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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.5 by root, Sat Aug 1 07:44:02 2009 UTC vs.
Revision 1.63 by root, Thu Aug 27 21:29:37 2009 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use AnyEvent::MP;	7	use AnyEvent::MP;
8		8
9	NODE # returns this node identifier
10	$NODE # contains this node identifier	9	$NODE # contains this node's noderef
		10	NODE # returns this node's noderef
		11	NODE $port # returns the noderef of the port
11		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
12	snd $port, type => data...;	21	snd $port, type => data...;
		22	snd $port, @msg;
		23	snd @msg_with_first_element_being_a_port;
13		24
14	rcv $port, smartmatch => $cb->($port, @msg);	25	# creating/using ports, the simple way
		26	my $simple_port = port { my @msg = @_; 0 };
15		27
16	# examples:	28	# creating/using ports, tagged message matching
		29	my $port = port;
17	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	30	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
18	rcv $port1, pong => sub { warn "pong received\n" };	31	rcv $port, pong => sub { warn "pong received\n"; 0 };
19	snd $port2, ping => $port1;
20		32
21	# more, smarter, matches (_any_ is exported by this module)	33	# create a port on another node
22	rcv $port, [child_died => $pid] => sub { ...	34	my $port = spawn $node, $initfunc, @initdata;
23	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		44	AnyEvent::MP::Intro - outdated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.
24		49
25	=head1 DESCRIPTION	50	=head1 DESCRIPTION
26		51
27	This module (-family) implements a simple message passing framework.	52	This module (-family) implements a simple message passing framework.
28		53
29	Despite its simplicity, you can securely message other processes running	54	Despite its simplicity, you can securely message other processes running
30	on the same or other hosts.	55	on the same or other hosts.
31		56
		57	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
		58	manual page.
		59
		60	At the moment, this module family is severly broken and underdocumented,
		61	so do not use. This was uploaded mainly to reserve the CPAN namespace -
		62	stay tuned!
		63
32	=head1 CONCEPTS	64	=head1 CONCEPTS
33		65
34	=over 4	66	=over 4
35		67
36	=item port	68	=item port
37		69
38	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).
39	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
40	messages they match, messages will not be queued.	73	some messages. Messages will not be queued.
41		74
42	=item port id - C<noderef#portname>	75	=item port ID - C<noderef#portname>
43		76
44	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
45	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.
46		81
47	=item node	82	=item node
48		83
49	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,
50	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
51	among other things.	86	ports.
52		87
53	Initially, nodes are either private (single-process only) or hidden	88	Nodes are either private (single-process only), slaves (can only talk to
54	(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
55	public" can you send them messages from unrelated other nodes.	90	from any other node).
56		91
57	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	92	=item node ID - C<[a-za-Z0-9_\-.:]+>
58		93
59	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
60	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
61	node (for public nodes).	96	node (for public nodes).
62		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
63	=back	107	=back
64		108
65	=head1 VARIABLES/FUNCTIONS	109	=head1 VARIABLES/FUNCTIONS
66		110
67	=over 4	111	=over 4
68		112
69	=cut	113	=cut
70		114
71	package AnyEvent::MP;	115	package AnyEvent::MP;
72		116
73	use AnyEvent::MP::Util ();
74	use AnyEvent::MP::Node;	117	use AnyEvent::MP::Kernel;
75	use AnyEvent::MP::Transport;
76		118
77	use utf8;
78	use common::sense;	119	use common::sense;
79		120
80	use Carp ();	121	use Carp ();
81		122
82	use AE ();	123	use AE ();
83		124
84	use base "Exporter";	125	use base "Exporter";
85		126
86	our $VERSION = '0.0';	127	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
87	our @EXPORT = qw(NODE $NODE $PORT snd rcv _any_);
88		128
89	our $DEFAULT_SECRET;	129	our @EXPORT = qw(
90	our $DEFAULT_PORT = "4040";	130	NODE $NODE *SELF node_of after
		131	resolve_node initialise_node
		132	snd rcv mon mon_guard kil reg psub spawn
		133	port
		134	);
91		135
92	our $CONNECT_INTERVAL = 5; # new connect every 5s, at least	136	our $SELF;
93	our $CONNECT_TIMEOUT = 30; # includes handshake
94		137
95	sub default_secret {	138	sub _self_die() {
96	unless (defined $DEFAULT_SECRET) {	139	my $msg = $@;
97	if (open my $fh, "<$ENV{HOME}/.aemp-secret") {	140	$msg =~ s/\n+$// unless ref $msg;
98	sysread $fh, $DEFAULT_SECRET, -s $fh;	141	kil $SELF, die => $msg;
99	} else {
100	$DEFAULT_SECRET = AnyEvent::MP::Util::nonce 32;
101	}
102	}
103
104	$DEFAULT_SECRET
105	}	142	}
106		143
107	=item NODE / $NODE	144	=item $thisnode = NODE / $NODE
108		145
109	The C<NODE ()> function and the C<$NODE> variable contain the noderef of	146	The C<NODE> function returns, and the C<$NODE> variable contains the
110	the local node. The value is initialised by a call to C<become_public> or	147	node id of the local node. The value is initialised by a call to
111	C<become_slave>, after which all local port identifiers become invalid.	148	C<initialise_node>.
112		149
113	=cut	150	=item $nodeid = node_of $port
114		151
115	our $UNIQ = sprintf "%x.%x", $$, time; # per-process/node unique cookie	152	Extracts and returns the noderef from a port ID or a node ID.
116	our $PUBLIC = 0;
117	our $NODE;
118	our $PORT;
119		153
120	our %NODE; # node id to transport mapping, or "undef", for local node	154	=item initialise_node $profile_name
121	our %PORT; # local ports
122	our %LISTENER; # local transports
123		155
124	sub NODE() { $NODE }	156	Before a node can talk to other nodes on the network it has to initialise
		157	itself - the minimum a node needs to know is it's own name, and optionally
		158	it should know the noderefs of some other nodes in the network.
125		159
126	{	160	This function initialises a node - it must be called exactly once (or
127	use POSIX ();	161	never) before calling other AnyEvent::MP functions.
128	my $nodename = (POSIX::uname)[1];
129	$NODE = "$$\@$nodename";
130	}
131		162
132	sub _ANY_() { 1 }	163	All arguments (optionally except for the first) are noderefs, which can be
133	sub _any_() { \&_ANY_ }	164	either resolved or unresolved.
134		165
135	sub add_node {	166	The first argument will be looked up in the configuration database first
136	my ($noderef) = @_;	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.
137		171
138	return $NODE{$noderef}	172	There are two types of networked nodes, public nodes and slave nodes:
139	if exists $NODE{$noderef};
140		173
141	for (split /,/, $noderef) {	174	=over 4
142	return $NODE{$noderef} = $NODE{$_}
143	if exists $NODE{$_};
144	}
145		175
146	# for indirect sends, use a different class	176	=item public nodes
147	my $node = new AnyEvent::MP::Node::Direct $noderef;
148		177
149	$NODE{$_} = $node	178	For public nodes, C<$noderef> (supplied either directly to
150	for $noderef, split /,/, $noderef;	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).
151		181
152	$node	182	After resolving, the node will bind itself on all endpoints.
153	}
154		183
		184	=item slave nodes
		185
		186	When the C<$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
		257
		258	=item $SELF
		259
		260	Contains the current port id while executing C<rcv> callbacks or C<psub>
		261	blocks.
		262
		263	=item SELF, %SELF, @SELF...
		264
		265	Due to some quirks in how perl exports variables, it is impossible to
		266	just export C<$SELF>, all the symbols called C<SELF> are exported by this
		267	module, but only C<$SELF> is currently used.
		268
155	=item snd $portid, type => @data	269	=item snd $port, type => @data
156		270
157	=item snd $portid, @msg	271	=item snd $port, @msg
158		272
159	Send the given message to the given port ID, which can identify either a	273	Send the given message to the given port ID, which can identify either
160	local or a remote port.	274	a local or a remote port, and must be a port ID.
161		275
162	While the message can be about anything, it is highly recommended to use	276	While the message can be about anything, it is highly recommended to use a
163	a constant string as first element.	277	string as first element (a port ID, or some word that indicates a request
		278	type etc.).
164		279
165	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
166	function: modifying any argument is not allowed and can cause many	281	function: modifying any argument is not allowed and can cause many
167	problems.	282	problems.
168		283
…		…
170	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
171	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
172	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
173	node, anything can be passed.	288	node, anything can be passed.
174		289
175	=cut	290	=item $local_port = port
176		291
177	sub snd(@) {	292	Create a new local port object and returns its port ID. Initially it has
178	my ($noderef, $port) = split /#/, shift, 2;	293	no callbacks set and will throw an error when it receives messages.
179		294
180	add_node $noderef	295	=item $local_port = port { my @msg = @_ }
181	unless exists $NODE{$noderef};
182		296
183	$NODE{$noderef}->send (["$port", [@_]]);	297	Creates a new local port, and returns its ID. Semantically the same as
184	}	298	creating a port and calling C<rcv $port, $callback> on it.
185		299
		300	The block will be called for every message received on the port, with the
		301	global variable C<$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.
		304
		305	If you want to stop/destroy the port, simply C<kil> it:
		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
186	=item rcv $portid, type => $callback->(@msg)	330	=item rcv $local_port, $callback->(@msg)
187		331
188	=item rcv $portid, $smartmatch => $callback->(@msg)	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.
189		335
190	=item rcv $portid, [$smartmatch...] => $callback->(@msg)	336	The global C<$SELF> (exported by this module) contains C<$port> while
		337	executing the callback. Runtime errors during callback execution will
		338	result in the port being C<kil>ed.
191		339
192	Register a callback on the port identified by C<$portid>, which I<must> be	340	The default callback received all messages not matched by a more specific
193	a local port.	341	C<tag> match.
194		342
195	The callback has to return a true value when its work is done, after	343	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
196	which is will be removed, or a false value in which case it will stay
197	registered.
198		344
199	If the match is an array reference, then it will be matched against the	345	Register (or replace) callbacks to be called on messages starting with the
200	first elements of the message, otherwise only the first element is being	346	given tag on the given port (and return the port), or unregister it (when
201	matched.	347	C<$callback> is C<$undef> or missing). There can only be one callback
		348	registered for each tag.
202		349
203	Any element in the match that is specified as C<_any_> (a function	350	The original message will be passed to the callback, after the first
204	exported by this module) matches any single element of the message.	351	element (the tag) has been removed. The callback will use the same
		352	environment as the default callback (see above).
205		353
206	While not required, it is highly recommended that the first matching	354	Example: create a port and bind receivers on it in one go.
207	element is a string identifying the message. The one-string-only match is	355
208	also the most efficient match (by far).	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, $otherport;
		377	};
209		378
210	=cut	379	=cut
211		380
212	sub rcv($@) {	381	sub rcv($@) {
213	my ($port, $match, $cb) = @_;	382	my $port = shift;
214
215	my $port = $PORT{$port}
216	or do {
217	my ($noderef, $lport) = split /#/, $port;	383	my ($noderef, $portid) = split /#/, $port, 2;
218	"AnyEvent::MP::Node::Self" eq ref $NODE{$noderef}	384
		385	$NODE{$noderef} == $NODE{""}
219	or Carp::croak "$port: can only rcv on local ports";	386	or Carp::croak "$port: rcv can only be called on local ports, caught";
220		387
221	$PORT{$lport}	388	while (@_) {
222	or Carp::croak "$port: port does not exist";	389	if (ref $_[0]) {
223		390	if (my $self = $PORT_DATA{$portid}) {
224	$PORT{$port} = $PORT{$lport} # also return	391	"AnyEvent::MP::Port" eq ref $self
225	};	392	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
226		393
227	if (!ref $match) {	394	$self->[2] = shift;
228	push @{ $port->{rc0}{$match} }, [$cb];
229	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
230	my ($type, @match) = @$match;
231	@match
232	? push @{ $port->{rcv}{$match->[0]} }, [$cb, \@match]
233	: push @{ $port->{rc0}{$match->[0]} }, [$cb];
234	} else {	395	} else {
235	push @{ $port->{any} }, [$cb, $match];	396	my $cb = shift;
236	}	397	$PORT{$portid} = sub {
237	}	398	local $SELF = $port;
238		399	eval { &$cb }; _self_die if $@;
239	sub _inject {
240	my ($port, $msg) = @{+shift};
241
242	$port = $PORT{$port}
243	or return;
244
245	@_ = @$msg;
246
247	for (@{ $port->{rc0}{$msg->[0]} }) {
248	$_ && &{$_->[0]}
249	&& undef $_;
250	}
251
252	for (@{ $port->{rcv}{$msg->[0]} }) {
253	$_ && [@_[1..$#{$_->[1]}]] ~~ $_->[1]
254	&& &{$_->[0]}
255	&& undef $_;
256	}
257
258	for (@{ $port->{any} }) {
259	$_ && [@_[0..$#{$_->[1]}]] ~~ $_->[1]
260	&& &{$_->[0]}
261	&& undef $_;
262	}
263	}
264
265	sub normalise_noderef($) {
266	my ($noderef) = @_;
267
268	my $cv = AE::cv;
269	my @res;
270
271	$cv->begin (sub {
272	my %seen;
273	my @refs;
274	for (sort { $a->[0] <=> $b->[0] } @res) {
275	push @refs, $_->[1] unless $seen{$_->[1]}++
276	}
277	shift->send (join ",", @refs);
278	});
279
280	$noderef = $DEFAULT_PORT unless length $noderef;
281
282	my $idx;
283	for my $t (split /,/, $noderef) {
284	my $pri = ++$idx;
285
286	#TODO: this should be outside normalise_noderef and in become_public
287	if ($t =~ /^\d*$/) {
288	my $nodename = (POSIX::uname)[1];
289
290	$cv->begin;
291	AnyEvent::Socket::resolve_sockaddr $nodename, $t \|\| "aemp=$DEFAULT_PORT", "tcp", 0, undef, sub {
292	for (@_) {
293	my ($service, $host) = AnyEvent::Socket::unpack_sockaddr $_->[3];
294	push @res, [
295	$pri += 1e-5,
296	AnyEvent::Socket::format_hostport AnyEvent::Socket::format_address $host, $service
297	];
298	}	400	};
299	$cv->end;	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
300	};	418	};
301		419
302	# my (undef, undef, undef, undef, @ipv4) = gethostbyname $nodename;	420	"AnyEvent::MP::Port" eq ref $self
303	#	421	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
304	# for (@ipv4) {	422
305	# push @res, [	423	my ($tag, $cb) = splice @_, 0, 2;
306	# $pri,	424
307	# AnyEvent::Socket::format_hostport AnyEvent::Socket::format_address $_, $t \|\| $DEFAULT_PORT,	425	if (defined $cb) {
308	# ];	426	$self->[1]{$tag} = $cb;
309	# }
310	} else {	427	} else {
311	my ($host, $port) = AnyEvent::Socket::parse_hostport $t, "aemp=$DEFAULT_PORT"	428	delete $self->[1]{$tag};
312	or Carp::croak "$t: unparsable transport descriptor";
313
314	$cv->begin;
315	AnyEvent::Socket::resolve_sockaddr $host, $port, "tcp", 0, undef, sub {
316	for (@_) {
317	my ($service, $host) = AnyEvent::Socket::unpack_sockaddr $_->[3];
318	push @res, [
319	$pri += 1e-5,
320	AnyEvent::Socket::format_hostport AnyEvent::Socket::format_address $host, $service
321	];
322	}
323	$cv->end;
324	}	429	}
325	}	430	}
326	}	431	}
327		432
328	$cv->end;	433	$port
329
330	$cv
331	}	434	}
332		435
333	sub become_public {	436	=item $closure = psub { BLOCK }
334	return if $PUBLIC;
335		437
336	my $noderef = join ",", ref $_[0] ? @{+shift} : shift;	438	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
337	my @args = @_;	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.
338		441
339	$NODE = (normalise_noderef $noderef)->recv;	442	This is useful when you register callbacks from C<rcv> callbacks:
340		443
341	for my $t (split /,/, $NODE) {	444	rcv delayed_reply => sub {
342	$NODE{$t} = $NODE{""};	445	my ($delay, @reply) = @_;
343		446	my $timer = AE::timer $delay, 0, psub {
344	my ($host, $port) = AnyEvent::Socket::parse_hostport $t;	447	snd @reply, $SELF;
345
346	$LISTENER{$t} = AnyEvent::MP::Transport::mp_server $host, $port,
347	@args,
348	on_error => sub {
349	die "on_error<@_>\n";#d#
350	},
351	on_connect => sub {
352	my ($tp) = @_;
353
354	$NODE{$tp->{remote_id}} = $_[0];
355	},
356	sub {
357	my ($tp) = @_;
358
359	$NODE{"$tp->{peerhost}:$tp->{peerport}"} = $tp;
360	},
361	;	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	}
362	}	471	}
		472	}
363		473
364	$PUBLIC = 1;	474	=item $guard = mon $port, $cb->(@reason)
		475
		476	=item $guard = mon $port, $rcvport
		477
		478	=item $guard = mon $port
		479
		480	=item $guard = mon $port, $rcvport, @msg
		481
		482	Monitor the given port and do something when the port is killed or
		483	messages to it were lost, and optionally return a guard that can be used
		484	to stop monitoring again.
		485
		486	C<mon> effectively guarantees that, in the absence of hardware failures,
		487	that after starting the monitor, either all messages sent to the port
		488	will arrive, or the monitoring action will be invoked after possible
		489	message loss has been detected. No messages will be lost "in between"
		490	(after the first lost message no further messages will be received by the
		491	port). After the monitoring action was invoked, further messages might get
		492	delivered again.
		493
		494	Note that monitoring-actions are one-shot: once released, they are removed
		495	and will not trigger again.
		496
		497	In the first form (callback), the callback is simply called with any
		498	number of C<@reason> elements (no @reason means that the port was deleted
		499	"normally"). Note also that I<< the callback B<must> never die >>, so use
		500	C<eval> if unsure.
		501
		502	In the second form (another port given), the other port (C<$rcvport>)
		503	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
		504	"normal" kils nothing happens, while under all other conditions, the other
		505	port is killed with the same reason.
		506
		507	The third form (kill self) is the same as the second form, except that
		508	C<$rvport> defaults to C<$SELF>.
		509
		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.
		519
		520	Example: call a given callback when C<$port> is killed.
		521
		522	mon $port, sub { warn "port died because of <@_>\n" };
		523
		524	Example: kill ourselves when C<$port> is killed abnormally.
		525
		526	mon $port;
		527
		528	Example: send us a restart message when another C<$port> is killed.
		529
		530	mon $port, $self => "restart";
		531
		532	=cut
		533
		534	sub mon {
		535	my ($noderef, $port) = split /#/, shift, 2;
		536
		537	my $node = $NODE{$noderef} \|\| add_node $noderef;
		538
		539	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
		540
		541	unless (ref $cb) {
		542	if (@_) {
		543	# send a kill info message
		544	my (@msg) = ($cb, @_);
		545	$cb = sub { snd @msg, @_ };
		546	} else {
		547	# simply kill other port
		548	my $port = $cb;
		549	$cb = sub { kil $port, @_ if @_ };
		550	}
		551	}
		552
		553	$node->monitor ($port, $cb);
		554
		555	defined wantarray
		556	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
		557	}
		558
		559	=item $guard = mon_guard $port, $ref, $ref...
		560
		561	Monitors the given C<$port> and keeps the passed references. When the port
		562	is killed, the references will be freed.
		563
		564	Optionally returns a guard that will stop the monitoring.
		565
		566	This function is useful when you create e.g. timers or other watchers and
		567	want to free them when the port gets killed:
		568
		569	$port->rcv (start => sub {
		570	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
		571	undef $timer if 0.9 < rand;
		572	});
		573	});
		574
		575	=cut
		576
		577	sub mon_guard {
		578	my ($port, @refs) = @_;
		579
		580	#TODO: mon-less form?
		581
		582	mon $port, sub { 0 && @refs }
		583	}
		584
		585	=item kil $port[, @reason]
		586
		587	Kill the specified port with the given C<@reason>.
		588
		589	If no C<@reason> is specified, then the port is killed "normally" (linked
		590	ports will not be kileld, or even notified).
		591
		592	Otherwise, linked ports get killed with the same reason (second form of
		593	C<mon>, see below).
		594
		595	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		596	will be reported as reason C<< die => $@ >>.
		597
		598	Transport/communication errors are reported as C<< transport_error =>
		599	$message >>.
		600
		601	=cut
		602
		603	=item $port = spawn $node, $initfunc[, @initdata]
		604
		605	Creates a port on the node C<$node> (which can also be a port ID, in which
		606	case it's the node where that port resides).
		607
		608	The port ID of the newly created port is return immediately, and it is
		609	permissible to immediately start sending messages or monitor the port.
		610
		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 {
		641	...
		642	};
		643	}
		644
		645	=cut
		646
		647	sub _spawn {
		648	my $port = shift;
		649	my $init = shift;
		650
		651	local $SELF = "$NODE#$port";
		652	eval {
		653	&{ load_func $init }
		654	};
		655	_self_die if $@;
		656	}
		657
		658	sub spawn(@) {
		659	my ($noderef, undef) = split /#/, shift, 2;
		660
		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	? $action[0]()
		689	: snd @action;
		690	};
365	}	691	}
366		692
367	=back	693	=back
368		694
369	=head1 NODE MESSAGES	695	=head1 AnyEvent::MP vs. Distributed Erlang
370		696
371	Nodes understand the following messages sent to them. Many of them take	697	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
372	arguments called C<@reply>, which will simply be used to compose a reply	698	== aemp node, Erlang process == aemp port), so many of the documents and
373	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and	699	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
374	the remaining arguments are simply the message data.	700	sample:
		701
		702	http://www.Erlang.se/doc/programming_rules.shtml
		703	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		704	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		705	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		706
		707	Despite the similarities, there are also some important differences:
375		708
376	=over 4	709	=over 4
377		710
378	=cut	711	=item * Node references contain the recipe on how to contact them.
379		712
380	#############################################################################	713	Erlang relies on special naming and DNS to work everywhere in the
381	# self node code	714	same way. AEMP relies on each node knowing it's own address(es), with
		715	convenience functionality.
382		716
383	sub _new_port($) {	717	This means that AEMP requires a less tightly controlled environment at the
384	my ($name) = @_;	718	cost of longer node references and a slightly higher management overhead.
385		719
386	my ($noderef, $portname) = split /#/, $name;	720	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
		721	uses "local ports are like remote ports".
387		722
388	$PORT{$name} =	723	The failure modes for local ports are quite different (runtime errors
389	$PORT{$portname} = {	724	only) then for remote ports - when a local port dies, you I<know> it dies,
390	names => [$name, $portname],	725	when a connection to another node dies, you know nothing about the other
391	};	726	port.
392	}
393		727
394	$NODE{""} = new AnyEvent::MP::Node::Self noderef => $NODE;	728	Erlang pretends remote ports are as reliable as local ports, even when
395	_new_port "";	729	they are not.
396		730
397	=item relay => $port, @msg	731	AEMP encourages a "treat remote ports differently" philosophy, with local
		732	ports being the special case/exception, where transport errors cannot
		733	occur.
398		734
399	Simply forwards the message to the given port.	735	=item * Erlang uses processes and a mailbox, AEMP does not queue.
400		736
401	=cut	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.
402		742
403	rcv "", relay => \&snd;	743	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
404		744
405	=item eval => $string[ @reply]	745	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
406		746
407	Evaluates the given string. If C<@reply> is given, then a message of the	747	Sending messages in Erlang is synchronous and blocks the process (and
408	form C<@reply, $@, @evalres> is sent.	748	so does not need a queue that can overflow). AEMP sends are immediate,
		749	connection establishment is handled in the background.
409		750
410	Example: crash another node.	751	=item * Erlang suffers from silent message loss, AEMP does not.
411		752
412	snd $othernode, eval => "exit";	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).
413		756
414	=cut	757	AEMP guarantees correct ordering, and the guarantee that there are no
		758	holes in the message sequence.
415		759
416	rcv "", eval => sub {	760	=item * In Erlang, processes can be declared dead and later be found to be
417	my (undef, $string, @reply) = @_;	761	alive.
418	my @res = eval $string;
419	snd @reply, "$@", @res if @reply;
420	};
421		762
422	=item time => @reply	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.
423		766
424	Replies the the current node time to C<@reply>.	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.
425		770
426	Example: tell the current node to send the current time to C<$myport> in a	771	=item * Erlang can send messages to the wrong port, AEMP does not.
427	C<timereply> message.
428		772
429	snd $NODE, time => $myport, timereply => 1, 2;	773	In Erlang it is quite likely that a node that restarts reuses a process ID
430	# => snd $myport, timereply => 1, 2, <time>	774	known to other nodes for a completely different process, causing messages
		775	destined for that process to end up in an unrelated process.
431		776
432	=cut	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.
433		779
434	rcv "", time => sub { shift; snd @_, AE::time };	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).
		818
		819	=back
		820
		821	=head1 RATIONALE
		822
		823	=over 4
		824
		825	=item Why strings for ports and noderefs, why not objects?
		826
		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.
		831
		832	Strings can easily be printed, easily serialised etc. and need no special
		833	procedures to be "valid".
		834
		835	And a a miniport consists of a single closure stored in a global hash - it
		836	can't become much cheaper.
		837
		838	=item Why favour JSON, why not real serialising format such as Storable?
		839
		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.
		843
		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.
		850
		851	Keeping your messages simple, concentrating on data structures rather than
		852	objects, will keep your messages clean, tidy and efficient.
435		853
436	=back	854	=back
437		855
438	=head1 SEE ALSO	856	=head1 SEE ALSO
439		857

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