[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 1.37 by root, Fri Aug 7 16:47:23 2009 UTC

…		…
23		23
24	# more, smarter, matches (_any_ is exported by this module)	24	# more, smarter, matches (_any_ is exported by this module)
25	rcv $port, [child_died => $pid] => sub { ...	25	rcv $port, [child_died => $pid] => sub { ...
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
27		27
		28	# monitoring
		29	mon $port, $cb->(@msg) # callback is invoked on death
		30	mon $port, $otherport # kill otherport on abnormal death
		31	mon $port, $otherport, @msg # send message on death
		32
28	=head1 DESCRIPTION	33	=head1 DESCRIPTION
29		34
30	This module (-family) implements a simple message passing framework.	35	This module (-family) implements a simple message passing framework.
31		36
32	Despite its simplicity, you can securely message other processes running	37	Despite its simplicity, you can securely message other processes running
33	on the same or other hosts.	38	on the same or other hosts.
34		39
		40	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
		41	manual page.
		42
35	At the moment, this module family is severly brokena nd underdocumented,	43	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 -	44	so do not use. This was uploaded mainly to reserve the CPAN namespace -
37	stay tuned!	45	stay tuned! The basic API should be finished, however.
38		46
39	=head1 CONCEPTS	47	=head1 CONCEPTS
40		48
41	=over 4	49	=over 4
42		50
43	=item port	51	=item port
44		52
45	A port is something you can send messages to with the C<snd> function, and	53	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	54
47	messages they match, messages will not be queued.	55	Some ports allow you to register C<rcv> handlers that can match specific
		56	messages. All C<rcv> handlers will receive messages they match, messages
		57	will not be queued.
48		58
49	=item port id - C<noderef#portname>	59	=item port id - C<noderef#portname>
50		60
51	A port id is always the noderef, a hash-mark (C<#>) as separator, followed	61	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).	62	separator, and a port name (a printable string of unspecified format). An
		63	exception is the the node port, whose ID is identical to its node
		64	reference.
53		65
54	=item node	66	=item node
55		67
56	A node is a single process containing at least one port - the node	68	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,	69	port. You can send messages to node ports to find existing ports or to
58	among other things.	70	create new ports, among other things.
59		71
60	Initially, nodes are either private (single-process only) or hidden	72	Nodes are either private (single-process only), slaves (connected to a
61	(connected to a master node only). Only when they epxlicitly "become	73	master node only) or public nodes (connectable from unrelated nodes).
62	public" can you send them messages from unrelated other nodes.
63		74
64	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	75	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>
65		76
66	A noderef is a string that either uniquely identifies a given node (for	77	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	78	private and slave nodes), or contains a recipe on how to reach a given
68	node (for public nodes).	79	node (for public nodes).
69		80
		81	This recipe is simply a comma-separated list of C<address:port> pairs (for
		82	TCP/IP, other protocols might look different).
		83
		84	Node references come in two flavours: resolved (containing only numerical
		85	addresses) or unresolved (where hostnames are used instead of addresses).
		86
		87	Before using an unresolved node reference in a message you first have to
		88	resolve it.
		89
70	=back	90	=back
71		91
72	=head1 VARIABLES/FUNCTIONS	92	=head1 VARIABLES/FUNCTIONS
73		93
74	=over 4	94	=over 4
…		…
85		105
86	use AE ();	106	use AE ();
87		107
88	use base "Exporter";	108	use base "Exporter";
89		109
90	our $VERSION = '0.02';	110	our $VERSION = '0.1';
91	our @EXPORT = qw(	111	our @EXPORT = qw(
92	NODE $NODE *SELF node_of _any_	112	NODE $NODE *SELF node_of _any_
93	become_slave become_public	113	resolve_node initialise_node
94	snd rcv mon kil reg psub	114	snd rcv mon kil reg psub
95	port	115	port
96	);	116	);
97		117
98	our $SELF;	118	our $SELF;
…		…
108	The C<NODE> function returns, and the C<$NODE> variable contains	128	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	129	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	130	to C<become_public> or C<become_slave>, after which all local port
111	identifiers become invalid.	131	identifiers become invalid.
112		132
113	=item $noderef = node_of $portid	133	=item $noderef = node_of $port
114		134
115	Extracts and returns the noderef from a portid or a noderef.	135	Extracts and returns the noderef from a portid or a noderef.
		136
		137	=item initialise_node $noderef, $seednode, $seednode...
		138
		139	=item initialise_node "slave/", $master, $master...
		140
		141	Before a node can talk to other nodes on the network it has to initialise
		142	itself - the minimum a node needs to know is it's own name, and optionally
		143	it should know the noderefs of some other nodes in the network.
		144
		145	This function initialises a node - it must be called exactly once (or
		146	never) before calling other AnyEvent::MP functions.
		147
		148	All arguments are noderefs, which can be either resolved or unresolved.
		149
		150	There are two types of networked nodes, public nodes and slave nodes:
		151
		152	=over 4
		153
		154	=item public nodes
		155
		156	For public nodes, C<$noderef> must either be a (possibly unresolved)
		157	noderef, in which case it will be resolved, or C<undef> (or missing), in
		158	which case the noderef will be guessed.
		159
		160	Afterwards, the node will bind itself on all endpoints and try to connect
		161	to all additional C<$seednodes> that are specified. Seednodes are optional
		162	and can be used to quickly bootstrap the node into an existing network.
		163
		164	=item slave nodes
		165
		166	When the C<$noderef> is the special string C<slave/>, then the node will
		167	become a slave node. Slave nodes cannot be contacted from outside and will
		168	route most of their traffic to the master node that they attach to.
		169
		170	At least one additional noderef is required: The node will try to connect
		171	to all of them and will become a slave attached to the first node it can
		172	successfully connect to.
		173
		174	=back
		175
		176	This function will block until all nodes have been resolved and, for slave
		177	nodes, until it has successfully established a connection to a master
		178	server.
		179
		180	Example: become a public node listening on the default node.
		181
		182	initialise_node;
		183
		184	Example: become a public node, and try to contact some well-known master
		185	servers to become part of the network.
		186
		187	initialise_node undef, "master1", "master2";
		188
		189	Example: become a public node listening on port C<4041>.
		190
		191	initialise_node 4041;
		192
		193	Example: become a public node, only visible on localhost port 4044.
		194
		195	initialise_node "locahost:4044";
		196
		197	Example: become a slave node to any of the specified master servers.
		198
		199	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
		200
		201	=item $cv = resolve_node $noderef
		202
		203	Takes an unresolved node reference that may contain hostnames and
		204	abbreviated IDs, resolves all of them and returns a resolved node
		205	reference.
		206
		207	In addition to C<address:port> pairs allowed in resolved noderefs, the
		208	following forms are supported:
		209
		210	=over 4
		211
		212	=item the empty string
		213
		214	An empty-string component gets resolved as if the default port (4040) was
		215	specified.
		216
		217	=item naked port numbers (e.g. C<1234>)
		218
		219	These are resolved by prepending the local nodename and a colon, to be
		220	further resolved.
		221
		222	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
		223
		224	These are resolved by using AnyEvent::DNS to resolve them, optionally
		225	looking up SRV records for the C<aemp=4040> port, if no port was
		226	specified.
		227
		228	=back
116		229
117	=item $SELF	230	=item $SELF
118		231
119	Contains the current port id while executing C<rcv> callbacks or C<psub>	232	Contains the current port id while executing C<rcv> callbacks or C<psub>
120	blocks.	233	blocks.
…		…
123		236
124	Due to some quirks in how perl exports variables, it is impossible to	237	Due to some quirks in how perl exports variables, it is impossible to
125	just export C<$SELF>, all the symbols called C<SELF> are exported by this	238	just export C<$SELF>, all the symbols called C<SELF> are exported by this
126	module, but only C<$SELF> is currently used.	239	module, but only C<$SELF> is currently used.
127		240
128	=item snd $portid, type => @data	241	=item snd $port, type => @data
129		242
130	=item snd $portid, @msg	243	=item snd $port, @msg
131		244
132	Send the given message to the given port ID, which can identify either	245	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	246	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 :).	247	stringifies a sa port ID (such as a port object :).
135		248
…		…
145	JSON is used, then only strings, numbers and arrays and hashes consisting	258	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	259	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	260	that Storable can serialise and deserialise is allowed, and for the local
148	node, anything can be passed.	261	node, anything can be passed.
149		262
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	263	=item $local_port = port
248		264
249	Create a new local port object that supports message matching.	265	Create a new local port object that can be used either as a pattern
		266	matching port ("full port") or a single-callback port ("miniport"),
		267	depending on how C<rcv> callbacks are bound to the object.
250		268
251	=item $portid = port { my @msg = @_; $finished }	269	=item $port = port { my @msg = @_; $finished }
252		270
253	Creates a "mini port", that is, a very lightweight port without any	271	Creates a "miniport", that is, a very lightweight port without any pattern
254	pattern matching behind it, and returns its ID.	272	matching behind it, and returns its ID. Semantically the same as creating
		273	a port and calling C<rcv $port, $callback> on it.
255		274
256	The block will be called for every message received on the port. When the	275	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	276	callback returns a true value its job is considered "done" and the port
258	will be destroyed. Otherwise it will stay alive.	277	will be destroyed. Otherwise it will stay alive.
259		278
260	The message will be passed as-is, no extra argument (i.e. no port id) will	279	The message will be passed as-is, no extra argument (i.e. no port id) will
261	be passed to the callback.	280	be passed to the callback.
262		281
263	If you need the local port id in the callback, this works nicely:	282	If you need the local port id in the callback, this works nicely:
264		283
265	my $port; $port = miniport {	284	my $port; $port = port {
266	snd $otherport, reply => $port;	285	snd $otherport, reply => $port;
267	};	286	};
268		287
269	=cut	288	=cut
		289
		290	sub rcv($@);
270		291
271	sub port(;&) {	292	sub port(;&) {
272	my $id = "$UNIQ." . $ID++;	293	my $id = "$UNIQ." . $ID++;
273	my $port = "$NODE#$id";	294	my $port = "$NODE#$id";
274		295
275	if (@_) {	296	if (@_) {
		297	rcv $port, shift;
		298	} else {
		299	$PORT{$id} = sub { }; # nop
		300	}
		301
		302	$port
		303	}
		304
		305	=item reg $port, $name
		306
		307	=item reg $name
		308
		309	Registers the given port (or C<$SELF><<< if missing) under the name
		310	C<$name>. If the name already exists it is replaced.
		311
		312	A port can only be registered under one well known name.
		313
		314	A port automatically becomes unregistered when it is killed.
		315
		316	=cut
		317
		318	sub reg(@) {
		319	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
		320
		321	$REG{$_[0]} = $port;
		322	}
		323
		324	=item rcv $port, $callback->(@msg)
		325
		326	Replaces the callback on the specified miniport (after converting it to
		327	one if required).
		328
		329	=item rcv $port, tagstring => $callback->(@msg), ...
		330
		331	=item rcv $port, $smartmatch => $callback->(@msg), ...
		332
		333	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
		334
		335	Register callbacks to be called on matching messages on the given full
		336	port (after converting it to one if required) and return the port.
		337
		338	The callback has to return a true value when its work is done, after
		339	which is will be removed, or a false value in which case it will stay
		340	registered.
		341
		342	The global C<$SELF> (exported by this module) contains C<$port> while
		343	executing the callback.
		344
		345	Runtime errors wdurign callback execution will result in the port being
		346	C<kil>ed.
		347
		348	If the match is an array reference, then it will be matched against the
		349	first elements of the message, otherwise only the first element is being
		350	matched.
		351
		352	Any element in the match that is specified as C<_any_> (a function
		353	exported by this module) matches any single element of the message.
		354
		355	While not required, it is highly recommended that the first matching
		356	element is a string identifying the message. The one-string-only match is
		357	also the most efficient match (by far).
		358
		359	Example: create a port and bind receivers on it in one go.
		360
		361	my $port = rcv port,
		362	msg1 => sub { ...; 0 },
		363	msg2 => sub { ...; 0 },
		364	;
		365
		366	Example: create a port, bind receivers and send it in a message elsewhere
		367	in one go:
		368
		369	snd $otherport, reply =>
		370	rcv port,
		371	msg1 => sub { ...; 0 },
		372	...
		373	;
		374
		375	=cut
		376
		377	sub rcv($@) {
		378	my $port = shift;
		379	my ($noderef, $portid) = split /#/, $port, 2;
		380
		381	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
		382	or Carp::croak "$port: rcv can only be called on local ports, caught";
		383
		384	if (@_ == 1) {
276	my $cb = shift;	385	my $cb = shift;
		386	delete $PORT_DATA{$portid};
277	$PORT{$id} = sub {	387	$PORT{$portid} = sub {
278	local $SELF = $port;	388	local $SELF = $port;
279	eval {	389	eval {
280	&$cb	390	&$cb
281	and kil $id;	391	and kil $port;
282	};	392	};
283	_self_die if $@;	393	_self_die if $@;
284	};	394	};
285	} else {	395	} else {
		396	my $self = $PORT_DATA{$portid} \|\|= do {
286	my $self = bless {	397	my $self = bless {
287	id => "$NODE#$id",	398	id => $port,
288	}, "AnyEvent::MP::Port";	399	}, "AnyEvent::MP::Port";
289		400
290	$PORT_DATA{$id} = $self;
291	$PORT{$id} = sub {	401	$PORT{$portid} = sub {
292	local $SELF = $port;	402	local $SELF = $port;
293		403
294	eval {	404	eval {
295	for (@{ $self->{rc0}{$_[0]} }) {	405	for (@{ $self->{rc0}{$_[0]} }) {
296	$_ && &{$_->[0]}	406	$_ && &{$_->[0]}
297	&& undef $_;	407	&& undef $_;
298	}	408	}
299		409
300	for (@{ $self->{rcv}{$_[0]} }) {	410	for (@{ $self->{rcv}{$_[0]} }) {
301	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]	411	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
302	&& &{$_->[0]}	412	&& &{$_->[0]}
303	&& undef $_;	413	&& undef $_;
304	}	414	}
305		415
306	for (@{ $self->{any} }) {	416	for (@{ $self->{any} }) {
307	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]	417	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
308	&& &{$_->[0]}	418	&& &{$_->[0]}
309	&& undef $_;	419	&& undef $_;
		420	}
310	}	421	};
		422	_self_die if $@;
311	};	423	};
312	_self_die if $@;	424
		425	$self
313	};	426	};
314	}
315		427
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	428	"AnyEvent::MP::Port" eq ref $self
377	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";	429	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
378		430
379	while (@_) {	431	while (@_) {
380	my ($match, $cb) = splice @_, 0, 2;	432	my ($match, $cb) = splice @_, 0, 2;
381		433
382	if (!ref $match) {	434	if (!ref $match) {
383	push @{ $self->{rc0}{$match} }, [$cb];	435	push @{ $self->{rc0}{$match} }, [$cb];
384	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {	436	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
385	my ($type, @match) = @$match;	437	my ($type, @match) = @$match;
386	@match	438	@match
387	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]	439	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
388	: push @{ $self->{rc0}{$match->[0]} }, [$cb];	440	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
389	} else {	441	} else {
390	push @{ $self->{any} }, [$cb, $match];	442	push @{ $self->{any} }, [$cb, $match];
		443	}
391	}	444	}
392	}	445	}
		446
		447	$port
393	}	448	}
394		449
395	=item $closure = psub { BLOCK }	450	=item $closure = psub { BLOCK }
396		451
397	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	452	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
…		…
428	$res	483	$res
429	}	484	}
430	}	485	}
431	}	486	}
432		487
433	=back	488	=item $guard = mon $port, $cb->(@reason)
434		489
435	=head1 FUNCTIONS FOR NODES	490	=item $guard = mon $port, $rcvport
436		491
437	=over 4	492	=item $guard = mon $port
438		493
439	=item become_public endpoint...	494	=item $guard = mon $port, $rcvport, @msg
440		495
441	Tells the node to become a public node, i.e. reachable from other nodes.	496	Monitor the given port and do something when the port is killed, and
		497	optionally return a guard that can be used to stop monitoring again.
442		498
443	If no arguments are given, or the first argument is C<undef>, then	499	In the first form (callback), the callback is simply called with any
444	AnyEvent::MP tries to bind on port C<4040> on all IP addresses that the	500	number of C<@reason> elements (no @reason means that the port was deleted
445	local nodename resolves to.	501	"normally"). Note also that I<< the callback B<must> never die >>, so use
		502	C<eval> if unsure.
446		503
447	Otherwise the first argument must be an array-reference with transport	504	In the second form (another port given), the other port (C<$rcvport)
448	endpoints ("ip:port", "hostname:port") or port numbers (in which case the	505	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
449	local nodename is used as hostname). The endpoints are all resolved and	506	"normal" kils nothing happens, while under all other conditions, the other
450	will become the node reference.	507	port is killed with the same reason.
451		508
		509	The third form (kill self) is the same as the second form, except that
		510	C<$rvport> defaults to C<$SELF>.
		511
		512	In the last form (message), a message of the form C<@msg, @reason> will be
		513	C<snd>.
		514
		515	As a rule of thumb, monitoring requests should always monitor a port from
		516	a local port (or callback). The reason is that kill messages might get
		517	lost, just like any other message. Another less obvious reason is that
		518	even monitoring requests can get lost (for exmaple, when the connection
		519	to the other node goes down permanently). When monitoring a port locally
		520	these problems do not exist.
		521
		522	Example: call a given callback when C<$port> is killed.
		523
		524	mon $port, sub { warn "port died because of <@_>\n" };
		525
		526	Example: kill ourselves when C<$port> is killed abnormally.
		527
		528	mon $port;
		529
		530	Example: send us a restart message when another C<$port> is killed.
		531
		532	mon $port, $self => "restart";
		533
452	=cut	534	=cut
		535
		536	sub mon {
		537	my ($noderef, $port) = split /#/, shift, 2;
		538
		539	my $node = $NODE{$noderef} \|\| add_node $noderef;
		540
		541	my $cb = @_ ? $_[0] : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
		542
		543	unless (ref $cb) {
		544	if (@_) {
		545	# send a kill info message
		546	my (@msg) = @_;
		547	$cb = sub { snd @msg, @_ };
		548	} else {
		549	# simply kill other port
		550	my $port = $cb;
		551	$cb = sub { kil $port, @_ if @_ };
		552	}
		553	}
		554
		555	$node->monitor ($port, $cb);
		556
		557	defined wantarray
		558	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
		559	}
		560
		561	=item $guard = mon_guard $port, $ref, $ref...
		562
		563	Monitors the given C<$port> and keeps the passed references. When the port
		564	is killed, the references will be freed.
		565
		566	Optionally returns a guard that will stop the monitoring.
		567
		568	This function is useful when you create e.g. timers or other watchers and
		569	want to free them when the port gets killed:
		570
		571	$port->rcv (start => sub {
		572	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
		573	undef $timer if 0.9 < rand;
		574	});
		575	});
		576
		577	=cut
		578
		579	sub mon_guard {
		580	my ($port, @refs) = @_;
		581
		582	#TODO: mon-less form?
		583
		584	mon $port, sub { 0 && @refs }
		585	}
		586
		587	=item kil $port[, @reason]
		588
		589	Kill the specified port with the given C<@reason>.
		590
		591	If no C<@reason> is specified, then the port is killed "normally" (linked
		592	ports will not be kileld, or even notified).
		593
		594	Otherwise, linked ports get killed with the same reason (second form of
		595	C<mon>, see below).
		596
		597	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		598	will be reported as reason C<< die => $@ >>.
		599
		600	Transport/communication errors are reported as C<< transport_error =>
		601	$message >>.
453		602
454	=back	603	=back
455		604
456	=head1 NODE MESSAGES	605	=head1 NODE MESSAGES
457		606
458	Nodes understand the following messages sent to them. Many of them take	607	Nodes understand the following messages sent to them. Many of them take
459	arguments called C<@reply>, which will simply be used to compose a reply	608	arguments called C<@reply>, which will simply be used to compose a reply
460	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and	609	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
461	the remaining arguments are simply the message data.	610	the remaining arguments are simply the message data.
462		611
		612	While other messages exist, they are not public and subject to change.
		613
463	=over 4	614	=over 4
464		615
465	=cut	616	=cut
466		617
467	=item lookup => $name, @reply	618	=item lookup => $name, @reply
…		…
495	snd $NODE, time => $myport, timereply => 1, 2;	646	snd $NODE, time => $myport, timereply => 1, 2;
496	# => snd $myport, timereply => 1, 2, <time>	647	# => snd $myport, timereply => 1, 2, <time>
497		648
498	=back	649	=back
499		650
		651	=head1 AnyEvent::MP vs. Distributed Erlang
		652
		653	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
		654	== aemp node, Erlang process == aemp port), so many of the documents and
		655	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		656	sample:
		657
		658	http://www.Erlang.se/doc/programming_rules.shtml
		659	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		660	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		661	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		662
		663	Despite the similarities, there are also some important differences:
		664
		665	=over 4
		666
		667	=item * Node references contain the recipe on how to contact them.
		668
		669	Erlang relies on special naming and DNS to work everywhere in the
		670	same way. AEMP relies on each node knowing it's own address(es), with
		671	convenience functionality.
		672
		673	This means that AEMP requires a less tightly controlled environment at the
		674	cost of longer node references and a slightly higher management overhead.
		675
		676	=item * Erlang uses processes and a mailbox, AEMP does not queue.
		677
		678	Erlang uses processes that selctively receive messages, and therefore
		679	needs a queue. AEMP is event based, queuing messages would serve no useful
		680	purpose.
		681
		682	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
		683
		684	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
		685
		686	Sending messages in Erlang is synchronous and blocks the process. AEMP
		687	sends are immediate, connection establishment is handled in the
		688	background.
		689
		690	=item * Erlang can silently lose messages, AEMP cannot.
		691
		692	Erlang makes few guarantees on messages delivery - messages can get lost
		693	without any of the processes realising it (i.e. you send messages a, b,
		694	and c, and the other side only receives messages a and c).
		695
		696	AEMP guarantees correct ordering, and the guarantee that there are no
		697	holes in the message sequence.
		698
		699	=item * In Erlang, processes can be declared dead and later be found to be
		700	alive.
		701
		702	In Erlang it can happen that a monitored process is declared dead and
		703	linked processes get killed, but later it turns out that the process is
		704	still alive - and can receive messages.
		705
		706	In AEMP, when port monitoring detects a port as dead, then that port will
		707	eventually be killed - it cannot happen that a node detects a port as dead
		708	and then later sends messages to it, finding it is still alive.
		709
		710	=item * Erlang can send messages to the wrong port, AEMP does not.
		711
		712	In Erlang it is quite possible that a node that restarts reuses a process
		713	ID known to other nodes for a completely different process, causing
		714	messages destined for that process to end up in an unrelated process.
		715
		716	AEMP never reuses port IDs, so old messages or old port IDs floating
		717	around in the network will not be sent to an unrelated port.
		718
		719	=item * Erlang uses unprotected connections, AEMP uses secure
		720	authentication and can use TLS.
		721
		722	AEMP can use a proven protocol - SSL/TLS - to protect connections and
		723	securely authenticate nodes.
		724
		725	=item * The AEMP protocol is optimised for both text-based and binary
		726	communications.
		727
		728	The AEMP protocol, unlike the Erlang protocol, supports both
		729	language-independent text-only protocols (good for debugging) and binary,
		730	language-specific serialisers (e.g. Storable).
		731
		732	It has also been carefully designed to be implementable in other languages
		733	with a minimum of work while gracefully degrading fucntionality to make the
		734	protocol simple.
		735
		736	=item * AEMP has more flexible monitoring options than Erlang.
		737
		738	In Erlang, you can chose to receive I<all> exit signals as messages
		739	or I<none>, there is no in-between, so monitoring single processes is
		740	difficult to implement. Monitoring in AEMP is more flexible than in
		741	Erlang, as one can choose between automatic kill, exit message or callback
		742	on a per-process basis.
		743
		744	=item * Erlang tries to hide remote/local connections, AEMP does not.
		745
		746	Monitoring in Erlang is not an indicator of process death/crashes,
		747	as linking is (except linking is unreliable in Erlang).
		748
		749	In AEMP, you don't "look up" registered port names or send to named ports
		750	that might or might not be persistent. Instead, you normally spawn a port
		751	on the remote node. The init function monitors the you, and you monitor
		752	the remote port. Since both monitors are local to the node, they are much
		753	more reliable.
		754
		755	This also saves round-trips and avoids sending messages to the wrong port
		756	(hard to do in Erlang).
		757
		758	=back
		759
500	=head1 SEE ALSO	760	=head1 SEE ALSO
501		761
502	L<AnyEvent>.	762	L<AnyEvent>.
503		763
504	=head1 AUTHOR	764	=head1 AUTHOR

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Revision 1.22 by root, Tue Aug 4 18:33:30 2009 UTC vs.
Revision 1.37 by root, Fri Aug 7 16:47:23 2009 UTC