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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.7 by root, Sat Aug 1 15:04:30 2009 UTC vs.
Revision 1.115 by root, Fri May 7 18:14:21 2010 UTC

…		…
1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent::MP - multi-processing/message-passing framework	3	AnyEvent::MP - erlang-style multi-processing/message-passing framework
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 node ID
		10	NODE # returns this node's node ID
11		11
		12	$SELF # receiving/own port id in rcv callbacks
		13
		14	# initialise the node so it can send/receive messages
		15	configure;
		16
		17	# ports are message destinations
		18
		19	# sending messages
12	snd $port, type => data...;	20	snd $port, type => data...;
		21	snd $port, @msg;
		22	snd @msg_with_first_element_being_a_port;
13		23
14	rcv $port, smartmatch => $cb->($port, @msg);	24	# creating/using ports, the simple way
		25	my $simple_port = port { my @msg = @_ };
15		26
16	# examples:	27	# creating/using ports, tagged message matching
		28	my $port = port;
17	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	29	rcv $port, ping => sub { snd $_[0], "pong" };
18	rcv $port1, pong => sub { warn "pong received\n" };	30	rcv $port, pong => sub { warn "pong received\n" };
19	snd $port2, ping => $port1;
20		31
21	# more, smarter, matches (_any_ is exported by this module)	32	# create a port on another node
22	rcv $port, [child_died => $pid] => sub { ...	33	my $port = spawn $node, $initfunc, @initdata;
23	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	34
		35	# destroy a prot again
		36	kil $port; # "normal" kill
		37	kil $port, my_error => "everything is broken"; # error kill
		38
		39	# monitoring
		40	mon $localport, $cb->(@msg) # callback is invoked on death
		41	mon $localport, $otherport # kill otherport on abnormal death
		42	mon $localport, $otherport, @msg # send message on death
		43
		44	# temporarily execute code in port context
		45	peval $port, sub { die "kill the port!" };
		46
		47	# execute callbacks in $SELF port context
		48	my $timer = AE::timer 1, 0, psub {
		49	die "kill the port, delayed";
		50	};
		51
		52	=head1 CURRENT STATUS
		53
		54	bin/aemp - stable.
		55	AnyEvent::MP - stable API, should work.
		56	AnyEvent::MP::Intro - explains most concepts.
		57	AnyEvent::MP::Kernel - mostly stable API.
		58	AnyEvent::MP::Global - stable API.
24		59
25	=head1 DESCRIPTION	60	=head1 DESCRIPTION
26		61
27	This module (-family) implements a simple message passing framework.	62	This module (-family) implements a simple message passing framework.
28		63
29	Despite its simplicity, you can securely message other processes running	64	Despite its simplicity, you can securely message other processes running
30	on the same or other hosts.	65	on the same or other hosts, and you can supervise entities remotely.
31		66
32	At the moment, this module family is severly brokena nd underdocumented,	67	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
33	so do not use. This was uploaded mainly to resreve the CPAN namespace -	68	manual page and the examples under F<eg/>.
34	stay tuned!
35		69
36	=head1 CONCEPTS	70	=head1 CONCEPTS
37		71
38	=over 4	72	=over 4
39		73
40	=item port	74	=item port
41		75
42	A port is something you can send messages to with the C<snd> function, and	76	Not to be confused with a TCP port, a "port" is something you can send
43	you can register C<rcv> handlers with. All C<rcv> handlers will receive	77	messages to (with the C<snd> function).
44	messages they match, messages will not be queued.
45		78
		79	Ports allow you to register C<rcv> handlers that can match all or just
		80	some messages. Messages send to ports will not be queued, regardless of
		81	anything was listening for them or not.
		82
46	=item port id - C<noderef#portname>	83	=item port ID - C<nodeid#portname>
47		84
48	A port id is always the noderef, a hash-mark (C<#>) as separator, followed	85	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as
49	by a port name (a printable string of unspecified format).	86	separator, and a port name (a printable string of unspecified format).
50		87
51	=item node	88	=item node
52		89
53	A node is a single process containing at least one port - the node	90	A node is a single process containing at least one port - the node port,
54	port. You can send messages to node ports to let them create new ports,	91	which enables nodes to manage each other remotely, and to create new
55	among other things.	92	ports.
56		93
57	Initially, nodes are either private (single-process only) or hidden	94	Nodes are either public (have one or more listening ports) or private
58	(connected to a master node only). Only when they epxlicitly "become	95	(no listening ports). Private nodes cannot talk to other private nodes
59	public" can you send them messages from unrelated other nodes.	96	currently.
60		97
61	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	98	=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*>
62		99
63	A noderef is a string that either uniquely identifies a given node (for	100	A node ID is a string that uniquely identifies the node within a
64	private and hidden nodes), or contains a recipe on how to reach a given	101	network. Depending on the configuration used, node IDs can look like a
65	node (for public nodes).	102	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
		103	doesn't interpret node IDs in any way.
		104
		105	=item binds - C<ip:port>
		106
		107	Nodes can only talk to each other by creating some kind of connection to
		108	each other. To do this, nodes should listen on one or more local transport
		109	endpoints - binds. Currently, only standard C<ip:port> specifications can
		110	be used, which specify TCP ports to listen on.
		111
		112	=item seed nodes
		113
		114	When a node starts, it knows nothing about the network. To teach the node
		115	about the network it first has to contact some other node within the
		116	network. This node is called a seed.
		117
		118	Apart from the fact that other nodes know them as seed nodes and they have
		119	to have fixed listening addresses, seed nodes are perfectly normal nodes -
		120	any node can function as a seed node for others.
		121
		122	In addition to discovering the network, seed nodes are also used to
		123	maintain the network and to connect nodes that otherwise would have
		124	trouble connecting. They form the backbone of an AnyEvent::MP network.
		125
		126	Seed nodes are expected to be long-running, and at least one seed node
		127	should always be available. They should also be relatively responsive - a
		128	seed node that blocks for long periods will slow down everybody else.
		129
		130	=item seeds - C<host:port>
		131
		132	Seeds are transport endpoint(s) (usually a hostname/IP address and a
		133	TCP port) of nodes that should be used as seed nodes.
		134
		135	The nodes listening on those endpoints are expected to be long-running,
		136	and at least one of those should always be available. When nodes run out
		137	of connections (e.g. due to a network error), they try to re-establish
		138	connections to some seednodes again to join the network.
66		139
67	=back	140	=back
68		141
69	=head1 VARIABLES/FUNCTIONS	142	=head1 VARIABLES/FUNCTIONS
70		143
72		145
73	=cut	146	=cut
74		147
75	package AnyEvent::MP;	148	package AnyEvent::MP;
76		149
77	use AnyEvent::MP::Util ();
78	use AnyEvent::MP::Node;	150	use AnyEvent::MP::Kernel;
79	use AnyEvent::MP::Transport;
80		151
81	use utf8;
82	use common::sense;	152	use common::sense;
83		153
84	use Carp ();	154	use Carp ();
85		155
86	use AE ();	156	use AE ();
87		157
88	use base "Exporter";	158	use base "Exporter";
89		159
90	our $VERSION = '0.01';	160	our $VERSION = 1.29;
91	our @EXPORT = qw(NODE $NODE $PORT snd rcv _any_);
92		161
93	our $DEFAULT_SECRET;	162	our @EXPORT = qw(
94	our $DEFAULT_PORT = "4040";	163	NODE $NODE *SELF node_of after
		164	configure
		165	snd rcv mon mon_guard kil psub peval spawn cal
		166	port
		167	);
95		168
96	our $CONNECT_INTERVAL = 5; # new connect every 5s, at least	169	our $SELF;
97	our $CONNECT_TIMEOUT = 30; # includes handshake
98		170
99	sub default_secret {	171	sub _self_die() {
100	unless (defined $DEFAULT_SECRET) {	172	my $msg = $@;
101	if (open my $fh, "<$ENV{HOME}/.aemp-secret") {	173	$msg =~ s/\n+$// unless ref $msg;
102	sysread $fh, $DEFAULT_SECRET, -s $fh;	174	kil $SELF, die => $msg;
103	} else {
104	$DEFAULT_SECRET = AnyEvent::MP::Util::nonce 32;
105	}
106	}
107
108	$DEFAULT_SECRET
109	}	175	}
110		176
111	=item NODE / $NODE	177	=item $thisnode = NODE / $NODE
112		178
113	The C<NODE ()> function and the C<$NODE> variable contain the noderef of	179	The C<NODE> function returns, and the C<$NODE> variable contains, the node
114	the local node. The value is initialised by a call to C<become_public> or	180	ID of the node running in the current process. This value is initialised by
115	C<become_slave>, after which all local port identifiers become invalid.	181	a call to C<configure>.
116		182
117	=cut	183	=item $nodeid = node_of $port
118		184
119	our $UNIQ = sprintf "%x.%x", $$, time; # per-process/node unique cookie	185	Extracts and returns the node ID from a port ID or a node ID.
120	our $ID = "a0";
121	our $PUBLIC = 0;
122	our $NODE;
123	our $PORT;
124		186
125	our %NODE; # node id to transport mapping, or "undef", for local node	187	=item configure $profile, key => value...
126	our %PORT; # local ports
127	our %LISTENER; # local transports
128		188
129	sub NODE() { $NODE }	189	=item configure key => value...
130		190
131	{	191	Before a node can talk to other nodes on the network (i.e. enter
132	use POSIX ();	192	"distributed mode") it has to configure itself - the minimum a node needs
133	my $nodename = (POSIX::uname)[1];	193	to know is its own name, and optionally it should know the addresses of
134	$NODE = "$$\@$nodename";	194	some other nodes in the network to discover other nodes.
135	}
136		195
137	sub _ANY_() { 1 }	196	The key/value pairs are basically the same ones as documented for the
138	sub _any_() { \&_ANY_ }	197	F<aemp> command line utility (sans the set/del prefix).
139		198
140	sub add_node {	199	This function configures a node - it must be called exactly once (or
141	my ($noderef) = @_;	200	never) before calling other AnyEvent::MP functions.
142		201
143	return $NODE{$noderef}	202	=over 4
144	if exists $NODE{$noderef};
145		203
146	for (split /,/, $noderef) {	204	=item step 1, gathering configuration from profiles
147	return $NODE{$noderef} = $NODE{$_}
148	if exists $NODE{$_};
149	}
150		205
151	# for indirect sends, use a different class	206	The function first looks up a profile in the aemp configuration (see the
152	my $node = new AnyEvent::MP::Node::Direct $noderef;	207	L<aemp> commandline utility). The profile name can be specified via the
		208	named C<profile> parameter or can simply be the first parameter). If it is
		209	missing, then the nodename (F<uname -n>) will be used as profile name.
153		210
154	$NODE{$_} = $node	211	The profile data is then gathered as follows:
155	for $noderef, split /,/, $noderef;
156		212
157	$node	213	First, all remaining key => value pairs (all of which are conveniently
158	}	214	undocumented at the moment) will be interpreted as configuration
		215	data. Then they will be overwritten by any values specified in the global
		216	default configuration (see the F<aemp> utility), then the chain of
		217	profiles chosen by the profile name (and any C<parent> attributes).
159		218
		219	That means that the values specified in the profile have highest priority
		220	and the values specified directly via C<configure> have lowest priority,
		221	and can only be used to specify defaults.
		222
		223	If the profile specifies a node ID, then this will become the node ID of
		224	this process. If not, then the profile name will be used as node ID. The
		225	special node ID of C<anon/> will be replaced by a random node ID.
		226
		227	=item step 2, bind listener sockets
		228
		229	The next step is to look up the binds in the profile, followed by binding
		230	aemp protocol listeners on all binds specified (it is possible and valid
		231	to have no binds, meaning that the node cannot be contacted form the
		232	outside. This means the node cannot talk to other nodes that also have no
		233	binds, but it can still talk to all "normal" nodes).
		234
		235	If the profile does not specify a binds list, then a default of C<*> is
		236	used, meaning the node will bind on a dynamically-assigned port on every
		237	local IP address it finds.
		238
		239	=item step 3, connect to seed nodes
		240
		241	As the last step, the seeds list from the profile is passed to the
		242	L<AnyEvent::MP::Global> module, which will then use it to keep
		243	connectivity with at least one node at any point in time.
		244
		245	=back
		246
		247	Example: become a distributed node using the local node name as profile.
		248	This should be the most common form of invocation for "daemon"-type nodes.
		249
		250	configure
		251
		252	Example: become an anonymous node. This form is often used for commandline
		253	clients.
		254
		255	configure nodeid => "anon/";
		256
		257	Example: configure a node using a profile called seed, which si suitable
		258	for a seed node as it binds on all local addresses on a fixed port (4040,
		259	customary for aemp).
		260
		261	# use the aemp commandline utility
		262	# aemp profile seed nodeid anon/ binds '*:4040'
		263
		264	# then use it
		265	configure profile => "seed";
		266
		267	# or simply use aemp from the shell again:
		268	# aemp run profile seed
		269
		270	# or provide a nicer-to-remember nodeid
		271	# aemp run profile seed nodeid "$(hostname)"
		272
		273	=item $SELF
		274
		275	Contains the current port id while executing C<rcv> callbacks or C<psub>
		276	blocks.
		277
		278	=item *SELF, SELF, %SELF, @SELF...
		279
		280	Due to some quirks in how perl exports variables, it is impossible to
		281	just export C<$SELF>, all the symbols named C<SELF> are exported by this
		282	module, but only C<$SELF> is currently used.
		283
160	=item snd $portid, type => @data	284	=item snd $port, type => @data
161		285
162	=item snd $portid, @msg	286	=item snd $port, @msg
163		287
164	Send the given message to the given port ID, which can identify either a	288	Send the given message to the given port, which can identify either a
165	local or a remote port.	289	local or a remote port, and must be a port ID.
166		290
167	While the message can be about anything, it is highly recommended to use	291	While the message can be almost anything, it is highly recommended to
168	a constant string as first element.	292	use a string as first element (a port ID, or some word that indicates a
		293	request type etc.) and to consist if only simple perl values (scalars,
		294	arrays, hashes) - if you think you need to pass an object, think again.
169		295
170	The message data effectively becomes read-only after a call to this	296	The message data logically becomes read-only after a call to this
171	function: modifying any argument is not allowed and can cause many	297	function: modifying any argument (or values referenced by them) is
172	problems.	298	forbidden, as there can be considerable time between the call to C<snd>
		299	and the time the message is actually being serialised - in fact, it might
		300	never be copied as within the same process it is simply handed to the
		301	receiving port.
173		302
174	The type of data you can transfer depends on the transport protocol: when	303	The type of data you can transfer depends on the transport protocol: when
175	JSON is used, then only strings, numbers and arrays and hashes consisting	304	JSON is used, then only strings, numbers and arrays and hashes consisting
176	of those are allowed (no objects). When Storable is used, then anything	305	of those are allowed (no objects). When Storable is used, then anything
177	that Storable can serialise and deserialise is allowed, and for the local	306	that Storable can serialise and deserialise is allowed, and for the local
178	node, anything can be passed.	307	node, anything can be passed. Best rely only on the common denominator of
		308	these.
179		309
180	=cut	310	=item $local_port = port
181		311
182	sub snd(@) {	312	Create a new local port object and returns its port ID. Initially it has
183	my ($noderef, $port) = split /#/, shift, 2;	313	no callbacks set and will throw an error when it receives messages.
184		314
185	add_node $noderef	315	=item $local_port = port { my @msg = @_ }
186	unless exists $NODE{$noderef};
187		316
188	$NODE{$noderef}->send (["$port", [@_]]);	317	Creates a new local port, and returns its ID. Semantically the same as
189	}	318	creating a port and calling C<rcv $port, $callback> on it.
190		319
		320	The block will be called for every message received on the port, with the
		321	global variable C<$SELF> set to the port ID. Runtime errors will cause the
		322	port to be C<kil>ed. The message will be passed as-is, no extra argument
		323	(i.e. no port ID) will be passed to the callback.
		324
		325	If you want to stop/destroy the port, simply C<kil> it:
		326
		327	my $port = port {
		328	my @msg = @_;
		329	...
		330	kil $SELF;
		331	};
		332
		333	=cut
		334
		335	sub rcv($@);
		336
		337	sub _kilme {
		338	die "received message on port without callback";
		339	}
		340
		341	sub port(;&) {
		342	my $id = "$UNIQ." . $ID++;
		343	my $port = "$NODE#$id";
		344
		345	rcv $port, shift \|\| \&_kilme;
		346
		347	$port
		348	}
		349
191	=item rcv $portid, type => $callback->(@msg)	350	=item rcv $local_port, $callback->(@msg)
192		351
193	=item rcv $portid, $smartmatch => $callback->(@msg)	352	Replaces the default callback on the specified port. There is no way to
		353	remove the default callback: use C<sub { }> to disable it, or better
		354	C<kil> the port when it is no longer needed.
194		355
195	=item rcv $portid, [$smartmatch...] => $callback->(@msg)	356	The global C<$SELF> (exported by this module) contains C<$port> while
		357	executing the callback. Runtime errors during callback execution will
		358	result in the port being C<kil>ed.
196		359
197	Register a callback on the port identified by C<$portid>, which I<must> be	360	The default callback received all messages not matched by a more specific
198	a local port.	361	C<tag> match.
199		362
200	The callback has to return a true value when its work is done, after	363	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
201	which is will be removed, or a false value in which case it will stay
202	registered.
203		364
204	If the match is an array reference, then it will be matched against the	365	Register (or replace) callbacks to be called on messages starting with the
205	first elements of the message, otherwise only the first element is being	366	given tag on the given port (and return the port), or unregister it (when
206	matched.	367	C<$callback> is C<$undef> or missing). There can only be one callback
		368	registered for each tag.
207		369
208	Any element in the match that is specified as C<_any_> (a function	370	The original message will be passed to the callback, after the first
209	exported by this module) matches any single element of the message.	371	element (the tag) has been removed. The callback will use the same
		372	environment as the default callback (see above).
210		373
211	While not required, it is highly recommended that the first matching	374	Example: create a port and bind receivers on it in one go.
212	element is a string identifying the message. The one-string-only match is	375
213	also the most efficient match (by far).	376	my $port = rcv port,
		377	msg1 => sub { ... },
		378	msg2 => sub { ... },
		379	;
		380
		381	Example: create a port, bind receivers and send it in a message elsewhere
		382	in one go:
		383
		384	snd $otherport, reply =>
		385	rcv port,
		386	msg1 => sub { ... },
		387	...
		388	;
		389
		390	Example: temporarily register a rcv callback for a tag matching some port
		391	(e.g. for an rpc reply) and unregister it after a message was received.
		392
		393	rcv $port, $otherport => sub {
		394	my @reply = @_;
		395
		396	rcv $SELF, $otherport;
		397	};
214		398
215	=cut	399	=cut
216		400
217	sub rcv($@) {	401	sub rcv($@) {
218	my ($port, $match, $cb) = @_;	402	my $port = shift;
219
220	my $port = $PORT{$port}
221	or do {
222	my ($noderef, $lport) = split /#/, $port;	403	my ($nodeid, $portid) = split /#/, $port, 2;
223	"AnyEvent::MP::Node::Self" eq ref $NODE{$noderef}	404
		405	$NODE{$nodeid} == $NODE{""}
224	or Carp::croak "$port: can only rcv on local ports";	406	or Carp::croak "$port: rcv can only be called on local ports, caught";
225		407
226	$PORT{$lport}	408	while (@_) {
227	or Carp::croak "$port: port does not exist";	409	if (ref $_[0]) {
228		410	if (my $self = $PORT_DATA{$portid}) {
229	$PORT{$port} = $PORT{$lport} # also return	411	"AnyEvent::MP::Port" eq ref $self
230	};	412	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
231		413
232	if (!ref $match) {	414	$self->[0] = shift;
233	push @{ $port->{rc0}{$match} }, [$cb];
234	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
235	my ($type, @match) = @$match;
236	@match
237	? push @{ $port->{rcv}{$match->[0]} }, [$cb, \@match]
238	: push @{ $port->{rc0}{$match->[0]} }, [$cb];
239	} else {	415	} else {
240	push @{ $port->{any} }, [$cb, $match];	416	my $cb = shift;
241	}	417	$PORT{$portid} = sub {
242	}	418	local $SELF = $port;
243		419	eval { &$cb }; _self_die if $@;
244	sub _inject {
245	my ($port, $msg) = @{+shift};
246
247	$port = $PORT{$port}
248	or return;
249
250	@_ = @$msg;
251
252	for (@{ $port->{rc0}{$msg->[0]} }) {
253	$_ && &{$_->[0]}
254	&& undef $_;
255	}
256
257	for (@{ $port->{rcv}{$msg->[0]} }) {
258	$_ && [@_[1..$#{$_->[1]}]] ~~ $_->[1]
259	&& &{$_->[0]}
260	&& undef $_;
261	}
262
263	for (@{ $port->{any} }) {
264	$_ && [@_[0..$#{$_->[1]}]] ~~ $_->[1]
265	&& &{$_->[0]}
266	&& undef $_;
267	}
268	}
269
270	sub normalise_noderef($) {
271	my ($noderef) = @_;
272
273	my $cv = AE::cv;
274	my @res;
275
276	$cv->begin (sub {
277	my %seen;
278	my @refs;
279	for (sort { $a->[0] <=> $b->[0] } @res) {
280	push @refs, $_->[1] unless $seen{$_->[1]}++
281	}
282	shift->send (join ",", @refs);
283	});
284
285	$noderef = $DEFAULT_PORT unless length $noderef;
286
287	my $idx;
288	for my $t (split /,/, $noderef) {
289	my $pri = ++$idx;
290
291	#TODO: this should be outside normalise_noderef and in become_public
292	if ($t =~ /^\d*$/) {
293	my $nodename = (POSIX::uname)[1];
294
295	$cv->begin;
296	AnyEvent::Socket::resolve_sockaddr $nodename, $t \|\| "aemp=$DEFAULT_PORT", "tcp", 0, undef, sub {
297	for (@_) {
298	my ($service, $host) = AnyEvent::Socket::unpack_sockaddr $_->[3];
299	push @res, [
300	$pri += 1e-5,
301	AnyEvent::Socket::format_hostport AnyEvent::Socket::format_address $host, $service
302	];
303	}	420	};
304	$cv->end;	421	}
		422	} elsif (defined $_[0]) {
		423	my $self = $PORT_DATA{$portid} \|\|= do {
		424	my $self = bless [$PORT{$portid} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
		425
		426	$PORT{$portid} = sub {
		427	local $SELF = $port;
		428
		429	if (my $cb = $self->[1]{$_[0]}) {
		430	shift;
		431	eval { &$cb }; _self_die if $@;
		432	} else {
		433	&{ $self->[0] };
		434	}
		435	};
		436
		437	$self
305	};	438	};
306		439
307	# my (undef, undef, undef, undef, @ipv4) = gethostbyname $nodename;	440	"AnyEvent::MP::Port" eq ref $self
308	#	441	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
309	# for (@ipv4) {	442
310	# push @res, [	443	my ($tag, $cb) = splice @_, 0, 2;
311	# $pri,	444
312	# AnyEvent::Socket::format_hostport AnyEvent::Socket::format_address $_, $t \|\| $DEFAULT_PORT,	445	if (defined $cb) {
313	# ];	446	$self->[1]{$tag} = $cb;
314	# }
315	} else {	447	} else {
316	my ($host, $port) = AnyEvent::Socket::parse_hostport $t, "aemp=$DEFAULT_PORT"	448	delete $self->[1]{$tag};
317	or Carp::croak "$t: unparsable transport descriptor";
318
319	$cv->begin;
320	AnyEvent::Socket::resolve_sockaddr $host, $port, "tcp", 0, undef, sub {
321	for (@_) {
322	my ($service, $host) = AnyEvent::Socket::unpack_sockaddr $_->[3];
323	push @res, [
324	$pri += 1e-5,
325	AnyEvent::Socket::format_hostport AnyEvent::Socket::format_address $host, $service
326	];
327	}
328	$cv->end;
329	}	449	}
330	}	450	}
331	}	451	}
332		452
333	$cv->end;	453	$port
334
335	$cv
336	}	454	}
337		455
338	sub become_public {	456	=item peval $port, $coderef[, @args]
339	return if $PUBLIC;
340		457
341	my $noderef = join ",", ref $_[0] ? @{+shift} : shift;	458	Evaluates the given C<$codref> within the contetx of C<$port>, that is,
342	my @args = @_;	459	when the code throews an exception the C<$port> will be killed.
343		460
344	$NODE = (normalise_noderef $noderef)->recv;	461	Any remaining args will be passed to the callback. Any return values will
		462	be returned to the caller.
345		463
346	for my $t (split /,/, $NODE) {	464	This is useful when you temporarily want to execute code in the context of
347	$NODE{$t} = $NODE{""};	465	a port.
348		466
349	my ($host, $port) = AnyEvent::Socket::parse_hostport $t;	467	Example: create a port and run some initialisation code in it's context.
350		468
351	$LISTENER{$t} = AnyEvent::MP::Transport::mp_server $host, $port,	469	my $port = port { ... };
352	@args,
353	on_error => sub {
354	die "on_error<@_>\n";#d#
355	},
356	on_connect => sub {
357	my ($tp) = @_;
358		470
359	$NODE{$tp->{remote_id}} = $_[0];	471	peval $port, sub {
360	},	472	init
361	sub {	473	or die "unable to init";
362	my ($tp) = @_;	474	};
363		475
364	$NODE{"$tp->{peerhost}:$tp->{peerport}"} = $tp;	476	=cut
365	},	477
366	;	478	sub peval($$) {
		479	local $SELF = shift;
		480	my $cb = shift;
		481
		482	if (wantarray) {
		483	my @res = eval { &$cb };
		484	_self_die if $@;
		485	@res
		486	} else {
		487	my $res = eval { &$cb };
		488	_self_die if $@;
		489	$res
367	}	490	}
		491	}
368		492
369	$PUBLIC = 1;	493	=item $closure = psub { BLOCK }
		494
		495	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
		496	closure is executed, sets up the environment in the same way as in C<rcv>
		497	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		498
		499	The effect is basically as if it returned C<< sub { peval $SELF, sub {
		500	BLOCK }, @_ } >>.
		501
		502	This is useful when you register callbacks from C<rcv> callbacks:
		503
		504	rcv delayed_reply => sub {
		505	my ($delay, @reply) = @_;
		506	my $timer = AE::timer $delay, 0, psub {
		507	snd @reply, $SELF;
		508	};
		509	};
		510
		511	=cut
		512
		513	sub psub(&) {
		514	my $cb = shift;
		515
		516	my $port = $SELF
		517	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
		518
		519	sub {
		520	local $SELF = $port;
		521
		522	if (wantarray) {
		523	my @res = eval { &$cb };
		524	_self_die if $@;
		525	@res
		526	} else {
		527	my $res = eval { &$cb };
		528	_self_die if $@;
		529	$res
		530	}
		531	}
		532	}
		533
		534	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
		535
		536	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
		537
		538	=item $guard = mon $port # kill $SELF when $port dies
		539
		540	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
		541
		542	Monitor the given port and do something when the port is killed or
		543	messages to it were lost, and optionally return a guard that can be used
		544	to stop monitoring again.
		545
		546	In the first form (callback), the callback is simply called with any
		547	number of C<@reason> elements (no @reason means that the port was deleted
		548	"normally"). Note also that I<< the callback B<must> never die >>, so use
		549	C<eval> if unsure.
		550
		551	In the second form (another port given), the other port (C<$rcvport>)
		552	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
		553	"normal" kils nothing happens, while under all other conditions, the other
		554	port is killed with the same reason.
		555
		556	The third form (kill self) is the same as the second form, except that
		557	C<$rvport> defaults to C<$SELF>.
		558
		559	In the last form (message), a message of the form C<@msg, @reason> will be
		560	C<snd>.
		561
		562	Monitoring-actions are one-shot: once messages are lost (and a monitoring
		563	alert was raised), they are removed and will not trigger again.
		564
		565	As a rule of thumb, monitoring requests should always monitor a port from
		566	a local port (or callback). The reason is that kill messages might get
		567	lost, just like any other message. Another less obvious reason is that
		568	even monitoring requests can get lost (for example, when the connection
		569	to the other node goes down permanently). When monitoring a port locally
		570	these problems do not exist.
		571
		572	C<mon> effectively guarantees that, in the absence of hardware failures,
		573	after starting the monitor, either all messages sent to the port will
		574	arrive, or the monitoring action will be invoked after possible message
		575	loss has been detected. No messages will be lost "in between" (after
		576	the first lost message no further messages will be received by the
		577	port). After the monitoring action was invoked, further messages might get
		578	delivered again.
		579
		580	Inter-host-connection timeouts and monitoring depend on the transport
		581	used. The only transport currently implemented is TCP, and AnyEvent::MP
		582	relies on TCP to detect node-downs (this can take 10-15 minutes on a
		583	non-idle connection, and usually around two hours for idle connections).
		584
		585	This means that monitoring is good for program errors and cleaning up
		586	stuff eventually, but they are no replacement for a timeout when you need
		587	to ensure some maximum latency.
		588
		589	Example: call a given callback when C<$port> is killed.
		590
		591	mon $port, sub { warn "port died because of <@_>\n" };
		592
		593	Example: kill ourselves when C<$port> is killed abnormally.
		594
		595	mon $port;
		596
		597	Example: send us a restart message when another C<$port> is killed.
		598
		599	mon $port, $self => "restart";
		600
		601	=cut
		602
		603	sub mon {
		604	my ($nodeid, $port) = split /#/, shift, 2;
		605
		606	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
		607
		608	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
		609
		610	unless (ref $cb) {
		611	if (@_) {
		612	# send a kill info message
		613	my (@msg) = ($cb, @_);
		614	$cb = sub { snd @msg, @_ };
		615	} else {
		616	# simply kill other port
		617	my $port = $cb;
		618	$cb = sub { kil $port, @_ if @_ };
		619	}
		620	}
		621
		622	$node->monitor ($port, $cb);
		623
		624	defined wantarray
		625	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })
		626	}
		627
		628	=item $guard = mon_guard $port, $ref, $ref...
		629
		630	Monitors the given C<$port> and keeps the passed references. When the port
		631	is killed, the references will be freed.
		632
		633	Optionally returns a guard that will stop the monitoring.
		634
		635	This function is useful when you create e.g. timers or other watchers and
		636	want to free them when the port gets killed (note the use of C<psub>):
		637
		638	$port->rcv (start => sub {
		639	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
		640	undef $timer if 0.9 < rand;
		641	});
		642	});
		643
		644	=cut
		645
		646	sub mon_guard {
		647	my ($port, @refs) = @_;
		648
		649	#TODO: mon-less form?
		650
		651	mon $port, sub { 0 && @refs }
		652	}
		653
		654	=item kil $port[, @reason]
		655
		656	Kill the specified port with the given C<@reason>.
		657
		658	If no C<@reason> is specified, then the port is killed "normally" -
		659	monitor callback will be invoked, but the kil will not cause linked ports
		660	(C<mon $mport, $lport> form) to get killed.
		661
		662	If a C<@reason> is specified, then linked ports (C<mon $mport, $lport>
		663	form) get killed with the same reason.
		664
		665	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		666	will be reported as reason C<< die => $@ >>.
		667
		668	Transport/communication errors are reported as C<< transport_error =>
		669	$message >>.
		670
		671	=cut
		672
		673	=item $port = spawn $node, $initfunc[, @initdata]
		674
		675	Creates a port on the node C<$node> (which can also be a port ID, in which
		676	case it's the node where that port resides).
		677
		678	The port ID of the newly created port is returned immediately, and it is
		679	possible to immediately start sending messages or to monitor the port.
		680
		681	After the port has been created, the init function is called on the remote
		682	node, in the same context as a C<rcv> callback. This function must be a
		683	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
		684	specify a function in the main program, use C<::name>.
		685
		686	If the function doesn't exist, then the node tries to C<require>
		687	the package, then the package above the package and so on (e.g.
		688	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		689	exists or it runs out of package names.
		690
		691	The init function is then called with the newly-created port as context
		692	object (C<$SELF>) and the C<@initdata> values as arguments. It I<must>
		693	call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise
		694	the port might not get created.
		695
		696	A common idiom is to pass a local port, immediately monitor the spawned
		697	port, and in the remote init function, immediately monitor the passed
		698	local port. This two-way monitoring ensures that both ports get cleaned up
		699	when there is a problem.
		700
		701	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
		702	caller before C<spawn> returns (by delaying invocation when spawn is
		703	called for the local node).
		704
		705	Example: spawn a chat server port on C<$othernode>.
		706
		707	# this node, executed from within a port context:
		708	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		709	mon $server;
		710
		711	# init function on C<$othernode>
		712	sub connect {
		713	my ($srcport) = @_;
		714
		715	mon $srcport;
		716
		717	rcv $SELF, sub {
		718	...
		719	};
		720	}
		721
		722	=cut
		723
		724	sub _spawn {
		725	my $port = shift;
		726	my $init = shift;
		727
		728	# rcv will create the actual port
		729	local $SELF = "$NODE#$port";
		730	eval {
		731	&{ load_func $init }
		732	};
		733	_self_die if $@;
		734	}
		735
		736	sub spawn(@) {
		737	my ($nodeid, undef) = split /#/, shift, 2;
		738
		739	my $id = "$RUNIQ." . $ID++;
		740
		741	$_[0] =~ /::/
		742	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		743
		744	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
		745
		746	"$nodeid#$id"
		747	}
		748
		749	=item after $timeout, @msg
		750
		751	=item after $timeout, $callback
		752
		753	Either sends the given message, or call the given callback, after the
		754	specified number of seconds.
		755
		756	This is simply a utility function that comes in handy at times - the
		757	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		758	so it may go away in the future.
		759
		760	=cut
		761
		762	sub after($@) {
		763	my ($timeout, @action) = @_;
		764
		765	my $t; $t = AE::timer $timeout, 0, sub {
		766	undef $t;
		767	ref $action[0]
		768	? $action[0]()
		769	: snd @action;
		770	};
		771	}
		772
		773	=item cal $port, @msg, $callback[, $timeout]
		774
		775	A simple form of RPC - sends a message to the given C<$port> with the
		776	given contents (C<@msg>), but adds a reply port to the message.
		777
		778	The reply port is created temporarily just for the purpose of receiving
		779	the reply, and will be C<kil>ed when no longer needed.
		780
		781	A reply message sent to the port is passed to the C<$callback> as-is.
		782
		783	If an optional time-out (in seconds) is given and it is not C<undef>,
		784	then the callback will be called without any arguments after the time-out
		785	elapsed and the port is C<kil>ed.
		786
		787	If no time-out is given (or it is C<undef>), then the local port will
		788	monitor the remote port instead, so it eventually gets cleaned-up.
		789
		790	Currently this function returns the temporary port, but this "feature"
		791	might go in future versions unless you can make a convincing case that
		792	this is indeed useful for something.
		793
		794	=cut
		795
		796	sub cal(@) {
		797	my $timeout = ref $_[-1] ? undef : pop;
		798	my $cb = pop;
		799
		800	my $port = port {
		801	undef $timeout;
		802	kil $SELF;
		803	&$cb;
		804	};
		805
		806	if (defined $timeout) {
		807	$timeout = AE::timer $timeout, 0, sub {
		808	undef $timeout;
		809	kil $port;
		810	$cb->();
		811	};
		812	} else {
		813	mon $_[0], sub {
		814	kil $port;
		815	$cb->();
		816	};
		817	}
		818
		819	push @_, $port;
		820	&snd;
		821
		822	$port
370	}	823	}
371		824
372	=back	825	=back
373		826
374	=head1 NODE MESSAGES	827	=head1 AnyEvent::MP vs. Distributed Erlang
375		828
376	Nodes understand the following messages sent to them. Many of them take	829	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
377	arguments called C<@reply>, which will simply be used to compose a reply	830	== aemp node, Erlang process == aemp port), so many of the documents and
378	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and	831	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
379	the remaining arguments are simply the message data.	832	sample:
		833
		834	http://www.erlang.se/doc/programming_rules.shtml
		835	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		836	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6
		837	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		838
		839	Despite the similarities, there are also some important differences:
380		840
381	=over 4	841	=over 4
382		842
383	=cut	843	=item * Node IDs are arbitrary strings in AEMP.
384		844
385	#############################################################################	845	Erlang relies on special naming and DNS to work everywhere in the same
386	# self node code	846	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
		847	configuration or DNS), and possibly the addresses of some seed nodes, but
		848	will otherwise discover other nodes (and their IDs) itself.
387		849
388	sub _new_port($) {	850	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
389	my ($name) = @_;	851	uses "local ports are like remote ports".
390		852
391	my ($noderef, $portname) = split /#/, $name;	853	The failure modes for local ports are quite different (runtime errors
		854	only) then for remote ports - when a local port dies, you I<know> it dies,
		855	when a connection to another node dies, you know nothing about the other
		856	port.
392		857
393	$PORT{$name} =	858	Erlang pretends remote ports are as reliable as local ports, even when
394	$PORT{$portname} = {	859	they are not.
395	names => [$name, $portname],
396	};
397	}
398		860
399	$NODE{""} = new AnyEvent::MP::Node::Self noderef => $NODE;	861	AEMP encourages a "treat remote ports differently" philosophy, with local
400	_new_port "";	862	ports being the special case/exception, where transport errors cannot
		863	occur.
401		864
402	=item devnull => ...	865	=item * Erlang uses processes and a mailbox, AEMP does not queue.
403		866
404	Generic data sink/CPU heat conversion.	867	Erlang uses processes that selectively receive messages, and therefore
		868	needs a queue. AEMP is event based, queuing messages would serve no
		869	useful purpose. For the same reason the pattern-matching abilities of
		870	AnyEvent::MP are more limited, as there is little need to be able to
		871	filter messages without dequeuing them.
405		872
406	=cut	873	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
407		874
408	rcv "", devnull => sub { () };	875	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
409		876
410	=item relay => $port, @msg	877	Sending messages in Erlang is synchronous and blocks the process (and
		878	so does not need a queue that can overflow). AEMP sends are immediate,
		879	connection establishment is handled in the background.
411		880
412	Simply forwards the message to the given port.	881	=item * Erlang suffers from silent message loss, AEMP does not.
413		882
414	=cut	883	Erlang implements few guarantees on messages delivery - messages can get
		884	lost without any of the processes realising it (i.e. you send messages a,
		885	b, and c, and the other side only receives messages a and c).
415		886
416	rcv "", relay => sub { \&snd; () };	887	AEMP guarantees correct ordering, and the guarantee that after one message
		888	is lost, all following ones sent to the same port are lost as well, until
		889	monitoring raises an error, so there are no silent "holes" in the message
		890	sequence.
417		891
418	=item eval => $string[ @reply]	892	=item * Erlang can send messages to the wrong port, AEMP does not.
419		893
420	Evaluates the given string. If C<@reply> is given, then a message of the	894	In Erlang it is quite likely that a node that restarts reuses a process ID
421	form C<@reply, $@, @evalres> is sent.	895	known to other nodes for a completely different process, causing messages
		896	destined for that process to end up in an unrelated process.
422		897
423	Example: crash another node.	898	AEMP never reuses port IDs, so old messages or old port IDs floating
		899	around in the network will not be sent to an unrelated port.
424		900
425	snd $othernode, eval => "exit";	901	=item * Erlang uses unprotected connections, AEMP uses secure
		902	authentication and can use TLS.
426		903
427	=cut	904	AEMP can use a proven protocol - TLS - to protect connections and
		905	securely authenticate nodes.
428		906
429	rcv "", eval => sub {	907	=item * The AEMP protocol is optimised for both text-based and binary
430	my (undef, $string, @reply) = @_;	908	communications.
431	my @res = eval $string;
432	snd @reply, "$@", @res if @reply;
433	()
434	};
435		909
436	=item time => @reply	910	The AEMP protocol, unlike the Erlang protocol, supports both programming
		911	language independent text-only protocols (good for debugging) and binary,
		912	language-specific serialisers (e.g. Storable). By default, unless TLS is
		913	used, the protocol is actually completely text-based.
437		914
438	Replies the the current node time to C<@reply>.	915	It has also been carefully designed to be implementable in other languages
		916	with a minimum of work while gracefully degrading functionality to make the
		917	protocol simple.
439		918
440	Example: tell the current node to send the current time to C<$myport> in a	919	=item * AEMP has more flexible monitoring options than Erlang.
441	C<timereply> message.
442		920
443	snd $NODE, time => $myport, timereply => 1, 2;	921	In Erlang, you can chose to receive I<all> exit signals as messages
444	# => snd $myport, timereply => 1, 2, <time>	922	or I<none>, there is no in-between, so monitoring single processes is
		923	difficult to implement. Monitoring in AEMP is more flexible than in
		924	Erlang, as one can choose between automatic kill, exit message or callback
		925	on a per-process basis.
445		926
446	=cut	927	=item * Erlang tries to hide remote/local connections, AEMP does not.
447		928
448	rcv "", time => sub { shift; snd @_, AE::time; () };	929	Monitoring in Erlang is not an indicator of process death/crashes, in the
		930	same way as linking is (except linking is unreliable in Erlang).
		931
		932	In AEMP, you don't "look up" registered port names or send to named ports
		933	that might or might not be persistent. Instead, you normally spawn a port
		934	on the remote node. The init function monitors you, and you monitor the
		935	remote port. Since both monitors are local to the node, they are much more
		936	reliable (no need for C<spawn_link>).
		937
		938	This also saves round-trips and avoids sending messages to the wrong port
		939	(hard to do in Erlang).
449		940
450	=back	941	=back
451		942
		943	=head1 RATIONALE
		944
		945	=over 4
		946
		947	=item Why strings for port and node IDs, why not objects?
		948
		949	We considered "objects", but found that the actual number of methods
		950	that can be called are quite low. Since port and node IDs travel over
		951	the network frequently, the serialising/deserialising would add lots of
		952	overhead, as well as having to keep a proxy object everywhere.
		953
		954	Strings can easily be printed, easily serialised etc. and need no special
		955	procedures to be "valid".
		956
		957	And as a result, a port with just a default receiver consists of a single
		958	closure stored in a global hash - it can't become much cheaper.
		959
		960	=item Why favour JSON, why not a real serialising format such as Storable?
		961
		962	In fact, any AnyEvent::MP node will happily accept Storable as framing
		963	format, but currently there is no way to make a node use Storable by
		964	default (although all nodes will accept it).
		965
		966	The default framing protocol is JSON because a) JSON::XS is many times
		967	faster for small messages and b) most importantly, after years of
		968	experience we found that object serialisation is causing more problems
		969	than it solves: Just like function calls, objects simply do not travel
		970	easily over the network, mostly because they will always be a copy, so you
		971	always have to re-think your design.
		972
		973	Keeping your messages simple, concentrating on data structures rather than
		974	objects, will keep your messages clean, tidy and efficient.
		975
		976	=back
		977
452	=head1 SEE ALSO	978	=head1 SEE ALSO
		979
		980	L<AnyEvent::MP::Intro> - a gentle introduction.
		981
		982	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		983
		984	L<AnyEvent::MP::Global> - network maintenance and port groups, to find
		985	your applications.
		986
		987	L<AnyEvent::MP::DataConn> - establish data connections between nodes.
		988
		989	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
		990	all nodes.
453		991
454	L<AnyEvent>.	992	L<AnyEvent>.
455		993
456	=head1 AUTHOR	994	=head1 AUTHOR
457		995

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.7 by root, Sat Aug 1 15:04:30 2009 UTC vs. Revision 1.115 by root, Fri May 7 18:14:21 2010 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.7 by root, Sat Aug 1 15:04:30 2009 UTC vs.
Revision 1.115 by root, Fri May 7 18:14:21 2010 UTC