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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.24 by root, Tue Aug 4 20:00:00 2009 UTC vs.
Revision 1.35 by root, Thu Aug 6 10:21:48 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	# linking two ports, so they both crash together
		29	lnk $port1, $port2;
		30
		31	# monitoring
		32	mon $port, $cb->(@msg) # callback is invoked on death
		33	mon $port, $otherport # kill otherport on abnormal death
		34	mon $port, $otherport, @msg # send message on death
		35
28	=head1 DESCRIPTION	36	=head1 DESCRIPTION
29		37
30	This module (-family) implements a simple message passing framework.	38	This module (-family) implements a simple message passing framework.
31		39
32	Despite its simplicity, you can securely message other processes running	40	Despite its simplicity, you can securely message other processes running
…		…
43		51
44	=over 4	52	=over 4
45		53
46	=item port	54	=item port
47		55
48	A port is something you can send messages to with the C<snd> function, and	56	A port is something you can send messages to (with the C<snd> function).
49	you can register C<rcv> handlers with. All C<rcv> handlers will receive	57
50	messages they match, messages will not be queued.	58	Some ports allow you to register C<rcv> handlers that can match specific
		59	messages. All C<rcv> handlers will receive messages they match, messages
		60	will not be queued.
51		61
52	=item port id - C<noderef#portname>	62	=item port id - C<noderef#portname>
53		63
54	A port id is always the noderef, a hash-mark (C<#>) as separator, followed	64	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as
55	by a port name (a printable string of unspecified format).	65	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
		67	reference.
56		68
57	=item node	69	=item node
58		70
59	A node is a single process containing at least one port - the node	71	A node is a single process containing at least one port - the node
60	port. You can send messages to node ports to let them create new ports,	72	port. You can send messages to node ports to find existing ports or to
61	among other things.	73	create new ports, among other things.
62		74
63	Initially, nodes are either private (single-process only) or hidden	75	Nodes are either private (single-process only), slaves (connected to a
64	(connected to a master node only). Only when they epxlicitly "become	76	master node only) or public nodes (connectable from unrelated nodes).
65	public" can you send them messages from unrelated other nodes.
66		77
67	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	78	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>
68		79
69	A noderef is a string that either uniquely identifies a given node (for	80	A node reference is a string that either simply identifies the node (for
70	private and hidden nodes), or contains a recipe on how to reach a given	81	private and slave nodes), or contains a recipe on how to reach a given
71	node (for public nodes).	82	node (for public nodes).
72		83
		84	This recipe is simply a comma-separated list of C<address:port> pairs (for
		85	TCP/IP, other protocols might look different).
		86
		87	Node references come in two flavours: resolved (containing only numerical
		88	addresses) or unresolved (where hostnames are used instead of addresses).
		89
		90	Before using an unresolved node reference in a message you first have to
		91	resolve it.
		92
73	=back	93	=back
74		94
75	=head1 VARIABLES/FUNCTIONS	95	=head1 VARIABLES/FUNCTIONS
76		96
77	=over 4	97	=over 4
…		…
88		108
89	use AE ();	109	use AE ();
90		110
91	use base "Exporter";	111	use base "Exporter";
92		112
93	our $VERSION = '0.02';	113	our $VERSION = '0.1';
94	our @EXPORT = qw(	114	our @EXPORT = qw(
95	NODE $NODE *SELF node_of _any_	115	NODE $NODE *SELF node_of _any_
96	become_slave become_public	116	resolve_node initialise_node
97	snd rcv mon kil reg psub	117	snd rcv mon kil reg psub
98	port	118	port
99	);	119	);
100		120
101	our $SELF;	121	our $SELF;
…		…
111	The C<NODE> function returns, and the C<$NODE> variable contains	131	The C<NODE> function returns, and the C<$NODE> variable contains
112	the noderef of the local node. The value is initialised by a call	132	the noderef of the local node. The value is initialised by a call
113	to C<become_public> or C<become_slave>, after which all local port	133	to C<become_public> or C<become_slave>, after which all local port
114	identifiers become invalid.	134	identifiers become invalid.
115		135
116	=item $noderef = node_of $portid	136	=item $noderef = node_of $port
117		137
118	Extracts and returns the noderef from a portid or a noderef.	138	Extracts and returns the noderef from a portid or a noderef.
		139
		140	=item initialise_node $noderef, $seednode, $seednode...
		141
		142	=item initialise_node "slave/", $master, $master...
		143
		144	Before a node can talk to other nodes on the network it has to initialise
		145	itself - the minimum a node needs to know is it's own name, and optionally
		146	it should know the noderefs of some other nodes in the network.
		147
		148	This function initialises a node - it must be called exactly once (or
		149	never) before calling other AnyEvent::MP functions.
		150
		151	All arguments are noderefs, which can be either resolved or unresolved.
		152
		153	There are two types of networked nodes, public nodes and slave nodes:
		154
		155	=over 4
		156
		157	=item public nodes
		158
		159	For public nodes, C<$noderef> must either be a (possibly unresolved)
		160	noderef, in which case it will be resolved, or C<undef> (or missing), in
		161	which case the noderef will be guessed.
		162
		163	Afterwards, the node will bind itself on all endpoints and try to connect
		164	to all additional C<$seednodes> that are specified. Seednodes are optional
		165	and can be used to quickly bootstrap the node into an existing network.
		166
		167	=item slave nodes
		168
		169	When the C<$noderef> is the special string C<slave/>, then the node will
		170	become a slave node. Slave nodes cannot be contacted from outside and will
		171	route most of their traffic to the master node that they attach to.
		172
		173	At least one additional noderef is required: The node will try to connect
		174	to all of them and will become a slave attached to the first node it can
		175	successfully connect to.
		176
		177	=back
		178
		179	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
		181	server.
		182
		183	Example: become a public node listening on the default node.
		184
		185	initialise_node;
		186
		187	Example: become a public node, and try to contact some well-known master
		188	servers to become part of the network.
		189
		190	initialise_node undef, "master1", "master2";
		191
		192	Example: become a public node listening on port C<4041>.
		193
		194	initialise_node 4041;
		195
		196	Example: become a public node, only visible on localhost port 4044.
		197
		198	initialise_node "locahost: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
		204	=item $cv = resolve_node $noderef
		205
		206	Takes an unresolved node reference that may contain hostnames and
		207	abbreviated IDs, resolves all of them and returns a resolved node
		208	reference.
		209
		210	In addition to C<address:port> pairs allowed in resolved noderefs, the
		211	following forms are supported:
		212
		213	=over 4
		214
		215	=item the empty string
		216
		217	An empty-string component gets resolved as if the default port (4040) was
		218	specified.
		219
		220	=item naked port numbers (e.g. C<1234>)
		221
		222	These are resolved by prepending the local nodename and a colon, to be
		223	further resolved.
		224
		225	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
		226
		227	These are resolved by using AnyEvent::DNS to resolve them, optionally
		228	looking up SRV records for the C<aemp=4040> port, if no port was
		229	specified.
		230
		231	=back
119		232
120	=item $SELF	233	=item $SELF
121		234
122	Contains the current port id while executing C<rcv> callbacks or C<psub>	235	Contains the current port id while executing C<rcv> callbacks or C<psub>
123	blocks.	236	blocks.
…		…
126		239
127	Due to some quirks in how perl exports variables, it is impossible to	240	Due to some quirks in how perl exports variables, it is impossible to
128	just export C<$SELF>, all the symbols called C<SELF> are exported by this	241	just export C<$SELF>, all the symbols called C<SELF> are exported by this
129	module, but only C<$SELF> is currently used.	242	module, but only C<$SELF> is currently used.
130		243
131	=item snd $portid, type => @data	244	=item snd $port, type => @data
132		245
133	=item snd $portid, @msg	246	=item snd $port, @msg
134		247
135	Send the given message to the given port ID, which can identify either	248	Send the given message to the given port ID, which can identify either
136	a local or a remote port, and can be either a string or soemthignt hat	249	a local or a remote port, and can be either a string or soemthignt hat
137	stringifies a sa port ID (such as a port object :).	250	stringifies a sa port ID (such as a port object :).
138		251
…		…
148	JSON is used, then only strings, numbers and arrays and hashes consisting	261	JSON is used, then only strings, numbers and arrays and hashes consisting
149	of those are allowed (no objects). When Storable is used, then anything	262	of those are allowed (no objects). When Storable is used, then anything
150	that Storable can serialise and deserialise is allowed, and for the local	263	that Storable can serialise and deserialise is allowed, and for the local
151	node, anything can be passed.	264	node, anything can be passed.
152		265
153	=item kil $portid[, @reason]
154
155	Kill the specified port with the given C<@reason>.
156
157	If no C<@reason> is specified, then the port is killed "normally" (linked
158	ports will not be kileld, or even notified).
159
160	Otherwise, linked ports get killed with the same reason (second form of
161	C<mon>, see below).
162
163	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
164	will be reported as reason C<< die => $@ >>.
165
166	Transport/communication errors are reported as C<< transport_error =>
167	$message >>.
168
169	=item $guard = mon $portid, $cb->(@reason)
170
171	=item $guard = mon $portid, $otherport
172
173	=item $guard = mon $portid, $otherport, @msg
174
175	Monitor the given port and do something when the port is killed.
176
177	In the first form, the callback is simply called with any number
178	of C<@reason> elements (no @reason means that the port was deleted
179	"normally"). Note also that I<< the callback B<must> never die >>, so use
180	C<eval> if unsure.
181
182	In the second form, the other port will be C<kil>'ed with C<@reason>, iff
183	a @reason was specified, i.e. on "normal" kils nothing happens, while
184	under all other conditions, the other port is killed with the same reason.
185
186	In the last form, a message of the form C<@msg, @reason> will be C<snd>.
187
188	Example: call a given callback when C<$port> is killed.
189
190	mon $port, sub { warn "port died because of <@_>\n" };
191
192	Example: kill ourselves when C<$port> is killed abnormally.
193
194	mon $port, $self;
195
196	Example: send us a restart message another C<$port> is killed.
197
198	mon $port, $self => "restart";
199
200	=cut
201
202	sub mon {
203	my ($noderef, $port, $cb) = ((split /#/, shift, 2), shift);
204
205	my $node = $NODE{$noderef} \|\| add_node $noderef;
206
207	#TODO: ports must not be references
208	if (!ref $cb or "AnyEvent::MP::Port" eq ref $cb) {
209	if (@_) {
210	# send a kill info message
211	my (@msg) = ($cb, @_);
212	$cb = sub { snd @msg, @_ };
213	} else {
214	# simply kill other port
215	my $port = $cb;
216	$cb = sub { kil $port, @_ if @_ };
217	}
218	}
219
220	$node->monitor ($port, $cb);
221
222	defined wantarray
223	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
224	}
225
226	=item $guard = mon_guard $port, $ref, $ref...
227
228	Monitors the given C<$port> and keeps the passed references. When the port
229	is killed, the references will be freed.
230
231	Optionally returns a guard that will stop the monitoring.
232
233	This function is useful when you create e.g. timers or other watchers and
234	want to free them when the port gets killed:
235
236	$port->rcv (start => sub {
237	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
238	undef $timer if 0.9 < rand;
239	});
240	});
241
242	=cut
243
244	sub mon_guard {
245	my ($port, @refs) = @_;
246
247	mon $port, sub { 0 && @refs }
248	}
249
250	=item lnk $port1, $port2
251
252	Link two ports. This is simply a shorthand for:
253
254	mon $port1, $port2;
255	mon $port2, $port1;
256
257	It means that if either one is killed abnormally, the other one gets
258	killed as well.
259
260	=item $local_port = port	266	=item $local_port = port
261		267
262	Create a new local port object that supports message matching.	268	Create a new local port object that can be used either as a pattern
		269	matching port ("full port") or a single-callback port ("miniport"),
		270	depending on how C<rcv> callbacks are bound to the object.
263		271
264	=item $portid = port { my @msg = @_; $finished }	272	=item $port = port { my @msg = @_; $finished }
265		273
266	Creates a "mini port", that is, a very lightweight port without any	274	Creates a "miniport", that is, a very lightweight port without any pattern
267	pattern matching behind it, and returns its ID.	275	matching behind it, and returns its ID. Semantically the same as creating
		276	a port and calling C<rcv $port, $callback> on it.
268		277
269	The block will be called for every message received on the port. When the	278	The block will be called for every message received on the port. When the
270	callback returns a true value its job is considered "done" and the port	279	callback returns a true value its job is considered "done" and the port
271	will be destroyed. Otherwise it will stay alive.	280	will be destroyed. Otherwise it will stay alive.
272		281
273	The message will be passed as-is, no extra argument (i.e. no port id) will	282	The message will be passed as-is, no extra argument (i.e. no port id) will
274	be passed to the callback.	283	be passed to the callback.
275		284
276	If you need the local port id in the callback, this works nicely:	285	If you need the local port id in the callback, this works nicely:
277		286
278	my $port; $port = miniport {	287	my $port; $port = port {
279	snd $otherport, reply => $port;	288	snd $otherport, reply => $port;
280	};	289	};
281		290
282	=cut	291	=cut
		292
		293	sub rcv($@);
283		294
284	sub port(;&) {	295	sub port(;&) {
285	my $id = "$UNIQ." . $ID++;	296	my $id = "$UNIQ." . $ID++;
286	my $port = "$NODE#$id";	297	my $port = "$NODE#$id";
287		298
288	if (@_) {	299	if (@_) {
		300	rcv $port, shift;
		301	} else {
		302	$PORT{$id} = sub { }; # nop
		303	}
		304
		305	$port
		306	}
		307
		308	=item reg $port, $name
		309
		310	Registers the given port under the name C<$name>. If the name already
		311	exists it is replaced.
		312
		313	A port can only be registered under one well known name.
		314
		315	A port automatically becomes unregistered when it is killed.
		316
		317	=cut
		318
		319	sub reg(@) {
		320	my ($port, $name) = @_;
		321
		322	$REG{$name} = $port;
		323	}
		324
		325	=item rcv $port, $callback->(@msg)
		326
		327	Replaces the callback on the specified miniport (after converting it to
		328	one if required).
		329
		330	=item rcv $port, tagstring => $callback->(@msg), ...
		331
		332	=item rcv $port, $smartmatch => $callback->(@msg), ...
		333
		334	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
		335
		336	Register callbacks to be called on matching messages on the given full
		337	port (after converting it to one if required).
		338
		339	The callback has to return a true value when its work is done, after
		340	which is will be removed, or a false value in which case it will stay
		341	registered.
		342
		343	The global C<$SELF> (exported by this module) contains C<$port> while
		344	executing the callback.
		345
		346	Runtime errors wdurign callback execution will result in the port being
		347	C<kil>ed.
		348
		349	If the match is an array reference, then it will be matched against the
		350	first elements of the message, otherwise only the first element is being
		351	matched.
		352
		353	Any element in the match that is specified as C<_any_> (a function
		354	exported by this module) matches any single element of the message.
		355
		356	While not required, it is highly recommended that the first matching
		357	element is a string identifying the message. The one-string-only match is
		358	also the most efficient match (by far).
		359
		360	=cut
		361
		362	sub rcv($@) {
		363	my $port = shift;
		364	my ($noderef, $portid) = split /#/, $port, 2;
		365
		366	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
		367	or Carp::croak "$port: rcv can only be called on local ports, caught";
		368
		369	if (@_ == 1) {
289	my $cb = shift;	370	my $cb = shift;
		371	delete $PORT_DATA{$portid};
290	$PORT{$id} = sub {	372	$PORT{$portid} = sub {
291	local $SELF = $port;	373	local $SELF = $port;
292	eval {	374	eval {
293	&$cb	375	&$cb
294	and kil $id;	376	and kil $port;
295	};	377	};
296	_self_die if $@;	378	_self_die if $@;
297	};	379	};
298	} else {	380	} else {
		381	my $self = $PORT_DATA{$portid} \|\|= do {
299	my $self = bless {	382	my $self = bless {
300	id => "$NODE#$id",	383	id => $port,
301	}, "AnyEvent::MP::Port";	384	}, "AnyEvent::MP::Port";
302		385
303	$PORT_DATA{$id} = $self;
304	$PORT{$id} = sub {	386	$PORT{$portid} = sub {
305	local $SELF = $port;	387	local $SELF = $port;
306		388
307	eval {	389	eval {
308	for (@{ $self->{rc0}{$_[0]} }) {	390	for (@{ $self->{rc0}{$_[0]} }) {
309	$_ && &{$_->[0]}	391	$_ && &{$_->[0]}
310	&& undef $_;	392	&& undef $_;
311	}	393	}
312		394
313	for (@{ $self->{rcv}{$_[0]} }) {	395	for (@{ $self->{rcv}{$_[0]} }) {
314	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]	396	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
315	&& &{$_->[0]}	397	&& &{$_->[0]}
316	&& undef $_;	398	&& undef $_;
317	}	399	}
318		400
319	for (@{ $self->{any} }) {	401	for (@{ $self->{any} }) {
320	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]	402	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
321	&& &{$_->[0]}	403	&& &{$_->[0]}
322	&& undef $_;	404	&& undef $_;
		405	}
323	}	406	};
		407	_self_die if $@;
324	};	408	};
325	_self_die if $@;	409
		410	$self
326	};	411	};
327	}
328		412
329	$port
330	}
331
332	=item reg $portid, $name
333
334	Registers the given port under the name C<$name>. If the name already
335	exists it is replaced.
336
337	A port can only be registered under one well known name.
338
339	A port automatically becomes unregistered when it is killed.
340
341	=cut
342
343	sub reg(@) {
344	my ($portid, $name) = @_;
345
346	$REG{$name} = $portid;
347	}
348
349	=item rcv $portid, tagstring => $callback->(@msg), ...
350
351	=item rcv $portid, $smartmatch => $callback->(@msg), ...
352
353	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
354
355	Register callbacks to be called on matching messages on the given port.
356
357	The callback has to return a true value when its work is done, after
358	which is will be removed, or a false value in which case it will stay
359	registered.
360
361	The global C<$SELF> (exported by this module) contains C<$portid> while
362	executing the callback.
363
364	Runtime errors wdurign callback execution will result in the port being
365	C<kil>ed.
366
367	If the match is an array reference, then it will be matched against the
368	first elements of the message, otherwise only the first element is being
369	matched.
370
371	Any element in the match that is specified as C<_any_> (a function
372	exported by this module) matches any single element of the message.
373
374	While not required, it is highly recommended that the first matching
375	element is a string identifying the message. The one-string-only match is
376	also the most efficient match (by far).
377
378	=cut
379
380	sub rcv($@) {
381	my ($noderef, $port) = split /#/, shift, 2;
382
383	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
384	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";
385
386	my $self = $PORT_DATA{$port}
387	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
388
389	"AnyEvent::MP::Port" eq ref $self	413	"AnyEvent::MP::Port" eq ref $self
390	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";	414	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
391		415
392	while (@_) {	416	while (@_) {
393	my ($match, $cb) = splice @_, 0, 2;	417	my ($match, $cb) = splice @_, 0, 2;
394		418
395	if (!ref $match) {	419	if (!ref $match) {
396	push @{ $self->{rc0}{$match} }, [$cb];	420	push @{ $self->{rc0}{$match} }, [$cb];
397	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {	421	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
398	my ($type, @match) = @$match;	422	my ($type, @match) = @$match;
399	@match	423	@match
400	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]	424	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
401	: push @{ $self->{rc0}{$match->[0]} }, [$cb];	425	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
402	} else {	426	} else {
403	push @{ $self->{any} }, [$cb, $match];	427	push @{ $self->{any} }, [$cb, $match];
		428	}
404	}	429	}
405	}	430	}
		431
		432	$port
406	}	433	}
407		434
408	=item $closure = psub { BLOCK }	435	=item $closure = psub { BLOCK }
409		436
410	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	437	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
…		…
441	$res	468	$res
442	}	469	}
443	}	470	}
444	}	471	}
445		472
446	=back	473	=item $guard = mon $port, $cb->(@reason)
447		474
448	=head1 FUNCTIONS FOR NODES	475	=item $guard = mon $port, $otherport
449		476
450	=over 4	477	=item $guard = mon $port, $otherport, @msg
451		478
452	=item become_public endpoint...	479	Monitor the given port and do something when the port is killed.
453		480
454	Tells the node to become a public node, i.e. reachable from other nodes.	481	In the first form, the callback is simply called with any number
		482	of C<@reason> elements (no @reason means that the port was deleted
		483	"normally"). Note also that I<< the callback B<must> never die >>, so use
		484	C<eval> if unsure.
455		485
456	If no arguments are given, or the first argument is C<undef>, then	486	In the second form, the other port will be C<kil>'ed with C<@reason>, iff
457	AnyEvent::MP tries to bind on port C<4040> on all IP addresses that the	487	a @reason was specified, i.e. on "normal" kils nothing happens, while
458	local nodename resolves to.	488	under all other conditions, the other port is killed with the same reason.
459		489
460	Otherwise the first argument must be an array-reference with transport	490	In the last form, a message of the form C<@msg, @reason> will be C<snd>.
461	endpoints ("ip:port", "hostname:port") or port numbers (in which case the
462	local nodename is used as hostname). The endpoints are all resolved and
463	will become the node reference.
464		491
		492	Example: call a given callback when C<$port> is killed.
		493
		494	mon $port, sub { warn "port died because of <@_>\n" };
		495
		496	Example: kill ourselves when C<$port> is killed abnormally.
		497
		498	mon $port, $self;
		499
		500	Example: send us a restart message another C<$port> is killed.
		501
		502	mon $port, $self => "restart";
		503
465	=cut	504	=cut
		505
		506	sub mon {
		507	my ($noderef, $port) = split /#/, shift, 2;
		508
		509	my $node = $NODE{$noderef} \|\| add_node $noderef;
		510
		511	my $cb = shift;
		512
		513	unless (ref $cb) {
		514	if (@_) {
		515	# send a kill info message
		516	my (@msg) = ($cb, @_);
		517	$cb = sub { snd @msg, @_ };
		518	} else {
		519	# simply kill other port
		520	my $port = $cb;
		521	$cb = sub { kil $port, @_ if @_ };
		522	}
		523	}
		524
		525	$node->monitor ($port, $cb);
		526
		527	defined wantarray
		528	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
		529	}
		530
		531	=item $guard = mon_guard $port, $ref, $ref...
		532
		533	Monitors the given C<$port> and keeps the passed references. When the port
		534	is killed, the references will be freed.
		535
		536	Optionally returns a guard that will stop the monitoring.
		537
		538	This function is useful when you create e.g. timers or other watchers and
		539	want to free them when the port gets killed:
		540
		541	$port->rcv (start => sub {
		542	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
		543	undef $timer if 0.9 < rand;
		544	});
		545	});
		546
		547	=cut
		548
		549	sub mon_guard {
		550	my ($port, @refs) = @_;
		551
		552	mon $port, sub { 0 && @refs }
		553	}
		554
		555	=item lnk $port1, $port2
		556
		557	Link two ports. This is simply a shorthand for:
		558
		559	mon $port1, $port2;
		560	mon $port2, $port1;
		561
		562	It means that if either one is killed abnormally, the other one gets
		563	killed as well.
		564
		565	=item kil $port[, @reason]
		566
		567	Kill the specified port with the given C<@reason>.
		568
		569	If no C<@reason> is specified, then the port is killed "normally" (linked
		570	ports will not be kileld, or even notified).
		571
		572	Otherwise, linked ports get killed with the same reason (second form of
		573	C<mon>, see below).
		574
		575	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		576	will be reported as reason C<< die => $@ >>.
		577
		578	Transport/communication errors are reported as C<< transport_error =>
		579	$message >>.
466		580
467	=back	581	=back
468		582
469	=head1 NODE MESSAGES	583	=head1 NODE MESSAGES
470		584
471	Nodes understand the following messages sent to them. Many of them take	585	Nodes understand the following messages sent to them. Many of them take
472	arguments called C<@reply>, which will simply be used to compose a reply	586	arguments called C<@reply>, which will simply be used to compose a reply
473	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and	587	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
474	the remaining arguments are simply the message data.	588	the remaining arguments are simply the message data.
475		589
		590	While other messages exist, they are not public and subject to change.
		591
476	=over 4	592	=over 4
477		593
478	=cut	594	=cut
479		595
480	=item lookup => $name, @reply	596	=item lookup => $name, @reply
…		…
508	snd $NODE, time => $myport, timereply => 1, 2;	624	snd $NODE, time => $myport, timereply => 1, 2;
509	# => snd $myport, timereply => 1, 2, <time>	625	# => snd $myport, timereply => 1, 2, <time>
510		626
511	=back	627	=back
512		628
		629	=head1 AnyEvent::MP vs. Distributed Erlang
		630
		631	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
		632	== aemp node, Erlang process == aemp port), so many of the documents and
		633	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		634	sample:
		635
		636	http://www.Erlang.se/doc/programming_rules.shtml
		637	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		638	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		639	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		640
		641	Despite the similarities, there are also some important differences:
		642
		643	=over 4
		644
		645	=item * Node references contain the recipe on how to contact them.
		646
		647	Erlang relies on special naming and DNS to work everywhere in the
		648	same way. AEMP relies on each node knowing it's own address(es), with
		649	convenience functionality.
		650
		651	This means that AEMP requires a less tightly controlled environment at the
		652	cost of longer node references and a slightly higher management overhead.
		653
		654	=item * Erlang uses processes and a mailbox, AEMP does not queue.
		655
		656	Erlang uses processes that selctively receive messages, and therefore
		657	needs a queue. AEMP is event based, queuing messages would serve no useful
		658	purpose.
		659
		660	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
		661
		662	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
		663
		664	Sending messages in Erlang is synchronous and blocks the process. AEMP
		665	sends are immediate, connection establishment is handled in the
		666	background.
		667
		668	=item * Erlang can silently lose messages, AEMP cannot.
		669
		670	Erlang makes few guarantees on messages delivery - messages can get lost
		671	without any of the processes realising it (i.e. you send messages a, b,
		672	and c, and the other side only receives messages a and c).
		673
		674	AEMP guarantees correct ordering, and the guarantee that there are no
		675	holes in the message sequence.
		676
		677	=item * In Erlang, processes can be declared dead and later be found to be
		678	alive.
		679
		680	In Erlang it can happen that a monitored process is declared dead and
		681	linked processes get killed, but later it turns out that the process is
		682	still alive - and can receive messages.
		683
		684	In AEMP, when port monitoring detects a port as dead, then that port will
		685	eventually be killed - it cannot happen that a node detects a port as dead
		686	and then later sends messages to it, finding it is still alive.
		687
		688	=item * Erlang can send messages to the wrong port, AEMP does not.
		689
		690	In Erlang it is quite possible that a node that restarts reuses a process
		691	ID known to other nodes for a completely different process, causing
		692	messages destined for that process to end up in an unrelated process.
		693
		694	AEMP never reuses port IDs, so old messages or old port IDs floating
		695	around in the network will not be sent to an unrelated port.
		696
		697	=item * Erlang uses unprotected connections, AEMP uses secure
		698	authentication and can use TLS.
		699
		700	AEMP can use a proven protocol - SSL/TLS - to protect connections and
		701	securely authenticate nodes.
		702
		703	=item * The AEMP protocol is optimised for both text-based and binary
		704	communications.
		705
		706	The AEMP protocol, unlike the Erlang protocol, supports both
		707	language-independent text-only protocols (good for debugging) and binary,
		708	language-specific serialisers (e.g. Storable).
		709
		710	It has also been carefully designed to be implementable in other languages
		711	with a minimum of work while gracefully degrading fucntionality to make the
		712	protocol simple.
		713
		714	=item * AEMP has more flexible monitoring options than Erlang.
		715
		716	In Erlang, you can chose to receive I<all> exit signals as messages
		717	or I<none>, there is no in-between, so monitoring single processes is
		718	difficult to implement. Monitoring in AEMP is more flexible than in
		719	Erlang, as one can choose between automatic kill, exit message or callback
		720	on a per-process basis.
		721
		722	=item * Erlang has different semantics for monitoring and linking, AEMP has the same.
		723
		724	Monitoring in Erlang is not an indicator of process death/crashes,
		725	as linking is (except linking is unreliable in Erlang). In AEMP, the
		726	semantics of monitoring and linking are identical, linking is simply
		727	two-way monitoring with automatic kill.
		728
		729	=back
		730
513	=head1 SEE ALSO	731	=head1 SEE ALSO
514		732
515	L<AnyEvent>.	733	L<AnyEvent>.
516		734
517	=head1 AUTHOR	735	=head1 AUTHOR

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Revision 1.35 by root, Thu Aug 6 10:21:48 2009 UTC