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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.22 by root, Tue Aug 4 18:33:30 2009 UTC vs.
Revision 1.34 by root, Wed Aug 5 23:50:46 2009 UTC

…		…
30	This module (-family) implements a simple message passing framework.	30	This module (-family) implements a simple message passing framework.
31		31
32	Despite its simplicity, you can securely message other processes running	32	Despite its simplicity, you can securely message other processes running
33	on the same or other hosts.	33	on the same or other hosts.
34		34
		35	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
		36	manual page.
		37
35	At the moment, this module family is severly brokena nd underdocumented,	38	At the moment, this module family is severly broken and underdocumented,
36	so do not use. This was uploaded mainly to reserve the CPAN namespace -	39	so do not use. This was uploaded mainly to reserve the CPAN namespace -
37	stay tuned!	40	stay tuned! The basic API should be finished, however.
38		41
39	=head1 CONCEPTS	42	=head1 CONCEPTS
40		43
41	=over 4	44	=over 4
42		45
43	=item port	46	=item port
44		47
45	A port is something you can send messages to with the C<snd> function, and	48	A port is something you can send messages to (with the C<snd> function).
46	you can register C<rcv> handlers with. All C<rcv> handlers will receive	49
47	messages they match, messages will not be queued.	50	Some ports allow you to register C<rcv> handlers that can match specific
		51	messages. All C<rcv> handlers will receive messages they match, messages
		52	will not be queued.
48		53
49	=item port id - C<noderef#portname>	54	=item port id - C<noderef#portname>
50		55
51	A port id is always the noderef, a hash-mark (C<#>) as separator, followed	56	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as
52	by a port name (a printable string of unspecified format).	57	separator, and a port name (a printable string of unspecified format). An
		58	exception is the the node port, whose ID is identical to its node
		59	reference.
53		60
54	=item node	61	=item node
55		62
56	A node is a single process containing at least one port - the node	63	A node is a single process containing at least one port - the node
57	port. You can send messages to node ports to let them create new ports,	64	port. You can send messages to node ports to find existing ports or to
58	among other things.	65	create new ports, among other things.
59		66
60	Initially, nodes are either private (single-process only) or hidden	67	Nodes are either private (single-process only), slaves (connected to a
61	(connected to a master node only). Only when they epxlicitly "become	68	master node only) or public nodes (connectable from unrelated nodes).
62	public" can you send them messages from unrelated other nodes.
63		69
64	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	70	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>
65		71
66	A noderef is a string that either uniquely identifies a given node (for	72	A node reference is a string that either simply identifies the node (for
67	private and hidden nodes), or contains a recipe on how to reach a given	73	private and slave nodes), or contains a recipe on how to reach a given
68	node (for public nodes).	74	node (for public nodes).
69		75
		76	This recipe is simply a comma-separated list of C<address:port> pairs (for
		77	TCP/IP, other protocols might look different).
		78
		79	Node references come in two flavours: resolved (containing only numerical
		80	addresses) or unresolved (where hostnames are used instead of addresses).
		81
		82	Before using an unresolved node reference in a message you first have to
		83	resolve it.
		84
70	=back	85	=back
71		86
72	=head1 VARIABLES/FUNCTIONS	87	=head1 VARIABLES/FUNCTIONS
73		88
74	=over 4	89	=over 4
…		…
85		100
86	use AE ();	101	use AE ();
87		102
88	use base "Exporter";	103	use base "Exporter";
89		104
90	our $VERSION = '0.02';	105	our $VERSION = '0.1';
91	our @EXPORT = qw(	106	our @EXPORT = qw(
92	NODE $NODE *SELF node_of _any_	107	NODE $NODE *SELF node_of _any_
93	become_slave become_public	108	resolve_node initialise_node
94	snd rcv mon kil reg psub	109	snd rcv mon kil reg psub
95	port	110	port
96	);	111	);
97		112
98	our $SELF;	113	our $SELF;
…		…
108	The C<NODE> function returns, and the C<$NODE> variable contains	123	The C<NODE> function returns, and the C<$NODE> variable contains
109	the noderef of the local node. The value is initialised by a call	124	the noderef of the local node. The value is initialised by a call
110	to C<become_public> or C<become_slave>, after which all local port	125	to C<become_public> or C<become_slave>, after which all local port
111	identifiers become invalid.	126	identifiers become invalid.
112		127
113	=item $noderef = node_of $portid	128	=item $noderef = node_of $port
114		129
115	Extracts and returns the noderef from a portid or a noderef.	130	Extracts and returns the noderef from a portid or a noderef.
		131
		132	=item initialise_node $noderef, $seednode, $seednode...
		133
		134	=item initialise_node "slave/", $master, $master...
		135
		136	Before a node can talk to other nodes on the network it has to initialise
		137	itself - the minimum a node needs to know is it's own name, and optionally
		138	it should know the noderefs of some other nodes in the network.
		139
		140	This function initialises a node - it must be called exactly once (or
		141	never) before calling other AnyEvent::MP functions.
		142
		143	All arguments are noderefs, which can be either resolved or unresolved.
		144
		145	There are two types of networked nodes, public nodes and slave nodes:
		146
		147	=over 4
		148
		149	=item public nodes
		150
		151	For public nodes, C<$noderef> must either be a (possibly unresolved)
		152	noderef, in which case it will be resolved, or C<undef> (or missing), in
		153	which case the noderef will be guessed.
		154
		155	Afterwards, the node will bind itself on all endpoints and try to connect
		156	to all additional C<$seednodes> that are specified. Seednodes are optional
		157	and can be used to quickly bootstrap the node into an existing network.
		158
		159	=item slave nodes
		160
		161	When the C<$noderef> is the special string C<slave/>, then the node will
		162	become a slave node. Slave nodes cannot be contacted from outside and will
		163	route most of their traffic to the master node that they attach to.
		164
		165	At least one additional noderef is required: The node will try to connect
		166	to all of them and will become a slave attached to the first node it can
		167	successfully connect to.
		168
		169	=back
		170
		171	This function will block until all nodes have been resolved and, for slave
		172	nodes, until it has successfully established a connection to a master
		173	server.
		174
		175	Example: become a public node listening on the default node.
		176
		177	initialise_node;
		178
		179	Example: become a public node, and try to contact some well-known master
		180	servers to become part of the network.
		181
		182	initialise_node undef, "master1", "master2";
		183
		184	Example: become a public node listening on port C<4041>.
		185
		186	initialise_node 4041;
		187
		188	Example: become a public node, only visible on localhost port 4044.
		189
		190	initialise_node "locahost:4044";
		191
		192	Example: become a slave node to any of the specified master servers.
		193
		194	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
		195
		196	=item $cv = resolve_node $noderef
		197
		198	Takes an unresolved node reference that may contain hostnames and
		199	abbreviated IDs, resolves all of them and returns a resolved node
		200	reference.
		201
		202	In addition to C<address:port> pairs allowed in resolved noderefs, the
		203	following forms are supported:
		204
		205	=over 4
		206
		207	=item the empty string
		208
		209	An empty-string component gets resolved as if the default port (4040) was
		210	specified.
		211
		212	=item naked port numbers (e.g. C<1234>)
		213
		214	These are resolved by prepending the local nodename and a colon, to be
		215	further resolved.
		216
		217	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
		218
		219	These are resolved by using AnyEvent::DNS to resolve them, optionally
		220	looking up SRV records for the C<aemp=4040> port, if no port was
		221	specified.
		222
		223	=back
116		224
117	=item $SELF	225	=item $SELF
118		226
119	Contains the current port id while executing C<rcv> callbacks or C<psub>	227	Contains the current port id while executing C<rcv> callbacks or C<psub>
120	blocks.	228	blocks.
…		…
123		231
124	Due to some quirks in how perl exports variables, it is impossible to	232	Due to some quirks in how perl exports variables, it is impossible to
125	just export C<$SELF>, all the symbols called C<SELF> are exported by this	233	just export C<$SELF>, all the symbols called C<SELF> are exported by this
126	module, but only C<$SELF> is currently used.	234	module, but only C<$SELF> is currently used.
127		235
128	=item snd $portid, type => @data	236	=item snd $port, type => @data
129		237
130	=item snd $portid, @msg	238	=item snd $port, @msg
131		239
132	Send the given message to the given port ID, which can identify either	240	Send the given message to the given port ID, which can identify either
133	a local or a remote port, and can be either a string or soemthignt hat	241	a local or a remote port, and can be either a string or soemthignt hat
134	stringifies a sa port ID (such as a port object :).	242	stringifies a sa port ID (such as a port object :).
135		243
…		…
145	JSON is used, then only strings, numbers and arrays and hashes consisting	253	JSON is used, then only strings, numbers and arrays and hashes consisting
146	of those are allowed (no objects). When Storable is used, then anything	254	of those are allowed (no objects). When Storable is used, then anything
147	that Storable can serialise and deserialise is allowed, and for the local	255	that Storable can serialise and deserialise is allowed, and for the local
148	node, anything can be passed.	256	node, anything can be passed.
149		257
150	=item kil $portid[, @reason]
151
152	Kill the specified port with the given C<@reason>.
153
154	If no C<@reason> is specified, then the port is killed "normally" (linked
155	ports will not be kileld, or even notified).
156
157	Otherwise, linked ports get killed with the same reason (second form of
158	C<mon>, see below).
159
160	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
161	will be reported as reason C<< die => $@ >>.
162
163	Transport/communication errors are reported as C<< transport_error =>
164	$message >>.
165
166	=item $guard = mon $portid, $cb->(@reason)
167
168	=item $guard = mon $portid, $otherport
169
170	=item $guard = mon $portid, $otherport, @msg
171
172	Monitor the given port and do something when the port is killed.
173
174	In the first form, the callback is simply called with any number
175	of C<@reason> elements (no @reason means that the port was deleted
176	"normally"). Note also that I<< the callback B<must> never die >>, so use
177	C<eval> if unsure.
178
179	In the second form, the other port will be C<kil>'ed with C<@reason>, iff
180	a @reason was specified, i.e. on "normal" kils nothing happens, while
181	under all other conditions, the other port is killed with the same reason.
182
183	In the last form, a message of the form C<@msg, @reason> will be C<snd>.
184
185	Example: call a given callback when C<$port> is killed.
186
187	mon $port, sub { warn "port died because of <@_>\n" };
188
189	Example: kill ourselves when C<$port> is killed abnormally.
190
191	mon $port, $self;
192
193	Example: send us a restart message another C<$port> is killed.
194
195	mon $port, $self => "restart";
196
197	=cut
198
199	sub mon {
200	my ($noderef, $port, $cb) = ((split /#/, shift, 2), shift);
201
202	my $node = $NODE{$noderef} \|\| add_node $noderef;
203
204	#TODO: ports must not be references
205	if (!ref $cb or "AnyEvent::MP::Port" eq ref $cb) {
206	if (@_) {
207	# send a kill info message
208	my (@msg) = ($cb, @_);
209	$cb = sub { snd @msg, @_ };
210	} else {
211	# simply kill other port
212	my $port = $cb;
213	$cb = sub { kil $port, @_ if @_ };
214	}
215	}
216
217	$node->monitor ($port, $cb);
218
219	defined wantarray
220	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
221	}
222
223	=item $guard = mon_guard $port, $ref, $ref...
224
225	Monitors the given C<$port> and keeps the passed references. When the port
226	is killed, the references will be freed.
227
228	Optionally returns a guard that will stop the monitoring.
229
230	This function is useful when you create e.g. timers or other watchers and
231	want to free them when the port gets killed:
232
233	$port->rcv (start => sub {
234	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
235	undef $timer if 0.9 < rand;
236	});
237	});
238
239	=cut
240
241	sub mon_guard {
242	my ($port, @refs) = @_;
243
244	mon $port, sub { 0 && @refs }
245	}
246
247	=item $local_port = port	258	=item $local_port = port
248		259
249	Create a new local port object that supports message matching.	260	Create a new local port object that can be used either as a pattern
		261	matching port ("full port") or a single-callback port ("miniport"),
		262	depending on how C<rcv> callbacks are bound to the object.
250		263
251	=item $portid = port { my @msg = @_; $finished }	264	=item $port = port { my @msg = @_; $finished }
252		265
253	Creates a "mini port", that is, a very lightweight port without any	266	Creates a "miniport", that is, a very lightweight port without any pattern
254	pattern matching behind it, and returns its ID.	267	matching behind it, and returns its ID. Semantically the same as creating
		268	a port and calling C<rcv $port, $callback> on it.
255		269
256	The block will be called for every message received on the port. When the	270	The block will be called for every message received on the port. When the
257	callback returns a true value its job is considered "done" and the port	271	callback returns a true value its job is considered "done" and the port
258	will be destroyed. Otherwise it will stay alive.	272	will be destroyed. Otherwise it will stay alive.
259		273
260	The message will be passed as-is, no extra argument (i.e. no port id) will	274	The message will be passed as-is, no extra argument (i.e. no port id) will
261	be passed to the callback.	275	be passed to the callback.
262		276
263	If you need the local port id in the callback, this works nicely:	277	If you need the local port id in the callback, this works nicely:
264		278
265	my $port; $port = miniport {	279	my $port; $port = port {
266	snd $otherport, reply => $port;	280	snd $otherport, reply => $port;
267	};	281	};
268		282
269	=cut	283	=cut
		284
		285	sub rcv($@);
270		286
271	sub port(;&) {	287	sub port(;&) {
272	my $id = "$UNIQ." . $ID++;	288	my $id = "$UNIQ." . $ID++;
273	my $port = "$NODE#$id";	289	my $port = "$NODE#$id";
274		290
275	if (@_) {	291	if (@_) {
		292	rcv $port, shift;
		293	} else {
		294	$PORT{$id} = sub { }; # nop
		295	}
		296
		297	$port
		298	}
		299
		300	=item reg $port, $name
		301
		302	Registers the given port under the name C<$name>. If the name already
		303	exists it is replaced.
		304
		305	A port can only be registered under one well known name.
		306
		307	A port automatically becomes unregistered when it is killed.
		308
		309	=cut
		310
		311	sub reg(@) {
		312	my ($port, $name) = @_;
		313
		314	$REG{$name} = $port;
		315	}
		316
		317	=item rcv $port, $callback->(@msg)
		318
		319	Replaces the callback on the specified miniport (after converting it to
		320	one if required).
		321
		322	=item rcv $port, tagstring => $callback->(@msg), ...
		323
		324	=item rcv $port, $smartmatch => $callback->(@msg), ...
		325
		326	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
		327
		328	Register callbacks to be called on matching messages on the given full
		329	port (after converting it to one if required).
		330
		331	The callback has to return a true value when its work is done, after
		332	which is will be removed, or a false value in which case it will stay
		333	registered.
		334
		335	The global C<$SELF> (exported by this module) contains C<$port> while
		336	executing the callback.
		337
		338	Runtime errors wdurign callback execution will result in the port being
		339	C<kil>ed.
		340
		341	If the match is an array reference, then it will be matched against the
		342	first elements of the message, otherwise only the first element is being
		343	matched.
		344
		345	Any element in the match that is specified as C<_any_> (a function
		346	exported by this module) matches any single element of the message.
		347
		348	While not required, it is highly recommended that the first matching
		349	element is a string identifying the message. The one-string-only match is
		350	also the most efficient match (by far).
		351
		352	=cut
		353
		354	sub rcv($@) {
		355	my $port = shift;
		356	my ($noderef, $portid) = split /#/, $port, 2;
		357
		358	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
		359	or Carp::croak "$port: rcv can only be called on local ports, caught";
		360
		361	if (@_ == 1) {
276	my $cb = shift;	362	my $cb = shift;
		363	delete $PORT_DATA{$portid};
277	$PORT{$id} = sub {	364	$PORT{$portid} = sub {
278	local $SELF = $port;	365	local $SELF = $port;
279	eval {	366	eval {
280	&$cb	367	&$cb
281	and kil $id;	368	and kil $port;
282	};	369	};
283	_self_die if $@;	370	_self_die if $@;
284	};	371	};
285	} else {	372	} else {
		373	my $self = $PORT_DATA{$portid} \|\|= do {
286	my $self = bless {	374	my $self = bless {
287	id => "$NODE#$id",	375	id => $port,
288	}, "AnyEvent::MP::Port";	376	}, "AnyEvent::MP::Port";
289		377
290	$PORT_DATA{$id} = $self;
291	$PORT{$id} = sub {	378	$PORT{$portid} = sub {
292	local $SELF = $port;	379	local $SELF = $port;
293		380
294	eval {	381	eval {
295	for (@{ $self->{rc0}{$_[0]} }) {	382	for (@{ $self->{rc0}{$_[0]} }) {
296	$_ && &{$_->[0]}	383	$_ && &{$_->[0]}
297	&& undef $_;	384	&& undef $_;
298	}	385	}
299		386
300	for (@{ $self->{rcv}{$_[0]} }) {	387	for (@{ $self->{rcv}{$_[0]} }) {
301	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]	388	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
302	&& &{$_->[0]}	389	&& &{$_->[0]}
303	&& undef $_;	390	&& undef $_;
304	}	391	}
305		392
306	for (@{ $self->{any} }) {	393	for (@{ $self->{any} }) {
307	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]	394	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
308	&& &{$_->[0]}	395	&& &{$_->[0]}
309	&& undef $_;	396	&& undef $_;
		397	}
310	}	398	};
		399	_self_die if $@;
311	};	400	};
312	_self_die if $@;	401
		402	$self
313	};	403	};
314	}
315		404
316	$port
317	}
318
319	=item reg $portid, $name
320
321	Registers the given port under the name C<$name>. If the name already
322	exists it is replaced.
323
324	A port can only be registered under one well known name.
325
326	A port automatically becomes unregistered when it is killed.
327
328	=cut
329
330	sub reg(@) {
331	my ($portid, $name) = @_;
332
333	$REG{$name} = $portid;
334	}
335
336	=item rcv $portid, tagstring => $callback->(@msg), ...
337
338	=item rcv $portid, $smartmatch => $callback->(@msg), ...
339
340	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
341
342	Register callbacks to be called on matching messages on the given port.
343
344	The callback has to return a true value when its work is done, after
345	which is will be removed, or a false value in which case it will stay
346	registered.
347
348	The global C<$SELF> (exported by this module) contains C<$portid> while
349	executing the callback.
350
351	Runtime errors wdurign callback execution will result in the port being
352	C<kil>ed.
353
354	If the match is an array reference, then it will be matched against the
355	first elements of the message, otherwise only the first element is being
356	matched.
357
358	Any element in the match that is specified as C<_any_> (a function
359	exported by this module) matches any single element of the message.
360
361	While not required, it is highly recommended that the first matching
362	element is a string identifying the message. The one-string-only match is
363	also the most efficient match (by far).
364
365	=cut
366
367	sub rcv($@) {
368	my ($noderef, $port) = split /#/, shift, 2;
369
370	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
371	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";
372
373	my $self = $PORT_DATA{$port}
374	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
375
376	"AnyEvent::MP::Port" eq ref $self	405	"AnyEvent::MP::Port" eq ref $self
377	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";	406	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
378		407
379	while (@_) {	408	while (@_) {
380	my ($match, $cb) = splice @_, 0, 2;	409	my ($match, $cb) = splice @_, 0, 2;
381		410
382	if (!ref $match) {	411	if (!ref $match) {
383	push @{ $self->{rc0}{$match} }, [$cb];	412	push @{ $self->{rc0}{$match} }, [$cb];
384	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {	413	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
385	my ($type, @match) = @$match;	414	my ($type, @match) = @$match;
386	@match	415	@match
387	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]	416	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
388	: push @{ $self->{rc0}{$match->[0]} }, [$cb];	417	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
389	} else {	418	} else {
390	push @{ $self->{any} }, [$cb, $match];	419	push @{ $self->{any} }, [$cb, $match];
		420	}
391	}	421	}
392	}	422	}
		423
		424	$port
393	}	425	}
394		426
395	=item $closure = psub { BLOCK }	427	=item $closure = psub { BLOCK }
396		428
397	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	429	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
…		…
428	$res	460	$res
429	}	461	}
430	}	462	}
431	}	463	}
432		464
433	=back	465	=item $guard = mon $port, $cb->(@reason)
434		466
435	=head1 FUNCTIONS FOR NODES	467	=item $guard = mon $port, $otherport
436		468
437	=over 4	469	=item $guard = mon $port, $otherport, @msg
438		470
439	=item become_public endpoint...	471	Monitor the given port and do something when the port is killed.
440		472
441	Tells the node to become a public node, i.e. reachable from other nodes.	473	In the first form, the callback is simply called with any number
		474	of C<@reason> elements (no @reason means that the port was deleted
		475	"normally"). Note also that I<< the callback B<must> never die >>, so use
		476	C<eval> if unsure.
442		477
443	If no arguments are given, or the first argument is C<undef>, then	478	In the second form, the other port will be C<kil>'ed with C<@reason>, iff
444	AnyEvent::MP tries to bind on port C<4040> on all IP addresses that the	479	a @reason was specified, i.e. on "normal" kils nothing happens, while
445	local nodename resolves to.	480	under all other conditions, the other port is killed with the same reason.
446		481
447	Otherwise the first argument must be an array-reference with transport	482	In the last form, a message of the form C<@msg, @reason> will be C<snd>.
448	endpoints ("ip:port", "hostname:port") or port numbers (in which case the
449	local nodename is used as hostname). The endpoints are all resolved and
450	will become the node reference.
451		483
		484	Example: call a given callback when C<$port> is killed.
		485
		486	mon $port, sub { warn "port died because of <@_>\n" };
		487
		488	Example: kill ourselves when C<$port> is killed abnormally.
		489
		490	mon $port, $self;
		491
		492	Example: send us a restart message another C<$port> is killed.
		493
		494	mon $port, $self => "restart";
		495
452	=cut	496	=cut
		497
		498	sub mon {
		499	my ($noderef, $port) = split /#/, shift, 2;
		500
		501	my $node = $NODE{$noderef} \|\| add_node $noderef;
		502
		503	my $cb = shift;
		504
		505	unless (ref $cb) {
		506	if (@_) {
		507	# send a kill info message
		508	my (@msg) = ($cb, @_);
		509	$cb = sub { snd @msg, @_ };
		510	} else {
		511	# simply kill other port
		512	my $port = $cb;
		513	$cb = sub { kil $port, @_ if @_ };
		514	}
		515	}
		516
		517	$node->monitor ($port, $cb);
		518
		519	defined wantarray
		520	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
		521	}
		522
		523	=item $guard = mon_guard $port, $ref, $ref...
		524
		525	Monitors the given C<$port> and keeps the passed references. When the port
		526	is killed, the references will be freed.
		527
		528	Optionally returns a guard that will stop the monitoring.
		529
		530	This function is useful when you create e.g. timers or other watchers and
		531	want to free them when the port gets killed:
		532
		533	$port->rcv (start => sub {
		534	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
		535	undef $timer if 0.9 < rand;
		536	});
		537	});
		538
		539	=cut
		540
		541	sub mon_guard {
		542	my ($port, @refs) = @_;
		543
		544	mon $port, sub { 0 && @refs }
		545	}
		546
		547	=item lnk $port1, $port2
		548
		549	Link two ports. This is simply a shorthand for:
		550
		551	mon $port1, $port2;
		552	mon $port2, $port1;
		553
		554	It means that if either one is killed abnormally, the other one gets
		555	killed as well.
		556
		557	=item kil $port[, @reason]
		558
		559	Kill the specified port with the given C<@reason>.
		560
		561	If no C<@reason> is specified, then the port is killed "normally" (linked
		562	ports will not be kileld, or even notified).
		563
		564	Otherwise, linked ports get killed with the same reason (second form of
		565	C<mon>, see below).
		566
		567	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		568	will be reported as reason C<< die => $@ >>.
		569
		570	Transport/communication errors are reported as C<< transport_error =>
		571	$message >>.
453		572
454	=back	573	=back
455		574
456	=head1 NODE MESSAGES	575	=head1 NODE MESSAGES
457		576
458	Nodes understand the following messages sent to them. Many of them take	577	Nodes understand the following messages sent to them. Many of them take
459	arguments called C<@reply>, which will simply be used to compose a reply	578	arguments called C<@reply>, which will simply be used to compose a reply
460	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and	579	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
461	the remaining arguments are simply the message data.	580	the remaining arguments are simply the message data.
462		581
		582	While other messages exist, they are not public and subject to change.
		583
463	=over 4	584	=over 4
464		585
465	=cut	586	=cut
466		587
467	=item lookup => $name, @reply	588	=item lookup => $name, @reply
…		…
495	snd $NODE, time => $myport, timereply => 1, 2;	616	snd $NODE, time => $myport, timereply => 1, 2;
496	# => snd $myport, timereply => 1, 2, <time>	617	# => snd $myport, timereply => 1, 2, <time>
497		618
498	=back	619	=back
499		620
		621	=head1 AnyEvent::MP vs. Distributed Erlang
		622
		623	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node
		624	== aemp node, erlang process == aemp port), so many of the documents and
		625	programming techniques employed by erlang apply to AnyEvent::MP. Here is a
		626	sample:
		627
		628	http://www.erlang.se/doc/programming_rules.shtml
		629	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		630	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6
		631	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		632
		633	Despite the similarities, there are also some important differences:
		634
		635	=over 4
		636
		637	=item * Node references contain the recipe on how to contact them.
		638
		639	Erlang relies on special naming and DNS to work everywhere in the
		640	same way. AEMP relies on each node knowing it's own address(es), with
		641	convenience functionality.
		642
		643	This means that AEMP requires a less tightly controlled environment at the
		644	cost of longer node references and a slightly higher management overhead.
		645
		646	=item * Erlang uses processes and a mailbox, AEMP does not queue.
		647
		648	Erlang uses processes that selctively receive messages, and therefore
		649	needs a queue. AEMP is event based, queuing messages would serve no useful
		650	purpose.
		651
		652	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).
		653
		654	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
		655
		656	Sending messages in erlang is synchronous and blocks the process. AEMP
		657	sends are immediate, connection establishment is handled in the
		658	background.
		659
		660	=item * Erlang can silently lose messages, AEMP cannot.
		661
		662	Erlang makes few guarantees on messages delivery - messages can get lost
		663	without any of the processes realising it (i.e. you send messages a, b,
		664	and c, and the other side only receives messages a and c).
		665
		666	AEMP guarantees correct ordering, and the guarantee that there are no
		667	holes in the message sequence.
		668
		669	=item * In erlang, processes can be declared dead and later be found to be
		670	alive.
		671
		672	In erlang it can happen that a monitored process is declared dead and
		673	linked processes get killed, but later it turns out that the process is
		674	still alive - and can receive messages.
		675
		676	In AEMP, when port monitoring detects a port as dead, then that port will
		677	eventually be killed - it cannot happen that a node detects a port as dead
		678	and then later sends messages to it, finding it is still alive.
		679
		680	=item * Erlang can send messages to the wrong port, AEMP does not.
		681
		682	In erlang it is quite possible that a node that restarts reuses a process
		683	ID known to other nodes for a completely different process, causing
		684	messages destined for that process to end up in an unrelated process.
		685
		686	AEMP never reuses port IDs, so old messages or old port IDs floating
		687	around in the network will not be sent to an unrelated port.
		688
		689	=item * Erlang uses unprotected connections, AEMP uses secure
		690	authentication and can use TLS.
		691
		692	AEMP can use a proven protocol - SSL/TLS - to protect connections and
		693	securely authenticate nodes.
		694
		695	=item * The AEMP protocol is optimised for both text-based and binary
		696	communications.
		697
		698	The AEMP protocol, unlike the erlang protocol, supports both
		699	language-independent text-only protocols (good for debugging) and binary,
		700	language-specific serialisers (e.g. Storable).
		701
		702	It has also been carefully designed to be implementable in other languages
		703	with a minimum of work while gracefully degrading fucntionality to make the
		704	protocol simple.
		705
		706	=back
		707
500	=head1 SEE ALSO	708	=head1 SEE ALSO
501		709
502	L<AnyEvent>.	710	L<AnyEvent>.
503		711
504	=head1 AUTHOR	712	=head1 AUTHOR

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Revision 1.34 by root, Wed Aug 5 23:50:46 2009 UTC