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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.23 by root, Tue Aug 4 18:46:16 2009 UTC vs.
Revision 1.47 by root, Thu Aug 13 01:57:10 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
		43	=head1 CURRENT STATUS
		44
		45	AnyEvent::MP - stable API, should work
		46	AnyEvent::MP::Intro - outdated
		47	AnyEvent::MP::Kernel - WIP
		48	AnyEvent::MP::Transport - mostly stable
		49
		50	stay tuned.
		51
28	=head1 DESCRIPTION	52	=head1 DESCRIPTION
29		53
30	This module (-family) implements a simple message passing framework.	54	This module (-family) implements a simple message passing framework.
31		55
32	Despite its simplicity, you can securely message other processes running	56	Despite its simplicity, you can securely message other processes running
…		…
35	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	59	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
36	manual page.	60	manual page.
37		61
38	At the moment, this module family is severly broken and underdocumented,	62	At the moment, this module family is severly broken and underdocumented,
39	so do not use. This was uploaded mainly to reserve the CPAN namespace -	63	so do not use. This was uploaded mainly to reserve the CPAN namespace -
40	stay tuned! The basic API should be finished, however.	64	stay tuned!
41		65
42	=head1 CONCEPTS	66	=head1 CONCEPTS
43		67
44	=over 4	68	=over 4
45		69
46	=item port	70	=item port
47		71
48	A port is something you can send messages to with the C<snd> function, and	72	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	73
50	messages they match, messages will not be queued.	74	Some ports allow you to register C<rcv> handlers that can match specific
		75	messages. All C<rcv> handlers will receive messages they match, messages
		76	will not be queued.
51		77
52	=item port id - C<noderef#portname>	78	=item port id - C<noderef#portname>
53		79
54	A port id is always the noderef, a hash-mark (C<#>) as separator, followed	80	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).	81	separator, and a port name (a printable string of unspecified format). An
		82	exception is the the node port, whose ID is identical to its node
		83	reference.
56		84
57	=item node	85	=item node
58		86
59	A node is a single process containing at least one port - the node	87	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,	88	port. You can send messages to node ports to find existing ports or to
61	among other things.	89	create new ports, among other things.
62		90
63	Initially, nodes are either private (single-process only) or hidden	91	Nodes are either private (single-process only), slaves (connected to a
64	(connected to a master node only). Only when they epxlicitly "become	92	master node only) or public nodes (connectable from unrelated nodes).
65	public" can you send them messages from unrelated other nodes.
66		93
67	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	94	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>
68		95
69	A noderef is a string that either uniquely identifies a given node (for	96	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	97	private and slave nodes), or contains a recipe on how to reach a given
71	node (for public nodes).	98	node (for public nodes).
72		99
		100	This recipe is simply a comma-separated list of C<address:port> pairs (for
		101	TCP/IP, other protocols might look different).
		102
		103	Node references come in two flavours: resolved (containing only numerical
		104	addresses) or unresolved (where hostnames are used instead of addresses).
		105
		106	Before using an unresolved node reference in a message you first have to
		107	resolve it.
		108
73	=back	109	=back
74		110
75	=head1 VARIABLES/FUNCTIONS	111	=head1 VARIABLES/FUNCTIONS
76		112
77	=over 4	113	=over 4
78		114
79	=cut	115	=cut
80		116
81	package AnyEvent::MP;	117	package AnyEvent::MP;
82		118
83	use AnyEvent::MP::Base;	119	use AnyEvent::MP::Kernel;
84		120
85	use common::sense;	121	use common::sense;
86		122
87	use Carp ();	123	use Carp ();
88		124
89	use AE ();	125	use AE ();
90		126
91	use base "Exporter";	127	use base "Exporter";
92		128
93	our $VERSION = '0.02';	129	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		130
94	our @EXPORT = qw(	131	our @EXPORT = qw(
95	NODE $NODE *SELF node_of _any_	132	NODE $NODE *SELF node_of _any_
96	become_slave become_public	133	resolve_node initialise_node
97	snd rcv mon kil reg psub	134	snd rcv mon kil reg psub spawn
98	port	135	port
99	);	136	);
100		137
101	our $SELF;	138	our $SELF;
102		139
…		…
111	The C<NODE> function returns, and the C<$NODE> variable contains	148	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	149	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	150	to C<become_public> or C<become_slave>, after which all local port
114	identifiers become invalid.	151	identifiers become invalid.
115		152
116	=item $noderef = node_of $portid	153	=item $noderef = node_of $port
117		154
118	Extracts and returns the noderef from a portid or a noderef.	155	Extracts and returns the noderef from a portid or a noderef.
		156
		157	=item initialise_node $noderef, $seednode, $seednode...
		158
		159	=item initialise_node "slave/", $master, $master...
		160
		161	Before a node can talk to other nodes on the network it has to initialise
		162	itself - the minimum a node needs to know is it's own name, and optionally
		163	it should know the noderefs of some other nodes in the network.
		164
		165	This function initialises a node - it must be called exactly once (or
		166	never) before calling other AnyEvent::MP functions.
		167
		168	All arguments are noderefs, which can be either resolved or unresolved.
		169
		170	There are two types of networked nodes, public nodes and slave nodes:
		171
		172	=over 4
		173
		174	=item public nodes
		175
		176	For public nodes, C<$noderef> must either be a (possibly unresolved)
		177	noderef, in which case it will be resolved, or C<undef> (or missing), in
		178	which case the noderef will be guessed.
		179
		180	Afterwards, the node will bind itself on all endpoints and try to connect
		181	to all additional C<$seednodes> that are specified. Seednodes are optional
		182	and can be used to quickly bootstrap the node into an existing network.
		183
		184	=item slave nodes
		185
		186	When the C<$noderef> is the special string C<slave/>, then the node will
		187	become a slave node. Slave nodes cannot be contacted from outside and will
		188	route most of their traffic to the master node that they attach to.
		189
		190	At least one additional noderef is required: The node will try to connect
		191	to all of them and will become a slave attached to the first node it can
		192	successfully connect to.
		193
		194	=back
		195
		196	This function will block until all nodes have been resolved and, for slave
		197	nodes, until it has successfully established a connection to a master
		198	server.
		199
		200	Example: become a public node listening on the default node.
		201
		202	initialise_node;
		203
		204	Example: become a public node, and try to contact some well-known master
		205	servers to become part of the network.
		206
		207	initialise_node undef, "master1", "master2";
		208
		209	Example: become a public node listening on port C<4041>.
		210
		211	initialise_node 4041;
		212
		213	Example: become a public node, only visible on localhost port 4044.
		214
		215	initialise_node "locahost:4044";
		216
		217	Example: become a slave node to any of the specified master servers.
		218
		219	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
		220
		221	=item $cv = resolve_node $noderef
		222
		223	Takes an unresolved node reference that may contain hostnames and
		224	abbreviated IDs, resolves all of them and returns a resolved node
		225	reference.
		226
		227	In addition to C<address:port> pairs allowed in resolved noderefs, the
		228	following forms are supported:
		229
		230	=over 4
		231
		232	=item the empty string
		233
		234	An empty-string component gets resolved as if the default port (4040) was
		235	specified.
		236
		237	=item naked port numbers (e.g. C<1234>)
		238
		239	These are resolved by prepending the local nodename and a colon, to be
		240	further resolved.
		241
		242	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
		243
		244	These are resolved by using AnyEvent::DNS to resolve them, optionally
		245	looking up SRV records for the C<aemp=4040> port, if no port was
		246	specified.
		247
		248	=back
119		249
120	=item $SELF	250	=item $SELF
121		251
122	Contains the current port id while executing C<rcv> callbacks or C<psub>	252	Contains the current port id while executing C<rcv> callbacks or C<psub>
123	blocks.	253	blocks.
…		…
126		256
127	Due to some quirks in how perl exports variables, it is impossible to	257	Due to some quirks in how perl exports variables, it is impossible to
128	just export C<$SELF>, all the symbols called C<SELF> are exported by this	258	just export C<$SELF>, all the symbols called C<SELF> are exported by this
129	module, but only C<$SELF> is currently used.	259	module, but only C<$SELF> is currently used.
130		260
131	=item snd $portid, type => @data	261	=item snd $port, type => @data
132		262
133	=item snd $portid, @msg	263	=item snd $port, @msg
134		264
135	Send the given message to the given port ID, which can identify either	265	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	266	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 :).	267	stringifies a sa port ID (such as a port object :).
138		268
…		…
148	JSON is used, then only strings, numbers and arrays and hashes consisting	278	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	279	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	280	that Storable can serialise and deserialise is allowed, and for the local
151	node, anything can be passed.	281	node, anything can be passed.
152		282
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 $local_port = port	283	=item $local_port = port
251		284
252	Create a new local port object that supports message matching.	285	Create a new local port object that can be used either as a pattern
		286	matching port ("full port") or a single-callback port ("miniport"),
		287	depending on how C<rcv> callbacks are bound to the object.
253		288
254	=item $portid = port { my @msg = @_; $finished }	289	=item $port = port { my @msg = @_; $finished }
255		290
256	Creates a "mini port", that is, a very lightweight port without any	291	Creates a "miniport", that is, a very lightweight port without any pattern
257	pattern matching behind it, and returns its ID.	292	matching behind it, and returns its ID. Semantically the same as creating
		293	a port and calling C<rcv $port, $callback> on it.
258		294
259	The block will be called for every message received on the port. When the	295	The block will be called for every message received on the port. When the
260	callback returns a true value its job is considered "done" and the port	296	callback returns a true value its job is considered "done" and the port
261	will be destroyed. Otherwise it will stay alive.	297	will be destroyed. Otherwise it will stay alive.
262		298
263	The message will be passed as-is, no extra argument (i.e. no port id) will	299	The message will be passed as-is, no extra argument (i.e. no port id) will
264	be passed to the callback.	300	be passed to the callback.
265		301
266	If you need the local port id in the callback, this works nicely:	302	If you need the local port id in the callback, this works nicely:
267		303
268	my $port; $port = miniport {	304	my $port; $port = port {
269	snd $otherport, reply => $port;	305	snd $otherport, reply => $port;
270	};	306	};
271		307
272	=cut	308	=cut
		309
		310	sub rcv($@);
273		311
274	sub port(;&) {	312	sub port(;&) {
275	my $id = "$UNIQ." . $ID++;	313	my $id = "$UNIQ." . $ID++;
276	my $port = "$NODE#$id";	314	my $port = "$NODE#$id";
277		315
278	if (@_) {	316	if (@_) {
		317	rcv $port, shift;
		318	} else {
		319	$PORT{$id} = sub { }; # nop
		320	}
		321
		322	$port
		323	}
		324
		325	=item reg $port, $name
		326
		327	=item reg $name
		328
		329	Registers the given port (or C<$SELF><<< if missing) under the name
		330	C<$name>. If the name already exists it is replaced.
		331
		332	A port can only be registered under one well known name.
		333
		334	A port automatically becomes unregistered when it is killed.
		335
		336	=cut
		337
		338	sub reg(@) {
		339	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
		340
		341	$REG{$_[0]} = $port;
		342	}
		343
		344	=item rcv $port, $callback->(@msg)
		345
		346	Replaces the callback on the specified miniport (after converting it to
		347	one if required).
		348
		349	=item rcv $port, tagstring => $callback->(@msg), ...
		350
		351	=item rcv $port, $smartmatch => $callback->(@msg), ...
		352
		353	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
		354
		355	Register callbacks to be called on matching messages on the given full
		356	port (after converting it to one if required) and return the port.
		357
		358	The callback has to return a true value when its work is done, after
		359	which is will be removed, or a false value in which case it will stay
		360	registered.
		361
		362	The global C<$SELF> (exported by this module) contains C<$port> while
		363	executing the callback.
		364
		365	Runtime errors during callback execution will result in the port being
		366	C<kil>ed.
		367
		368	If the match is an array reference, then it will be matched against the
		369	first elements of the message, otherwise only the first element is being
		370	matched.
		371
		372	Any element in the match that is specified as C<_any_> (a function
		373	exported by this module) matches any single element of the message.
		374
		375	While not required, it is highly recommended that the first matching
		376	element is a string identifying the message. The one-string-only match is
		377	also the most efficient match (by far).
		378
		379	Example: create a port and bind receivers on it in one go.
		380
		381	my $port = rcv port,
		382	msg1 => sub { ...; 0 },
		383	msg2 => sub { ...; 0 },
		384	;
		385
		386	Example: create a port, bind receivers and send it in a message elsewhere
		387	in one go:
		388
		389	snd $otherport, reply =>
		390	rcv port,
		391	msg1 => sub { ...; 0 },
		392	...
		393	;
		394
		395	=cut
		396
		397	sub rcv($@) {
		398	my $port = shift;
		399	my ($noderef, $portid) = split /#/, $port, 2;
		400
		401	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
		402	or Carp::croak "$port: rcv can only be called on local ports, caught";
		403
		404	if (@_ == 1) {
279	my $cb = shift;	405	my $cb = shift;
		406	delete $PORT_DATA{$portid};
280	$PORT{$id} = sub {	407	$PORT{$portid} = sub {
281	local $SELF = $port;	408	local $SELF = $port;
282	eval {	409	eval {
283	&$cb	410	&$cb
284	and kil $id;	411	and kil $port;
285	};	412	};
286	_self_die if $@;	413	_self_die if $@;
287	};	414	};
288	} else {	415	} else {
		416	my $self = $PORT_DATA{$portid} \|\|= do {
289	my $self = bless {	417	my $self = bless {
290	id => "$NODE#$id",	418	id => $port,
291	}, "AnyEvent::MP::Port";	419	}, "AnyEvent::MP::Port";
292		420
293	$PORT_DATA{$id} = $self;
294	$PORT{$id} = sub {	421	$PORT{$portid} = sub {
295	local $SELF = $port;	422	local $SELF = $port;
296		423
297	eval {	424	eval {
298	for (@{ $self->{rc0}{$_[0]} }) {	425	for (@{ $self->{rc0}{$_[0]} }) {
299	$_ && &{$_->[0]}	426	$_ && &{$_->[0]}
300	&& undef $_;	427	&& undef $_;
301	}	428	}
302		429
303	for (@{ $self->{rcv}{$_[0]} }) {	430	for (@{ $self->{rcv}{$_[0]} }) {
304	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]	431	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
305	&& &{$_->[0]}	432	&& &{$_->[0]}
306	&& undef $_;	433	&& undef $_;
307	}	434	}
308		435
309	for (@{ $self->{any} }) {	436	for (@{ $self->{any} }) {
310	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]	437	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
311	&& &{$_->[0]}	438	&& &{$_->[0]}
312	&& undef $_;	439	&& undef $_;
		440	}
313	}	441	};
		442	_self_die if $@;
314	};	443	};
315	_self_die if $@;	444
		445	$self
316	};	446	};
317	}
318		447
319	$port
320	}
321
322	=item reg $portid, $name
323
324	Registers the given port under the name C<$name>. If the name already
325	exists it is replaced.
326
327	A port can only be registered under one well known name.
328
329	A port automatically becomes unregistered when it is killed.
330
331	=cut
332
333	sub reg(@) {
334	my ($portid, $name) = @_;
335
336	$REG{$name} = $portid;
337	}
338
339	=item rcv $portid, tagstring => $callback->(@msg), ...
340
341	=item rcv $portid, $smartmatch => $callback->(@msg), ...
342
343	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
344
345	Register callbacks to be called on matching messages on the given port.
346
347	The callback has to return a true value when its work is done, after
348	which is will be removed, or a false value in which case it will stay
349	registered.
350
351	The global C<$SELF> (exported by this module) contains C<$portid> while
352	executing the callback.
353
354	Runtime errors wdurign callback execution will result in the port being
355	C<kil>ed.
356
357	If the match is an array reference, then it will be matched against the
358	first elements of the message, otherwise only the first element is being
359	matched.
360
361	Any element in the match that is specified as C<_any_> (a function
362	exported by this module) matches any single element of the message.
363
364	While not required, it is highly recommended that the first matching
365	element is a string identifying the message. The one-string-only match is
366	also the most efficient match (by far).
367
368	=cut
369
370	sub rcv($@) {
371	my ($noderef, $port) = split /#/, shift, 2;
372
373	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
374	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";
375
376	my $self = $PORT_DATA{$port}
377	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
378
379	"AnyEvent::MP::Port" eq ref $self	448	"AnyEvent::MP::Port" eq ref $self
380	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";	449	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
381		450
382	while (@_) {	451	while (@_) {
383	my ($match, $cb) = splice @_, 0, 2;	452	my ($match, $cb) = splice @_, 0, 2;
384		453
385	if (!ref $match) {	454	if (!ref $match) {
386	push @{ $self->{rc0}{$match} }, [$cb];	455	push @{ $self->{rc0}{$match} }, [$cb];
387	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {	456	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
388	my ($type, @match) = @$match;	457	my ($type, @match) = @$match;
389	@match	458	@match
390	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]	459	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
391	: push @{ $self->{rc0}{$match->[0]} }, [$cb];	460	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
392	} else {	461	} else {
393	push @{ $self->{any} }, [$cb, $match];	462	push @{ $self->{any} }, [$cb, $match];
		463	}
394	}	464	}
395	}	465	}
		466
		467	$port
396	}	468	}
397		469
398	=item $closure = psub { BLOCK }	470	=item $closure = psub { BLOCK }
399		471
400	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	472	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
…		…
431	$res	503	$res
432	}	504	}
433	}	505	}
434	}	506	}
435		507
436	=back	508	=item $guard = mon $port, $cb->(@reason)
437		509
438	=head1 FUNCTIONS FOR NODES	510	=item $guard = mon $port, $rcvport
439		511
440	=over 4	512	=item $guard = mon $port
441		513
442	=item become_public endpoint...	514	=item $guard = mon $port, $rcvport, @msg
443		515
444	Tells the node to become a public node, i.e. reachable from other nodes.	516	Monitor the given port and do something when the port is killed or
		517	messages to it were lost, and optionally return a guard that can be used
		518	to stop monitoring again.
445		519
446	If no arguments are given, or the first argument is C<undef>, then	520	C<mon> effectively guarantees that, in the absence of hardware failures,
447	AnyEvent::MP tries to bind on port C<4040> on all IP addresses that the	521	that after starting the monitor, either all messages sent to the port
448	local nodename resolves to.	522	will arrive, or the monitoring action will be invoked after possible
		523	message loss has been detected. No messages will be lost "in between"
		524	(after the first lost message no further messages will be received by the
		525	port). After the monitoring action was invoked, further messages might get
		526	delivered again.
449		527
450	Otherwise the first argument must be an array-reference with transport	528	In the first form (callback), the callback is simply called with any
451	endpoints ("ip:port", "hostname:port") or port numbers (in which case the	529	number of C<@reason> elements (no @reason means that the port was deleted
452	local nodename is used as hostname). The endpoints are all resolved and	530	"normally"). Note also that I<< the callback B<must> never die >>, so use
453	will become the node reference.	531	C<eval> if unsure.
454		532
		533	In the second form (another port given), the other port (C<$rcvport>)
		534	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
		535	"normal" kils nothing happens, while under all other conditions, the other
		536	port is killed with the same reason.
		537
		538	The third form (kill self) is the same as the second form, except that
		539	C<$rvport> defaults to C<$SELF>.
		540
		541	In the last form (message), a message of the form C<@msg, @reason> will be
		542	C<snd>.
		543
		544	As a rule of thumb, monitoring requests should always monitor a port from
		545	a local port (or callback). The reason is that kill messages might get
		546	lost, just like any other message. Another less obvious reason is that
		547	even monitoring requests can get lost (for exmaple, when the connection
		548	to the other node goes down permanently). When monitoring a port locally
		549	these problems do not exist.
		550
		551	Example: call a given callback when C<$port> is killed.
		552
		553	mon $port, sub { warn "port died because of <@_>\n" };
		554
		555	Example: kill ourselves when C<$port> is killed abnormally.
		556
		557	mon $port;
		558
		559	Example: send us a restart message when another C<$port> is killed.
		560
		561	mon $port, $self => "restart";
		562
455	=cut	563	=cut
		564
		565	sub mon {
		566	my ($noderef, $port) = split /#/, shift, 2;
		567
		568	my $node = $NODE{$noderef} \|\| add_node $noderef;
		569
		570	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
		571
		572	unless (ref $cb) {
		573	if (@_) {
		574	# send a kill info message
		575	my (@msg) = ($cb, @_);
		576	$cb = sub { snd @msg, @_ };
		577	} else {
		578	# simply kill other port
		579	my $port = $cb;
		580	$cb = sub { kil $port, @_ if @_ };
		581	}
		582	}
		583
		584	$node->monitor ($port, $cb);
		585
		586	defined wantarray
		587	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
		588	}
		589
		590	=item $guard = mon_guard $port, $ref, $ref...
		591
		592	Monitors the given C<$port> and keeps the passed references. When the port
		593	is killed, the references will be freed.
		594
		595	Optionally returns a guard that will stop the monitoring.
		596
		597	This function is useful when you create e.g. timers or other watchers and
		598	want to free them when the port gets killed:
		599
		600	$port->rcv (start => sub {
		601	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
		602	undef $timer if 0.9 < rand;
		603	});
		604	});
		605
		606	=cut
		607
		608	sub mon_guard {
		609	my ($port, @refs) = @_;
		610
		611	#TODO: mon-less form?
		612
		613	mon $port, sub { 0 && @refs }
		614	}
		615
		616	=item kil $port[, @reason]
		617
		618	Kill the specified port with the given C<@reason>.
		619
		620	If no C<@reason> is specified, then the port is killed "normally" (linked
		621	ports will not be kileld, or even notified).
		622
		623	Otherwise, linked ports get killed with the same reason (second form of
		624	C<mon>, see below).
		625
		626	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		627	will be reported as reason C<< die => $@ >>.
		628
		629	Transport/communication errors are reported as C<< transport_error =>
		630	$message >>.
		631
		632	=cut
		633
		634	=item $port = spawn $node, $initfunc[, @initdata]
		635
		636	Creates a port on the node C<$node> (which can also be a port ID, in which
		637	case it's the node where that port resides).
		638
		639	The port ID of the newly created port is return immediately, and it is
		640	permissible to immediately start sending messages or monitor the port.
		641
		642	After the port has been created, the init function is
		643	called. This function must be a fully-qualified function name
		644	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		645	program, use C<::name>.
		646
		647	If the function doesn't exist, then the node tries to C<require>
		648	the package, then the package above the package and so on (e.g.
		649	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		650	exists or it runs out of package names.
		651
		652	The init function is then called with the newly-created port as context
		653	object (C<$SELF>) and the C<@initdata> values as arguments.
		654
		655	A common idiom is to pass your own port, monitor the spawned port, and
		656	in the init function, monitor the original port. This two-way monitoring
		657	ensures that both ports get cleaned up when there is a problem.
		658
		659	Example: spawn a chat server port on C<$othernode>.
		660
		661	# this node, executed from within a port context:
		662	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		663	mon $server;
		664
		665	# init function on C<$othernode>
		666	sub connect {
		667	my ($srcport) = @_;
		668
		669	mon $srcport;
		670
		671	rcv $SELF, sub {
		672	...
		673	};
		674	}
		675
		676	=cut
		677
		678	sub _spawn {
		679	my $port = shift;
		680	my $init = shift;
		681
		682	local $SELF = "$NODE#$port";
		683	eval {
		684	&{ load_func $init }
		685	};
		686	_self_die if $@;
		687	}
		688
		689	sub spawn(@) {
		690	my ($noderef, undef) = split /#/, shift, 2;
		691
		692	my $id = "$RUNIQ." . $ID++;
		693
		694	$_[0] =~ /::/
		695	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		696
		697	($NODE{$noderef} \|\| add_node $noderef)
		698	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
		699
		700	"$noderef#$id"
		701	}
456		702
457	=back	703	=back
458		704
459	=head1 NODE MESSAGES	705	=head1 NODE MESSAGES
460		706
461	Nodes understand the following messages sent to them. Many of them take	707	Nodes understand the following messages sent to them. Many of them take
462	arguments called C<@reply>, which will simply be used to compose a reply	708	arguments called C<@reply>, which will simply be used to compose a reply
463	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and	709	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
464	the remaining arguments are simply the message data.	710	the remaining arguments are simply the message data.
465		711
		712	While other messages exist, they are not public and subject to change.
		713
466	=over 4	714	=over 4
467		715
468	=cut	716	=cut
469		717
470	=item lookup => $name, @reply	718	=item lookup => $name, @reply
…		…
498	snd $NODE, time => $myport, timereply => 1, 2;	746	snd $NODE, time => $myport, timereply => 1, 2;
499	# => snd $myport, timereply => 1, 2, <time>	747	# => snd $myport, timereply => 1, 2, <time>
500		748
501	=back	749	=back
502		750
		751	=head1 AnyEvent::MP vs. Distributed Erlang
		752
		753	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
		754	== aemp node, Erlang process == aemp port), so many of the documents and
		755	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		756	sample:
		757
		758	http://www.Erlang.se/doc/programming_rules.shtml
		759	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		760	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		761	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		762
		763	Despite the similarities, there are also some important differences:
		764
		765	=over 4
		766
		767	=item * Node references contain the recipe on how to contact them.
		768
		769	Erlang relies on special naming and DNS to work everywhere in the
		770	same way. AEMP relies on each node knowing it's own address(es), with
		771	convenience functionality.
		772
		773	This means that AEMP requires a less tightly controlled environment at the
		774	cost of longer node references and a slightly higher management overhead.
		775
		776	=item * Erlang uses processes and a mailbox, AEMP does not queue.
		777
		778	Erlang uses processes that selctively receive messages, and therefore
		779	needs a queue. AEMP is event based, queuing messages would serve no useful
		780	purpose.
		781
		782	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
		783
		784	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
		785
		786	Sending messages in Erlang is synchronous and blocks the process. AEMP
		787	sends are immediate, connection establishment is handled in the
		788	background.
		789
		790	=item * Erlang can silently lose messages, AEMP cannot.
		791
		792	Erlang makes few guarantees on messages delivery - messages can get lost
		793	without any of the processes realising it (i.e. you send messages a, b,
		794	and c, and the other side only receives messages a and c).
		795
		796	AEMP guarantees correct ordering, and the guarantee that there are no
		797	holes in the message sequence.
		798
		799	=item * In Erlang, processes can be declared dead and later be found to be
		800	alive.
		801
		802	In Erlang it can happen that a monitored process is declared dead and
		803	linked processes get killed, but later it turns out that the process is
		804	still alive - and can receive messages.
		805
		806	In AEMP, when port monitoring detects a port as dead, then that port will
		807	eventually be killed - it cannot happen that a node detects a port as dead
		808	and then later sends messages to it, finding it is still alive.
		809
		810	=item * Erlang can send messages to the wrong port, AEMP does not.
		811
		812	In Erlang it is quite possible that a node that restarts reuses a process
		813	ID known to other nodes for a completely different process, causing
		814	messages destined for that process to end up in an unrelated process.
		815
		816	AEMP never reuses port IDs, so old messages or old port IDs floating
		817	around in the network will not be sent to an unrelated port.
		818
		819	=item * Erlang uses unprotected connections, AEMP uses secure
		820	authentication and can use TLS.
		821
		822	AEMP can use a proven protocol - SSL/TLS - to protect connections and
		823	securely authenticate nodes.
		824
		825	=item * The AEMP protocol is optimised for both text-based and binary
		826	communications.
		827
		828	The AEMP protocol, unlike the Erlang protocol, supports both
		829	language-independent text-only protocols (good for debugging) and binary,
		830	language-specific serialisers (e.g. Storable).
		831
		832	It has also been carefully designed to be implementable in other languages
		833	with a minimum of work while gracefully degrading fucntionality to make the
		834	protocol simple.
		835
		836	=item * AEMP has more flexible monitoring options than Erlang.
		837
		838	In Erlang, you can chose to receive I<all> exit signals as messages
		839	or I<none>, there is no in-between, so monitoring single processes is
		840	difficult to implement. Monitoring in AEMP is more flexible than in
		841	Erlang, as one can choose between automatic kill, exit message or callback
		842	on a per-process basis.
		843
		844	=item * Erlang tries to hide remote/local connections, AEMP does not.
		845
		846	Monitoring in Erlang is not an indicator of process death/crashes,
		847	as linking is (except linking is unreliable in Erlang).
		848
		849	In AEMP, you don't "look up" registered port names or send to named ports
		850	that might or might not be persistent. Instead, you normally spawn a port
		851	on the remote node. The init function monitors the you, and you monitor
		852	the remote port. Since both monitors are local to the node, they are much
		853	more reliable.
		854
		855	This also saves round-trips and avoids sending messages to the wrong port
		856	(hard to do in Erlang).
		857
		858	=back
		859
		860	=head1 RATIONALE
		861
		862	=over 4
		863
		864	=item Why strings for ports and noderefs, why not objects?
		865
		866	We considered "objects", but found that the actual number of methods
		867	thatc an be called are very low. Since port IDs and noderefs travel over
		868	the network frequently, the serialising/deserialising would add lots of
		869	overhead, as well as having to keep a proxy object.
		870
		871	Strings can easily be printed, easily serialised etc. and need no special
		872	procedures to be "valid".
		873
		874	And a a miniport consists of a single closure stored in a global hash - it
		875	can't become much cheaper.
		876
		877	=item Why favour JSON, why not real serialising format such as Storable?
		878
		879	In fact, any AnyEvent::MP node will happily accept Storable as framing
		880	format, but currently there is no way to make a node use Storable by
		881	default.
		882
		883	The default framing protocol is JSON because a) JSON::XS is many times
		884	faster for small messages and b) most importantly, after years of
		885	experience we found that object serialisation is causing more problems
		886	than it gains: Just like function calls, objects simply do not travel
		887	easily over the network, mostly because they will always be a copy, so you
		888	always have to re-think your design.
		889
		890	Keeping your messages simple, concentrating on data structures rather than
		891	objects, will keep your messages clean, tidy and efficient.
		892
		893	=back
		894
503	=head1 SEE ALSO	895	=head1 SEE ALSO
504		896
505	L<AnyEvent>.	897	L<AnyEvent>.
506		898
507	=head1 AUTHOR	899	=head1 AUTHOR

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.23 by root, Tue Aug 4 18:46:16 2009 UTC vs. Revision 1.47 by root, Thu Aug 13 01:57:10 2009 UTC

Diff Legend

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.23 by root, Tue Aug 4 18:46:16 2009 UTC vs.
Revision 1.47 by root, Thu Aug 13 01:57:10 2009 UTC