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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.38 by root, Fri Aug 7 22:55:18 2009 UTC vs.
Revision 1.51 by root, Fri Aug 14 14:07:44 2009 UTC

…		…
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	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"
14		19
15	# ports are message endpoints	20	# ports are message endpoints
16		21
17	# sending messages	22	# sending messages
18	snd $port, type => data...;	23	snd $port, type => data...;
19	snd $port, @msg;	24	snd $port, @msg;
20	snd @msg_with_first_element_being_a_port;	25	snd @msg_with_first_element_being_a_port;
21		26
22	# miniports	27	# creating/using ports, the simple way
23	my $miniport = port { my @msg = @_; 0 };	28	my $somple_port = port { my @msg = @_; 0 };
24		29
25	# full ports	30	# creating/using ports, type matching
26	my $port = port;	31	my $port = port;
27	rcv $port, smartmatch => $cb->(@msg);
28	rcv $port, ping => sub { snd $_[0], "pong"; 0 };	32	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
29	rcv $port, pong => sub { warn "pong received\n"; 0 };	33	rcv $port, pong => sub { warn "pong received\n"; 0 };
30		34
31	# remote ports	35	# create a port on another node
32	my $port = spawn $node, $initfunc, @initdata;	36	my $port = spawn $node, $initfunc, @initdata;
33
34	# more, smarter, matches (_any_ is exported by this module)
35	rcv $port, [child_died => $pid] => sub { ...
36	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
37		37
38	# monitoring	38	# monitoring
39	mon $port, $cb->(@msg) # callback is invoked on death	39	mon $port, $cb->(@msg) # callback is invoked on death
40	mon $port, $otherport # kill otherport on abnormal death	40	mon $port, $otherport # kill otherport on abnormal death
41	mon $port, $otherport, @msg # send message on death	41	mon $port, $otherport, @msg # send message on death
42		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		46	AnyEvent::MP::Intro - outdated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
43	=head1 DESCRIPTION	52	=head1 DESCRIPTION
44		53
45	This module (-family) implements a simple message passing framework.	54	This module (-family) implements a simple message passing framework.
46		55
47	Despite its simplicity, you can securely message other processes running	56	Despite its simplicity, you can securely message other processes running
…		…
50	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>
51	manual page.	60	manual page.
52		61
53	At the moment, this module family is severly broken and underdocumented,	62	At the moment, this module family is severly broken and underdocumented,
54	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 -
55	stay tuned! The basic API should be finished, however.	64	stay tuned!
56		65
57	=head1 CONCEPTS	66	=head1 CONCEPTS
58		67
59	=over 4	68	=over 4
60		69
…		…
105		114
106	=cut	115	=cut
107		116
108	package AnyEvent::MP;	117	package AnyEvent::MP;
109		118
110	use AnyEvent::MP::Base;	119	use AnyEvent::MP::Kernel;
111		120
112	use common::sense;	121	use common::sense;
113		122
114	use Carp ();	123	use Carp ();
115		124
116	use AE ();	125	use AE ();
117		126
118	use base "Exporter";	127	use base "Exporter";
119		128
120	our $VERSION = '0.1';	129	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		130
121	our @EXPORT = qw(	131	our @EXPORT = qw(
122	NODE $NODE *SELF node_of _any_	132	NODE $NODE *SELF node_of _any_
123	resolve_node initialise_node	133	resolve_node initialise_node
124	snd rcv mon kil reg psub spawn	134	snd rcv mon kil reg psub spawn
125	port	135	port
…		…
153	it should know the noderefs of some other nodes in the network.	163	it should know the noderefs of some other nodes in the network.
154		164
155	This function initialises a node - it must be called exactly once (or	165	This function initialises a node - it must be called exactly once (or
156	never) before calling other AnyEvent::MP functions.	166	never) before calling other AnyEvent::MP functions.
157		167
158	All arguments are noderefs, which can be either resolved or unresolved.	168	All arguments (optionally except for the first) are noderefs, which can be
		169	either resolved or unresolved.
		170
		171	The first argument will be looked up in the configuration database first
		172	(if it is C<undef> then the current nodename will be used instead) to find
		173	the relevant configuration profile (see L<aemp>). If none is found then
		174	the default configuration is used. The configuration supplies additional
		175	seed/master nodes and can override the actual noderef.
159		176
160	There are two types of networked nodes, public nodes and slave nodes:	177	There are two types of networked nodes, public nodes and slave nodes:
161		178
162	=over 4	179	=over 4
163		180
164	=item public nodes	181	=item public nodes
165		182
166	For public nodes, C<$noderef> must either be a (possibly unresolved)	183	For public nodes, C<$noderef> (supplied either directly to
167	noderef, in which case it will be resolved, or C<undef> (or missing), in	184	C<initialise_node> or indirectly via a profile or the nodename) must be a
168	which case the noderef will be guessed.	185	noderef (possibly unresolved, in which case it will be resolved).
169		186
170	Afterwards, the node will bind itself on all endpoints and try to connect	187	After resolving, the node will bind itself on all endpoints and try to
171	to all additional C<$seednodes> that are specified. Seednodes are optional	188	connect to all additional C<$seednodes> that are specified. Seednodes are
172	and can be used to quickly bootstrap the node into an existing network.	189	optional and can be used to quickly bootstrap the node into an existing
		190	network.
173		191
174	=item slave nodes	192	=item slave nodes
175		193
176	When the C<$noderef> is the special string C<slave/>, then the node will	194	When the C<$noderef> (either as given or overriden by the config file)
		195	is the special string C<slave/>, then the node will become a slave
177	become a slave node. Slave nodes cannot be contacted from outside and will	196	node. Slave nodes cannot be contacted from outside and will route most of
178	route most of their traffic to the master node that they attach to.	197	their traffic to the master node that they attach to.
179		198
180	At least one additional noderef is required: The node will try to connect	199	At least one additional noderef is required (either by specifying it
181	to all of them and will become a slave attached to the first node it can	200	directly or because it is part of the configuration profile): The node
182	successfully connect to.	201	will try to connect to all of them and will become a slave attached to the
		202	first node it can successfully connect to.
183		203
184	=back	204	=back
185		205
186	This function will block until all nodes have been resolved and, for slave	206	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	207	nodes, until it has successfully established a connection to a master
188	server.	208	server.
189		209
190	Example: become a public node listening on the default node.	210	Example: become a public node listening on the guessed noderef, or the one
		211	specified via C<aemp> for the current node. This should be the most common
		212	form of invocation for "daemon"-type nodes.
191		213
192	initialise_node;	214	initialise_node;
		215
		216	Example: become a slave node to any of the the seednodes specified via
		217	C<aemp>. This form is often used for commandline clients.
		218
		219	initialise_node "slave/";
		220
		221	Example: become a slave node to any of the specified master servers. This
		222	form is also often used for commandline clients.
		223
		224	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
193		225
194	Example: become a public node, and try to contact some well-known master	226	Example: become a public node, and try to contact some well-known master
195	servers to become part of the network.	227	servers to become part of the network.
196		228
197	initialise_node undef, "master1", "master2";	229	initialise_node undef, "master1", "master2";
…		…
200		232
201	initialise_node 4041;	233	initialise_node 4041;
202		234
203	Example: become a public node, only visible on localhost port 4044.	235	Example: become a public node, only visible on localhost port 4044.
204		236
205	initialise_node "locahost:4044";	237	initialise_node "localhost: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";
210		238
211	=item $cv = resolve_node $noderef	239	=item $cv = resolve_node $noderef
212		240
213	Takes an unresolved node reference that may contain hostnames and	241	Takes an unresolved node reference that may contain hostnames and
214	abbreviated IDs, resolves all of them and returns a resolved node	242	abbreviated IDs, resolves all of them and returns a resolved node
…		…
270	that Storable can serialise and deserialise is allowed, and for the local	298	that Storable can serialise and deserialise is allowed, and for the local
271	node, anything can be passed.	299	node, anything can be passed.
272		300
273	=item $local_port = port	301	=item $local_port = port
274		302
275	Create a new local port object that can be used either as a pattern	303	Create a new local port object and returns its port ID. Initially it has
276	matching port ("full port") or a single-callback port ("miniport"),	304	no callbacks set and will throw an error when it receives messages.
277	depending on how C<rcv> callbacks are bound to the object.
278		305
279	=item $port = port { my @msg = @_; $finished }	306	=item $local_port = port { my @msg = @_ }
280		307
281	Creates a "miniport", that is, a very lightweight port without any pattern	308	Creates a new local port, and returns its ID. Semantically the same as
282	matching behind it, and returns its ID. Semantically the same as creating
283	a port and calling C<rcv $port, $callback> on it.	309	creating a port and calling C<rcv $port, $callback> on it.
284		310
285	The block will be called for every message received on the port. When the	311	The block will be called for every message received on the port, with the
286	callback returns a true value its job is considered "done" and the port	312	global variable C<$SELF> set to the port ID. Runtime errors will cause the
287	will be destroyed. Otherwise it will stay alive.	313	port to be C<kil>ed. The message will be passed as-is, no extra argument
		314	(i.e. no port ID) will be passed to the callback.
288		315
289	The message will be passed as-is, no extra argument (i.e. no port id) will	316	If you want to stop/destroy the port, simply C<kil> it:
290	be passed to the callback.
291		317
292	If you need the local port id in the callback, this works nicely:	318	my $port = port {
293		319	my @msg = @_;
294	my $port; $port = port {	320	...
295	snd $otherport, reply => $port;	321	kil $SELF;
296	};	322	};
297		323
298	=cut	324	=cut
299		325
300	sub rcv($@);	326	sub rcv($@);
		327
		328	sub _kilme {
		329	die "received message on port without callback";
		330	}
301		331
302	sub port(;&) {	332	sub port(;&) {
303	my $id = "$UNIQ." . $ID++;	333	my $id = "$UNIQ." . $ID++;
304	my $port = "$NODE#$id";	334	my $port = "$NODE#$id";
305		335
306	if (@_) {	336	rcv $port, shift \|\| \&_kilme;
307	rcv $port, shift;
308	} else {
309	$PORT{$id} = sub { }; # nop
310	}
311		337
312	$port	338	$port
313	}	339	}
314		340
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)	341	=item rcv $local_port, $callback->(@msg)
335		342
336	Replaces the callback on the specified miniport (after converting it to	343	Replaces the default callback on the specified port. There is no way to
337	one if required).	344	remove the default callback: use C<sub { }> to disable it, or better
338		345	C<kil> the port when it is no longer needed.
339	=item rcv $port, tagstring => $callback->(@msg), ...
340
341	=item rcv $port, $smartmatch => $callback->(@msg), ...
342
343	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
344
345	Register callbacks to be called on matching messages on the given full
346	port (after converting it to one if required) and return the port.
347
348	The callback has to return a true value when its work is done, after
349	which is will be removed, or a false value in which case it will stay
350	registered.
351		346
352	The global C<$SELF> (exported by this module) contains C<$port> while	347	The global C<$SELF> (exported by this module) contains C<$port> while
353	executing the callback.	348	executing the callback. Runtime errors during callback execution will
		349	result in the port being C<kil>ed.
354		350
355	Runtime errors during callback execution will result in the port being	351	The default callback received all messages not matched by a more specific
356	C<kil>ed.	352	C<tag> match.
357		353
358	If the match is an array reference, then it will be matched against the	354	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
359	first elements of the message, otherwise only the first element is being
360	matched.
361		355
362	Any element in the match that is specified as C<_any_> (a function	356	Register callbacks to be called on messages starting with the given tag on
363	exported by this module) matches any single element of the message.	357	the given port (and return the port), or unregister it (when C<$callback>
		358	is C<$undef>).
364		359
365	While not required, it is highly recommended that the first matching	360	The original message will be passed to the callback, after the first
366	element is a string identifying the message. The one-string-only match is	361	element (the tag) has been removed. The callback will use the same
367	also the most efficient match (by far).	362	environment as the default callback (see above).
368		363
369	Example: create a port and bind receivers on it in one go.	364	Example: create a port and bind receivers on it in one go.
370		365
371	my $port = rcv port,	366	my $port = rcv port,
372	msg1 => sub { ...; 0 },	367	msg1 => sub { ... },
373	msg2 => sub { ...; 0 },	368	msg2 => sub { ... },
374	;	369	;
375		370
376	Example: create a port, bind receivers and send it in a message elsewhere	371	Example: create a port, bind receivers and send it in a message elsewhere
377	in one go:	372	in one go:
378		373
379	snd $otherport, reply =>	374	snd $otherport, reply =>
380	rcv port,	375	rcv port,
381	msg1 => sub { ...; 0 },	376	msg1 => sub { ... },
382	...	377	...
383	;	378	;
384		379
385	=cut	380	=cut
386		381
…		…
389	my ($noderef, $portid) = split /#/, $port, 2;	384	my ($noderef, $portid) = split /#/, $port, 2;
390		385
391	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	386	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
392	or Carp::croak "$port: rcv can only be called on local ports, caught";	387	or Carp::croak "$port: rcv can only be called on local ports, caught";
393		388
394	if (@_ == 1) {	389	while (@_) {
		390	if (ref $_[0]) {
		391	if (my $self = $PORT_DATA{$portid}) {
		392	"AnyEvent::MP::Port" eq ref $self
		393	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		394
		395	$self->[2] = shift;
		396	} else {
395	my $cb = shift;	397	my $cb = shift;
396	delete $PORT_DATA{$portid};
397	$PORT{$portid} = sub {	398	$PORT{$portid} = sub {
398	local $SELF = $port;	399	local $SELF = $port;
399	eval {	400	eval { &$cb }; _self_die if $@;
400	&$cb	401	};
401	and kil $port;
402	};	402	}
403	_self_die if $@;	403	} elsif (defined $_[0]) {
404	};
405	} else {
406	my $self = $PORT_DATA{$portid} \|\|= do {	404	my $self = $PORT_DATA{$portid} \|\|= do {
407	my $self = bless {	405	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
408	id => $port,
409	}, "AnyEvent::MP::Port";
410		406
411	$PORT{$portid} = sub {	407	$PORT{$portid} = sub {
412	local $SELF = $port;	408	local $SELF = $port;
413		409
414	eval {
415	for (@{ $self->{rc0}{$_[0]} }) {	410	if (my $cb = $self->[1]{$_[0]}) {
416	$_ && &{$_->[0]}	411	shift;
417	&& undef $_;	412	eval { &$cb }; _self_die if $@;
418	}	413	} else {
419
420	for (@{ $self->{rcv}{$_[0]} }) {
421	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
422	&& &{$_->[0]}	414	&{ $self->[0] };
423	&& undef $_;
424	}
425
426	for (@{ $self->{any} }) {
427	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
428	&& &{$_->[0]}
429	&& undef $_;
430	}	415	}
431	};	416	};
432	_self_die if $@;	417
		418	$self
433	};	419	};
434		420
435	$self
436	};
437
438	"AnyEvent::MP::Port" eq ref $self	421	"AnyEvent::MP::Port" eq ref $self
439	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	422	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
440		423
441	while (@_) {
442	my ($match, $cb) = splice @_, 0, 2;	424	my ($tag, $cb) = splice @_, 0, 2;
443		425
444	if (!ref $match) {	426	if (defined $cb) {
445	push @{ $self->{rc0}{$match} }, [$cb];	427	$self->[1]{$tag} = $cb;
446	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
447	my ($type, @match) = @$match;
448	@match
449	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
450	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
451	} else {	428	} else {
452	push @{ $self->{any} }, [$cb, $match];	429	delete $self->[1]{$tag};
453	}	430	}
454	}	431	}
455	}	432	}
456		433
457	$port	434	$port
…		…
501		478
502	=item $guard = mon $port	479	=item $guard = mon $port
503		480
504	=item $guard = mon $port, $rcvport, @msg	481	=item $guard = mon $port, $rcvport, @msg
505		482
506	Monitor the given port and do something when the port is killed, and	483	Monitor the given port and do something when the port is killed or
507	optionally return a guard that can be used to stop monitoring again.	484	messages to it were lost, and optionally return a guard that can be used
		485	to stop monitoring again.
		486
		487	C<mon> effectively guarantees that, in the absence of hardware failures,
		488	that after starting the monitor, either all messages sent to the port
		489	will arrive, or the monitoring action will be invoked after possible
		490	message loss has been detected. No messages will be lost "in between"
		491	(after the first lost message no further messages will be received by the
		492	port). After the monitoring action was invoked, further messages might get
		493	delivered again.
508		494
509	In the first form (callback), the callback is simply called with any	495	In the first form (callback), the callback is simply called with any
510	number of C<@reason> elements (no @reason means that the port was deleted	496	number of C<@reason> elements (no @reason means that the port was deleted
511	"normally"). Note also that I<< the callback B<must> never die >>, so use	497	"normally"). Note also that I<< the callback B<must> never die >>, so use
512	C<eval> if unsure.	498	C<eval> if unsure.
513		499
514	In the second form (another port given), the other port (C<$rcvport)	500	In the second form (another port given), the other port (C<$rcvport>)
515	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on	501	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
516	"normal" kils nothing happens, while under all other conditions, the other	502	"normal" kils nothing happens, while under all other conditions, the other
517	port is killed with the same reason.	503	port is killed with the same reason.
518		504
519	The third form (kill self) is the same as the second form, except that	505	The third form (kill self) is the same as the second form, except that
…		…
546	sub mon {	532	sub mon {
547	my ($noderef, $port) = split /#/, shift, 2;	533	my ($noderef, $port) = split /#/, shift, 2;
548		534
549	my $node = $NODE{$noderef} \|\| add_node $noderef;	535	my $node = $NODE{$noderef} \|\| add_node $noderef;
550		536
551	my $cb = @_ ? $_[0] : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	537	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
552		538
553	unless (ref $cb) {	539	unless (ref $cb) {
554	if (@_) {	540	if (@_) {
555	# send a kill info message	541	# send a kill info message
556	my (@msg) = @_;	542	my (@msg) = ($cb, @_);
557	$cb = sub { snd @msg, @_ };	543	$cb = sub { snd @msg, @_ };
558	} else {	544	} else {
559	# simply kill other port	545	# simply kill other port
560	my $port = $cb;	546	my $port = $cb;
561	$cb = sub { kil $port, @_ if @_ };	547	$cb = sub { kil $port, @_ if @_ };
…		…
619		605
620	The port ID of the newly created port is return immediately, and it is	606	The port ID of the newly created port is return immediately, and it is
621	permissible to immediately start sending messages or monitor the port.	607	permissible to immediately start sending messages or monitor the port.
622		608
623	After the port has been created, the init function is	609	After the port has been created, the init function is
624	called. This fucntion must be a fully-qualified function name	610	called. This function must be a fully-qualified function name
625	(e.g. C<MyApp::Chat::Server::init>).	611	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		612	program, use C<::name>.
626		613
627	If the function doesn't exist, then the node tries to C<require>	614	If the function doesn't exist, then the node tries to C<require>
628	the package, then the package above the package and so on (e.g.	615	the package, then the package above the package and so on (e.g.
629	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	616	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
630	exists or it runs out of package names.	617	exists or it runs out of package names.
…		…
669	sub spawn(@) {	656	sub spawn(@) {
670	my ($noderef, undef) = split /#/, shift, 2;	657	my ($noderef, undef) = split /#/, shift, 2;
671		658
672	my $id = "$RUNIQ." . $ID++;	659	my $id = "$RUNIQ." . $ID++;
673		660
		661	$_[0] =~ /::/
		662	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		663
674	($NODE{$noderef} \|\| add_node $noderef)	664	($NODE{$noderef} \|\| add_node $noderef)
675	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);	665	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
676		666
677	"$noderef#$id"	667	"$noderef#$id"
678	}	668	}
…		…
748	convenience functionality.	738	convenience functionality.
749		739
750	This means that AEMP requires a less tightly controlled environment at the	740	This means that AEMP requires a less tightly controlled environment at the
751	cost of longer node references and a slightly higher management overhead.	741	cost of longer node references and a slightly higher management overhead.
752		742
		743	=item Erlang has a "remote ports are like local ports" philosophy, AEMP
		744	uses "local ports are like remote ports".
		745
		746	The failure modes for local ports are quite different (runtime errors
		747	only) then for remote ports - when a local port dies, you I<know> it dies,
		748	when a connection to another node dies, you know nothing about the other
		749	port.
		750
		751	Erlang pretends remote ports are as reliable as local ports, even when
		752	they are not.
		753
		754	AEMP encourages a "treat remote ports differently" philosophy, with local
		755	ports being the special case/exception, where transport errors cannot
		756	occur.
		757
753	=item * Erlang uses processes and a mailbox, AEMP does not queue.	758	=item * Erlang uses processes and a mailbox, AEMP does not queue.
754		759
755	Erlang uses processes that selctively receive messages, and therefore	760	Erlang uses processes that selectively receive messages, and therefore
756	needs a queue. AEMP is event based, queuing messages would serve no useful	761	needs a queue. AEMP is event based, queuing messages would serve no
757	purpose.	762	useful purpose. For the same reason the pattern-matching abilities of
		763	AnyEvent::MP are more limited, as there is little need to be able to
		764	filter messages without dequeing them.
758		765
759	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	766	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
760		767
761	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	768	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
762		769
763	Sending messages in Erlang is synchronous and blocks the process. AEMP	770	Sending messages in Erlang is synchronous and blocks the process (and
764	sends are immediate, connection establishment is handled in the	771	so does not need a queue that can overflow). AEMP sends are immediate,
765	background.	772	connection establishment is handled in the background.
766		773
767	=item * Erlang can silently lose messages, AEMP cannot.	774	=item * Erlang suffers from silent message loss, AEMP does not.
768		775
769	Erlang makes few guarantees on messages delivery - messages can get lost	776	Erlang makes few guarantees on messages delivery - messages can get lost
770	without any of the processes realising it (i.e. you send messages a, b,	777	without any of the processes realising it (i.e. you send messages a, b,
771	and c, and the other side only receives messages a and c).	778	and c, and the other side only receives messages a and c).
772		779
…		…
784	eventually be killed - it cannot happen that a node detects a port as dead	791	eventually be killed - it cannot happen that a node detects a port as dead
785	and then later sends messages to it, finding it is still alive.	792	and then later sends messages to it, finding it is still alive.
786		793
787	=item * Erlang can send messages to the wrong port, AEMP does not.	794	=item * Erlang can send messages to the wrong port, AEMP does not.
788		795
789	In Erlang it is quite possible that a node that restarts reuses a process	796	In Erlang it is quite likely that a node that restarts reuses a process ID
790	ID known to other nodes for a completely different process, causing	797	known to other nodes for a completely different process, causing messages
791	messages destined for that process to end up in an unrelated process.	798	destined for that process to end up in an unrelated process.
792		799
793	AEMP never reuses port IDs, so old messages or old port IDs floating	800	AEMP never reuses port IDs, so old messages or old port IDs floating
794	around in the network will not be sent to an unrelated port.	801	around in the network will not be sent to an unrelated port.
795		802
796	=item * Erlang uses unprotected connections, AEMP uses secure	803	=item * Erlang uses unprotected connections, AEMP uses secure
…		…
832	This also saves round-trips and avoids sending messages to the wrong port	839	This also saves round-trips and avoids sending messages to the wrong port
833	(hard to do in Erlang).	840	(hard to do in Erlang).
834		841
835	=back	842	=back
836		843
		844	=head1 RATIONALE
		845
		846	=over 4
		847
		848	=item Why strings for ports and noderefs, why not objects?
		849
		850	We considered "objects", but found that the actual number of methods
		851	thatc an be called are very low. Since port IDs and noderefs travel over
		852	the network frequently, the serialising/deserialising would add lots of
		853	overhead, as well as having to keep a proxy object.
		854
		855	Strings can easily be printed, easily serialised etc. and need no special
		856	procedures to be "valid".
		857
		858	And a a miniport consists of a single closure stored in a global hash - it
		859	can't become much cheaper.
		860
		861	=item Why favour JSON, why not real serialising format such as Storable?
		862
		863	In fact, any AnyEvent::MP node will happily accept Storable as framing
		864	format, but currently there is no way to make a node use Storable by
		865	default.
		866
		867	The default framing protocol is JSON because a) JSON::XS is many times
		868	faster for small messages and b) most importantly, after years of
		869	experience we found that object serialisation is causing more problems
		870	than it gains: Just like function calls, objects simply do not travel
		871	easily over the network, mostly because they will always be a copy, so you
		872	always have to re-think your design.
		873
		874	Keeping your messages simple, concentrating on data structures rather than
		875	objects, will keep your messages clean, tidy and efficient.
		876
		877	=back
		878
837	=head1 SEE ALSO	879	=head1 SEE ALSO
838		880
839	L<AnyEvent>.	881	L<AnyEvent>.
840		882
841	=head1 AUTHOR	883	=head1 AUTHOR

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.38 by root, Fri Aug 7 22:55:18 2009 UTC vs. Revision 1.51 by root, Fri Aug 14 14:07:44 2009 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.38 by root, Fri Aug 7 22:55:18 2009 UTC vs.
Revision 1.51 by root, Fri Aug 14 14:07:44 2009 UTC