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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.4 by root, Sat Aug 1 07:36:30 2009 UTC vs.
Revision 1.73 by root, Mon Aug 31 11:08:25 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	configure;
		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 = @_ };
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" };
18	rcv $port1, pong => sub { warn "pong received\n" };	31	rcv $port, pong => sub { warn "pong received\n" };
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	bin/aemp - stable.
		44	AnyEvent::MP - stable API, should work.
		45	AnyEvent::MP::Intro - uptodate, but incomplete.
		46	AnyEvent::MP::Kernel - mostly stable.
		47	AnyEvent::MP::Global - stable API, protocol not yet final.
		48
		49	stay tuned.
24		50
25	=head1 DESCRIPTION	51	=head1 DESCRIPTION
26		52
27	This module (-family) implements a simple message passing framework.	53	This module (-family) implements a simple message passing framework.
28		54
29	Despite its simplicity, you can securely message other processes running	55	Despite its simplicity, you can securely message other processes running
30	on the same or other hosts.	56	on the same or other hosts, and you can supervise entities remotely.
		57
		58	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
		59	manual page and the examples under F<eg/>.
		60
		61	At the moment, this module family is a bit underdocumented.
31		62
32	=head1 CONCEPTS	63	=head1 CONCEPTS
33		64
34	=over 4	65	=over 4
35		66
36	=item port	67	=item port
37		68
38	A port is something you can send messages to with the C<snd> function, and	69	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
40	messages they match, messages will not be queued.
41		70
		71	Ports allow you to register C<rcv> handlers that can match all or just
		72	some messages. Messages send to ports will not be queued, regardless of
		73	anything was listening for them or not.
		74
42	=item port id - C<noderef#portname>	75	=item port ID - C<nodeid#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 node ID, 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).
46		79
47	=item node	80	=item node
48		81
49	A node is a single process containing at least one port - the node	82	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,	83	which enables nodes to manage each other remotely, and to create new
51	among other things.	84	ports.
52		85
53	Initially, nodes are either private (single-process only) or hidden	86	Nodes are either public (have one or more listening ports) or private
54	(connected to a master node only). Only when they epxlicitly "become	87	(no listening ports). Private nodes cannot talk to other private nodes
55	public" can you send them messages from unrelated other nodes.	88	currently.
56		89
57	=item noderef - C<host:port,host:port...>, C<id@noderef, C<id>	90	=item node ID - C<[a-za-Z0-9_\-.:]+>
58		91
59	A noderef is a string that either uniquely identifies a given node (for	92	A node ID is a string that uniquely identifies the node within a
60	private and hidden nodes), or contains a recipe on how to reach a given	93	network. Depending on the configuration used, node IDs can look like a
61	node (for public nodes).	94	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
		95	doesn't interpret node IDs in any way.
		96
		97	=item binds - C<ip:port>
		98
		99	Nodes can only talk to each other by creating some kind of connection to
		100	each other. To do this, nodes should listen on one or more local transport
		101	endpoints - binds. Currently, only standard C<ip:port> specifications can
		102	be used, which specify TCP ports to listen on.
		103
		104	=item seeds - C<host:port>
		105
		106	When a node starts, it knows nothing about the network. To teach the node
		107	about the network it first has to contact some other node within the
		108	network. This node is called a seed.
		109
		110	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes
		111	are expected to be long-running, and at least one of those should always
		112	be available. When nodes run out of connections (e.g. due to a network
		113	error), they try to re-establish connections to some seednodes again to
		114	join the network.
		115
		116	Apart from being sued for seeding, seednodes are not special in any way -
		117	every public node can be a seednode.
62		118
63	=back	119	=back
64		120
65	=head1 VARIABLES/FUNCTIONS	121	=head1 VARIABLES/FUNCTIONS
66		122
…		…
68		124
69	=cut	125	=cut
70		126
71	package AnyEvent::MP;	127	package AnyEvent::MP;
72		128
73	use AnyEvent::MP::Util ();
74	use AnyEvent::MP::Node;	129	use AnyEvent::MP::Kernel;
75	use AnyEvent::MP::Transport;
76		130
77	use utf8;
78	use common::sense;	131	use common::sense;
79		132
80	use Carp ();	133	use Carp ();
81		134
82	use AE ();	135	use AE ();
83		136
84	use base "Exporter";	137	use base "Exporter";
85		138
86	our $VERSION = '0.0';	139	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
87	our @EXPORT = qw(NODE $NODE $PORT snd rcv _any_);
88		140
89	our $DEFAULT_SECRET;	141	our @EXPORT = qw(
90	our $DEFAULT_PORT = "4040";	142	NODE $NODE *SELF node_of after
		143	configure
		144	snd rcv mon mon_guard kil reg psub spawn
		145	port
		146	);
91		147
92	our $CONNECT_INTERVAL = 5; # new connect every 5s, at least	148	our $SELF;
93	our $CONNECT_TIMEOUT = 30; # includes handshake
94		149
95	sub default_secret {	150	sub _self_die() {
96	unless (defined $DEFAULT_SECRET) {	151	my $msg = $@;
97	if (open my $fh, "<$ENV{HOME}/.aemp-secret") {	152	$msg =~ s/\n+$// unless ref $msg;
98	sysread $fh, $DEFAULT_SECRET, -s $fh;	153	kil $SELF, die => $msg;
99	} else {
100	$DEFAULT_SECRET = AnyEvent::MP::Util::nonce 32;
101	}
102	}
103
104	$DEFAULT_SECRET
105	}	154	}
106		155
107	=item NODE / $NODE	156	=item $thisnode = NODE / $NODE
108		157
109	The C<NODE ()> function and the C<$NODE> variable contain the noderef of	158	The C<NODE> function returns, and the C<$NODE> variable contains, the node
110	the local node. The value is initialised by a call to C<become_public> or	159	ID of the node running in the current process. This value is initialised by
111	C<become_slave>, after which all local port identifiers become invalid.	160	a call to C<configure>.
112		161
113	=cut	162	=item $nodeid = node_of $port
114		163
115	our $UNIQ = sprintf "%x.%x", $$, time; # per-process/node unique cookie	164	Extracts and returns the node ID from a port ID or a node ID.
116	our $PUBLIC = 0;
117	our $NODE;
118	our $PORT;
119		165
120	our %NODE; # node id to transport mapping, or "undef", for local node	166	=item configure key => value...
121	our %PORT; # local ports
122	our %LISTENER; # local transports
123		167
124	sub NODE() { $NODE }	168	Before a node can talk to other nodes on the network (i.e. enter
		169	"distributed mode") it has to configure itself - the minimum a node needs
		170	to know is its own name, and optionally it should know the addresses of
		171	some other nodes in the network to discover other nodes.
125		172
126	{	173	This function configures a node - it must be called exactly once (or
127	use POSIX ();	174	never) before calling other AnyEvent::MP functions.
128	my $nodename = (POSIX::uname)[1];
129	$NODE = "$$\@$nodename";
130	}
131		175
132	sub _ANY_() { 1 }	176	=over 4
133	sub _any_() { \&_ANY_ }
134		177
135	sub add_node {	178	=item step 1, gathering configuration from profiles
136	my ($noderef) = @_;
137		179
138	return $NODE{$noderef}	180	The function first looks up a profile in the aemp configuration (see the
139	if exists $NODE{$noderef};	181	L<aemp> commandline utility). The profile name can be specified via the
		182	named C<profile> parameter. If it is missing, then the nodename (F<uname
		183	-n>) will be used as profile name.
140		184
141	for (split /,/, $noderef) {	185	The profile data is then gathered as follows:
142	return $NODE{$noderef} = $NODE{$_}
143	if exists $NODE{$_};
144	}
145		186
146	# for indirect sends, use a different class	187	First, all remaining key => value pairs (all of which are conviniently
147	my $node = new AnyEvent::MP::Node::Direct $noderef;	188	undocumented at the moment) will be interpreted as configuration
		189	data. Then they will be overwritten by any values specified in the global
		190	default configuration (see the F<aemp> utility), then the chain of
		191	profiles chosen by the profile name (and any C<parent> attributes).
148		192
149	$NODE{$_} = $node	193	That means that the values specified in the profile have highest priority
150	for $noderef, split /,/, $noderef;	194	and the values specified directly via C<configure> have lowest priority,
		195	and can only be used to specify defaults.
151		196
152	$node	197	If the profile specifies a node ID, then this will become the node ID of
153	}	198	this process. If not, then the profile name will be used as node ID. The
		199	special node ID of C<anon/> will be replaced by a random node ID.
154		200
		201	=item step 2, bind listener sockets
		202
		203	The next step is to look up the binds in the profile, followed by binding
		204	aemp protocol listeners on all binds specified (it is possible and valid
		205	to have no binds, meaning that the node cannot be contacted form the
		206	outside. This means the node cannot talk to other nodes that also have no
		207	binds, but it can still talk to all "normal" nodes).
		208
		209	If the profile does not specify a binds list, then a default of C<*> is
		210	used, meaning the node will bind on a dynamically-assigned port on every
		211	local IP address it finds.
		212
		213	=item step 3, connect to seed nodes
		214
		215	As the last step, the seeds list from the profile is passed to the
		216	L<AnyEvent::MP::Global> module, which will then use it to keep
		217	connectivity with at least one node at any point in time.
		218
		219	=back
		220
		221	Example: become a distributed node using the locla node name as profile.
		222	This should be the most common form of invocation for "daemon"-type nodes.
		223
		224	configure
		225
		226	Example: become an anonymous node. This form is often used for commandline
		227	clients.
		228
		229	configure nodeid => "anon/";
		230
		231	Example: configure a node using a profile called seed, which si suitable
		232	for a seed node as it binds on all local addresses on a fixed port (4040,
		233	customary for aemp).
		234
		235	# use the aemp commandline utility
		236	# aemp profile seed setnodeid anon/ setbinds '*:4040'
		237
		238	# then use it
		239	configure profile => "seed";
		240
		241	# or simply use aemp from the shell again:
		242	# aemp run profile seed
		243
		244	# or provide a nicer-to-remember nodeid
		245	# aemp run profile seed nodeid "$(hostname)"
		246
		247	=item $SELF
		248
		249	Contains the current port id while executing C<rcv> callbacks or C<psub>
		250	blocks.
		251
		252	=item *SELF, SELF, %SELF, @SELF...
		253
		254	Due to some quirks in how perl exports variables, it is impossible to
		255	just export C<$SELF>, all the symbols named C<SELF> are exported by this
		256	module, but only C<$SELF> is currently used.
		257
155	=item snd $portid, type => @data	258	=item snd $port, type => @data
156		259
157	=item snd $portid, @msg	260	=item snd $port, @msg
158		261
159	Send the given message to the given port ID, which can identify either a	262	Send the given message to the given port, which can identify either a
160	local or a remote port.	263	local or a remote port, and must be a port ID.
161		264
162	While the message can be about anything, it is highly recommended to use	265	While the message can be almost anything, it is highly recommended to
163	a constant string as first element.	266	use a string as first element (a port ID, or some word that indicates a
		267	request type etc.) and to consist if only simple perl values (scalars,
		268	arrays, hashes) - if you think you need to pass an object, think again.
164		269
165	The message data effectively becomes read-only after a call to this	270	The message data logically becomes read-only after a call to this
166	function: modifying any argument is not allowed and can cause many	271	function: modifying any argument (or values referenced by them) is
167	problems.	272	forbidden, as there can be considerable time between the call to C<snd>
		273	and the time the message is actually being serialised - in fact, it might
		274	never be copied as within the same process it is simply handed to the
		275	receiving port.
168		276
169	The type of data you can transfer depends on the transport protocol: when	277	The type of data you can transfer depends on the transport protocol: when
170	JSON is used, then only strings, numbers and arrays and hashes consisting	278	JSON is used, then only strings, numbers and arrays and hashes consisting
171	of those are allowed (no objects). When Storable is used, then anything	279	of those are allowed (no objects). When Storable is used, then anything
172	that Storable can serialise and deserialise is allowed, and for the local	280	that Storable can serialise and deserialise is allowed, and for the local
173	node, anything can be passed.	281	node, anything can be passed. Best rely only on the common denominator of
		282	these.
174		283
175	=cut	284	=item $local_port = port
176		285
177	sub snd(@) {	286	Create a new local port object and returns its port ID. Initially it has
178	my ($noderef, $port) = split /#/, shift, 2;	287	no callbacks set and will throw an error when it receives messages.
179		288
180	add_node $noderef	289	=item $local_port = port { my @msg = @_ }
181	unless exists $NODE{$noderef};
182		290
183	$NODE{$noderef}->send (["$port", [@_]]);	291	Creates a new local port, and returns its ID. Semantically the same as
184	}	292	creating a port and calling C<rcv $port, $callback> on it.
185		293
		294	The block will be called for every message received on the port, with the
		295	global variable C<$SELF> set to the port ID. Runtime errors will cause the
		296	port to be C<kil>ed. The message will be passed as-is, no extra argument
		297	(i.e. no port ID) will be passed to the callback.
		298
		299	If you want to stop/destroy the port, simply C<kil> it:
		300
		301	my $port = port {
		302	my @msg = @_;
		303	...
		304	kil $SELF;
		305	};
		306
		307	=cut
		308
		309	sub rcv($@);
		310
		311	sub _kilme {
		312	die "received message on port without callback";
		313	}
		314
		315	sub port(;&) {
		316	my $id = "$UNIQ." . $ID++;
		317	my $port = "$NODE#$id";
		318
		319	rcv $port, shift \|\| \&_kilme;
		320
		321	$port
		322	}
		323
186	=item rcv $portid, type => $callback->(@msg)	324	=item rcv $local_port, $callback->(@msg)
187		325
188	=item rcv $portid, $smartmatch => $callback->(@msg)	326	Replaces the default callback on the specified port. There is no way to
		327	remove the default callback: use C<sub { }> to disable it, or better
		328	C<kil> the port when it is no longer needed.
189		329
190	=item rcv $portid, [$smartmatch...] => $callback->(@msg)	330	The global C<$SELF> (exported by this module) contains C<$port> while
		331	executing the callback. Runtime errors during callback execution will
		332	result in the port being C<kil>ed.
191		333
192	Register a callback on the port identified by C<$portid>, which I<must> be	334	The default callback received all messages not matched by a more specific
193	a local port.	335	C<tag> match.
194		336
195	The callback has to return a true value when its work is done, after	337	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
196	which is will be removed, or a false value in which case it will stay
197	registered.
198		338
199	If the match is an array reference, then it will be matched against the	339	Register (or replace) callbacks to be called on messages starting with the
200	first elements of the message, otherwise only the first element is being	340	given tag on the given port (and return the port), or unregister it (when
201	matched.	341	C<$callback> is C<$undef> or missing). There can only be one callback
		342	registered for each tag.
202		343
203	Any element in the match that is specified as C<_any_> (a function	344	The original message will be passed to the callback, after the first
204	exported by this module) matches any single element of the message.	345	element (the tag) has been removed. The callback will use the same
		346	environment as the default callback (see above).
205		347
206	While not required, it is highly recommended that the first matching	348	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	349
208	also the most efficient match (by far).	350	my $port = rcv port,
		351	msg1 => sub { ... },
		352	msg2 => sub { ... },
		353	;
		354
		355	Example: create a port, bind receivers and send it in a message elsewhere
		356	in one go:
		357
		358	snd $otherport, reply =>
		359	rcv port,
		360	msg1 => sub { ... },
		361	...
		362	;
		363
		364	Example: temporarily register a rcv callback for a tag matching some port
		365	(e.g. for a rpc reply) and unregister it after a message was received.
		366
		367	rcv $port, $otherport => sub {
		368	my @reply = @_;
		369
		370	rcv $SELF, $otherport;
		371	};
209		372
210	=cut	373	=cut
211		374
212	sub rcv($@) {	375	sub rcv($@) {
213	my ($port, $match, $cb) = @_;	376	my $port = shift;
214
215	my $port = $PORT{$port}
216	or do {
217	my ($noderef, $lport) = split /#/, $port;	377	my ($noderef, $portid) = split /#/, $port, 2;
218	"AnyEvent::MP::Node::Self" eq ref $NODE{$noderef}	378
		379	$NODE{$noderef} == $NODE{""}
219	or Carp::croak "$port: can only rcv on local ports";	380	or Carp::croak "$port: rcv can only be called on local ports, caught";
220		381
221	$PORT{$lport}	382	while (@_) {
222	or Carp::croak "$port: port does not exist";	383	if (ref $_[0]) {
223		384	if (my $self = $PORT_DATA{$portid}) {
224	$PORT{$port} = $PORT{$lport} # also return	385	"AnyEvent::MP::Port" eq ref $self
225	};	386	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
226		387
227	if (!ref $match) {	388	$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 {	389	} else {
235	push @{ $port->{any} }, [$cb, $match];	390	my $cb = shift;
236	}	391	$PORT{$portid} = sub {
237	}	392	local $SELF = $port;
238		393	eval { &$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	}	394	};
299	$cv->end;	395	}
		396	} elsif (defined $_[0]) {
		397	my $self = $PORT_DATA{$portid} \|\|= do {
		398	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
		399
		400	$PORT{$portid} = sub {
		401	local $SELF = $port;
		402
		403	if (my $cb = $self->[1]{$_[0]}) {
		404	shift;
		405	eval { &$cb }; _self_die if $@;
		406	} else {
		407	&{ $self->[0] };
		408	}
		409	};
		410
		411	$self
300	};	412	};
301		413
302	# my (undef, undef, undef, undef, @ipv4) = gethostbyname $nodename;	414	"AnyEvent::MP::Port" eq ref $self
303	#	415	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
304	# for (@ipv4) {	416
305	# push @res, [	417	my ($tag, $cb) = splice @_, 0, 2;
306	# $pri,	418
307	# AnyEvent::Socket::format_hostport AnyEvent::Socket::format_address $_, $t \|\| $DEFAULT_PORT,	419	if (defined $cb) {
308	# ];	420	$self->[1]{$tag} = $cb;
309	# }
310	} else {	421	} else {
311	my ($host, $port) = AnyEvent::Socket::parse_hostport $t, "aemp=$DEFAULT_PORT"	422	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	}	423	}
325	}	424	}
326	}	425	}
327		426
328	$cv->end;	427	$port
329
330	$cv
331	}	428	}
332		429
333	sub become_public {	430	=item $closure = psub { BLOCK }
334	return if $PUBLIC;
335		431
336	my $noderef = join ",", ref $_[0] ? @{+shift} : shift;	432	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
337	my @args = @_;	433	closure is executed, sets up the environment in the same way as in C<rcv>
		434	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
338		435
339	$NODE = (normalise_noderef $noderef)->recv;	436	This is useful when you register callbacks from C<rcv> callbacks:
340		437
341	for my $t (split /,/, $NODE) {	438	rcv delayed_reply => sub {
342	$NODE{$t} = $NODE{""};	439	my ($delay, @reply) = @_;
343		440	my $timer = AE::timer $delay, 0, psub {
344	my ($host, $port) = AnyEvent::Socket::parse_hostport $t;	441	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	;	442	};
		443	};
		444
		445	=cut
		446
		447	sub psub(&) {
		448	my $cb = shift;
		449
		450	my $port = $SELF
		451	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
		452
		453	sub {
		454	local $SELF = $port;
		455
		456	if (wantarray) {
		457	my @res = eval { &$cb };
		458	_self_die if $@;
		459	@res
		460	} else {
		461	my $res = eval { &$cb };
		462	_self_die if $@;
		463	$res
		464	}
362	}	465	}
		466	}
363		467
364	$PUBLIC = 1;	468	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
		469
		470	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
		471
		472	=item $guard = mon $port # kill $SELF when $port dies
		473
		474	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
		475
		476	Monitor the given port and do something when the port is killed or
		477	messages to it were lost, and optionally return a guard that can be used
		478	to stop monitoring again.
		479
		480	C<mon> effectively guarantees that, in the absence of hardware failures,
		481	after starting the monitor, either all messages sent to the port will
		482	arrive, or the monitoring action will be invoked after possible message
		483	loss has been detected. No messages will be lost "in between" (after
		484	the first lost message no further messages will be received by the
		485	port). After the monitoring action was invoked, further messages might get
		486	delivered again.
		487
		488	Note that monitoring-actions are one-shot: once messages are lost (and a
		489	monitoring alert was raised), they are removed and will not trigger again.
		490
		491	In the first form (callback), the callback is simply called with any
		492	number of C<@reason> elements (no @reason means that the port was deleted
		493	"normally"). Note also that I<< the callback B<must> never die >>, so use
		494	C<eval> if unsure.
		495
		496	In the second form (another port given), the other port (C<$rcvport>)
		497	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
		498	"normal" kils nothing happens, while under all other conditions, the other
		499	port is killed with the same reason.
		500
		501	The third form (kill self) is the same as the second form, except that
		502	C<$rvport> defaults to C<$SELF>.
		503
		504	In the last form (message), a message of the form C<@msg, @reason> will be
		505	C<snd>.
		506
		507	As a rule of thumb, monitoring requests should always monitor a port from
		508	a local port (or callback). The reason is that kill messages might get
		509	lost, just like any other message. Another less obvious reason is that
		510	even monitoring requests can get lost (for exmaple, when the connection
		511	to the other node goes down permanently). When monitoring a port locally
		512	these problems do not exist.
		513
		514	Example: call a given callback when C<$port> is killed.
		515
		516	mon $port, sub { warn "port died because of <@_>\n" };
		517
		518	Example: kill ourselves when C<$port> is killed abnormally.
		519
		520	mon $port;
		521
		522	Example: send us a restart message when another C<$port> is killed.
		523
		524	mon $port, $self => "restart";
		525
		526	=cut
		527
		528	sub mon {
		529	my ($noderef, $port) = split /#/, shift, 2;
		530
		531	my $node = $NODE{$noderef} \|\| add_node $noderef;
		532
		533	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
		534
		535	unless (ref $cb) {
		536	if (@_) {
		537	# send a kill info message
		538	my (@msg) = ($cb, @_);
		539	$cb = sub { snd @msg, @_ };
		540	} else {
		541	# simply kill other port
		542	my $port = $cb;
		543	$cb = sub { kil $port, @_ if @_ };
		544	}
		545	}
		546
		547	$node->monitor ($port, $cb);
		548
		549	defined wantarray
		550	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
		551	}
		552
		553	=item $guard = mon_guard $port, $ref, $ref...
		554
		555	Monitors the given C<$port> and keeps the passed references. When the port
		556	is killed, the references will be freed.
		557
		558	Optionally returns a guard that will stop the monitoring.
		559
		560	This function is useful when you create e.g. timers or other watchers and
		561	want to free them when the port gets killed (note the use of C<psub>):
		562
		563	$port->rcv (start => sub {
		564	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
		565	undef $timer if 0.9 < rand;
		566	});
		567	});
		568
		569	=cut
		570
		571	sub mon_guard {
		572	my ($port, @refs) = @_;
		573
		574	#TODO: mon-less form?
		575
		576	mon $port, sub { 0 && @refs }
		577	}
		578
		579	=item kil $port[, @reason]
		580
		581	Kill the specified port with the given C<@reason>.
		582
		583	If no C<@reason> is specified, then the port is killed "normally" (ports
		584	monitoring other ports will not necessarily die because a port dies
		585	"normally").
		586
		587	Otherwise, linked ports get killed with the same reason (second form of
		588	C<mon>, see above).
		589
		590	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		591	will be reported as reason C<< die => $@ >>.
		592
		593	Transport/communication errors are reported as C<< transport_error =>
		594	$message >>.
		595
		596	=cut
		597
		598	=item $port = spawn $node, $initfunc[, @initdata]
		599
		600	Creates a port on the node C<$node> (which can also be a port ID, in which
		601	case it's the node where that port resides).
		602
		603	The port ID of the newly created port is returned immediately, and it is
		604	possible to immediately start sending messages or to monitor the port.
		605
		606	After the port has been created, the init function is called on the remote
		607	node, in the same context as a C<rcv> callback. This function must be a
		608	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
		609	specify a function in the main program, use C<::name>.
		610
		611	If the function doesn't exist, then the node tries to C<require>
		612	the package, then the package above the package and so on (e.g.
		613	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		614	exists or it runs out of package names.
		615
		616	The init function is then called with the newly-created port as context
		617	object (C<$SELF>) and the C<@initdata> values as arguments.
		618
		619	A common idiom is to pass a local port, immediately monitor the spawned
		620	port, and in the remote init function, immediately monitor the passed
		621	local port. This two-way monitoring ensures that both ports get cleaned up
		622	when there is a problem.
		623
		624	Example: spawn a chat server port on C<$othernode>.
		625
		626	# this node, executed from within a port context:
		627	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		628	mon $server;
		629
		630	# init function on C<$othernode>
		631	sub connect {
		632	my ($srcport) = @_;
		633
		634	mon $srcport;
		635
		636	rcv $SELF, sub {
		637	...
		638	};
		639	}
		640
		641	=cut
		642
		643	sub _spawn {
		644	my $port = shift;
		645	my $init = shift;
		646
		647	local $SELF = "$NODE#$port";
		648	eval {
		649	&{ load_func $init }
		650	};
		651	_self_die if $@;
		652	}
		653
		654	sub spawn(@) {
		655	my ($noderef, undef) = split /#/, shift, 2;
		656
		657	my $id = "$RUNIQ." . $ID++;
		658
		659	$_[0] =~ /::/
		660	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		661
		662	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
		663
		664	"$noderef#$id"
		665	}
		666
		667	=item after $timeout, @msg
		668
		669	=item after $timeout, $callback
		670
		671	Either sends the given message, or call the given callback, after the
		672	specified number of seconds.
		673
		674	This is simply a utility function that comes in handy at times - the
		675	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		676	so it may go away in the future.
		677
		678	=cut
		679
		680	sub after($@) {
		681	my ($timeout, @action) = @_;
		682
		683	my $t; $t = AE::timer $timeout, 0, sub {
		684	undef $t;
		685	ref $action[0]
		686	? $action[0]()
		687	: snd @action;
		688	};
365	}	689	}
366		690
367	=back	691	=back
368		692
369	=head1 NODE MESSAGES	693	=head1 AnyEvent::MP vs. Distributed Erlang
370		694
371	Nodes understand the following messages sent to them:	695	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
		696	== aemp node, Erlang process == aemp port), so many of the documents and
		697	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		698	sample:
		699
		700	http://www.Erlang.se/doc/programming_rules.shtml
		701	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		702	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		703	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		704
		705	Despite the similarities, there are also some important differences:
372		706
373	=over 4	707	=over 4
374		708
375	=cut	709	=item * Node IDs are arbitrary strings in AEMP.
376		710
377	#############################################################################	711	Erlang relies on special naming and DNS to work everywhere in the same
378	# self node code	712	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
		713	configuraiton or DNS), but will otherwise discover other odes itself.
379		714
380	sub _new_port($) {	715	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
381	my ($name) = @_;	716	uses "local ports are like remote ports".
382		717
383	my ($noderef, $portname) = split /#/, $name;	718	The failure modes for local ports are quite different (runtime errors
		719	only) then for remote ports - when a local port dies, you I<know> it dies,
		720	when a connection to another node dies, you know nothing about the other
		721	port.
384		722
385	$PORT{$name} =	723	Erlang pretends remote ports are as reliable as local ports, even when
386	$PORT{$portname} = {	724	they are not.
387	names => [$name, $portname],
388	};
389	}
390		725
391	$NODE{""} = new AnyEvent::MP::Node::Self noderef => $NODE;	726	AEMP encourages a "treat remote ports differently" philosophy, with local
392	_new_port "";	727	ports being the special case/exception, where transport errors cannot
		728	occur.
393		729
394	=item relay => $port, @msg	730	=item * Erlang uses processes and a mailbox, AEMP does not queue.
395		731
396	Simply forwards the message to the given port.	732	Erlang uses processes that selectively receive messages, and therefore
		733	needs a queue. AEMP is event based, queuing messages would serve no
		734	useful purpose. For the same reason the pattern-matching abilities of
		735	AnyEvent::MP are more limited, as there is little need to be able to
		736	filter messages without dequeing them.
397		737
398	=cut	738	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
399		739
400	rcv "", relay => \&snd;	740	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
401		741
402	=item eval => $string[ @reply]	742	Sending messages in Erlang is synchronous and blocks the process (and
		743	so does not need a queue that can overflow). AEMP sends are immediate,
		744	connection establishment is handled in the background.
403		745
404	Evaluates the given string. If C<@reply> is given, then a message of the	746	=item * Erlang suffers from silent message loss, AEMP does not.
405	form C<@reply, $@, @evalres> is sent (C<$reply[0]> is the port to reply to).
406		747
407	=cut	748	Erlang makes few guarantees on messages delivery - messages can get lost
		749	without any of the processes realising it (i.e. you send messages a, b,
		750	and c, and the other side only receives messages a and c).
408		751
409	rcv "", eval => sub {	752	AEMP guarantees correct ordering, and the guarantee that after one message
410	my (undef, $string, @reply) = @_;	753	is lost, all following ones sent to the same port are lost as well, until
411	my @res = eval $string;	754	monitoring raises an error, so there are no silent "holes" in the message
412	snd @reply, "$@", @res if @reply;	755	sequence.
413	};
414		756
415	=item time => @reply	757	=item * Erlang can send messages to the wrong port, AEMP does not.
416		758
417	Replies the the current node time to C<@reply>.	759	In Erlang it is quite likely that a node that restarts reuses a process ID
		760	known to other nodes for a completely different process, causing messages
		761	destined for that process to end up in an unrelated process.
418		762
419	=cut	763	AEMP never reuses port IDs, so old messages or old port IDs floating
		764	around in the network will not be sent to an unrelated port.
420		765
421	rcv "", time => sub { shift; snd @_, AE::time };	766	=item * Erlang uses unprotected connections, AEMP uses secure
		767	authentication and can use TLS.
		768
		769	AEMP can use a proven protocol - TLS - to protect connections and
		770	securely authenticate nodes.
		771
		772	=item * The AEMP protocol is optimised for both text-based and binary
		773	communications.
		774
		775	The AEMP protocol, unlike the Erlang protocol, supports both programming
		776	language independent text-only protocols (good for debugging) and binary,
		777	language-specific serialisers (e.g. Storable). By default, unless TLS is
		778	used, the protocol is actually completely text-based.
		779
		780	It has also been carefully designed to be implementable in other languages
		781	with a minimum of work while gracefully degrading functionality to make the
		782	protocol simple.
		783
		784	=item * AEMP has more flexible monitoring options than Erlang.
		785
		786	In Erlang, you can chose to receive I<all> exit signals as messages
		787	or I<none>, there is no in-between, so monitoring single processes is
		788	difficult to implement. Monitoring in AEMP is more flexible than in
		789	Erlang, as one can choose between automatic kill, exit message or callback
		790	on a per-process basis.
		791
		792	=item * Erlang tries to hide remote/local connections, AEMP does not.
		793
		794	Monitoring in Erlang is not an indicator of process death/crashes, in the
		795	same way as linking is (except linking is unreliable in Erlang).
		796
		797	In AEMP, you don't "look up" registered port names or send to named ports
		798	that might or might not be persistent. Instead, you normally spawn a port
		799	on the remote node. The init function monitors you, and you monitor the
		800	remote port. Since both monitors are local to the node, they are much more
		801	reliable (no need for C<spawn_link>).
		802
		803	This also saves round-trips and avoids sending messages to the wrong port
		804	(hard to do in Erlang).
422		805
423	=back	806	=back
424		807
		808	=head1 RATIONALE
		809
		810	=over 4
		811
		812	=item Why strings for port and node IDs, why not objects?
		813
		814	We considered "objects", but found that the actual number of methods
		815	that can be called are quite low. Since port and node IDs travel over
		816	the network frequently, the serialising/deserialising would add lots of
		817	overhead, as well as having to keep a proxy object everywhere.
		818
		819	Strings can easily be printed, easily serialised etc. and need no special
		820	procedures to be "valid".
		821
		822	And as a result, a miniport consists of a single closure stored in a
		823	global hash - it can't become much cheaper.
		824
		825	=item Why favour JSON, why not a real serialising format such as Storable?
		826
		827	In fact, any AnyEvent::MP node will happily accept Storable as framing
		828	format, but currently there is no way to make a node use Storable by
		829	default (although all nodes will accept it).
		830
		831	The default framing protocol is JSON because a) JSON::XS is many times
		832	faster for small messages and b) most importantly, after years of
		833	experience we found that object serialisation is causing more problems
		834	than it solves: Just like function calls, objects simply do not travel
		835	easily over the network, mostly because they will always be a copy, so you
		836	always have to re-think your design.
		837
		838	Keeping your messages simple, concentrating on data structures rather than
		839	objects, will keep your messages clean, tidy and efficient.
		840
		841	=back
		842
425	=head1 SEE ALSO	843	=head1 SEE ALSO
		844
		845	L<AnyEvent::MP::Intro> - a gentle introduction.
		846
		847	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		848
		849	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		850	your applications.
426		851
427	L<AnyEvent>.	852	L<AnyEvent>.
428		853
429	=head1 AUTHOR	854	=head1 AUTHOR
430		855

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Revision 1.4 by root, Sat Aug 1 07:36:30 2009 UTC vs.
Revision 1.73 by root, Mon Aug 31 11:08:25 2009 UTC