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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.22 by root, Tue Aug 4 18:33:30 2009 UTC vs.
Revision 1.63 by root, Thu Aug 27 21:29:37 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	# initialise the node so it can send/receive messages
		16	initialise_node;
		17
		18	# ports are message endpoints
		19
		20	# sending messages
13	snd $port, type => data...;	21	snd $port, type => data...;
		22	snd $port, @msg;
		23	snd @msg_with_first_element_being_a_port;
14		24
15	$SELF # receiving/own port id in rcv callbacks	25	# creating/using ports, the simple way
		26	my $simple_port = port { my @msg = @_; 0 };
16		27
17	rcv $port, smartmatch => $cb->($port, @msg);	28	# creating/using ports, tagged message matching
18		29	my $port = port;
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	30	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
21	rcv $port1, pong => sub { warn "pong received\n" };	31	rcv $port, pong => sub { warn "pong received\n"; 0 };
22	snd $port2, ping => $port1;
23		32
24	# more, smarter, matches (_any_ is exported by this module)	33	# create a port on another node
25	rcv $port, [child_died => $pid] => sub { ...	34	my $port = spawn $node, $initfunc, @initdata;
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	35
		36	# monitoring
		37	mon $port, $cb->(@msg) # callback is invoked on death
		38	mon $port, $otherport # kill otherport on abnormal death
		39	mon $port, $otherport, @msg # send message on death
		40
		41	=head1 CURRENT STATUS
		42
		43	AnyEvent::MP - stable API, should work
		44	AnyEvent::MP::Intro - outdated
		45	AnyEvent::MP::Kernel - WIP
		46	AnyEvent::MP::Transport - mostly stable
		47
		48	stay tuned.
27		49
28	=head1 DESCRIPTION	50	=head1 DESCRIPTION
29		51
30	This module (-family) implements a simple message passing framework.	52	This module (-family) implements a simple message passing framework.
31		53
32	Despite its simplicity, you can securely message other processes running	54	Despite its simplicity, you can securely message other processes running
33	on the same or other hosts.	55	on the same or other hosts.
34		56
		57	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
		58	manual page.
		59
35	At the moment, this module family is severly brokena nd underdocumented,	60	At the moment, this module family is severly broken and underdocumented,
36	so do not use. This was uploaded mainly to reserve the CPAN namespace -	61	so do not use. This was uploaded mainly to reserve the CPAN namespace -
37	stay tuned!	62	stay tuned!
38		63
39	=head1 CONCEPTS	64	=head1 CONCEPTS
40		65
41	=over 4	66	=over 4
42		67
43	=item port	68	=item port
44		69
45	A port is something you can send messages to with the C<snd> function, and	70	A port is something you can send messages to (with the C<snd> function).
46	you can register C<rcv> handlers with. All C<rcv> handlers will receive	71
		72	Ports allow you to register C<rcv> handlers that can match all or just
47	messages they match, messages will not be queued.	73	some messages. Messages will not be queued.
48		74
49	=item port id - C<noderef#portname>	75	=item port ID - C<noderef#portname>
50		76
51	A port id is always the noderef, a hash-mark (C<#>) as separator, followed	77	A port ID is the concatenation of a noderef, a hash-mark (C<#>) as
52	by a port name (a printable string of unspecified format).	78	separator, and a port name (a printable string of unspecified format). An
		79	exception is the the node port, whose ID is identical to its node
		80	reference.
53		81
54	=item node	82	=item node
55		83
56	A node is a single process containing at least one port - the node	84	A node is a single process containing at least one port - the node port,
57	port. You can send messages to node ports to let them create new ports,	85	which provides nodes to manage each other remotely, and to create new
58	among other things.	86	ports.
59		87
60	Initially, nodes are either private (single-process only) or hidden	88	Nodes are either private (single-process only), slaves (can only talk to
61	(connected to a master node only). Only when they epxlicitly "become	89	public nodes, but do not need an open port) or public nodes (connectable
62	public" can you send them messages from unrelated other nodes.	90	from any other node).
63		91
64	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	92	=item node ID - C<[a-za-Z0-9_\-.:]+>
65		93
66	A noderef is a string that either uniquely identifies a given node (for	94	A node ID is a string that either simply identifies the node (for
67	private and hidden nodes), or contains a recipe on how to reach a given	95	private and slave nodes), or contains a recipe on how to reach a given
68	node (for public nodes).	96	node (for public nodes).
69		97
		98	This recipe is simply a comma-separated list of C<address:port> pairs (for
		99	TCP/IP, other protocols might look different).
		100
		101	Node references come in two flavours: resolved (containing only numerical
		102	addresses) or unresolved (where hostnames are used instead of addresses).
		103
		104	Before using an unresolved node reference in a message you first have to
		105	resolve it.
		106
70	=back	107	=back
71		108
72	=head1 VARIABLES/FUNCTIONS	109	=head1 VARIABLES/FUNCTIONS
73		110
74	=over 4	111	=over 4
75		112
76	=cut	113	=cut
77		114
78	package AnyEvent::MP;	115	package AnyEvent::MP;
79		116
80	use AnyEvent::MP::Base;	117	use AnyEvent::MP::Kernel;
81		118
82	use common::sense;	119	use common::sense;
83		120
84	use Carp ();	121	use Carp ();
85		122
86	use AE ();	123	use AE ();
87		124
88	use base "Exporter";	125	use base "Exporter";
89		126
90	our $VERSION = '0.02';	127	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		128
91	our @EXPORT = qw(	129	our @EXPORT = qw(
92	NODE $NODE *SELF node_of _any_	130	NODE $NODE *SELF node_of after
93	become_slave become_public	131	resolve_node initialise_node
94	snd rcv mon kil reg psub	132	snd rcv mon mon_guard kil reg psub spawn
95	port	133	port
96	);	134	);
97		135
98	our $SELF;	136	our $SELF;
99		137
…		…
103	kil $SELF, die => $msg;	141	kil $SELF, die => $msg;
104	}	142	}
105		143
106	=item $thisnode = NODE / $NODE	144	=item $thisnode = NODE / $NODE
107		145
108	The C<NODE> function returns, and the C<$NODE> variable contains	146	The C<NODE> function returns, and the C<$NODE> variable contains the
109	the noderef of the local node. The value is initialised by a call	147	node id of the local node. The value is initialised by a call to
110	to C<become_public> or C<become_slave>, after which all local port	148	C<initialise_node>.
111	identifiers become invalid.
112		149
113	=item $noderef = node_of $portid	150	=item $nodeid = node_of $port
114		151
115	Extracts and returns the noderef from a portid or a noderef.	152	Extracts and returns the noderef from a port ID or a node ID.
		153
		154	=item initialise_node $profile_name
		155
		156	Before a node can talk to other nodes on the network it has to initialise
		157	itself - the minimum a node needs to know is it's own name, and optionally
		158	it should know the noderefs of some other nodes in the network.
		159
		160	This function initialises a node - it must be called exactly once (or
		161	never) before calling other AnyEvent::MP functions.
		162
		163	All arguments (optionally except for the first) are noderefs, which can be
		164	either resolved or unresolved.
		165
		166	The first argument will be looked up in the configuration database first
		167	(if it is C<undef> then the current nodename will be used instead) to find
		168	the relevant configuration profile (see L<aemp>). If none is found then
		169	the default configuration is used. The configuration supplies additional
		170	seed/master nodes and can override the actual noderef.
		171
		172	There are two types of networked nodes, public nodes and slave nodes:
		173
		174	=over 4
		175
		176	=item public nodes
		177
		178	For public nodes, C<$noderef> (supplied either directly to
		179	C<initialise_node> or indirectly via a profile or the nodename) must be a
		180	noderef (possibly unresolved, in which case it will be resolved).
		181
		182	After resolving, the node will bind itself on all endpoints.
		183
		184	=item slave nodes
		185
		186	When the C<$noderef> (either as given or overriden by the config file)
		187	is the special string C<slave/>, then the node will become a slave
		188	node. Slave nodes cannot be contacted from outside, and cannot talk to
		189	each other (at least in this version of AnyEvent::MP).
		190
		191	Slave nodes work by creating connections to all public nodes, using the
		192	L<AnyEvent::MP::Global> service.
		193
		194	=back
		195
		196	After initialising itself, the node will connect to all additional
		197	C<$seednodes> that are specified diretcly or via a profile. Seednodes are
		198	optional and can be used to quickly bootstrap the node into an existing
		199	network.
		200
		201	All the seednodes will also be specially marked to automatically retry
		202	connecting to them indefinitely, so make sure that seednodes are really
		203	reliable and up (this might also change in the future).
		204
		205	Example: become a public node listening on the guessed noderef, or the one
		206	specified via C<aemp> for the current node. This should be the most common
		207	form of invocation for "daemon"-type nodes.
		208
		209	initialise_node;
		210
		211	Example: become a slave node to any of the the seednodes specified via
		212	C<aemp>. This form is often used for commandline clients.
		213
		214	initialise_node "slave/";
		215
		216	Example: become a public node, and try to contact some well-known master
		217	servers to become part of the network.
		218
		219	initialise_node undef, "master1", "master2";
		220
		221	Example: become a public node listening on port C<4041>.
		222
		223	initialise_node 4041;
		224
		225	Example: become a public node, only visible on localhost port 4044.
		226
		227	initialise_node "localhost:4044";
		228
		229	=item $cv = resolve_node $noderef
		230
		231	Takes an unresolved node reference that may contain hostnames and
		232	abbreviated IDs, resolves all of them and returns a resolved node
		233	reference.
		234
		235	In addition to C<address:port> pairs allowed in resolved noderefs, the
		236	following forms are supported:
		237
		238	=over 4
		239
		240	=item the empty string
		241
		242	An empty-string component gets resolved as if the default port (4040) was
		243	specified.
		244
		245	=item naked port numbers (e.g. C<1234>)
		246
		247	These are resolved by prepending the local nodename and a colon, to be
		248	further resolved.
		249
		250	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
		251
		252	These are resolved by using AnyEvent::DNS to resolve them, optionally
		253	looking up SRV records for the C<aemp=4040> port, if no port was
		254	specified.
		255
		256	=back
116		257
117	=item $SELF	258	=item $SELF
118		259
119	Contains the current port id while executing C<rcv> callbacks or C<psub>	260	Contains the current port id while executing C<rcv> callbacks or C<psub>
120	blocks.	261	blocks.
…		…
123		264
124	Due to some quirks in how perl exports variables, it is impossible to	265	Due to some quirks in how perl exports variables, it is impossible to
125	just export C<$SELF>, all the symbols called C<SELF> are exported by this	266	just export C<$SELF>, all the symbols called C<SELF> are exported by this
126	module, but only C<$SELF> is currently used.	267	module, but only C<$SELF> is currently used.
127		268
128	=item snd $portid, type => @data	269	=item snd $port, type => @data
129		270
130	=item snd $portid, @msg	271	=item snd $port, @msg
131		272
132	Send the given message to the given port ID, which can identify either	273	Send the given message to the given port ID, which can identify either
133	a local or a remote port, and can be either a string or soemthignt hat	274	a local or a remote port, and must be a port ID.
134	stringifies a sa port ID (such as a port object :).
135		275
136	While the message can be about anything, it is highly recommended to use a	276	While the message can be about anything, it is highly recommended to use a
137	string as first element (a portid, or some word that indicates a request	277	string as first element (a port ID, or some word that indicates a request
138	type etc.).	278	type etc.).
139		279
140	The message data effectively becomes read-only after a call to this	280	The message data effectively becomes read-only after a call to this
141	function: modifying any argument is not allowed and can cause many	281	function: modifying any argument is not allowed and can cause many
142	problems.	282	problems.
…		…
145	JSON is used, then only strings, numbers and arrays and hashes consisting	285	JSON is used, then only strings, numbers and arrays and hashes consisting
146	of those are allowed (no objects). When Storable is used, then anything	286	of those are allowed (no objects). When Storable is used, then anything
147	that Storable can serialise and deserialise is allowed, and for the local	287	that Storable can serialise and deserialise is allowed, and for the local
148	node, anything can be passed.	288	node, anything can be passed.
149		289
150	=item kil $portid[, @reason]	290	=item $local_port = port
151		291
152	Kill the specified port with the given C<@reason>.	292	Create a new local port object and returns its port ID. Initially it has
		293	no callbacks set and will throw an error when it receives messages.
153		294
154	If no C<@reason> is specified, then the port is killed "normally" (linked	295	=item $local_port = port { my @msg = @_ }
155	ports will not be kileld, or even notified).
156		296
157	Otherwise, linked ports get killed with the same reason (second form of	297	Creates a new local port, and returns its ID. Semantically the same as
158	C<mon>, see below).	298	creating a port and calling C<rcv $port, $callback> on it.
159		299
160	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	300	The block will be called for every message received on the port, with the
161	will be reported as reason C<< die => $@ >>.	301	global variable C<$SELF> set to the port ID. Runtime errors will cause the
		302	port to be C<kil>ed. The message will be passed as-is, no extra argument
		303	(i.e. no port ID) will be passed to the callback.
162		304
163	Transport/communication errors are reported as C<< transport_error =>	305	If you want to stop/destroy the port, simply C<kil> it:
164	$message >>.
165		306
		307	my $port = port {
		308	my @msg = @_;
		309	...
		310	kil $SELF;
		311	};
		312
		313	=cut
		314
		315	sub rcv($@);
		316
		317	sub _kilme {
		318	die "received message on port without callback";
		319	}
		320
		321	sub port(;&) {
		322	my $id = "$UNIQ." . $ID++;
		323	my $port = "$NODE#$id";
		324
		325	rcv $port, shift \|\| \&_kilme;
		326
		327	$port
		328	}
		329
		330	=item rcv $local_port, $callback->(@msg)
		331
		332	Replaces the default callback on the specified port. There is no way to
		333	remove the default callback: use C<sub { }> to disable it, or better
		334	C<kil> the port when it is no longer needed.
		335
		336	The global C<$SELF> (exported by this module) contains C<$port> while
		337	executing the callback. Runtime errors during callback execution will
		338	result in the port being C<kil>ed.
		339
		340	The default callback received all messages not matched by a more specific
		341	C<tag> match.
		342
		343	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
		344
		345	Register (or replace) callbacks to be called on messages starting with the
		346	given tag on the given port (and return the port), or unregister it (when
		347	C<$callback> is C<$undef> or missing). There can only be one callback
		348	registered for each tag.
		349
		350	The original message will be passed to the callback, after the first
		351	element (the tag) has been removed. The callback will use the same
		352	environment as the default callback (see above).
		353
		354	Example: create a port and bind receivers on it in one go.
		355
		356	my $port = rcv port,
		357	msg1 => sub { ... },
		358	msg2 => sub { ... },
		359	;
		360
		361	Example: create a port, bind receivers and send it in a message elsewhere
		362	in one go:
		363
		364	snd $otherport, reply =>
		365	rcv port,
		366	msg1 => sub { ... },
		367	...
		368	;
		369
		370	Example: temporarily register a rcv callback for a tag matching some port
		371	(e.g. for a rpc reply) and unregister it after a message was received.
		372
		373	rcv $port, $otherport => sub {
		374	my @reply = @_;
		375
		376	rcv $SELF, $otherport;
		377	};
		378
		379	=cut
		380
		381	sub rcv($@) {
		382	my $port = shift;
		383	my ($noderef, $portid) = split /#/, $port, 2;
		384
		385	$NODE{$noderef} == $NODE{""}
		386	or Carp::croak "$port: rcv can only be called on local ports, caught";
		387
		388	while (@_) {
		389	if (ref $_[0]) {
		390	if (my $self = $PORT_DATA{$portid}) {
		391	"AnyEvent::MP::Port" eq ref $self
		392	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		393
		394	$self->[2] = shift;
		395	} else {
		396	my $cb = shift;
		397	$PORT{$portid} = sub {
		398	local $SELF = $port;
		399	eval { &$cb }; _self_die if $@;
		400	};
		401	}
		402	} elsif (defined $_[0]) {
		403	my $self = $PORT_DATA{$portid} \|\|= do {
		404	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
		405
		406	$PORT{$portid} = sub {
		407	local $SELF = $port;
		408
		409	if (my $cb = $self->[1]{$_[0]}) {
		410	shift;
		411	eval { &$cb }; _self_die if $@;
		412	} else {
		413	&{ $self->[0] };
		414	}
		415	};
		416
		417	$self
		418	};
		419
		420	"AnyEvent::MP::Port" eq ref $self
		421	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		422
		423	my ($tag, $cb) = splice @_, 0, 2;
		424
		425	if (defined $cb) {
		426	$self->[1]{$tag} = $cb;
		427	} else {
		428	delete $self->[1]{$tag};
		429	}
		430	}
		431	}
		432
		433	$port
		434	}
		435
		436	=item $closure = psub { BLOCK }
		437
		438	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
		439	closure is executed, sets up the environment in the same way as in C<rcv>
		440	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		441
		442	This is useful when you register callbacks from C<rcv> callbacks:
		443
		444	rcv delayed_reply => sub {
		445	my ($delay, @reply) = @_;
		446	my $timer = AE::timer $delay, 0, psub {
		447	snd @reply, $SELF;
		448	};
		449	};
		450
		451	=cut
		452
		453	sub psub(&) {
		454	my $cb = shift;
		455
		456	my $port = $SELF
		457	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
		458
		459	sub {
		460	local $SELF = $port;
		461
		462	if (wantarray) {
		463	my @res = eval { &$cb };
		464	_self_die if $@;
		465	@res
		466	} else {
		467	my $res = eval { &$cb };
		468	_self_die if $@;
		469	$res
		470	}
		471	}
		472	}
		473
166	=item $guard = mon $portid, $cb->(@reason)	474	=item $guard = mon $port, $cb->(@reason)
167		475
168	=item $guard = mon $portid, $otherport	476	=item $guard = mon $port, $rcvport
169		477
		478	=item $guard = mon $port
		479
170	=item $guard = mon $portid, $otherport, @msg	480	=item $guard = mon $port, $rcvport, @msg
171		481
172	Monitor the given port and do something when the port is killed.	482	Monitor the given port and do something when the port is killed or
		483	messages to it were lost, and optionally return a guard that can be used
		484	to stop monitoring again.
173		485
		486	C<mon> effectively guarantees that, in the absence of hardware failures,
		487	that after starting the monitor, either all messages sent to the port
		488	will arrive, or the monitoring action will be invoked after possible
		489	message loss has been detected. No messages will be lost "in between"
		490	(after the first lost message no further messages will be received by the
		491	port). After the monitoring action was invoked, further messages might get
		492	delivered again.
		493
		494	Note that monitoring-actions are one-shot: once released, they are removed
		495	and will not trigger again.
		496
174	In the first form, the callback is simply called with any number	497	In the first form (callback), the callback is simply called with any
175	of C<@reason> elements (no @reason means that the port was deleted	498	number of C<@reason> elements (no @reason means that the port was deleted
176	"normally"). Note also that I<< the callback B<must> never die >>, so use	499	"normally"). Note also that I<< the callback B<must> never die >>, so use
177	C<eval> if unsure.	500	C<eval> if unsure.
178		501
179	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	502	In the second form (another port given), the other port (C<$rcvport>)
180	a @reason was specified, i.e. on "normal" kils nothing happens, while	503	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
181	under all other conditions, the other port is killed with the same reason.	504	"normal" kils nothing happens, while under all other conditions, the other
		505	port is killed with the same reason.
182		506
		507	The third form (kill self) is the same as the second form, except that
		508	C<$rvport> defaults to C<$SELF>.
		509
183	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	510	In the last form (message), a message of the form C<@msg, @reason> will be
		511	C<snd>.
		512
		513	As a rule of thumb, monitoring requests should always monitor a port from
		514	a local port (or callback). The reason is that kill messages might get
		515	lost, just like any other message. Another less obvious reason is that
		516	even monitoring requests can get lost (for exmaple, when the connection
		517	to the other node goes down permanently). When monitoring a port locally
		518	these problems do not exist.
184		519
185	Example: call a given callback when C<$port> is killed.	520	Example: call a given callback when C<$port> is killed.
186		521
187	mon $port, sub { warn "port died because of <@_>\n" };	522	mon $port, sub { warn "port died because of <@_>\n" };
188		523
189	Example: kill ourselves when C<$port> is killed abnormally.	524	Example: kill ourselves when C<$port> is killed abnormally.
190		525
191	mon $port, $self;	526	mon $port;
192		527
193	Example: send us a restart message another C<$port> is killed.	528	Example: send us a restart message when another C<$port> is killed.
194		529
195	mon $port, $self => "restart";	530	mon $port, $self => "restart";
196		531
197	=cut	532	=cut
198		533
199	sub mon {	534	sub mon {
200	my ($noderef, $port, $cb) = ((split /#/, shift, 2), shift);	535	my ($noderef, $port) = split /#/, shift, 2;
201		536
202	my $node = $NODE{$noderef} \|\| add_node $noderef;	537	my $node = $NODE{$noderef} \|\| add_node $noderef;
203		538
204	#TODO: ports must not be references	539	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
205	if (!ref $cb or "AnyEvent::MP::Port" eq ref $cb) {	540
		541	unless (ref $cb) {
206	if (@_) {	542	if (@_) {
207	# send a kill info message	543	# send a kill info message
208	my (@msg) = ($cb, @_);	544	my (@msg) = ($cb, @_);
209	$cb = sub { snd @msg, @_ };	545	$cb = sub { snd @msg, @_ };
210	} else {	546	} else {
…		…
239	=cut	575	=cut
240		576
241	sub mon_guard {	577	sub mon_guard {
242	my ($port, @refs) = @_;	578	my ($port, @refs) = @_;
243		579
		580	#TODO: mon-less form?
		581
244	mon $port, sub { 0 && @refs }	582	mon $port, sub { 0 && @refs }
245	}	583	}
246		584
247	=item $local_port = port	585	=item kil $port[, @reason]
248		586
249	Create a new local port object that supports message matching.	587	Kill the specified port with the given C<@reason>.
250		588
251	=item $portid = port { my @msg = @_; $finished }	589	If no C<@reason> is specified, then the port is killed "normally" (linked
		590	ports will not be kileld, or even notified).
252		591
253	Creates a "mini port", that is, a very lightweight port without any	592	Otherwise, linked ports get killed with the same reason (second form of
254	pattern matching behind it, and returns its ID.	593	C<mon>, see below).
255		594
256	The block will be called for every message received on the port. When the	595	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
257	callback returns a true value its job is considered "done" and the port	596	will be reported as reason C<< die => $@ >>.
258	will be destroyed. Otherwise it will stay alive.
259		597
260	The message will be passed as-is, no extra argument (i.e. no port id) will	598	Transport/communication errors are reported as C<< transport_error =>
261	be passed to the callback.	599	$message >>.
262		600
263	If you need the local port id in the callback, this works nicely:
264
265	my $port; $port = miniport {
266	snd $otherport, reply => $port;
267	};
268
269	=cut	601	=cut
270		602
271	sub port(;&) {	603	=item $port = spawn $node, $initfunc[, @initdata]
272	my $id = "$UNIQ." . $ID++;
273	my $port = "$NODE#$id";
274		604
275	if (@_) {	605	Creates a port on the node C<$node> (which can also be a port ID, in which
276	my $cb = shift;	606	case it's the node where that port resides).
277	$PORT{$id} = sub {	607
278	local $SELF = $port;	608	The port ID of the newly created port is return immediately, and it is
279	eval {	609	permissible to immediately start sending messages or monitor the port.
280	&$cb	610
281	and kil $id;	611	After the port has been created, the init function is
		612	called. This function must be a fully-qualified function name
		613	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		614	program, use C<::name>.
		615
		616	If the function doesn't exist, then the node tries to C<require>
		617	the package, then the package above the package and so on (e.g.
		618	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		619	exists or it runs out of package names.
		620
		621	The init function is then called with the newly-created port as context
		622	object (C<$SELF>) and the C<@initdata> values as arguments.
		623
		624	A common idiom is to pass your own port, monitor the spawned port, and
		625	in the init function, monitor the original port. This two-way monitoring
		626	ensures that both ports get cleaned up when there is a problem.
		627
		628	Example: spawn a chat server port on C<$othernode>.
		629
		630	# this node, executed from within a port context:
		631	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		632	mon $server;
		633
		634	# init function on C<$othernode>
		635	sub connect {
		636	my ($srcport) = @_;
		637
		638	mon $srcport;
		639
		640	rcv $SELF, sub {
282	};	641	...
283	_self_die if $@;
284	};
285	} else {
286	my $self = bless {
287	id => "$NODE#$id",
288	}, "AnyEvent::MP::Port";
289
290	$PORT_DATA{$id} = $self;
291	$PORT{$id} = sub {
292	local $SELF = $port;
293
294	eval {
295	for (@{ $self->{rc0}{$_[0]} }) {
296	$_ && &{$_->[0]}
297	&& undef $_;
298	}
299
300	for (@{ $self->{rcv}{$_[0]} }) {
301	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
302	&& &{$_->[0]}
303	&& undef $_;
304	}
305
306	for (@{ $self->{any} }) {
307	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
308	&& &{$_->[0]}
309	&& undef $_;
310	}
311	};
312	_self_die if $@;
313	};	642	};
314	}	643	}
315		644
316	$port
317	}
318
319	=item reg $portid, $name
320
321	Registers the given port under the name C<$name>. If the name already
322	exists it is replaced.
323
324	A port can only be registered under one well known name.
325
326	A port automatically becomes unregistered when it is killed.
327
328	=cut	645	=cut
329		646
330	sub reg(@) {	647	sub _spawn {
331	my ($portid, $name) = @_;	648	my $port = shift;
		649	my $init = shift;
332		650
333	$REG{$name} = $portid;	651	local $SELF = "$NODE#$port";
334	}	652	eval {
335		653	&{ load_func $init }
336	=item rcv $portid, tagstring => $callback->(@msg), ...
337
338	=item rcv $portid, $smartmatch => $callback->(@msg), ...
339
340	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
341
342	Register callbacks to be called on matching messages on the given port.
343
344	The callback has to return a true value when its work is done, after
345	which is will be removed, or a false value in which case it will stay
346	registered.
347
348	The global C<$SELF> (exported by this module) contains C<$portid> while
349	executing the callback.
350
351	Runtime errors wdurign callback execution will result in the port being
352	C<kil>ed.
353
354	If the match is an array reference, then it will be matched against the
355	first elements of the message, otherwise only the first element is being
356	matched.
357
358	Any element in the match that is specified as C<_any_> (a function
359	exported by this module) matches any single element of the message.
360
361	While not required, it is highly recommended that the first matching
362	element is a string identifying the message. The one-string-only match is
363	also the most efficient match (by far).
364
365	=cut
366
367	sub rcv($@) {
368	my ($noderef, $port) = split /#/, shift, 2;
369
370	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
371	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";
372
373	my $self = $PORT_DATA{$port}
374	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
375
376	"AnyEvent::MP::Port" eq ref $self
377	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
378
379	while (@_) {
380	my ($match, $cb) = splice @_, 0, 2;
381
382	if (!ref $match) {
383	push @{ $self->{rc0}{$match} }, [$cb];
384	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
385	my ($type, @match) = @$match;
386	@match
387	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
388	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
389	} else {
390	push @{ $self->{any} }, [$cb, $match];
391	}
392	}
393	}
394
395	=item $closure = psub { BLOCK }
396
397	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
398	closure is executed, sets up the environment in the same way as in C<rcv>
399	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
400
401	This is useful when you register callbacks from C<rcv> callbacks:
402
403	rcv delayed_reply => sub {
404	my ($delay, @reply) = @_;
405	my $timer = AE::timer $delay, 0, psub {
406	snd @reply, $SELF;
407	};
408	};	654	};
409
410	=cut
411
412	sub psub(&) {
413	my $cb = shift;
414
415	my $port = $SELF
416	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
417
418	sub {
419	local $SELF = $port;
420
421	if (wantarray) {
422	my @res = eval { &$cb };
423	_self_die if $@;	655	_self_die if $@;
424	@res	656	}
425	} else {	657
426	my $res = eval { &$cb };	658	sub spawn(@) {
427	_self_die if $@;	659	my ($noderef, undef) = split /#/, shift, 2;
428	$res	660
429	}	661	my $id = "$RUNIQ." . $ID++;
		662
		663	$_[0] =~ /::/
		664	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		665
		666	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
		667
		668	"$noderef#$id"
		669	}
		670
		671	=item after $timeout, @msg
		672
		673	=item after $timeout, $callback
		674
		675	Either sends the given message, or call the given callback, after the
		676	specified number of seconds.
		677
		678	This is simply a utility function that come sin handy at times.
		679
		680	=cut
		681
		682	sub after($@) {
		683	my ($timeout, @action) = @_;
		684
		685	my $t; $t = AE::timer $timeout, 0, sub {
		686	undef $t;
		687	ref $action[0]
		688	? $action[0]()
		689	: snd @action;
430	}	690	};
431	}	691	}
432		692
433	=back	693	=back
434		694
435	=head1 FUNCTIONS FOR NODES	695	=head1 AnyEvent::MP vs. Distributed Erlang
		696
		697	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
		698	== aemp node, Erlang process == aemp port), so many of the documents and
		699	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		700	sample:
		701
		702	http://www.Erlang.se/doc/programming_rules.shtml
		703	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		704	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		705	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		706
		707	Despite the similarities, there are also some important differences:
436		708
437	=over 4	709	=over 4
438		710
439	=item become_public endpoint...	711	=item * Node references contain the recipe on how to contact them.
440		712
441	Tells the node to become a public node, i.e. reachable from other nodes.	713	Erlang relies on special naming and DNS to work everywhere in the
		714	same way. AEMP relies on each node knowing it's own address(es), with
		715	convenience functionality.
442		716
443	If no arguments are given, or the first argument is C<undef>, then	717	This means that AEMP requires a less tightly controlled environment at the
444	AnyEvent::MP tries to bind on port C<4040> on all IP addresses that the	718	cost of longer node references and a slightly higher management overhead.
445	local nodename resolves to.
446		719
447	Otherwise the first argument must be an array-reference with transport	720	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
448	endpoints ("ip:port", "hostname:port") or port numbers (in which case the	721	uses "local ports are like remote ports".
449	local nodename is used as hostname). The endpoints are all resolved and
450	will become the node reference.
451		722
452	=cut	723	The failure modes for local ports are quite different (runtime errors
		724	only) then for remote ports - when a local port dies, you I<know> it dies,
		725	when a connection to another node dies, you know nothing about the other
		726	port.
		727
		728	Erlang pretends remote ports are as reliable as local ports, even when
		729	they are not.
		730
		731	AEMP encourages a "treat remote ports differently" philosophy, with local
		732	ports being the special case/exception, where transport errors cannot
		733	occur.
		734
		735	=item * Erlang uses processes and a mailbox, AEMP does not queue.
		736
		737	Erlang uses processes that selectively receive messages, and therefore
		738	needs a queue. AEMP is event based, queuing messages would serve no
		739	useful purpose. For the same reason the pattern-matching abilities of
		740	AnyEvent::MP are more limited, as there is little need to be able to
		741	filter messages without dequeing them.
		742
		743	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
		744
		745	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
		746
		747	Sending messages in Erlang is synchronous and blocks the process (and
		748	so does not need a queue that can overflow). AEMP sends are immediate,
		749	connection establishment is handled in the background.
		750
		751	=item * Erlang suffers from silent message loss, AEMP does not.
		752
		753	Erlang makes few guarantees on messages delivery - messages can get lost
		754	without any of the processes realising it (i.e. you send messages a, b,
		755	and c, and the other side only receives messages a and c).
		756
		757	AEMP guarantees correct ordering, and the guarantee that there are no
		758	holes in the message sequence.
		759
		760	=item * In Erlang, processes can be declared dead and later be found to be
		761	alive.
		762
		763	In Erlang it can happen that a monitored process is declared dead and
		764	linked processes get killed, but later it turns out that the process is
		765	still alive - and can receive messages.
		766
		767	In AEMP, when port monitoring detects a port as dead, then that port will
		768	eventually be killed - it cannot happen that a node detects a port as dead
		769	and then later sends messages to it, finding it is still alive.
		770
		771	=item * Erlang can send messages to the wrong port, AEMP does not.
		772
		773	In Erlang it is quite likely that a node that restarts reuses a process ID
		774	known to other nodes for a completely different process, causing messages
		775	destined for that process to end up in an unrelated process.
		776
		777	AEMP never reuses port IDs, so old messages or old port IDs floating
		778	around in the network will not be sent to an unrelated port.
		779
		780	=item * Erlang uses unprotected connections, AEMP uses secure
		781	authentication and can use TLS.
		782
		783	AEMP can use a proven protocol - SSL/TLS - to protect connections and
		784	securely authenticate nodes.
		785
		786	=item * The AEMP protocol is optimised for both text-based and binary
		787	communications.
		788
		789	The AEMP protocol, unlike the Erlang protocol, supports both
		790	language-independent text-only protocols (good for debugging) and binary,
		791	language-specific serialisers (e.g. Storable).
		792
		793	It has also been carefully designed to be implementable in other languages
		794	with a minimum of work while gracefully degrading fucntionality to make the
		795	protocol simple.
		796
		797	=item * AEMP has more flexible monitoring options than Erlang.
		798
		799	In Erlang, you can chose to receive I<all> exit signals as messages
		800	or I<none>, there is no in-between, so monitoring single processes is
		801	difficult to implement. Monitoring in AEMP is more flexible than in
		802	Erlang, as one can choose between automatic kill, exit message or callback
		803	on a per-process basis.
		804
		805	=item * Erlang tries to hide remote/local connections, AEMP does not.
		806
		807	Monitoring in Erlang is not an indicator of process death/crashes,
		808	as linking is (except linking is unreliable in Erlang).
		809
		810	In AEMP, you don't "look up" registered port names or send to named ports
		811	that might or might not be persistent. Instead, you normally spawn a port
		812	on the remote node. The init function monitors the you, and you monitor
		813	the remote port. Since both monitors are local to the node, they are much
		814	more reliable.
		815
		816	This also saves round-trips and avoids sending messages to the wrong port
		817	(hard to do in Erlang).
453		818
454	=back	819	=back
455		820
456	=head1 NODE MESSAGES	821	=head1 RATIONALE
457
458	Nodes understand the following messages sent to them. Many of them take
459	arguments called C<@reply>, which will simply be used to compose a reply
460	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
461	the remaining arguments are simply the message data.
462		822
463	=over 4	823	=over 4
464		824
465	=cut	825	=item Why strings for ports and noderefs, why not objects?
466		826
467	=item lookup => $name, @reply	827	We considered "objects", but found that the actual number of methods
		828	thatc an be called are very low. Since port IDs and noderefs travel over
		829	the network frequently, the serialising/deserialising would add lots of
		830	overhead, as well as having to keep a proxy object.
468		831
469	Replies with the port ID of the specified well-known port, or C<undef>.	832	Strings can easily be printed, easily serialised etc. and need no special
		833	procedures to be "valid".
470		834
471	=item devnull => ...	835	And a a miniport consists of a single closure stored in a global hash - it
		836	can't become much cheaper.
472		837
473	Generic data sink/CPU heat conversion.	838	=item Why favour JSON, why not real serialising format such as Storable?
474		839
475	=item relay => $port, @msg	840	In fact, any AnyEvent::MP node will happily accept Storable as framing
		841	format, but currently there is no way to make a node use Storable by
		842	default.
476		843
477	Simply forwards the message to the given port.	844	The default framing protocol is JSON because a) JSON::XS is many times
		845	faster for small messages and b) most importantly, after years of
		846	experience we found that object serialisation is causing more problems
		847	than it gains: Just like function calls, objects simply do not travel
		848	easily over the network, mostly because they will always be a copy, so you
		849	always have to re-think your design.
478		850
479	=item eval => $string[ @reply]	851	Keeping your messages simple, concentrating on data structures rather than
480		852	objects, will keep your messages clean, tidy and efficient.
481	Evaluates the given string. If C<@reply> is given, then a message of the
482	form C<@reply, $@, @evalres> is sent.
483
484	Example: crash another node.
485
486	snd $othernode, eval => "exit";
487
488	=item time => @reply
489
490	Replies the the current node time to C<@reply>.
491
492	Example: tell the current node to send the current time to C<$myport> in a
493	C<timereply> message.
494
495	snd $NODE, time => $myport, timereply => 1, 2;
496	# => snd $myport, timereply => 1, 2, <time>
497		853
498	=back	854	=back
499		855
500	=head1 SEE ALSO	856	=head1 SEE ALSO
501		857

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Revision 1.63 by root, Thu Aug 27 21:29:37 2009 UTC