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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.36 by root, Thu Aug 6 10:46:48 2009 UTC vs.
Revision 1.53 by root, Fri Aug 14 15:31:21 2009 UTC

…		…
8		8
9	$NODE # contains this node's noderef	9	$NODE # contains this node's noderef
10	NODE # returns this node's noderef	10	NODE # returns this node's noderef
11	NODE $port # returns the noderef of the port	11	NODE $port # returns the noderef of the port
12		12
		13	$SELF # receiving/own port id in rcv callbacks
		14
		15	# initialise the node so it can send/receive messages
		16	initialise_node; # -OR-
		17	initialise_node "localhost:4040"; # -OR-
		18	initialise_node "slave/", "localhost:4040"
		19
		20	# ports are message endpoints
		21
		22	# sending messages
13	snd $port, type => data...;	23	snd $port, type => data...;
		24	snd $port, @msg;
		25	snd @msg_with_first_element_being_a_port;
14		26
15	$SELF # receiving/own port id in rcv callbacks	27	# creating/using ports, the simple way
		28	my $simple_port = port { my @msg = @_; 0 };
16		29
17	rcv $port, smartmatch => $cb->($port, @msg);	30	# creating/using ports, tagged message matching
18		31	my $port = port;
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	32	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
21	rcv $port1, pong => sub { warn "pong received\n" };	33	rcv $port, pong => sub { warn "pong received\n"; 0 };
22	snd $port2, ping => $port1;
23		34
24	# more, smarter, matches (_any_ is exported by this module)	35	# create a port on another node
25	rcv $port, [child_died => $pid] => sub { ...	36	my $port = spawn $node, $initfunc, @initdata;
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
27
28	# linking two ports, so they both crash together
29	lnk $port1, $port2;
30		37
31	# monitoring	38	# monitoring
32	mon $port, $cb->(@msg) # callback is invoked on death	39	mon $port, $cb->(@msg) # callback is invoked on death
33	mon $port, $otherport # kill otherport on abnormal death	40	mon $port, $otherport # kill otherport on abnormal death
34	mon $port, $otherport, @msg # send message on death	41	mon $port, $otherport, @msg # send message on death
35		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		46	AnyEvent::MP::Intro - outdated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
36	=head1 DESCRIPTION	52	=head1 DESCRIPTION
37		53
38	This module (-family) implements a simple message passing framework.	54	This module (-family) implements a simple message passing framework.
39		55
40	Despite its simplicity, you can securely message other processes running	56	Despite its simplicity, you can securely message other processes running
…		…
43	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>
44	manual page.	60	manual page.
45		61
46	At the moment, this module family is severly broken and underdocumented,	62	At the moment, this module family is severly broken and underdocumented,
47	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 -
48	stay tuned! The basic API should be finished, however.	64	stay tuned!
49		65
50	=head1 CONCEPTS	66	=head1 CONCEPTS
51		67
52	=over 4	68	=over 4
53		69
54	=item port	70	=item port
55		71
56	A port is something you can send messages to (with the C<snd> function).	72	A port is something you can send messages to (with the C<snd> function).
57		73
58	Some ports allow you to register C<rcv> handlers that can match specific	74	Ports allow you to register C<rcv> handlers that can match all or just
59	messages. All C<rcv> handlers will receive messages they match, messages	75	some messages. Messages will not be queued.
60	will not be queued.
61		76
62	=item port id - C<noderef#portname>	77	=item port id - C<noderef#portname>
63		78
64	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	79	A port ID is the concatenation of a noderef, a hash-mark (C<#>) as
65	separator, and a port name (a printable string of unspecified format). An	80	separator, and a port name (a printable string of unspecified format). An
66	exception is the the node port, whose ID is identical to its node	81	exception is the the node port, whose ID is identical to its node
67	reference.	82	reference.
68		83
69	=item node	84	=item node
70		85
71	A node is a single process containing at least one port - the node	86	A node is a single process containing at least one port - the node port,
72	port. You can send messages to node ports to find existing ports or to	87	which provides nodes to manage each other remotely, and to create new
73	create new ports, among other things.	88	ports.
74		89
75	Nodes are either private (single-process only), slaves (connected to a	90	Nodes are either private (single-process only), slaves (connected to a
76	master node only) or public nodes (connectable from unrelated nodes).	91	master node only) or public nodes (connectable from unrelated nodes).
77		92
78	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	93	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>
…		…
98		113
99	=cut	114	=cut
100		115
101	package AnyEvent::MP;	116	package AnyEvent::MP;
102		117
103	use AnyEvent::MP::Base;	118	use AnyEvent::MP::Kernel;
104		119
105	use common::sense;	120	use common::sense;
106		121
107	use Carp ();	122	use Carp ();
108		123
109	use AE ();	124	use AE ();
110		125
111	use base "Exporter";	126	use base "Exporter";
112		127
113	our $VERSION = '0.1';	128	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		129
114	our @EXPORT = qw(	130	our @EXPORT = qw(
115	NODE $NODE *SELF node_of _any_	131	NODE $NODE *SELF node_of _any_
116	resolve_node initialise_node	132	resolve_node initialise_node
117	snd rcv mon kil reg psub	133	snd rcv mon kil reg psub spawn
118	port	134	port
119	);	135	);
120		136
121	our $SELF;	137	our $SELF;
122		138
…		…
126	kil $SELF, die => $msg;	142	kil $SELF, die => $msg;
127	}	143	}
128		144
129	=item $thisnode = NODE / $NODE	145	=item $thisnode = NODE / $NODE
130		146
131	The C<NODE> function returns, and the C<$NODE> variable contains	147	The C<NODE> function returns, and the C<$NODE> variable contains the
132	the noderef of the local node. The value is initialised by a call	148	noderef of the local node. The value is initialised by a call to
133	to C<become_public> or C<become_slave>, after which all local port	149	C<initialise_node>.
134	identifiers become invalid.
135		150
136	=item $noderef = node_of $port	151	=item $noderef = node_of $port
137		152
138	Extracts and returns the noderef from a portid or a noderef.	153	Extracts and returns the noderef from a port ID or a noderef.
139		154
140	=item initialise_node $noderef, $seednode, $seednode...	155	=item initialise_node $noderef, $seednode, $seednode...
141		156
142	=item initialise_node "slave/", $master, $master...	157	=item initialise_node "slave/", $master, $master...
143		158
…		…
146	it should know the noderefs of some other nodes in the network.	161	it should know the noderefs of some other nodes in the network.
147		162
148	This function initialises a node - it must be called exactly once (or	163	This function initialises a node - it must be called exactly once (or
149	never) before calling other AnyEvent::MP functions.	164	never) before calling other AnyEvent::MP functions.
150		165
151	All arguments are noderefs, which can be either resolved or unresolved.	166	All arguments (optionally except for the first) are noderefs, which can be
		167	either resolved or unresolved.
		168
		169	The first argument will be looked up in the configuration database first
		170	(if it is C<undef> then the current nodename will be used instead) to find
		171	the relevant configuration profile (see L<aemp>). If none is found then
		172	the default configuration is used. The configuration supplies additional
		173	seed/master nodes and can override the actual noderef.
152		174
153	There are two types of networked nodes, public nodes and slave nodes:	175	There are two types of networked nodes, public nodes and slave nodes:
154		176
155	=over 4	177	=over 4
156		178
157	=item public nodes	179	=item public nodes
158		180
159	For public nodes, C<$noderef> must either be a (possibly unresolved)	181	For public nodes, C<$noderef> (supplied either directly to
160	noderef, in which case it will be resolved, or C<undef> (or missing), in	182	C<initialise_node> or indirectly via a profile or the nodename) must be a
161	which case the noderef will be guessed.	183	noderef (possibly unresolved, in which case it will be resolved).
162		184
163	Afterwards, the node will bind itself on all endpoints and try to connect	185	After resolving, the node will bind itself on all endpoints and try to
164	to all additional C<$seednodes> that are specified. Seednodes are optional	186	connect to all additional C<$seednodes> that are specified. Seednodes are
165	and can be used to quickly bootstrap the node into an existing network.	187	optional and can be used to quickly bootstrap the node into an existing
		188	network.
166		189
167	=item slave nodes	190	=item slave nodes
168		191
169	When the C<$noderef> is the special string C<slave/>, then the node will	192	When the C<$noderef> (either as given or overriden by the config file)
		193	is the special string C<slave/>, then the node will become a slave
170	become a slave node. Slave nodes cannot be contacted from outside and will	194	node. Slave nodes cannot be contacted from outside and will route most of
171	route most of their traffic to the master node that they attach to.	195	their traffic to the master node that they attach to.
172		196
173	At least one additional noderef is required: The node will try to connect	197	At least one additional noderef is required (either by specifying it
174	to all of them and will become a slave attached to the first node it can	198	directly or because it is part of the configuration profile): The node
175	successfully connect to.	199	will try to connect to all of them and will become a slave attached to the
		200	first node it can successfully connect to.
176		201
177	=back	202	=back
178		203
179	This function will block until all nodes have been resolved and, for slave	204	This function will block until all nodes have been resolved and, for slave
180	nodes, until it has successfully established a connection to a master	205	nodes, until it has successfully established a connection to a master
181	server.	206	server.
182		207
183	Example: become a public node listening on the default node.	208	Example: become a public node listening on the guessed noderef, or the one
		209	specified via C<aemp> for the current node. This should be the most common
		210	form of invocation for "daemon"-type nodes.
184		211
185	initialise_node;	212	initialise_node;
		213
		214	Example: become a slave node to any of the the seednodes specified via
		215	C<aemp>. This form is often used for commandline clients.
		216
		217	initialise_node "slave/";
		218
		219	Example: become a slave node to any of the specified master servers. This
		220	form is also often used for commandline clients.
		221
		222	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
186		223
187	Example: become a public node, and try to contact some well-known master	224	Example: become a public node, and try to contact some well-known master
188	servers to become part of the network.	225	servers to become part of the network.
189		226
190	initialise_node undef, "master1", "master2";	227	initialise_node undef, "master1", "master2";
…		…
193		230
194	initialise_node 4041;	231	initialise_node 4041;
195		232
196	Example: become a public node, only visible on localhost port 4044.	233	Example: become a public node, only visible on localhost port 4044.
197		234
198	initialise_node "locahost:4044";	235	initialise_node "localhost:4044";
199
200	Example: become a slave node to any of the specified master servers.
201
202	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
203		236
204	=item $cv = resolve_node $noderef	237	=item $cv = resolve_node $noderef
205		238
206	Takes an unresolved node reference that may contain hostnames and	239	Takes an unresolved node reference that may contain hostnames and
207	abbreviated IDs, resolves all of them and returns a resolved node	240	abbreviated IDs, resolves all of them and returns a resolved node
…		…
244	=item snd $port, type => @data	277	=item snd $port, type => @data
245		278
246	=item snd $port, @msg	279	=item snd $port, @msg
247		280
248	Send the given message to the given port ID, which can identify either	281	Send the given message to the given port ID, which can identify either
249	a local or a remote port, and can be either a string or soemthignt hat	282	a local or a remote port, and must be a port ID.
250	stringifies a sa port ID (such as a port object :).
251		283
252	While the message can be about anything, it is highly recommended to use a	284	While the message can be about anything, it is highly recommended to use a
253	string as first element (a portid, or some word that indicates a request	285	string as first element (a port ID, or some word that indicates a request
254	type etc.).	286	type etc.).
255		287
256	The message data effectively becomes read-only after a call to this	288	The message data effectively becomes read-only after a call to this
257	function: modifying any argument is not allowed and can cause many	289	function: modifying any argument is not allowed and can cause many
258	problems.	290	problems.
…		…
263	that Storable can serialise and deserialise is allowed, and for the local	295	that Storable can serialise and deserialise is allowed, and for the local
264	node, anything can be passed.	296	node, anything can be passed.
265		297
266	=item $local_port = port	298	=item $local_port = port
267		299
268	Create a new local port object that can be used either as a pattern	300	Create a new local port object and returns its port ID. Initially it has
269	matching port ("full port") or a single-callback port ("miniport"),	301	no callbacks set and will throw an error when it receives messages.
270	depending on how C<rcv> callbacks are bound to the object.
271		302
272	=item $port = port { my @msg = @_; $finished }	303	=item $local_port = port { my @msg = @_ }
273		304
274	Creates a "miniport", that is, a very lightweight port without any pattern	305	Creates a new local port, and returns its ID. Semantically the same as
275	matching behind it, and returns its ID. Semantically the same as creating
276	a port and calling C<rcv $port, $callback> on it.	306	creating a port and calling C<rcv $port, $callback> on it.
277		307
278	The block will be called for every message received on the port. When the	308	The block will be called for every message received on the port, with the
279	callback returns a true value its job is considered "done" and the port	309	global variable C<$SELF> set to the port ID. Runtime errors will cause the
280	will be destroyed. Otherwise it will stay alive.	310	port to be C<kil>ed. The message will be passed as-is, no extra argument
		311	(i.e. no port ID) will be passed to the callback.
281		312
282	The message will be passed as-is, no extra argument (i.e. no port id) will	313	If you want to stop/destroy the port, simply C<kil> it:
283	be passed to the callback.
284		314
285	If you need the local port id in the callback, this works nicely:	315	my $port = port {
286		316	my @msg = @_;
287	my $port; $port = port {	317	...
288	snd $otherport, reply => $port;	318	kil $SELF;
289	};	319	};
290		320
291	=cut	321	=cut
292		322
293	sub rcv($@);	323	sub rcv($@);
		324
		325	sub _kilme {
		326	die "received message on port without callback";
		327	}
294		328
295	sub port(;&) {	329	sub port(;&) {
296	my $id = "$UNIQ." . $ID++;	330	my $id = "$UNIQ." . $ID++;
297	my $port = "$NODE#$id";	331	my $port = "$NODE#$id";
298		332
299	if (@_) {	333	rcv $port, shift \|\| \&_kilme;
300	rcv $port, shift;
301	} else {
302	$PORT{$id} = sub { }; # nop
303	}
304		334
305	$port	335	$port
306	}	336	}
307		337
308	=item reg $port, $name
309
310	=item reg $name
311
312	Registers the given port (or C<$SELF><<< if missing) under the name
313	C<$name>. If the name already exists it is replaced.
314
315	A port can only be registered under one well known name.
316
317	A port automatically becomes unregistered when it is killed.
318
319	=cut
320
321	sub reg(@) {
322	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
323
324	$REG{$_[0]} = $port;
325	}
326
327	=item rcv $port, $callback->(@msg)	338	=item rcv $local_port, $callback->(@msg)
328		339
329	Replaces the callback on the specified miniport (after converting it to	340	Replaces the default callback on the specified port. There is no way to
330	one if required).	341	remove the default callback: use C<sub { }> to disable it, or better
331		342	C<kil> the port when it is no longer needed.
332	=item rcv $port, tagstring => $callback->(@msg), ...
333
334	=item rcv $port, $smartmatch => $callback->(@msg), ...
335
336	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
337
338	Register callbacks to be called on matching messages on the given full
339	port (after converting it to one if required) and return the port.
340
341	The callback has to return a true value when its work is done, after
342	which is will be removed, or a false value in which case it will stay
343	registered.
344		343
345	The global C<$SELF> (exported by this module) contains C<$port> while	344	The global C<$SELF> (exported by this module) contains C<$port> while
346	executing the callback.	345	executing the callback. Runtime errors during callback execution will
		346	result in the port being C<kil>ed.
347		347
348	Runtime errors wdurign callback execution will result in the port being	348	The default callback received all messages not matched by a more specific
349	C<kil>ed.	349	C<tag> match.
350		350
351	If the match is an array reference, then it will be matched against the	351	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
352	first elements of the message, otherwise only the first element is being
353	matched.
354		352
355	Any element in the match that is specified as C<_any_> (a function	353	Register callbacks to be called on messages starting with the given tag on
356	exported by this module) matches any single element of the message.	354	the given port (and return the port), or unregister it (when C<$callback>
		355	is C<$undef>).
357		356
358	While not required, it is highly recommended that the first matching	357	The original message will be passed to the callback, after the first
359	element is a string identifying the message. The one-string-only match is	358	element (the tag) has been removed. The callback will use the same
360	also the most efficient match (by far).	359	environment as the default callback (see above).
361		360
362	Example: create a port and bind receivers on it in one go.	361	Example: create a port and bind receivers on it in one go.
363		362
364	my $port = rcv port,	363	my $port = rcv port,
365	msg1 => sub { ...; 0 },	364	msg1 => sub { ... },
366	msg2 => sub { ...; 0 },	365	msg2 => sub { ... },
367	;	366	;
368		367
369	Example: create a port, bind receivers and send it in a message elsewhere	368	Example: create a port, bind receivers and send it in a message elsewhere
370	in one go:	369	in one go:
371		370
372	snd $otherport, reply =>	371	snd $otherport, reply =>
373	rcv port,	372	rcv port,
374	msg1 => sub { ...; 0 },	373	msg1 => sub { ... },
375	...	374	...
376	;	375	;
377		376
378	=cut	377	=cut
379		378
…		…
382	my ($noderef, $portid) = split /#/, $port, 2;	381	my ($noderef, $portid) = split /#/, $port, 2;
383		382
384	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	383	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
385	or Carp::croak "$port: rcv can only be called on local ports, caught";	384	or Carp::croak "$port: rcv can only be called on local ports, caught";
386		385
387	if (@_ == 1) {	386	while (@_) {
		387	if (ref $_[0]) {
		388	if (my $self = $PORT_DATA{$portid}) {
		389	"AnyEvent::MP::Port" eq ref $self
		390	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		391
		392	$self->[2] = shift;
		393	} else {
388	my $cb = shift;	394	my $cb = shift;
389	delete $PORT_DATA{$portid};
390	$PORT{$portid} = sub {	395	$PORT{$portid} = sub {
391	local $SELF = $port;	396	local $SELF = $port;
392	eval {	397	eval { &$cb }; _self_die if $@;
393	&$cb	398	};
394	and kil $port;
395	};	399	}
396	_self_die if $@;	400	} elsif (defined $_[0]) {
397	};
398	} else {
399	my $self = $PORT_DATA{$portid} \|\|= do {	401	my $self = $PORT_DATA{$portid} \|\|= do {
400	my $self = bless {	402	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
401	id => $port,
402	}, "AnyEvent::MP::Port";
403		403
404	$PORT{$portid} = sub {	404	$PORT{$portid} = sub {
405	local $SELF = $port;	405	local $SELF = $port;
406		406
407	eval {
408	for (@{ $self->{rc0}{$_[0]} }) {	407	if (my $cb = $self->[1]{$_[0]}) {
409	$_ && &{$_->[0]}	408	shift;
410	&& undef $_;	409	eval { &$cb }; _self_die if $@;
411	}	410	} else {
412
413	for (@{ $self->{rcv}{$_[0]} }) {
414	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
415	&& &{$_->[0]}	411	&{ $self->[0] };
416	&& undef $_;
417	}
418
419	for (@{ $self->{any} }) {
420	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
421	&& &{$_->[0]}
422	&& undef $_;
423	}	412	}
424	};	413	};
425	_self_die if $@;	414
		415	$self
426	};	416	};
427		417
428	$self
429	};
430
431	"AnyEvent::MP::Port" eq ref $self	418	"AnyEvent::MP::Port" eq ref $self
432	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	419	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
433		420
434	while (@_) {
435	my ($match, $cb) = splice @_, 0, 2;	421	my ($tag, $cb) = splice @_, 0, 2;
436		422
437	if (!ref $match) {	423	if (defined $cb) {
438	push @{ $self->{rc0}{$match} }, [$cb];	424	$self->[1]{$tag} = $cb;
439	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
440	my ($type, @match) = @$match;
441	@match
442	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
443	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
444	} else {	425	} else {
445	push @{ $self->{any} }, [$cb, $match];	426	delete $self->[1]{$tag};
446	}	427	}
447	}	428	}
448	}	429	}
449		430
450	$port	431	$port
…		…
494		475
495	=item $guard = mon $port	476	=item $guard = mon $port
496		477
497	=item $guard = mon $port, $rcvport, @msg	478	=item $guard = mon $port, $rcvport, @msg
498		479
499	Monitor the given port and do something when the port is killed, and	480	Monitor the given port and do something when the port is killed or
500	optionally return a guard that can be used to stop monitoring again.	481	messages to it were lost, and optionally return a guard that can be used
		482	to stop monitoring again.
		483
		484	C<mon> effectively guarantees that, in the absence of hardware failures,
		485	that after starting the monitor, either all messages sent to the port
		486	will arrive, or the monitoring action will be invoked after possible
		487	message loss has been detected. No messages will be lost "in between"
		488	(after the first lost message no further messages will be received by the
		489	port). After the monitoring action was invoked, further messages might get
		490	delivered again.
501		491
502	In the first form (callback), the callback is simply called with any	492	In the first form (callback), the callback is simply called with any
503	number of C<@reason> elements (no @reason means that the port was deleted	493	number of C<@reason> elements (no @reason means that the port was deleted
504	"normally"). Note also that I<< the callback B<must> never die >>, so use	494	"normally"). Note also that I<< the callback B<must> never die >>, so use
505	C<eval> if unsure.	495	C<eval> if unsure.
506		496
507	In the second form (another port given), the other port (C<$rcvport)	497	In the second form (another port given), the other port (C<$rcvport>)
508	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on	498	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
509	"normal" kils nothing happens, while under all other conditions, the other	499	"normal" kils nothing happens, while under all other conditions, the other
510	port is killed with the same reason.	500	port is killed with the same reason.
511		501
512	The third form (kill self) is the same as the second form, except that	502	The third form (kill self) is the same as the second form, except that
513	C<$rvport> defaults to C<$SELF>.	503	C<$rvport> defaults to C<$SELF>.
514		504
515	In the last form (message), a message of the form C<@msg, @reason> will be	505	In the last form (message), a message of the form C<@msg, @reason> will be
516	C<snd>.	506	C<snd>.
517		507
		508	As a rule of thumb, monitoring requests should always monitor a port from
		509	a local port (or callback). The reason is that kill messages might get
		510	lost, just like any other message. Another less obvious reason is that
		511	even monitoring requests can get lost (for exmaple, when the connection
		512	to the other node goes down permanently). When monitoring a port locally
		513	these problems do not exist.
		514
518	Example: call a given callback when C<$port> is killed.	515	Example: call a given callback when C<$port> is killed.
519		516
520	mon $port, sub { warn "port died because of <@_>\n" };	517	mon $port, sub { warn "port died because of <@_>\n" };
521		518
522	Example: kill ourselves when C<$port> is killed abnormally.	519	Example: kill ourselves when C<$port> is killed abnormally.
…		…
532	sub mon {	529	sub mon {
533	my ($noderef, $port) = split /#/, shift, 2;	530	my ($noderef, $port) = split /#/, shift, 2;
534		531
535	my $node = $NODE{$noderef} \|\| add_node $noderef;	532	my $node = $NODE{$noderef} \|\| add_node $noderef;
536		533
537	my $cb = @_ ? $_[0] : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	534	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
538		535
539	unless (ref $cb) {	536	unless (ref $cb) {
540	if (@_) {	537	if (@_) {
541	# send a kill info message	538	# send a kill info message
542	my (@msg) = @_;	539	my (@msg) = ($cb, @_);
543	$cb = sub { snd @msg, @_ };	540	$cb = sub { snd @msg, @_ };
544	} else {	541	} else {
545	# simply kill other port	542	# simply kill other port
546	my $port = $cb;	543	my $port = $cb;
547	$cb = sub { kil $port, @_ if @_ };	544	$cb = sub { kil $port, @_ if @_ };
…		…
578	#TODO: mon-less form?	575	#TODO: mon-less form?
579		576
580	mon $port, sub { 0 && @refs }	577	mon $port, sub { 0 && @refs }
581	}	578	}
582		579
583	=item lnk $port1, $port2
584
585	=item lnk $otherport
586
587	Link two ports. This is simply a shorthand for:
588
589	mon $port1, $port2;
590	mon $port2, $port1;
591
592	It means that if either one is killed abnormally, the other one gets
593	killed as well.
594
595	The one-argument form assumes that one port is C<$SELF>.
596
597	=cut
598
599	sub lnk {
600	my $port1 = shift;
601	my $port2 = @_ ? shift : $SELF \|\| Carp::croak 'lnk: called with one argument only, but $SELF not set,';
602
603	mon $port1, $port2;
604	mon $port2, $port1;
605	}
606
607	=item kil $port[, @reason]	580	=item kil $port[, @reason]
608		581
609	Kill the specified port with the given C<@reason>.	582	Kill the specified port with the given C<@reason>.
610		583
611	If no C<@reason> is specified, then the port is killed "normally" (linked	584	If no C<@reason> is specified, then the port is killed "normally" (linked
…		…
617	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	590	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
618	will be reported as reason C<< die => $@ >>.	591	will be reported as reason C<< die => $@ >>.
619		592
620	Transport/communication errors are reported as C<< transport_error =>	593	Transport/communication errors are reported as C<< transport_error =>
621	$message >>.	594	$message >>.
		595
		596	=cut
		597
		598	=item $port = spawn $node, $initfunc[, @initdata]
		599
		600	Creates a port on the node C<$node> (which can also be a port ID, in which
		601	case it's the node where that port resides).
		602
		603	The port ID of the newly created port is return immediately, and it is
		604	permissible to immediately start sending messages or monitor the port.
		605
		606	After the port has been created, the init function is
		607	called. This function must be a fully-qualified function name
		608	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		609	program, use C<::name>.
		610
		611	If the function doesn't exist, then the node tries to C<require>
		612	the package, then the package above the package and so on (e.g.
		613	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		614	exists or it runs out of package names.
		615
		616	The init function is then called with the newly-created port as context
		617	object (C<$SELF>) and the C<@initdata> values as arguments.
		618
		619	A common idiom is to pass your own port, monitor the spawned port, and
		620	in the init function, monitor the original port. This two-way monitoring
		621	ensures that both ports get cleaned up when there is a problem.
		622
		623	Example: spawn a chat server port on C<$othernode>.
		624
		625	# this node, executed from within a port context:
		626	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		627	mon $server;
		628
		629	# init function on C<$othernode>
		630	sub connect {
		631	my ($srcport) = @_;
		632
		633	mon $srcport;
		634
		635	rcv $SELF, sub {
		636	...
		637	};
		638	}
		639
		640	=cut
		641
		642	sub _spawn {
		643	my $port = shift;
		644	my $init = shift;
		645
		646	local $SELF = "$NODE#$port";
		647	eval {
		648	&{ load_func $init }
		649	};
		650	_self_die if $@;
		651	}
		652
		653	sub spawn(@) {
		654	my ($noderef, undef) = split /#/, shift, 2;
		655
		656	my $id = "$RUNIQ." . $ID++;
		657
		658	$_[0] =~ /::/
		659	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		660
		661	($NODE{$noderef} \|\| add_node $noderef)
		662	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
		663
		664	"$noderef#$id"
		665	}
622		666
623	=back	667	=back
624		668
625	=head1 NODE MESSAGES	669	=head1 NODE MESSAGES
626		670
…		…
691	convenience functionality.	735	convenience functionality.
692		736
693	This means that AEMP requires a less tightly controlled environment at the	737	This means that AEMP requires a less tightly controlled environment at the
694	cost of longer node references and a slightly higher management overhead.	738	cost of longer node references and a slightly higher management overhead.
695		739
		740	=item Erlang has a "remote ports are like local ports" philosophy, AEMP
		741	uses "local ports are like remote ports".
		742
		743	The failure modes for local ports are quite different (runtime errors
		744	only) then for remote ports - when a local port dies, you I<know> it dies,
		745	when a connection to another node dies, you know nothing about the other
		746	port.
		747
		748	Erlang pretends remote ports are as reliable as local ports, even when
		749	they are not.
		750
		751	AEMP encourages a "treat remote ports differently" philosophy, with local
		752	ports being the special case/exception, where transport errors cannot
		753	occur.
		754
696	=item * Erlang uses processes and a mailbox, AEMP does not queue.	755	=item * Erlang uses processes and a mailbox, AEMP does not queue.
697		756
698	Erlang uses processes that selctively receive messages, and therefore	757	Erlang uses processes that selectively receive messages, and therefore
699	needs a queue. AEMP is event based, queuing messages would serve no useful	758	needs a queue. AEMP is event based, queuing messages would serve no
700	purpose.	759	useful purpose. For the same reason the pattern-matching abilities of
		760	AnyEvent::MP are more limited, as there is little need to be able to
		761	filter messages without dequeing them.
701		762
702	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	763	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
703		764
704	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	765	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
705		766
706	Sending messages in Erlang is synchronous and blocks the process. AEMP	767	Sending messages in Erlang is synchronous and blocks the process (and
707	sends are immediate, connection establishment is handled in the	768	so does not need a queue that can overflow). AEMP sends are immediate,
708	background.	769	connection establishment is handled in the background.
709		770
710	=item * Erlang can silently lose messages, AEMP cannot.	771	=item * Erlang suffers from silent message loss, AEMP does not.
711		772
712	Erlang makes few guarantees on messages delivery - messages can get lost	773	Erlang makes few guarantees on messages delivery - messages can get lost
713	without any of the processes realising it (i.e. you send messages a, b,	774	without any of the processes realising it (i.e. you send messages a, b,
714	and c, and the other side only receives messages a and c).	775	and c, and the other side only receives messages a and c).
715		776
…		…
727	eventually be killed - it cannot happen that a node detects a port as dead	788	eventually be killed - it cannot happen that a node detects a port as dead
728	and then later sends messages to it, finding it is still alive.	789	and then later sends messages to it, finding it is still alive.
729		790
730	=item * Erlang can send messages to the wrong port, AEMP does not.	791	=item * Erlang can send messages to the wrong port, AEMP does not.
731		792
732	In Erlang it is quite possible that a node that restarts reuses a process	793	In Erlang it is quite likely that a node that restarts reuses a process ID
733	ID known to other nodes for a completely different process, causing	794	known to other nodes for a completely different process, causing messages
734	messages destined for that process to end up in an unrelated process.	795	destined for that process to end up in an unrelated process.
735		796
736	AEMP never reuses port IDs, so old messages or old port IDs floating	797	AEMP never reuses port IDs, so old messages or old port IDs floating
737	around in the network will not be sent to an unrelated port.	798	around in the network will not be sent to an unrelated port.
738		799
739	=item * Erlang uses unprotected connections, AEMP uses secure	800	=item * Erlang uses unprotected connections, AEMP uses secure
…		…
759	or I<none>, there is no in-between, so monitoring single processes is	820	or I<none>, there is no in-between, so monitoring single processes is
760	difficult to implement. Monitoring in AEMP is more flexible than in	821	difficult to implement. Monitoring in AEMP is more flexible than in
761	Erlang, as one can choose between automatic kill, exit message or callback	822	Erlang, as one can choose between automatic kill, exit message or callback
762	on a per-process basis.	823	on a per-process basis.
763		824
764	=item * Erlang has different semantics for monitoring and linking, AEMP has the same.	825	=item * Erlang tries to hide remote/local connections, AEMP does not.
765		826
766	Monitoring in Erlang is not an indicator of process death/crashes,	827	Monitoring in Erlang is not an indicator of process death/crashes,
767	as linking is (except linking is unreliable in Erlang). In AEMP, the	828	as linking is (except linking is unreliable in Erlang).
768	semantics of monitoring and linking are identical, linking is simply	829
769	two-way monitoring with automatic kill.	830	In AEMP, you don't "look up" registered port names or send to named ports
		831	that might or might not be persistent. Instead, you normally spawn a port
		832	on the remote node. The init function monitors the you, and you monitor
		833	the remote port. Since both monitors are local to the node, they are much
		834	more reliable.
		835
		836	This also saves round-trips and avoids sending messages to the wrong port
		837	(hard to do in Erlang).
		838
		839	=back
		840
		841	=head1 RATIONALE
		842
		843	=over 4
		844
		845	=item Why strings for ports and noderefs, why not objects?
		846
		847	We considered "objects", but found that the actual number of methods
		848	thatc an be called are very low. Since port IDs and noderefs travel over
		849	the network frequently, the serialising/deserialising would add lots of
		850	overhead, as well as having to keep a proxy object.
		851
		852	Strings can easily be printed, easily serialised etc. and need no special
		853	procedures to be "valid".
		854
		855	And a a miniport consists of a single closure stored in a global hash - it
		856	can't become much cheaper.
		857
		858	=item Why favour JSON, why not real serialising format such as Storable?
		859
		860	In fact, any AnyEvent::MP node will happily accept Storable as framing
		861	format, but currently there is no way to make a node use Storable by
		862	default.
		863
		864	The default framing protocol is JSON because a) JSON::XS is many times
		865	faster for small messages and b) most importantly, after years of
		866	experience we found that object serialisation is causing more problems
		867	than it gains: Just like function calls, objects simply do not travel
		868	easily over the network, mostly because they will always be a copy, so you
		869	always have to re-think your design.
		870
		871	Keeping your messages simple, concentrating on data structures rather than
		872	objects, will keep your messages clean, tidy and efficient.
770		873
771	=back	874	=back
772		875
773	=head1 SEE ALSO	876	=head1 SEE ALSO
774		877

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Revision 1.53 by root, Fri Aug 14 15:31:21 2009 UTC