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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.25 by root, Tue Aug 4 21:07:37 2009 UTC vs.
Revision 1.43 by root, Sun Aug 9 16:08:16 2009 UTC

…		…
8		8
9	$NODE # contains this node's noderef	9	$NODE # contains this node's noderef
10	NODE # returns this node's noderef	10	NODE # returns this node's noderef
11	NODE $port # returns the noderef of the port	11	NODE $port # returns the noderef of the port
12		12
		13	$SELF # receiving/own port id in rcv callbacks
		14
		15	# ports are message endpoints
		16
		17	# sending messages
13	snd $port, type => data...;	18	snd $port, type => data...;
		19	snd $port, @msg;
		20	snd @msg_with_first_element_being_a_port;
14		21
15	$SELF # receiving/own port id in rcv callbacks	22	# miniports
		23	my $miniport = port { my @msg = @_; 0 };
16		24
		25	# full ports
		26	my $port = port;
17	rcv $port, smartmatch => $cb->($port, @msg);	27	rcv $port, smartmatch => $cb->(@msg);
18
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	28	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
21	rcv $port1, pong => sub { warn "pong received\n" };	29	rcv $port, pong => sub { warn "pong received\n"; 0 };
22	snd $port2, ping => $port1;	30
		31	# remote ports
		32	my $port = spawn $node, $initfunc, @initdata;
23		33
24	# more, smarter, matches (_any_ is exported by this module)	34	# more, smarter, matches (_any_ is exported by this module)
25	rcv $port, [child_died => $pid] => sub { ...	35	rcv $port, [child_died => $pid] => sub { ...
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	36	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
27		37
		38	# monitoring
		39	mon $port, $cb->(@msg) # callback is invoked on death
		40	mon $port, $otherport # kill otherport on abnormal death
		41	mon $port, $otherport, @msg # send message on death
		42
28	=head1 DESCRIPTION	43	=head1 DESCRIPTION
29		44
30	This module (-family) implements a simple message passing framework.	45	This module (-family) implements a simple message passing framework.
31		46
32	Despite its simplicity, you can securely message other processes running	47	Despite its simplicity, you can securely message other processes running
…		…
43		58
44	=over 4	59	=over 4
45		60
46	=item port	61	=item port
47		62
48	A port is something you can send messages to with the C<snd> function, and	63	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	64
50	messages they match, messages will not be queued.	65	Some ports allow you to register C<rcv> handlers that can match specific
		66	messages. All C<rcv> handlers will receive messages they match, messages
		67	will not be queued.
51		68
52	=item port id - C<noderef#portname>	69	=item port id - C<noderef#portname>
53		70
54	A port id is always the noderef, a hash-mark (C<#>) as separator, followed	71	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).	72	separator, and a port name (a printable string of unspecified format). An
		73	exception is the the node port, whose ID is identical to its node
		74	reference.
56		75
57	=item node	76	=item node
58		77
59	A node is a single process containing at least one port - the node	78	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,	79	port. You can send messages to node ports to find existing ports or to
61	among other things.	80	create new ports, among other things.
62		81
63	Initially, nodes are either private (single-process only) or hidden	82	Nodes are either private (single-process only), slaves (connected to a
64	(connected to a master node only). Only when they epxlicitly "become	83	master node only) or public nodes (connectable from unrelated nodes).
65	public" can you send them messages from unrelated other nodes.
66		84
67	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	85	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>
68		86
69	A noderef is a string that either uniquely identifies a given node (for	87	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	88	private and slave nodes), or contains a recipe on how to reach a given
71	node (for public nodes).	89	node (for public nodes).
72		90
		91	This recipe is simply a comma-separated list of C<address:port> pairs (for
		92	TCP/IP, other protocols might look different).
		93
		94	Node references come in two flavours: resolved (containing only numerical
		95	addresses) or unresolved (where hostnames are used instead of addresses).
		96
		97	Before using an unresolved node reference in a message you first have to
		98	resolve it.
		99
73	=back	100	=back
74		101
75	=head1 VARIABLES/FUNCTIONS	102	=head1 VARIABLES/FUNCTIONS
76		103
77	=over 4	104	=over 4
…		…
88		115
89	use AE ();	116	use AE ();
90		117
91	use base "Exporter";	118	use base "Exporter";
92		119
93	our $VERSION = '0.1';	120	our $VERSION = $AnyEvent::MP::Base::VERSION;
		121
94	our @EXPORT = qw(	122	our @EXPORT = qw(
95	NODE $NODE *SELF node_of _any_	123	NODE $NODE *SELF node_of _any_
96	become_slave become_public	124	resolve_node initialise_node
97	snd rcv mon kil reg psub	125	snd rcv mon kil reg psub spawn
98	port	126	port
99	);	127	);
100		128
101	our $SELF;	129	our $SELF;
102		130
…		…
111	The C<NODE> function returns, and the C<$NODE> variable contains	139	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	140	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	141	to C<become_public> or C<become_slave>, after which all local port
114	identifiers become invalid.	142	identifiers become invalid.
115		143
116	=item $noderef = node_of $portid	144	=item $noderef = node_of $port
117		145
118	Extracts and returns the noderef from a portid or a noderef.	146	Extracts and returns the noderef from a portid or a noderef.
		147
		148	=item initialise_node $noderef, $seednode, $seednode...
		149
		150	=item initialise_node "slave/", $master, $master...
		151
		152	Before a node can talk to other nodes on the network it has to initialise
		153	itself - the minimum a node needs to know is it's own name, and optionally
		154	it should know the noderefs of some other nodes in the network.
		155
		156	This function initialises a node - it must be called exactly once (or
		157	never) before calling other AnyEvent::MP functions.
		158
		159	All arguments are noderefs, which can be either resolved or unresolved.
		160
		161	There are two types of networked nodes, public nodes and slave nodes:
		162
		163	=over 4
		164
		165	=item public nodes
		166
		167	For public nodes, C<$noderef> must either be a (possibly unresolved)
		168	noderef, in which case it will be resolved, or C<undef> (or missing), in
		169	which case the noderef will be guessed.
		170
		171	Afterwards, the node will bind itself on all endpoints and try to connect
		172	to all additional C<$seednodes> that are specified. Seednodes are optional
		173	and can be used to quickly bootstrap the node into an existing network.
		174
		175	=item slave nodes
		176
		177	When the C<$noderef> is the special string C<slave/>, then the node will
		178	become a slave node. Slave nodes cannot be contacted from outside and will
		179	route most of their traffic to the master node that they attach to.
		180
		181	At least one additional noderef is required: The node will try to connect
		182	to all of them and will become a slave attached to the first node it can
		183	successfully connect to.
		184
		185	=back
		186
		187	This function will block until all nodes have been resolved and, for slave
		188	nodes, until it has successfully established a connection to a master
		189	server.
		190
		191	Example: become a public node listening on the default node.
		192
		193	initialise_node;
		194
		195	Example: become a public node, and try to contact some well-known master
		196	servers to become part of the network.
		197
		198	initialise_node undef, "master1", "master2";
		199
		200	Example: become a public node listening on port C<4041>.
		201
		202	initialise_node 4041;
		203
		204	Example: become a public node, only visible on localhost port 4044.
		205
		206	initialise_node "locahost:4044";
		207
		208	Example: become a slave node to any of the specified master servers.
		209
		210	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
		211
		212	=item $cv = resolve_node $noderef
		213
		214	Takes an unresolved node reference that may contain hostnames and
		215	abbreviated IDs, resolves all of them and returns a resolved node
		216	reference.
		217
		218	In addition to C<address:port> pairs allowed in resolved noderefs, the
		219	following forms are supported:
		220
		221	=over 4
		222
		223	=item the empty string
		224
		225	An empty-string component gets resolved as if the default port (4040) was
		226	specified.
		227
		228	=item naked port numbers (e.g. C<1234>)
		229
		230	These are resolved by prepending the local nodename and a colon, to be
		231	further resolved.
		232
		233	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
		234
		235	These are resolved by using AnyEvent::DNS to resolve them, optionally
		236	looking up SRV records for the C<aemp=4040> port, if no port was
		237	specified.
		238
		239	=back
119		240
120	=item $SELF	241	=item $SELF
121		242
122	Contains the current port id while executing C<rcv> callbacks or C<psub>	243	Contains the current port id while executing C<rcv> callbacks or C<psub>
123	blocks.	244	blocks.
…		…
126		247
127	Due to some quirks in how perl exports variables, it is impossible to	248	Due to some quirks in how perl exports variables, it is impossible to
128	just export C<$SELF>, all the symbols called C<SELF> are exported by this	249	just export C<$SELF>, all the symbols called C<SELF> are exported by this
129	module, but only C<$SELF> is currently used.	250	module, but only C<$SELF> is currently used.
130		251
131	=item snd $portid, type => @data	252	=item snd $port, type => @data
132		253
133	=item snd $portid, @msg	254	=item snd $port, @msg
134		255
135	Send the given message to the given port ID, which can identify either	256	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	257	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 :).	258	stringifies a sa port ID (such as a port object :).
138		259
…		…
148	JSON is used, then only strings, numbers and arrays and hashes consisting	269	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	270	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	271	that Storable can serialise and deserialise is allowed, and for the local
151	node, anything can be passed.	272	node, anything can be passed.
152		273
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	274	=item $local_port = port
261		275
262	Create a new local port object that supports message matching.	276	Create a new local port object that can be used either as a pattern
		277	matching port ("full port") or a single-callback port ("miniport"),
		278	depending on how C<rcv> callbacks are bound to the object.
263		279
264	=item $portid = port { my @msg = @_; $finished }	280	=item $port = port { my @msg = @_; $finished }
265		281
266	Creates a "mini port", that is, a very lightweight port without any	282	Creates a "miniport", that is, a very lightweight port without any pattern
267	pattern matching behind it, and returns its ID.	283	matching behind it, and returns its ID. Semantically the same as creating
		284	a port and calling C<rcv $port, $callback> on it.
268		285
269	The block will be called for every message received on the port. When the	286	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	287	callback returns a true value its job is considered "done" and the port
271	will be destroyed. Otherwise it will stay alive.	288	will be destroyed. Otherwise it will stay alive.
272		289
273	The message will be passed as-is, no extra argument (i.e. no port id) will	290	The message will be passed as-is, no extra argument (i.e. no port id) will
274	be passed to the callback.	291	be passed to the callback.
275		292
276	If you need the local port id in the callback, this works nicely:	293	If you need the local port id in the callback, this works nicely:
277		294
278	my $port; $port = miniport {	295	my $port; $port = port {
279	snd $otherport, reply => $port;	296	snd $otherport, reply => $port;
280	};	297	};
281		298
282	=cut	299	=cut
		300
		301	sub rcv($@);
283		302
284	sub port(;&) {	303	sub port(;&) {
285	my $id = "$UNIQ." . $ID++;	304	my $id = "$UNIQ." . $ID++;
286	my $port = "$NODE#$id";	305	my $port = "$NODE#$id";
287		306
288	if (@_) {	307	if (@_) {
		308	rcv $port, shift;
		309	} else {
		310	$PORT{$id} = sub { }; # nop
		311	}
		312
		313	$port
		314	}
		315
		316	=item reg $port, $name
		317
		318	=item reg $name
		319
		320	Registers the given port (or C<$SELF><<< if missing) under the name
		321	C<$name>. If the name already exists it is replaced.
		322
		323	A port can only be registered under one well known name.
		324
		325	A port automatically becomes unregistered when it is killed.
		326
		327	=cut
		328
		329	sub reg(@) {
		330	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
		331
		332	$REG{$_[0]} = $port;
		333	}
		334
		335	=item rcv $port, $callback->(@msg)
		336
		337	Replaces the callback on the specified miniport (after converting it to
		338	one if required).
		339
		340	=item rcv $port, tagstring => $callback->(@msg), ...
		341
		342	=item rcv $port, $smartmatch => $callback->(@msg), ...
		343
		344	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
		345
		346	Register callbacks to be called on matching messages on the given full
		347	port (after converting it to one if required) and return the port.
		348
		349	The callback has to return a true value when its work is done, after
		350	which is will be removed, or a false value in which case it will stay
		351	registered.
		352
		353	The global C<$SELF> (exported by this module) contains C<$port> while
		354	executing the callback.
		355
		356	Runtime errors during callback execution will result in the port being
		357	C<kil>ed.
		358
		359	If the match is an array reference, then it will be matched against the
		360	first elements of the message, otherwise only the first element is being
		361	matched.
		362
		363	Any element in the match that is specified as C<_any_> (a function
		364	exported by this module) matches any single element of the message.
		365
		366	While not required, it is highly recommended that the first matching
		367	element is a string identifying the message. The one-string-only match is
		368	also the most efficient match (by far).
		369
		370	Example: create a port and bind receivers on it in one go.
		371
		372	my $port = rcv port,
		373	msg1 => sub { ...; 0 },
		374	msg2 => sub { ...; 0 },
		375	;
		376
		377	Example: create a port, bind receivers and send it in a message elsewhere
		378	in one go:
		379
		380	snd $otherport, reply =>
		381	rcv port,
		382	msg1 => sub { ...; 0 },
		383	...
		384	;
		385
		386	=cut
		387
		388	sub rcv($@) {
		389	my $port = shift;
		390	my ($noderef, $portid) = split /#/, $port, 2;
		391
		392	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
		393	or Carp::croak "$port: rcv can only be called on local ports, caught";
		394
		395	if (@_ == 1) {
289	my $cb = shift;	396	my $cb = shift;
		397	delete $PORT_DATA{$portid};
290	$PORT{$id} = sub {	398	$PORT{$portid} = sub {
291	local $SELF = $port;	399	local $SELF = $port;
292	eval {	400	eval {
293	&$cb	401	&$cb
294	and kil $id;	402	and kil $port;
295	};	403	};
296	_self_die if $@;	404	_self_die if $@;
297	};	405	};
298	} else {	406	} else {
		407	my $self = $PORT_DATA{$portid} \|\|= do {
299	my $self = bless {	408	my $self = bless {
300	id => "$NODE#$id",	409	id => $port,
301	}, "AnyEvent::MP::Port";	410	}, "AnyEvent::MP::Port";
302		411
303	$PORT_DATA{$id} = $self;
304	$PORT{$id} = sub {	412	$PORT{$portid} = sub {
305	local $SELF = $port;	413	local $SELF = $port;
306		414
307	eval {	415	eval {
308	for (@{ $self->{rc0}{$_[0]} }) {	416	for (@{ $self->{rc0}{$_[0]} }) {
309	$_ && &{$_->[0]}	417	$_ && &{$_->[0]}
310	&& undef $_;	418	&& undef $_;
311	}	419	}
312		420
313	for (@{ $self->{rcv}{$_[0]} }) {	421	for (@{ $self->{rcv}{$_[0]} }) {
314	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]	422	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
315	&& &{$_->[0]}	423	&& &{$_->[0]}
316	&& undef $_;	424	&& undef $_;
317	}	425	}
318		426
319	for (@{ $self->{any} }) {	427	for (@{ $self->{any} }) {
320	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]	428	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
321	&& &{$_->[0]}	429	&& &{$_->[0]}
322	&& undef $_;	430	&& undef $_;
		431	}
323	}	432	};
		433	_self_die if $@;
324	};	434	};
325	_self_die if $@;	435
		436	$self
326	};	437	};
327	}
328		438
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	439	"AnyEvent::MP::Port" eq ref $self
390	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";	440	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
391		441
392	while (@_) {	442	while (@_) {
393	my ($match, $cb) = splice @_, 0, 2;	443	my ($match, $cb) = splice @_, 0, 2;
394		444
395	if (!ref $match) {	445	if (!ref $match) {
396	push @{ $self->{rc0}{$match} }, [$cb];	446	push @{ $self->{rc0}{$match} }, [$cb];
397	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {	447	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
398	my ($type, @match) = @$match;	448	my ($type, @match) = @$match;
399	@match	449	@match
400	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]	450	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
401	: push @{ $self->{rc0}{$match->[0]} }, [$cb];	451	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
402	} else {	452	} else {
403	push @{ $self->{any} }, [$cb, $match];	453	push @{ $self->{any} }, [$cb, $match];
		454	}
404	}	455	}
405	}	456	}
		457
		458	$port
406	}	459	}
407		460
408	=item $closure = psub { BLOCK }	461	=item $closure = psub { BLOCK }
409		462
410	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	463	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
…		…
441	$res	494	$res
442	}	495	}
443	}	496	}
444	}	497	}
445		498
446	=back	499	=item $guard = mon $port, $cb->(@reason)
447		500
448	=head1 FUNCTIONS FOR NODES	501	=item $guard = mon $port, $rcvport
449		502
450	=over 4	503	=item $guard = mon $port
451		504
452	=item become_public endpoint...	505	=item $guard = mon $port, $rcvport, @msg
453		506
454	Tells the node to become a public node, i.e. reachable from other nodes.	507	Monitor the given port and do something when the port is killed or
		508	messages to it were lost, and optionally return a guard that can be used
		509	to stop monitoring again.
455		510
456	If no arguments are given, or the first argument is C<undef>, then	511	C<mon> effectively guarantees that, in the absence of hardware failures,
457	AnyEvent::MP tries to bind on port C<4040> on all IP addresses that the	512	that after starting the monitor, either all messages sent to the port
458	local nodename resolves to.	513	will arrive, or the monitoring action will be invoked after possible
		514	message loss has been detected. No messages will be lost "in between"
		515	(after the first lost message no further messages will be received by the
		516	port). After the monitoring action was invoked, further messages might get
		517	delivered again.
459		518
460	Otherwise the first argument must be an array-reference with transport	519	In the first form (callback), the callback is simply called with any
461	endpoints ("ip:port", "hostname:port") or port numbers (in which case the	520	number of C<@reason> elements (no @reason means that the port was deleted
462	local nodename is used as hostname). The endpoints are all resolved and	521	"normally"). Note also that I<< the callback B<must> never die >>, so use
463	will become the node reference.	522	C<eval> if unsure.
464		523
		524	In the second form (another port given), the other port (C<$rcvport>)
		525	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
		526	"normal" kils nothing happens, while under all other conditions, the other
		527	port is killed with the same reason.
		528
		529	The third form (kill self) is the same as the second form, except that
		530	C<$rvport> defaults to C<$SELF>.
		531
		532	In the last form (message), a message of the form C<@msg, @reason> will be
		533	C<snd>.
		534
		535	As a rule of thumb, monitoring requests should always monitor a port from
		536	a local port (or callback). The reason is that kill messages might get
		537	lost, just like any other message. Another less obvious reason is that
		538	even monitoring requests can get lost (for exmaple, when the connection
		539	to the other node goes down permanently). When monitoring a port locally
		540	these problems do not exist.
		541
		542	Example: call a given callback when C<$port> is killed.
		543
		544	mon $port, sub { warn "port died because of <@_>\n" };
		545
		546	Example: kill ourselves when C<$port> is killed abnormally.
		547
		548	mon $port;
		549
		550	Example: send us a restart message when another C<$port> is killed.
		551
		552	mon $port, $self => "restart";
		553
465	=cut	554	=cut
		555
		556	sub mon {
		557	my ($noderef, $port) = split /#/, shift, 2;
		558
		559	my $node = $NODE{$noderef} \|\| add_node $noderef;
		560
		561	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
		562
		563	unless (ref $cb) {
		564	if (@_) {
		565	# send a kill info message
		566	my (@msg) = ($cb, @_);
		567	$cb = sub { snd @msg, @_ };
		568	} else {
		569	# simply kill other port
		570	my $port = $cb;
		571	$cb = sub { kil $port, @_ if @_ };
		572	}
		573	}
		574
		575	$node->monitor ($port, $cb);
		576
		577	defined wantarray
		578	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
		579	}
		580
		581	=item $guard = mon_guard $port, $ref, $ref...
		582
		583	Monitors the given C<$port> and keeps the passed references. When the port
		584	is killed, the references will be freed.
		585
		586	Optionally returns a guard that will stop the monitoring.
		587
		588	This function is useful when you create e.g. timers or other watchers and
		589	want to free them when the port gets killed:
		590
		591	$port->rcv (start => sub {
		592	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
		593	undef $timer if 0.9 < rand;
		594	});
		595	});
		596
		597	=cut
		598
		599	sub mon_guard {
		600	my ($port, @refs) = @_;
		601
		602	#TODO: mon-less form?
		603
		604	mon $port, sub { 0 && @refs }
		605	}
		606
		607	=item kil $port[, @reason]
		608
		609	Kill the specified port with the given C<@reason>.
		610
		611	If no C<@reason> is specified, then the port is killed "normally" (linked
		612	ports will not be kileld, or even notified).
		613
		614	Otherwise, linked ports get killed with the same reason (second form of
		615	C<mon>, see below).
		616
		617	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		618	will be reported as reason C<< die => $@ >>.
		619
		620	Transport/communication errors are reported as C<< transport_error =>
		621	$message >>.
		622
		623	=cut
		624
		625	=item $port = spawn $node, $initfunc[, @initdata]
		626
		627	Creates a port on the node C<$node> (which can also be a port ID, in which
		628	case it's the node where that port resides).
		629
		630	The port ID of the newly created port is return immediately, and it is
		631	permissible to immediately start sending messages or monitor the port.
		632
		633	After the port has been created, the init function is
		634	called. This function must be a fully-qualified function name
		635	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		636	program, use C<::name>.
		637
		638	If the function doesn't exist, then the node tries to C<require>
		639	the package, then the package above the package and so on (e.g.
		640	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		641	exists or it runs out of package names.
		642
		643	The init function is then called with the newly-created port as context
		644	object (C<$SELF>) and the C<@initdata> values as arguments.
		645
		646	A common idiom is to pass your own port, monitor the spawned port, and
		647	in the init function, monitor the original port. This two-way monitoring
		648	ensures that both ports get cleaned up when there is a problem.
		649
		650	Example: spawn a chat server port on C<$othernode>.
		651
		652	# this node, executed from within a port context:
		653	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		654	mon $server;
		655
		656	# init function on C<$othernode>
		657	sub connect {
		658	my ($srcport) = @_;
		659
		660	mon $srcport;
		661
		662	rcv $SELF, sub {
		663	...
		664	};
		665	}
		666
		667	=cut
		668
		669	sub _spawn {
		670	my $port = shift;
		671	my $init = shift;
		672
		673	local $SELF = "$NODE#$port";
		674	eval {
		675	&{ load_func $init }
		676	};
		677	_self_die if $@;
		678	}
		679
		680	sub spawn(@) {
		681	my ($noderef, undef) = split /#/, shift, 2;
		682
		683	my $id = "$RUNIQ." . $ID++;
		684
		685	$_[0] =~ /::/
		686	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		687
		688	($NODE{$noderef} \|\| add_node $noderef)
		689	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
		690
		691	"$noderef#$id"
		692	}
466		693
467	=back	694	=back
468		695
469	=head1 NODE MESSAGES	696	=head1 NODE MESSAGES
470		697
471	Nodes understand the following messages sent to them. Many of them take	698	Nodes understand the following messages sent to them. Many of them take
472	arguments called C<@reply>, which will simply be used to compose a reply	699	arguments called C<@reply>, which will simply be used to compose a reply
473	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and	700	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
474	the remaining arguments are simply the message data.	701	the remaining arguments are simply the message data.
475		702
		703	While other messages exist, they are not public and subject to change.
		704
476	=over 4	705	=over 4
477		706
478	=cut	707	=cut
479		708
480	=item lookup => $name, @reply	709	=item lookup => $name, @reply
…		…
508	snd $NODE, time => $myport, timereply => 1, 2;	737	snd $NODE, time => $myport, timereply => 1, 2;
509	# => snd $myport, timereply => 1, 2, <time>	738	# => snd $myport, timereply => 1, 2, <time>
510		739
511	=back	740	=back
512		741
		742	=head1 AnyEvent::MP vs. Distributed Erlang
		743
		744	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
		745	== aemp node, Erlang process == aemp port), so many of the documents and
		746	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		747	sample:
		748
		749	http://www.Erlang.se/doc/programming_rules.shtml
		750	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		751	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		752	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		753
		754	Despite the similarities, there are also some important differences:
		755
		756	=over 4
		757
		758	=item * Node references contain the recipe on how to contact them.
		759
		760	Erlang relies on special naming and DNS to work everywhere in the
		761	same way. AEMP relies on each node knowing it's own address(es), with
		762	convenience functionality.
		763
		764	This means that AEMP requires a less tightly controlled environment at the
		765	cost of longer node references and a slightly higher management overhead.
		766
		767	=item * Erlang uses processes and a mailbox, AEMP does not queue.
		768
		769	Erlang uses processes that selctively receive messages, and therefore
		770	needs a queue. AEMP is event based, queuing messages would serve no useful
		771	purpose.
		772
		773	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
		774
		775	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
		776
		777	Sending messages in Erlang is synchronous and blocks the process. AEMP
		778	sends are immediate, connection establishment is handled in the
		779	background.
		780
		781	=item * Erlang can silently lose messages, AEMP cannot.
		782
		783	Erlang makes few guarantees on messages delivery - messages can get lost
		784	without any of the processes realising it (i.e. you send messages a, b,
		785	and c, and the other side only receives messages a and c).
		786
		787	AEMP guarantees correct ordering, and the guarantee that there are no
		788	holes in the message sequence.
		789
		790	=item * In Erlang, processes can be declared dead and later be found to be
		791	alive.
		792
		793	In Erlang it can happen that a monitored process is declared dead and
		794	linked processes get killed, but later it turns out that the process is
		795	still alive - and can receive messages.
		796
		797	In AEMP, when port monitoring detects a port as dead, then that port will
		798	eventually be killed - it cannot happen that a node detects a port as dead
		799	and then later sends messages to it, finding it is still alive.
		800
		801	=item * Erlang can send messages to the wrong port, AEMP does not.
		802
		803	In Erlang it is quite possible that a node that restarts reuses a process
		804	ID known to other nodes for a completely different process, causing
		805	messages destined for that process to end up in an unrelated process.
		806
		807	AEMP never reuses port IDs, so old messages or old port IDs floating
		808	around in the network will not be sent to an unrelated port.
		809
		810	=item * Erlang uses unprotected connections, AEMP uses secure
		811	authentication and can use TLS.
		812
		813	AEMP can use a proven protocol - SSL/TLS - to protect connections and
		814	securely authenticate nodes.
		815
		816	=item * The AEMP protocol is optimised for both text-based and binary
		817	communications.
		818
		819	The AEMP protocol, unlike the Erlang protocol, supports both
		820	language-independent text-only protocols (good for debugging) and binary,
		821	language-specific serialisers (e.g. Storable).
		822
		823	It has also been carefully designed to be implementable in other languages
		824	with a minimum of work while gracefully degrading fucntionality to make the
		825	protocol simple.
		826
		827	=item * AEMP has more flexible monitoring options than Erlang.
		828
		829	In Erlang, you can chose to receive I<all> exit signals as messages
		830	or I<none>, there is no in-between, so monitoring single processes is
		831	difficult to implement. Monitoring in AEMP is more flexible than in
		832	Erlang, as one can choose between automatic kill, exit message or callback
		833	on a per-process basis.
		834
		835	=item * Erlang tries to hide remote/local connections, AEMP does not.
		836
		837	Monitoring in Erlang is not an indicator of process death/crashes,
		838	as linking is (except linking is unreliable in Erlang).
		839
		840	In AEMP, you don't "look up" registered port names or send to named ports
		841	that might or might not be persistent. Instead, you normally spawn a port
		842	on the remote node. The init function monitors the you, and you monitor
		843	the remote port. Since both monitors are local to the node, they are much
		844	more reliable.
		845
		846	This also saves round-trips and avoids sending messages to the wrong port
		847	(hard to do in Erlang).
		848
		849	=back
		850
513	=head1 SEE ALSO	851	=head1 SEE ALSO
514		852
515	L<AnyEvent>.	853	L<AnyEvent>.
516		854
517	=head1 AUTHOR	855	=head1 AUTHOR

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.25 by root, Tue Aug 4 21:07:37 2009 UTC vs. Revision 1.43 by root, Sun Aug 9 16:08:16 2009 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.25 by root, Tue Aug 4 21:07:37 2009 UTC vs.
Revision 1.43 by root, Sun Aug 9 16:08:16 2009 UTC