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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.32 by root, Wed Aug 5 19:58:46 2009 UTC vs.
Revision 1.39 by root, Fri Aug 7 23:21:48 2009 UTC

…		…
8		8
9	$NODE # contains this node's noderef	9	$NODE # contains this node's noderef
10	NODE # returns this node's noderef	10	NODE # returns this node's noderef
11	NODE $port # returns the noderef of the port	11	NODE $port # returns the noderef of the port
12		12
		13	$SELF # receiving/own port id in rcv callbacks
		14
		15	# ports are message endpoints
		16
		17	# sending messages
13	snd $port, type => data...;	18	snd $port, type => data...;
		19	snd $port, @msg;
		20	snd @msg_with_first_element_being_a_port;
14		21
15	$SELF # receiving/own port id in rcv callbacks	22	# miniports
		23	my $miniport = port { my @msg = @_; 0 };
16		24
		25	# full ports
		26	my $port = port;
17	rcv $port, smartmatch => $cb->($port, @msg);	27	rcv $port, smartmatch => $cb->(@msg);
18
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	28	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
21	rcv $port1, pong => sub { warn "pong received\n" };	29	rcv $port, pong => sub { warn "pong received\n"; 0 };
22	snd $port2, ping => $port1;	30
		31	# remote ports
		32	my $port = spawn $node, $initfunc, @initdata;
23		33
24	# more, smarter, matches (_any_ is exported by this module)	34	# more, smarter, matches (_any_ is exported by this module)
25	rcv $port, [child_died => $pid] => sub { ...	35	rcv $port, [child_died => $pid] => sub { ...
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	36	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
		37
		38	# monitoring
		39	mon $port, $cb->(@msg) # callback is invoked on death
		40	mon $port, $otherport # kill otherport on abnormal death
		41	mon $port, $otherport, @msg # send message on death
27		42
28	=head1 DESCRIPTION	43	=head1 DESCRIPTION
29		44
30	This module (-family) implements a simple message passing framework.	45	This module (-family) implements a simple message passing framework.
31		46
…		…
104		119
105	our $VERSION = '0.1';	120	our $VERSION = '0.1';
106	our @EXPORT = qw(	121	our @EXPORT = qw(
107	NODE $NODE *SELF node_of _any_	122	NODE $NODE *SELF node_of _any_
108	resolve_node initialise_node	123	resolve_node initialise_node
109	snd rcv mon kil reg psub	124	snd rcv mon kil reg psub spawn
110	port	125	port
111	);	126	);
112		127
113	our $SELF;	128	our $SELF;
114		129
…		…
123	The C<NODE> function returns, and the C<$NODE> variable contains	138	The C<NODE> function returns, and the C<$NODE> variable contains
124	the noderef of the local node. The value is initialised by a call	139	the noderef of the local node. The value is initialised by a call
125	to C<become_public> or C<become_slave>, after which all local port	140	to C<become_public> or C<become_slave>, after which all local port
126	identifiers become invalid.	141	identifiers become invalid.
127		142
128	=item $noderef = node_of $portid	143	=item $noderef = node_of $port
129		144
130	Extracts and returns the noderef from a portid or a noderef.	145	Extracts and returns the noderef from a portid or a noderef.
		146
		147	=item initialise_node $noderef, $seednode, $seednode...
		148
		149	=item initialise_node "slave/", $master, $master...
		150
		151	Before a node can talk to other nodes on the network it has to initialise
		152	itself - the minimum a node needs to know is it's own name, and optionally
		153	it should know the noderefs of some other nodes in the network.
		154
		155	This function initialises a node - it must be called exactly once (or
		156	never) before calling other AnyEvent::MP functions.
		157
		158	All arguments are noderefs, which can be either resolved or unresolved.
		159
		160	There are two types of networked nodes, public nodes and slave nodes:
		161
		162	=over 4
		163
		164	=item public nodes
		165
		166	For public nodes, C<$noderef> must either be a (possibly unresolved)
		167	noderef, in which case it will be resolved, or C<undef> (or missing), in
		168	which case the noderef will be guessed.
		169
		170	Afterwards, the node will bind itself on all endpoints and try to connect
		171	to all additional C<$seednodes> that are specified. Seednodes are optional
		172	and can be used to quickly bootstrap the node into an existing network.
		173
		174	=item slave nodes
		175
		176	When the C<$noderef> is the special string C<slave/>, then the node will
		177	become a slave node. Slave nodes cannot be contacted from outside and will
		178	route most of their traffic to the master node that they attach to.
		179
		180	At least one additional noderef is required: The node will try to connect
		181	to all of them and will become a slave attached to the first node it can
		182	successfully connect to.
		183
		184	=back
		185
		186	This function will block until all nodes have been resolved and, for slave
		187	nodes, until it has successfully established a connection to a master
		188	server.
		189
		190	Example: become a public node listening on the default node.
		191
		192	initialise_node;
		193
		194	Example: become a public node, and try to contact some well-known master
		195	servers to become part of the network.
		196
		197	initialise_node undef, "master1", "master2";
		198
		199	Example: become a public node listening on port C<4041>.
		200
		201	initialise_node 4041;
		202
		203	Example: become a public node, only visible on localhost port 4044.
		204
		205	initialise_node "locahost:4044";
		206
		207	Example: become a slave node to any of the specified master servers.
		208
		209	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
131		210
132	=item $cv = resolve_node $noderef	211	=item $cv = resolve_node $noderef
133		212
134	Takes an unresolved node reference that may contain hostnames and	213	Takes an unresolved node reference that may contain hostnames and
135	abbreviated IDs, resolves all of them and returns a resolved node	214	abbreviated IDs, resolves all of them and returns a resolved node
…		…
167		246
168	Due to some quirks in how perl exports variables, it is impossible to	247	Due to some quirks in how perl exports variables, it is impossible to
169	just export C<$SELF>, all the symbols called C<SELF> are exported by this	248	just export C<$SELF>, all the symbols called C<SELF> are exported by this
170	module, but only C<$SELF> is currently used.	249	module, but only C<$SELF> is currently used.
171		250
172	=item snd $portid, type => @data	251	=item snd $port, type => @data
173		252
174	=item snd $portid, @msg	253	=item snd $port, @msg
175		254
176	Send the given message to the given port ID, which can identify either	255	Send the given message to the given port ID, which can identify either
177	a local or a remote port, and can be either a string or soemthignt hat	256	a local or a remote port, and can be either a string or soemthignt hat
178	stringifies a sa port ID (such as a port object :).	257	stringifies a sa port ID (such as a port object :).
179		258
…		…
195		274
196	Create a new local port object that can be used either as a pattern	275	Create a new local port object that can be used either as a pattern
197	matching port ("full port") or a single-callback port ("miniport"),	276	matching port ("full port") or a single-callback port ("miniport"),
198	depending on how C<rcv> callbacks are bound to the object.	277	depending on how C<rcv> callbacks are bound to the object.
199		278
200	=item $portid = port { my @msg = @_; $finished }	279	=item $port = port { my @msg = @_; $finished }
201		280
202	Creates a "mini port", that is, a very lightweight port without any	281	Creates a "miniport", that is, a very lightweight port without any pattern
203	pattern matching behind it, and returns its ID.	282	matching behind it, and returns its ID. Semantically the same as creating
		283	a port and calling C<rcv $port, $callback> on it.
204		284
205	The block will be called for every message received on the port. When the	285	The block will be called for every message received on the port. When the
206	callback returns a true value its job is considered "done" and the port	286	callback returns a true value its job is considered "done" and the port
207	will be destroyed. Otherwise it will stay alive.	287	will be destroyed. Otherwise it will stay alive.
208		288
…		…
215	snd $otherport, reply => $port;	295	snd $otherport, reply => $port;
216	};	296	};
217		297
218	=cut	298	=cut
219		299
		300	sub rcv($@);
		301
220	sub port(;&) {	302	sub port(;&) {
221	my $id = "$UNIQ." . $ID++;	303	my $id = "$UNIQ." . $ID++;
222	my $port = "$NODE#$id";	304	my $port = "$NODE#$id";
223		305
224	if (@_) {	306	if (@_) {
		307	rcv $port, shift;
		308	} else {
		309	$PORT{$id} = sub { }; # nop
		310	}
		311
		312	$port
		313	}
		314
		315	=item reg $port, $name
		316
		317	=item reg $name
		318
		319	Registers the given port (or C<$SELF><<< if missing) under the name
		320	C<$name>. If the name already exists it is replaced.
		321
		322	A port can only be registered under one well known name.
		323
		324	A port automatically becomes unregistered when it is killed.
		325
		326	=cut
		327
		328	sub reg(@) {
		329	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
		330
		331	$REG{$_[0]} = $port;
		332	}
		333
		334	=item rcv $port, $callback->(@msg)
		335
		336	Replaces the callback on the specified miniport (after converting it to
		337	one if required).
		338
		339	=item rcv $port, tagstring => $callback->(@msg), ...
		340
		341	=item rcv $port, $smartmatch => $callback->(@msg), ...
		342
		343	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
		344
		345	Register callbacks to be called on matching messages on the given full
		346	port (after converting it to one if required) and return the port.
		347
		348	The callback has to return a true value when its work is done, after
		349	which is will be removed, or a false value in which case it will stay
		350	registered.
		351
		352	The global C<$SELF> (exported by this module) contains C<$port> while
		353	executing the callback.
		354
		355	Runtime errors during callback execution will result in the port being
		356	C<kil>ed.
		357
		358	If the match is an array reference, then it will be matched against the
		359	first elements of the message, otherwise only the first element is being
		360	matched.
		361
		362	Any element in the match that is specified as C<_any_> (a function
		363	exported by this module) matches any single element of the message.
		364
		365	While not required, it is highly recommended that the first matching
		366	element is a string identifying the message. The one-string-only match is
		367	also the most efficient match (by far).
		368
		369	Example: create a port and bind receivers on it in one go.
		370
		371	my $port = rcv port,
		372	msg1 => sub { ...; 0 },
		373	msg2 => sub { ...; 0 },
		374	;
		375
		376	Example: create a port, bind receivers and send it in a message elsewhere
		377	in one go:
		378
		379	snd $otherport, reply =>
		380	rcv port,
		381	msg1 => sub { ...; 0 },
		382	...
		383	;
		384
		385	=cut
		386
		387	sub rcv($@) {
		388	my $port = shift;
		389	my ($noderef, $portid) = split /#/, $port, 2;
		390
		391	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
		392	or Carp::croak "$port: rcv can only be called on local ports, caught";
		393
		394	if (@_ == 1) {
225	my $cb = shift;	395	my $cb = shift;
		396	delete $PORT_DATA{$portid};
226	$PORT{$id} = sub {	397	$PORT{$portid} = sub {
227	local $SELF = $port;	398	local $SELF = $port;
228	eval {	399	eval {
229	&$cb	400	&$cb
230	and kil $id;	401	and kil $port;
231	};	402	};
232	_self_die if $@;	403	_self_die if $@;
233	};	404	};
234	} else {	405	} else {
		406	my $self = $PORT_DATA{$portid} \|\|= do {
235	my $self = bless {	407	my $self = bless {
236	id => "$NODE#$id",	408	id => $port,
237	}, "AnyEvent::MP::Port";	409	}, "AnyEvent::MP::Port";
238		410
239	$PORT_DATA{$id} = $self;
240	$PORT{$id} = sub {	411	$PORT{$portid} = sub {
241	local $SELF = $port;	412	local $SELF = $port;
242		413
243	eval {	414	eval {
244	for (@{ $self->{rc0}{$_[0]} }) {	415	for (@{ $self->{rc0}{$_[0]} }) {
245	$_ && &{$_->[0]}	416	$_ && &{$_->[0]}
246	&& undef $_;	417	&& undef $_;
247	}	418	}
248		419
249	for (@{ $self->{rcv}{$_[0]} }) {	420	for (@{ $self->{rcv}{$_[0]} }) {
250	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]	421	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
251	&& &{$_->[0]}	422	&& &{$_->[0]}
252	&& undef $_;	423	&& undef $_;
253	}	424	}
254		425
255	for (@{ $self->{any} }) {	426	for (@{ $self->{any} }) {
256	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]	427	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
257	&& &{$_->[0]}	428	&& &{$_->[0]}
258	&& undef $_;	429	&& undef $_;
		430	}
259	}	431	};
		432	_self_die if $@;
260	};	433	};
261	_self_die if $@;	434
		435	$self
262	};	436	};
263	}
264		437
265	$port
266	}
267
268	=item reg $portid, $name
269
270	Registers the given port under the name C<$name>. If the name already
271	exists it is replaced.
272
273	A port can only be registered under one well known name.
274
275	A port automatically becomes unregistered when it is killed.
276
277	=cut
278
279	sub reg(@) {
280	my ($portid, $name) = @_;
281
282	$REG{$name} = $portid;
283	}
284
285	=item rcv $portid, $callback->(@msg)
286
287	Replaces the callback on the specified miniport (or newly created port
288	object, see C<port>). Full ports are configured with the following calls:
289
290	=item rcv $portid, tagstring => $callback->(@msg), ...
291
292	=item rcv $portid, $smartmatch => $callback->(@msg), ...
293
294	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
295
296	Register callbacks to be called on matching messages on the given full
297	port (or newly created port).
298
299	The callback has to return a true value when its work is done, after
300	which is will be removed, or a false value in which case it will stay
301	registered.
302
303	The global C<$SELF> (exported by this module) contains C<$portid> while
304	executing the callback.
305
306	Runtime errors wdurign callback execution will result in the port being
307	C<kil>ed.
308
309	If the match is an array reference, then it will be matched against the
310	first elements of the message, otherwise only the first element is being
311	matched.
312
313	Any element in the match that is specified as C<_any_> (a function
314	exported by this module) matches any single element of the message.
315
316	While not required, it is highly recommended that the first matching
317	element is a string identifying the message. The one-string-only match is
318	also the most efficient match (by far).
319
320	=cut
321
322	sub rcv($@) {
323	my $portid = shift;
324	my ($noderef, $port) = split /#/, $port, 2;
325
326	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
327	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";
328
329	my $self = $PORT_DATA{$port}
330	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
331
332	"AnyEvent::MP::Port" eq ref $self	438	"AnyEvent::MP::Port" eq ref $self
333	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";	439	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
334		440
335	while (@_) {	441	while (@_) {
336	my ($match, $cb) = splice @_, 0, 2;	442	my ($match, $cb) = splice @_, 0, 2;
337		443
338	if (!ref $match) {	444	if (!ref $match) {
339	push @{ $self->{rc0}{$match} }, [$cb];	445	push @{ $self->{rc0}{$match} }, [$cb];
340	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {	446	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
341	my ($type, @match) = @$match;	447	my ($type, @match) = @$match;
342	@match	448	@match
343	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]	449	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
344	: push @{ $self->{rc0}{$match->[0]} }, [$cb];	450	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
345	} else {	451	} else {
346	push @{ $self->{any} }, [$cb, $match];	452	push @{ $self->{any} }, [$cb, $match];
		453	}
347	}	454	}
348	}	455	}
349		456
350	$portid	457	$port
351	}	458	}
352		459
353	=item $closure = psub { BLOCK }	460	=item $closure = psub { BLOCK }
354		461
355	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	462	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
…		…
386	$res	493	$res
387	}	494	}
388	}	495	}
389	}	496	}
390		497
391	=item $guard = mon $portid, $cb->(@reason)	498	=item $guard = mon $port, $cb->(@reason)
392		499
393	=item $guard = mon $portid, $otherport	500	=item $guard = mon $port, $rcvport
394		501
		502	=item $guard = mon $port
		503
395	=item $guard = mon $portid, $otherport, @msg	504	=item $guard = mon $port, $rcvport, @msg
396		505
397	Monitor the given port and do something when the port is killed.	506	Monitor the given port and do something when the port is killed, and
		507	optionally return a guard that can be used to stop monitoring again.
398		508
399	In the first form, the callback is simply called with any number	509	In the first form (callback), the callback is simply called with any
400	of C<@reason> elements (no @reason means that the port was deleted	510	number of C<@reason> elements (no @reason means that the port was deleted
401	"normally"). Note also that I<< the callback B<must> never die >>, so use	511	"normally"). Note also that I<< the callback B<must> never die >>, so use
402	C<eval> if unsure.	512	C<eval> if unsure.
403		513
404	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	514	In the second form (another port given), the other port (C<$rcvport)
405	a @reason was specified, i.e. on "normal" kils nothing happens, while	515	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
406	under all other conditions, the other port is killed with the same reason.	516	"normal" kils nothing happens, while under all other conditions, the other
		517	port is killed with the same reason.
407		518
		519	The third form (kill self) is the same as the second form, except that
		520	C<$rvport> defaults to C<$SELF>.
		521
408	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	522	In the last form (message), a message of the form C<@msg, @reason> will be
		523	C<snd>.
		524
		525	As a rule of thumb, monitoring requests should always monitor a port from
		526	a local port (or callback). The reason is that kill messages might get
		527	lost, just like any other message. Another less obvious reason is that
		528	even monitoring requests can get lost (for exmaple, when the connection
		529	to the other node goes down permanently). When monitoring a port locally
		530	these problems do not exist.
409		531
410	Example: call a given callback when C<$port> is killed.	532	Example: call a given callback when C<$port> is killed.
411		533
412	mon $port, sub { warn "port died because of <@_>\n" };	534	mon $port, sub { warn "port died because of <@_>\n" };
413		535
414	Example: kill ourselves when C<$port> is killed abnormally.	536	Example: kill ourselves when C<$port> is killed abnormally.
415		537
416	mon $port, $self;	538	mon $port;
417		539
418	Example: send us a restart message another C<$port> is killed.	540	Example: send us a restart message when another C<$port> is killed.
419		541
420	mon $port, $self => "restart";	542	mon $port, $self => "restart";
421		543
422	=cut	544	=cut
423		545
424	sub mon {	546	sub mon {
425	my ($noderef, $port) = split /#/, shift, 2;	547	my ($noderef, $port) = split /#/, shift, 2;
426		548
427	my $node = $NODE{$noderef} \|\| add_node $noderef;	549	my $node = $NODE{$noderef} \|\| add_node $noderef;
428		550
429	my $cb = shift;	551	my $cb = @_ ? $_[0] : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
430		552
431	unless (ref $cb) {	553	unless (ref $cb) {
432	if (@_) {	554	if (@_) {
433	# send a kill info message	555	# send a kill info message
434	my (@msg) = ($cb, @_);	556	my (@msg) = @_;
435	$cb = sub { snd @msg, @_ };	557	$cb = sub { snd @msg, @_ };
436	} else {	558	} else {
437	# simply kill other port	559	# simply kill other port
438	my $port = $cb;	560	my $port = $cb;
439	$cb = sub { kil $port, @_ if @_ };	561	$cb = sub { kil $port, @_ if @_ };
…		…
465	=cut	587	=cut
466		588
467	sub mon_guard {	589	sub mon_guard {
468	my ($port, @refs) = @_;	590	my ($port, @refs) = @_;
469		591
		592	#TODO: mon-less form?
		593
470	mon $port, sub { 0 && @refs }	594	mon $port, sub { 0 && @refs }
471	}	595	}
472		596
473	=item lnk $port1, $port2
474
475	Link two ports. This is simply a shorthand for:
476
477	mon $port1, $port2;
478	mon $port2, $port1;
479
480	It means that if either one is killed abnormally, the other one gets
481	killed as well.
482
483	=item kil $portid[, @reason]	597	=item kil $port[, @reason]
484		598
485	Kill the specified port with the given C<@reason>.	599	Kill the specified port with the given C<@reason>.
486		600
487	If no C<@reason> is specified, then the port is killed "normally" (linked	601	If no C<@reason> is specified, then the port is killed "normally" (linked
488	ports will not be kileld, or even notified).	602	ports will not be kileld, or even notified).
…		…
494	will be reported as reason C<< die => $@ >>.	608	will be reported as reason C<< die => $@ >>.
495		609
496	Transport/communication errors are reported as C<< transport_error =>	610	Transport/communication errors are reported as C<< transport_error =>
497	$message >>.	611	$message >>.
498		612
499	=back
500
501	=head1 FUNCTIONS FOR NODES
502
503	=over 4
504
505	=item become_public $noderef
506
507	Tells the node to become a public node, i.e. reachable from other nodes.
508
509	The first argument is the (unresolved) node reference of the local node
510	(if missing then the empty string is used).
511
512	It is quite common to not specify anything, in which case the local node
513	tries to listen on the default port, or to only specify a port number, in
514	which case AnyEvent::MP tries to guess the local addresses.
515
516	=cut	613	=cut
		614
		615	=item $port = spawn $node, $initfunc[, @initdata]
		616
		617	Creates a port on the node C<$node> (which can also be a port ID, in which
		618	case it's the node where that port resides).
		619
		620	The port ID of the newly created port is return immediately, and it is
		621	permissible to immediately start sending messages or monitor the port.
		622
		623	After the port has been created, the init function is
		624	called. This function must be a fully-qualified function name
		625	(e.g. C<MyApp::Chat::Server::init>).
		626
		627	If the function doesn't exist, then the node tries to C<require>
		628	the package, then the package above the package and so on (e.g.
		629	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		630	exists or it runs out of package names.
		631
		632	The init function is then called with the newly-created port as context
		633	object (C<$SELF>) and the C<@initdata> values as arguments.
		634
		635	A common idiom is to pass your own port, monitor the spawned port, and
		636	in the init function, monitor the original port. This two-way monitoring
		637	ensures that both ports get cleaned up when there is a problem.
		638
		639	Example: spawn a chat server port on C<$othernode>.
		640
		641	# this node, executed from within a port context:
		642	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		643	mon $server;
		644
		645	# init function on C<$othernode>
		646	sub connect {
		647	my ($srcport) = @_;
		648
		649	mon $srcport;
		650
		651	rcv $SELF, sub {
		652	...
		653	};
		654	}
		655
		656	=cut
		657
		658	sub _spawn {
		659	my $port = shift;
		660	my $init = shift;
		661
		662	local $SELF = "$NODE#$port";
		663	eval {
		664	&{ load_func $init }
		665	};
		666	_self_die if $@;
		667	}
		668
		669	sub spawn(@) {
		670	my ($noderef, undef) = split /#/, shift, 2;
		671
		672	my $id = "$RUNIQ." . $ID++;
		673
		674	$_[0] =~ /::/
		675	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		676
		677	($NODE{$noderef} \|\| add_node $noderef)
		678	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
		679
		680	"$noderef#$id"
		681	}
517		682
518	=back	683	=back
519		684
520	=head1 NODE MESSAGES	685	=head1 NODE MESSAGES
521		686
…		…
563		728
564	=back	729	=back
565		730
566	=head1 AnyEvent::MP vs. Distributed Erlang	731	=head1 AnyEvent::MP vs. Distributed Erlang
567		732
568	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node	733	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
569	== aemp node, erlang process == aemp port), so many of the documents and	734	== aemp node, Erlang process == aemp port), so many of the documents and
570	programming techniques employed by erlang apply to AnyEvent::MP. Here is a	735	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
571	sample:	736	sample:
572		737
573	http://www.erlang.se/doc/programming_rules.shtml	738	http://www.Erlang.se/doc/programming_rules.shtml
574	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	739	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
575	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6	740	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
576	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5	741	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
577		742
578	Despite the similarities, there are also some important differences:	743	Despite the similarities, there are also some important differences:
579		744
580	=over 4	745	=over 4
581		746
…		…
592		757
593	Erlang uses processes that selctively receive messages, and therefore	758	Erlang uses processes that selctively receive messages, and therefore
594	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 useful
595	purpose.	760	purpose.
596		761
597	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	762	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
598		763
599	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	764	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
600		765
601	Sending messages in erlang is synchronous and blocks the process. AEMP	766	Sending messages in Erlang is synchronous and blocks the process. AEMP
602	sends are immediate, connection establishment is handled in the	767	sends are immediate, connection establishment is handled in the
603	background.	768	background.
604		769
605	=item * Erlang can silently lose messages, AEMP cannot.	770	=item * Erlang can silently lose messages, AEMP cannot.
606		771
…		…
609	and c, and the other side only receives messages a and c).	774	and c, and the other side only receives messages a and c).
610		775
611	AEMP guarantees correct ordering, and the guarantee that there are no	776	AEMP guarantees correct ordering, and the guarantee that there are no
612	holes in the message sequence.	777	holes in the message sequence.
613		778
614	=item * In erlang, processes can be declared dead and later be found to be	779	=item * In Erlang, processes can be declared dead and later be found to be
615	alive.	780	alive.
616		781
617	In erlang it can happen that a monitored process is declared dead and	782	In Erlang it can happen that a monitored process is declared dead and
618	linked processes get killed, but later it turns out that the process is	783	linked processes get killed, but later it turns out that the process is
619	still alive - and can receive messages.	784	still alive - and can receive messages.
620		785
621	In AEMP, when port monitoring detects a port as dead, then that port will	786	In AEMP, when port monitoring detects a port as dead, then that port will
622	eventually be killed - it cannot happen that a node detects a port as dead	787	eventually be killed - it cannot happen that a node detects a port as dead
623	and then later sends messages to it, finding it is still alive.	788	and then later sends messages to it, finding it is still alive.
624		789
625	=item * Erlang can send messages to the wrong port, AEMP does not.	790	=item * Erlang can send messages to the wrong port, AEMP does not.
626		791
627	In erlang it is quite possible that a node that restarts reuses a process	792	In Erlang it is quite possible that a node that restarts reuses a process
628	ID known to other nodes for a completely different process, causing	793	ID known to other nodes for a completely different process, causing
629	messages destined for that process to end up in an unrelated process.	794	messages destined for that process to end up in an unrelated process.
630		795
631	AEMP never reuses port IDs, so old messages or old port IDs floating	796	AEMP never reuses port IDs, so old messages or old port IDs floating
632	around in the network will not be sent to an unrelated port.	797	around in the network will not be sent to an unrelated port.
…		…
638	securely authenticate nodes.	803	securely authenticate nodes.
639		804
640	=item * The AEMP protocol is optimised for both text-based and binary	805	=item * The AEMP protocol is optimised for both text-based and binary
641	communications.	806	communications.
642		807
643	The AEMP protocol, unlike the erlang protocol, supports both	808	The AEMP protocol, unlike the Erlang protocol, supports both
644	language-independent text-only protocols (good for debugging) and binary,	809	language-independent text-only protocols (good for debugging) and binary,
645	language-specific serialisers (e.g. Storable).	810	language-specific serialisers (e.g. Storable).
646		811
647	It has also been carefully designed to be implementable in other languages	812	It has also been carefully designed to be implementable in other languages
648	with a minimum of work while gracefully degrading fucntionality to make the	813	with a minimum of work while gracefully degrading fucntionality to make the
649	protocol simple.	814	protocol simple.
650		815
		816	=item * AEMP has more flexible monitoring options than Erlang.
		817
		818	In Erlang, you can chose to receive I<all> exit signals as messages
		819	or I<none>, there is no in-between, so monitoring single processes is
		820	difficult to implement. Monitoring in AEMP is more flexible than in
		821	Erlang, as one can choose between automatic kill, exit message or callback
		822	on a per-process basis.
		823
		824	=item * Erlang tries to hide remote/local connections, AEMP does not.
		825
		826	Monitoring in Erlang is not an indicator of process death/crashes,
		827	as linking is (except linking is unreliable in Erlang).
		828
		829	In AEMP, you don't "look up" registered port names or send to named ports
		830	that might or might not be persistent. Instead, you normally spawn a port
		831	on the remote node. The init function monitors the you, and you monitor
		832	the remote port. Since both monitors are local to the node, they are much
		833	more reliable.
		834
		835	This also saves round-trips and avoids sending messages to the wrong port
		836	(hard to do in Erlang).
		837
651	=back	838	=back
652		839
653	=head1 SEE ALSO	840	=head1 SEE ALSO
654		841
655	L<AnyEvent>.	842	L<AnyEvent>.

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