF, sub {
		637	...
		638	};
		639	}
		640
		641	=cut
		642
		643	sub _spawn {
		644	my $port = shift;
		645	my $init = shift;
		646
		647	local $SELF = "$NODE#$port";
		648	eval {
		649	&{ load_func $init }
		650	};
		651	_self_die if $@;
		652	}
		653
		654	sub spawn(@) {
		655	my ($noderef, undef) = split /#/, shift, 2;
		656
		657	my $id = "$RUNIQ." . $ID++;
		658
		659	$_[0] =~ /::/
		660	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		661
		662	($NODE{$noderef} \|\| add_node $noderef)
		663	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
		664
		665	"$noderef#$id"
		666	}
		667
603	=back	668	=back
604		669
605	=head1 NODE MESSAGES	670	=head1 NODE MESSAGES
606		671
607	Nodes understand the following messages sent to them. Many of them take	672	Nodes understand the following messages sent to them. Many of them take
…		…
671	convenience functionality.	736	convenience functionality.
672		737
673	This means that AEMP requires a less tightly controlled environment at the	738	This means that AEMP requires a less tightly controlled environment at the
674	cost of longer node references and a slightly higher management overhead.	739	cost of longer node references and a slightly higher management overhead.
675		740
		741	=item Erlang has a "remote ports are like local ports" philosophy, AEMP
		742	uses "local ports are like remote ports".
		743
		744	The failure modes for local ports are quite different (runtime errors
		745	only) then for remote ports - when a local port dies, you I<know> it dies,
		746	when a connection to another node dies, you know nothing about the other
		747	port.
		748
		749	Erlang pretends remote ports are as reliable as local ports, even when
		750	they are not.
		751
		752	AEMP encourages a "treat remote ports differently" philosophy, with local
		753	ports being the special case/exception, where transport errors cannot
		754	occur.
		755
676	=item * Erlang uses processes and a mailbox, AEMP does not queue.	756	=item * Erlang uses processes and a mailbox, AEMP does not queue.
677		757
678	Erlang uses processes that selctively receive messages, and therefore	758	Erlang uses processes that selectively receive messages, and therefore
679	needs a queue. AEMP is event based, queuing messages would serve no useful	759	needs a queue. AEMP is event based, queuing messages would serve no
680	purpose.	760	useful purpose. For the same reason the pattern-matching abilities of
		761	AnyEvent::MP are more limited, as there is little need to be able to
		762	filter messages without dequeing them.
681		763
682	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	764	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
683		765
684	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	766	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
685		767
686	Sending messages in Erlang is synchronous and blocks the process. AEMP	768	Sending messages in Erlang is synchronous and blocks the process (and
687	sends are immediate, connection establishment is handled in the	769	so does not need a queue that can overflow). AEMP sends are immediate,
688	background.	770	connection establishment is handled in the background.
689		771
690	=item * Erlang can silently lose messages, AEMP cannot.	772	=item * Erlang suffers from silent message loss, AEMP does not.
691		773
692	Erlang makes few guarantees on messages delivery - messages can get lost	774	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,	775	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).	776	and c, and the other side only receives messages a and c).
695		777
…		…
707	eventually be killed - it cannot happen that a node detects a port as dead	789	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.	790	and then later sends messages to it, finding it is still alive.
709		791
710	=item * Erlang can send messages to the wrong port, AEMP does not.	792	=item * Erlang can send messages to the wrong port, AEMP does not.
711		793
712	In Erlang it is quite possible that a node that restarts reuses a process	794	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	795	known to other nodes for a completely different process, causing messages
714	messages destined for that process to end up in an unrelated process.	796	destined for that process to end up in an unrelated process.
715		797
716	AEMP never reuses port IDs, so old messages or old port IDs floating	798	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.	799	around in the network will not be sent to an unrelated port.
718		800
719	=item * Erlang uses unprotected connections, AEMP uses secure	801	=item * Erlang uses unprotected connections, AEMP uses secure
…		…
755	This also saves round-trips and avoids sending messages to the wrong port	837	This also saves round-trips and avoids sending messages to the wrong port
756	(hard to do in Erlang).	838	(hard to do in Erlang).
757		839
758	=back	840	=back
759		841
		842	=head1 RATIONALE
		843
		844	=over 4
		845
		846	=item Why strings for ports and noderefs, why not objects?
		847
		848	We considered "objects", but found that the actual number of methods
		849	thatc an be called are very low. Since port IDs and noderefs travel over
		850	the network frequently, the serialising/deserialising would add lots of
		851	overhead, as well as having to keep a proxy object.
		852
		853	Strings can easily be printed, easily serialised etc. and need no special
		854	procedures to be "valid".
		855
		856	And a a miniport consists of a single closure stored in a global hash - it
		857	can't become much cheaper.
		858
		859	=item Why favour JSON, why not real serialising format such as Storable?
		860
		861	In fact, any AnyEvent::MP node will happily accept Storable as framing
		862	format, but currently there is no way to make a node use Storable by
		863	default.
		864
		865	The default framing protocol is JSON because a) JSON::XS is many times
		866	faster for small messages and b) most importantly, after years of
		867	experience we found that object serialisation is causing more problems
		868	than it gains: Just like function calls, objects simply do not travel
		869	easily over the network, mostly because they will always be a copy, so you
		870	always have to re-think your design.
		871
		872	Keeping your messages simple, concentrating on data structures rather than
		873	objects, will keep your messages clean, tidy and efficient.
		874
		875	=back
		876
760	=head1 SEE ALSO	877	=head1 SEE ALSO
761		878
762	L<AnyEvent>.	879	L<AnyEvent>.
763		880
764	=head1 AUTHOR	881	=head1 AUTHOR

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.37 by root, Fri Aug 7 16:47:23 2009 UTC vs.
Revision 1.52 by root, Fri Aug 14 15:13:20 2009 UTC