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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.27 by root, Tue Aug 4 22:13:45 2009 UTC vs.
Revision 1.64 by root, Fri Aug 28 00:58:44 2009 UTC

…		…
8		8
9	$NODE # contains this node's noderef	9	$NODE # contains this node's noderef
10	NODE # returns this node's noderef	10	NODE # returns this node's noderef
11	NODE $port # returns the noderef of the port	11	NODE $port # returns the noderef of the port
12		12
		13	$SELF # receiving/own port id in rcv callbacks
		14
		15	# initialise the node so it can send/receive messages
		16	initialise_node;
		17
		18	# ports are message endpoints
		19
		20	# sending messages
13	snd $port, type => data...;	21	snd $port, type => data...;
		22	snd $port, @msg;
		23	snd @msg_with_first_element_being_a_port;
14		24
15	$SELF # receiving/own port id in rcv callbacks	25	# creating/using ports, the simple way
		26	my $simple_port = port { my @msg = @_; 0 };
16		27
17	rcv $port, smartmatch => $cb->($port, @msg);	28	# creating/using ports, tagged message matching
18		29	my $port = port;
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	30	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
21	rcv $port1, pong => sub { warn "pong received\n" };	31	rcv $port, pong => sub { warn "pong received\n"; 0 };
22	snd $port2, ping => $port1;
23		32
24	# more, smarter, matches (_any_ is exported by this module)	33	# create a port on another node
25	rcv $port, [child_died => $pid] => sub { ...	34	my $port = spawn $node, $initfunc, @initdata;
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	35
		36	# monitoring
		37	mon $port, $cb->(@msg) # callback is invoked on death
		38	mon $port, $otherport # kill otherport on abnormal death
		39	mon $port, $otherport, @msg # send message on death
		40
		41	=head1 CURRENT STATUS
		42
		43	AnyEvent::MP - stable API, should work
		44	AnyEvent::MP::Intro - outdated
		45	AnyEvent::MP::Kernel - WIP
		46	AnyEvent::MP::Transport - mostly stable
		47
		48	stay tuned.
27		49
28	=head1 DESCRIPTION	50	=head1 DESCRIPTION
29		51
30	This module (-family) implements a simple message passing framework.	52	This module (-family) implements a simple message passing framework.
31		53
…		…
35	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	57	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
36	manual page.	58	manual page.
37		59
38	At the moment, this module family is severly broken and underdocumented,	60	At the moment, this module family is severly broken and underdocumented,
39	so do not use. This was uploaded mainly to reserve the CPAN namespace -	61	so do not use. This was uploaded mainly to reserve the CPAN namespace -
40	stay tuned! The basic API should be finished, however.	62	stay tuned!
41		63
42	=head1 CONCEPTS	64	=head1 CONCEPTS
43		65
44	=over 4	66	=over 4
45		67
46	=item port	68	=item port
47		69
48	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).
49	you can register C<rcv> handlers with. All C<rcv> handlers will receive
50	messages they match, messages will not be queued.
51		71
		72	Ports allow you to register C<rcv> handlers that can match all or just
		73	some messages. Messages send to ports will not be queued, regardless of
		74	anything was listening for them or not.
		75
52	=item port id - C<noderef#portname>	76	=item port ID - C<noderef#portname>
53		77
54	A port id is always the noderef, a hash-mark (C<#>) as separator, followed	78	A port ID is the concatenation of a noderef, a hash-mark (C<#>) as
55	by a port name (a printable string of unspecified format).	79	separator, and a port name (a printable string of unspecified format). An
		80	exception is the the node port, whose ID is identical to its node
		81	reference.
56		82
57	=item node	83	=item node
58		84
59	A node is a single process containing at least one port - the node	85	A node is a single process containing at least one port - the node port,
60	port. You can send messages to node ports to let them create new ports,	86	which provides nodes to manage each other remotely, and to create new
61	among other things.	87	ports.
62		88
63	Initially, nodes are either private (single-process only) or hidden	89	Nodes are either private (single-process only), slaves (can only talk to
64	(connected to a master node only). Only when they epxlicitly "become	90	public nodes, but do not need an open port) or public nodes (connectable
65	public" can you send them messages from unrelated other nodes.	91	from any other node).
66		92
67	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	93	=item node ID - C<[a-za-Z0-9_\-.:]+>
68		94
69	A noderef is a string that either uniquely identifies a given node (for	95	A node ID is a string that uniquely identifies the node within a
70	private and hidden nodes), or contains a recipe on how to reach a given	96	network. Depending on the configuration used, node IDs can look like a
71	node (for public nodes).	97	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
		98	doesn't interpret node IDs in any way.
		99
		100	=item binds - C<ip:port>
		101
		102	Nodes can only talk to each other by creating some kind of connection to
		103	each other. To do this, nodes should listen on one or more local transport
		104	endpoints - binds. Currently, only standard C<ip:port> specifications can
		105	be used, which specify TCP ports to listen on.
		106
		107	=item seeds - C<host:port>
		108
		109	When a node starts, it knows nothing about the network. To teach the node
		110	about the network it first has to contact some other node within the
		111	network. This node is called a seed.
		112
		113	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes
		114	are expected to be long-running, and at least one of those should always
		115	be available. When nodes run out of connections (e.g. due to a network
		116	error), they try to re-establish connections to some seednodes again to
		117	join the network.
72		118
73	=back	119	=back
74		120
75	=head1 VARIABLES/FUNCTIONS	121	=head1 VARIABLES/FUNCTIONS
76		122
…		…
78		124
79	=cut	125	=cut
80		126
81	package AnyEvent::MP;	127	package AnyEvent::MP;
82		128
83	use AnyEvent::MP::Base;	129	use AnyEvent::MP::Kernel;
84		130
85	use common::sense;	131	use common::sense;
86		132
87	use Carp ();	133	use Carp ();
88		134
89	use AE ();	135	use AE ();
90		136
91	use base "Exporter";	137	use base "Exporter";
92		138
93	our $VERSION = '0.1';	139	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		140
94	our @EXPORT = qw(	141	our @EXPORT = qw(
95	NODE $NODE *SELF node_of _any_	142	NODE $NODE *SELF node_of after
96	become_slave become_public	143	resolve_node initialise_node
97	snd rcv mon kil reg psub	144	snd rcv mon mon_guard kil reg psub spawn
98	port	145	port
99	);	146	);
100		147
101	our $SELF;	148	our $SELF;
102		149
…		…
106	kil $SELF, die => $msg;	153	kil $SELF, die => $msg;
107	}	154	}
108		155
109	=item $thisnode = NODE / $NODE	156	=item $thisnode = NODE / $NODE
110		157
111	The C<NODE> function returns, and the C<$NODE> variable contains	158	The C<NODE> function returns, and the C<$NODE> variable contains the node
112	the noderef of the local node. The value is initialised by a call	159	ID of the node running in the current process. This value is initialised by
113	to C<become_public> or C<become_slave>, after which all local port	160	a call to C<initialise_node>.
114	identifiers become invalid.
115		161
116	=item $noderef = node_of $portid	162	=item $nodeid = node_of $port
117		163
118	Extracts and returns the noderef from a portid or a noderef.	164	Extracts and returns the node ID part from a port ID or a node ID.
		165
		166	=item initialise_node $profile_name
		167
		168	Before a node can talk to other nodes on the network (i.e. enter
		169	"distributed mode") it has to initialise 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.
		172
		173	This function initialises a node - it must be called exactly once (or
		174	never) before calling other AnyEvent::MP functions.
		175
		176	The first argument is a profile name. If it is C<undef> or missing, then
		177	the current nodename will be used instead (i.e. F<uname -n>).
		178
		179	The function then looks up the profile in the aemp configuration (see the
		180	L<aemp> commandline utility).
		181
		182	If the profile specifies a node ID, then this will become the node ID of
		183	this process. If not, then the profile name will be used as node ID. The
		184	special node ID of C<anon/> will be replaced by a random node ID.
		185
		186	The next step is to look up the binds in the profile, followed by binding
		187	aemp protocol listeners on all binds specified (it is possible and valid
		188	to have no binds, meaning that the node cannot be contacted form the
		189	outside. This means the node cannot talk to other nodes that also have no
		190	binds, but it can still talk to all "normal" nodes).
		191
		192	If the profile does not specify a binds list, then the node ID will be
		193	treated as if it were of the form C<host:port>, which will be resolved and
		194	used as binds list.
		195
		196	Lastly, the seeds list from the profile is passed to the
		197	L<AnyEvent::MP::Global> module, which will then use it to keep
		198	connectivity with at least on of those seed nodes at any point in time.
		199
		200	Example: become a distributed node listening on the guessed noderef, or
		201	the one specified via C<aemp> for the current node. This should be the
		202	most common form of invocation for "daemon"-type nodes.
		203
		204	initialise_node;
		205
		206	Example: become an anonymous node. This form is often used for commandline
		207	clients.
		208
		209	initialise_node "anon/";
		210
		211	Example: become a distributed node. If there is no profile of the given
		212	name, or no binds list was specified, resolve C<localhost:4044> and bind
		213	on the resulting addresses.
		214
		215	initialise_node "localhost:4044";
119		216
120	=item $SELF	217	=item $SELF
121		218
122	Contains the current port id while executing C<rcv> callbacks or C<psub>	219	Contains the current port id while executing C<rcv> callbacks or C<psub>
123	blocks.	220	blocks.
…		…
126		223
127	Due to some quirks in how perl exports variables, it is impossible to	224	Due to some quirks in how perl exports variables, it is impossible to
128	just export C<$SELF>, all the symbols called C<SELF> are exported by this	225	just export C<$SELF>, all the symbols called C<SELF> are exported by this
129	module, but only C<$SELF> is currently used.	226	module, but only C<$SELF> is currently used.
130		227
131	=item snd $portid, type => @data	228	=item snd $port, type => @data
132		229
133	=item snd $portid, @msg	230	=item snd $port, @msg
134		231
135	Send the given message to the given port ID, which can identify either	232	Send the given message to the given port ID, which can identify either
136	a local or a remote port, and can be either a string or soemthignt hat	233	a local or a remote port, and must be a port ID.
137	stringifies a sa port ID (such as a port object :).
138		234
139	While the message can be about anything, it is highly recommended to use a	235	While the message can be about anything, it is highly recommended to use a
140	string as first element (a portid, or some word that indicates a request	236	string as first element (a port ID, or some word that indicates a request
141	type etc.).	237	type etc.).
142		238
143	The message data effectively becomes read-only after a call to this	239	The message data effectively becomes read-only after a call to this
144	function: modifying any argument is not allowed and can cause many	240	function: modifying any argument is not allowed and can cause many
145	problems.	241	problems.
…		…
148	JSON is used, then only strings, numbers and arrays and hashes consisting	244	JSON is used, then only strings, numbers and arrays and hashes consisting
149	of those are allowed (no objects). When Storable is used, then anything	245	of those are allowed (no objects). When Storable is used, then anything
150	that Storable can serialise and deserialise is allowed, and for the local	246	that Storable can serialise and deserialise is allowed, and for the local
151	node, anything can be passed.	247	node, anything can be passed.
152		248
153	=item kil $portid[, @reason]	249	=item $local_port = port
154		250
155	Kill the specified port with the given C<@reason>.	251	Create a new local port object and returns its port ID. Initially it has
		252	no callbacks set and will throw an error when it receives messages.
156		253
157	If no C<@reason> is specified, then the port is killed "normally" (linked	254	=item $local_port = port { my @msg = @_ }
158	ports will not be kileld, or even notified).
159		255
160	Otherwise, linked ports get killed with the same reason (second form of	256	Creates a new local port, and returns its ID. Semantically the same as
161	C<mon>, see below).	257	creating a port and calling C<rcv $port, $callback> on it.
162		258
163	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	259	The block will be called for every message received on the port, with the
164	will be reported as reason C<< die => $@ >>.	260	global variable C<$SELF> set to the port ID. Runtime errors will cause the
		261	port to be C<kil>ed. The message will be passed as-is, no extra argument
		262	(i.e. no port ID) will be passed to the callback.
165		263
166	Transport/communication errors are reported as C<< transport_error =>	264	If you want to stop/destroy the port, simply C<kil> it:
167	$message >>.
168		265
		266	my $port = port {
		267	my @msg = @_;
		268	...
		269	kil $SELF;
		270	};
		271
		272	=cut
		273
		274	sub rcv($@);
		275
		276	sub _kilme {
		277	die "received message on port without callback";
		278	}
		279
		280	sub port(;&) {
		281	my $id = "$UNIQ." . $ID++;
		282	my $port = "$NODE#$id";
		283
		284	rcv $port, shift \|\| \&_kilme;
		285
		286	$port
		287	}
		288
		289	=item rcv $local_port, $callback->(@msg)
		290
		291	Replaces the default callback on the specified port. There is no way to
		292	remove the default callback: use C<sub { }> to disable it, or better
		293	C<kil> the port when it is no longer needed.
		294
		295	The global C<$SELF> (exported by this module) contains C<$port> while
		296	executing the callback. Runtime errors during callback execution will
		297	result in the port being C<kil>ed.
		298
		299	The default callback received all messages not matched by a more specific
		300	C<tag> match.
		301
		302	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
		303
		304	Register (or replace) callbacks to be called on messages starting with the
		305	given tag on the given port (and return the port), or unregister it (when
		306	C<$callback> is C<$undef> or missing). There can only be one callback
		307	registered for each tag.
		308
		309	The original message will be passed to the callback, after the first
		310	element (the tag) has been removed. The callback will use the same
		311	environment as the default callback (see above).
		312
		313	Example: create a port and bind receivers on it in one go.
		314
		315	my $port = rcv port,
		316	msg1 => sub { ... },
		317	msg2 => sub { ... },
		318	;
		319
		320	Example: create a port, bind receivers and send it in a message elsewhere
		321	in one go:
		322
		323	snd $otherport, reply =>
		324	rcv port,
		325	msg1 => sub { ... },
		326	...
		327	;
		328
		329	Example: temporarily register a rcv callback for a tag matching some port
		330	(e.g. for a rpc reply) and unregister it after a message was received.
		331
		332	rcv $port, $otherport => sub {
		333	my @reply = @_;
		334
		335	rcv $SELF, $otherport;
		336	};
		337
		338	=cut
		339
		340	sub rcv($@) {
		341	my $port = shift;
		342	my ($noderef, $portid) = split /#/, $port, 2;
		343
		344	$NODE{$noderef} == $NODE{""}
		345	or Carp::croak "$port: rcv can only be called on local ports, caught";
		346
		347	while (@_) {
		348	if (ref $_[0]) {
		349	if (my $self = $PORT_DATA{$portid}) {
		350	"AnyEvent::MP::Port" eq ref $self
		351	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		352
		353	$self->[2] = shift;
		354	} else {
		355	my $cb = shift;
		356	$PORT{$portid} = sub {
		357	local $SELF = $port;
		358	eval { &$cb }; _self_die if $@;
		359	};
		360	}
		361	} elsif (defined $_[0]) {
		362	my $self = $PORT_DATA{$portid} \|\|= do {
		363	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
		364
		365	$PORT{$portid} = sub {
		366	local $SELF = $port;
		367
		368	if (my $cb = $self->[1]{$_[0]}) {
		369	shift;
		370	eval { &$cb }; _self_die if $@;
		371	} else {
		372	&{ $self->[0] };
		373	}
		374	};
		375
		376	$self
		377	};
		378
		379	"AnyEvent::MP::Port" eq ref $self
		380	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		381
		382	my ($tag, $cb) = splice @_, 0, 2;
		383
		384	if (defined $cb) {
		385	$self->[1]{$tag} = $cb;
		386	} else {
		387	delete $self->[1]{$tag};
		388	}
		389	}
		390	}
		391
		392	$port
		393	}
		394
		395	=item $closure = psub { BLOCK }
		396
		397	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
		398	closure is executed, sets up the environment in the same way as in C<rcv>
		399	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		400
		401	This is useful when you register callbacks from C<rcv> callbacks:
		402
		403	rcv delayed_reply => sub {
		404	my ($delay, @reply) = @_;
		405	my $timer = AE::timer $delay, 0, psub {
		406	snd @reply, $SELF;
		407	};
		408	};
		409
		410	=cut
		411
		412	sub psub(&) {
		413	my $cb = shift;
		414
		415	my $port = $SELF
		416	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
		417
		418	sub {
		419	local $SELF = $port;
		420
		421	if (wantarray) {
		422	my @res = eval { &$cb };
		423	_self_die if $@;
		424	@res
		425	} else {
		426	my $res = eval { &$cb };
		427	_self_die if $@;
		428	$res
		429	}
		430	}
		431	}
		432
169	=item $guard = mon $portid, $cb->(@reason)	433	=item $guard = mon $port, $cb->(@reason)
170		434
171	=item $guard = mon $portid, $otherport	435	=item $guard = mon $port, $rcvport
172		436
		437	=item $guard = mon $port
		438
173	=item $guard = mon $portid, $otherport, @msg	439	=item $guard = mon $port, $rcvport, @msg
174		440
175	Monitor the given port and do something when the port is killed.	441	Monitor the given port and do something when the port is killed or
		442	messages to it were lost, and optionally return a guard that can be used
		443	to stop monitoring again.
176		444
		445	C<mon> effectively guarantees that, in the absence of hardware failures,
		446	that after starting the monitor, either all messages sent to the port
		447	will arrive, or the monitoring action will be invoked after possible
		448	message loss has been detected. No messages will be lost "in between"
		449	(after the first lost message no further messages will be received by the
		450	port). After the monitoring action was invoked, further messages might get
		451	delivered again.
		452
		453	Note that monitoring-actions are one-shot: once released, they are removed
		454	and will not trigger again.
		455
177	In the first form, the callback is simply called with any number	456	In the first form (callback), the callback is simply called with any
178	of C<@reason> elements (no @reason means that the port was deleted	457	number of C<@reason> elements (no @reason means that the port was deleted
179	"normally"). Note also that I<< the callback B<must> never die >>, so use	458	"normally"). Note also that I<< the callback B<must> never die >>, so use
180	C<eval> if unsure.	459	C<eval> if unsure.
181		460
182	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	461	In the second form (another port given), the other port (C<$rcvport>)
183	a @reason was specified, i.e. on "normal" kils nothing happens, while	462	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
184	under all other conditions, the other port is killed with the same reason.	463	"normal" kils nothing happens, while under all other conditions, the other
		464	port is killed with the same reason.
185		465
		466	The third form (kill self) is the same as the second form, except that
		467	C<$rvport> defaults to C<$SELF>.
		468
186	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	469	In the last form (message), a message of the form C<@msg, @reason> will be
		470	C<snd>.
		471
		472	As a rule of thumb, monitoring requests should always monitor a port from
		473	a local port (or callback). The reason is that kill messages might get
		474	lost, just like any other message. Another less obvious reason is that
		475	even monitoring requests can get lost (for exmaple, when the connection
		476	to the other node goes down permanently). When monitoring a port locally
		477	these problems do not exist.
187		478
188	Example: call a given callback when C<$port> is killed.	479	Example: call a given callback when C<$port> is killed.
189		480
190	mon $port, sub { warn "port died because of <@_>\n" };	481	mon $port, sub { warn "port died because of <@_>\n" };
191		482
192	Example: kill ourselves when C<$port> is killed abnormally.	483	Example: kill ourselves when C<$port> is killed abnormally.
193		484
194	mon $port, $self;	485	mon $port;
195		486
196	Example: send us a restart message another C<$port> is killed.	487	Example: send us a restart message when another C<$port> is killed.
197		488
198	mon $port, $self => "restart";	489	mon $port, $self => "restart";
199		490
200	=cut	491	=cut
201		492
202	sub mon {	493	sub mon {
203	my ($noderef, $port, $cb) = ((split /#/, shift, 2), shift);	494	my ($noderef, $port) = split /#/, shift, 2;
204		495
205	my $node = $NODE{$noderef} \|\| add_node $noderef;	496	my $node = $NODE{$noderef} \|\| add_node $noderef;
206		497
207	#TODO: ports must not be references	498	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
208	if (!ref $cb or "AnyEvent::MP::Port" eq ref $cb) {	499
		500	unless (ref $cb) {
209	if (@_) {	501	if (@_) {
210	# send a kill info message	502	# send a kill info message
211	my (@msg) = ($cb, @_);	503	my (@msg) = ($cb, @_);
212	$cb = sub { snd @msg, @_ };	504	$cb = sub { snd @msg, @_ };
213	} else {	505	} else {
…		…
242	=cut	534	=cut
243		535
244	sub mon_guard {	536	sub mon_guard {
245	my ($port, @refs) = @_;	537	my ($port, @refs) = @_;
246		538
		539	#TODO: mon-less form?
		540
247	mon $port, sub { 0 && @refs }	541	mon $port, sub { 0 && @refs }
248	}	542	}
249		543
250	=item lnk $port1, $port2	544	=item kil $port[, @reason]
251		545
252	Link two ports. This is simply a shorthand for:	546	Kill the specified port with the given C<@reason>.
253		547
254	mon $port1, $port2;	548	If no C<@reason> is specified, then the port is killed "normally" (linked
255	mon $port2, $port1;	549	ports will not be kileld, or even notified).
256		550
257	It means that if either one is killed abnormally, the other one gets	551	Otherwise, linked ports get killed with the same reason (second form of
258	killed as well.	552	C<mon>, see below).
259		553
260	=item $local_port = port	554	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		555	will be reported as reason C<< die => $@ >>.
261		556
262	Create a new local port object that supports message matching.	557	Transport/communication errors are reported as C<< transport_error =>
		558	$message >>.
263		559
264	=item $portid = port { my @msg = @_; $finished }
265
266	Creates a "mini port", that is, a very lightweight port without any
267	pattern matching behind it, and returns its ID.
268
269	The block will be called for every message received on the port. When the
270	callback returns a true value its job is considered "done" and the port
271	will be destroyed. Otherwise it will stay alive.
272
273	The message will be passed as-is, no extra argument (i.e. no port id) will
274	be passed to the callback.
275
276	If you need the local port id in the callback, this works nicely:
277
278	my $port; $port = miniport {
279	snd $otherport, reply => $port;
280	};
281
282	=cut	560	=cut
283		561
284	sub port(;&) {	562	=item $port = spawn $node, $initfunc[, @initdata]
285	my $id = "$UNIQ." . $ID++;
286	my $port = "$NODE#$id";
287		563
288	if (@_) {	564	Creates a port on the node C<$node> (which can also be a port ID, in which
289	my $cb = shift;	565	case it's the node where that port resides).
290	$PORT{$id} = sub {	566
291	local $SELF = $port;	567	The port ID of the newly created port is return immediately, and it is
292	eval {	568	permissible to immediately start sending messages or monitor the port.
293	&$cb	569
294	and kil $id;	570	After the port has been created, the init function is
		571	called. This function must be a fully-qualified function name
		572	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		573	program, use C<::name>.
		574
		575	If the function doesn't exist, then the node tries to C<require>
		576	the package, then the package above the package and so on (e.g.
		577	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		578	exists or it runs out of package names.
		579
		580	The init function is then called with the newly-created port as context
		581	object (C<$SELF>) and the C<@initdata> values as arguments.
		582
		583	A common idiom is to pass your own port, monitor the spawned port, and
		584	in the init function, monitor the original port. This two-way monitoring
		585	ensures that both ports get cleaned up when there is a problem.
		586
		587	Example: spawn a chat server port on C<$othernode>.
		588
		589	# this node, executed from within a port context:
		590	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		591	mon $server;
		592
		593	# init function on C<$othernode>
		594	sub connect {
		595	my ($srcport) = @_;
		596
		597	mon $srcport;
		598
		599	rcv $SELF, sub {
295	};	600	...
296	_self_die if $@;
297	};
298	} else {
299	my $self = bless {
300	id => "$NODE#$id",
301	}, "AnyEvent::MP::Port";
302
303	$PORT_DATA{$id} = $self;
304	$PORT{$id} = sub {
305	local $SELF = $port;
306
307	eval {
308	for (@{ $self->{rc0}{$_[0]} }) {
309	$_ && &{$_->[0]}
310	&& undef $_;
311	}
312
313	for (@{ $self->{rcv}{$_[0]} }) {
314	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
315	&& &{$_->[0]}
316	&& undef $_;
317	}
318
319	for (@{ $self->{any} }) {
320	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
321	&& &{$_->[0]}
322	&& undef $_;
323	}
324	};
325	_self_die if $@;
326	};	601	};
327	}	602	}
328		603
329	$port
330	}
331
332	=item reg $portid, $name
333
334	Registers the given port under the name C<$name>. If the name already
335	exists it is replaced.
336
337	A port can only be registered under one well known name.
338
339	A port automatically becomes unregistered when it is killed.
340
341	=cut	604	=cut
342		605
343	sub reg(@) {	606	sub _spawn {
344	my ($portid, $name) = @_;	607	my $port = shift;
		608	my $init = shift;
345		609
346	$REG{$name} = $portid;	610	local $SELF = "$NODE#$port";
347	}	611	eval {
348		612	&{ load_func $init }
349	=item rcv $portid, tagstring => $callback->(@msg), ...
350
351	=item rcv $portid, $smartmatch => $callback->(@msg), ...
352
353	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
354
355	Register callbacks to be called on matching messages on the given port.
356
357	The callback has to return a true value when its work is done, after
358	which is will be removed, or a false value in which case it will stay
359	registered.
360
361	The global C<$SELF> (exported by this module) contains C<$portid> while
362	executing the callback.
363
364	Runtime errors wdurign callback execution will result in the port being
365	C<kil>ed.
366
367	If the match is an array reference, then it will be matched against the
368	first elements of the message, otherwise only the first element is being
369	matched.
370
371	Any element in the match that is specified as C<_any_> (a function
372	exported by this module) matches any single element of the message.
373
374	While not required, it is highly recommended that the first matching
375	element is a string identifying the message. The one-string-only match is
376	also the most efficient match (by far).
377
378	=cut
379
380	sub rcv($@) {
381	my ($noderef, $port) = split /#/, shift, 2;
382
383	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
384	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";
385
386	my $self = $PORT_DATA{$port}
387	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
388
389	"AnyEvent::MP::Port" eq ref $self
390	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
391
392	while (@_) {
393	my ($match, $cb) = splice @_, 0, 2;
394
395	if (!ref $match) {
396	push @{ $self->{rc0}{$match} }, [$cb];
397	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
398	my ($type, @match) = @$match;
399	@match
400	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
401	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
402	} else {
403	push @{ $self->{any} }, [$cb, $match];
404	}
405	}
406	}
407
408	=item $closure = psub { BLOCK }
409
410	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
411	closure is executed, sets up the environment in the same way as in C<rcv>
412	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
413
414	This is useful when you register callbacks from C<rcv> callbacks:
415
416	rcv delayed_reply => sub {
417	my ($delay, @reply) = @_;
418	my $timer = AE::timer $delay, 0, psub {
419	snd @reply, $SELF;
420	};
421	};	613	};
422
423	=cut
424
425	sub psub(&) {
426	my $cb = shift;
427
428	my $port = $SELF
429	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
430
431	sub {
432	local $SELF = $port;
433
434	if (wantarray) {
435	my @res = eval { &$cb };
436	_self_die if $@;	614	_self_die if $@;
437	@res	615	}
438	} else {	616
439	my $res = eval { &$cb };	617	sub spawn(@) {
440	_self_die if $@;	618	my ($noderef, undef) = split /#/, shift, 2;
441	$res	619
442	}	620	my $id = "$RUNIQ." . $ID++;
		621
		622	$_[0] =~ /::/
		623	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		624
		625	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
		626
		627	"$noderef#$id"
		628	}
		629
		630	=item after $timeout, @msg
		631
		632	=item after $timeout, $callback
		633
		634	Either sends the given message, or call the given callback, after the
		635	specified number of seconds.
		636
		637	This is simply a utility function that come sin handy at times.
		638
		639	=cut
		640
		641	sub after($@) {
		642	my ($timeout, @action) = @_;
		643
		644	my $t; $t = AE::timer $timeout, 0, sub {
		645	undef $t;
		646	ref $action[0]
		647	? $action[0]()
		648	: snd @action;
443	}	649	};
444	}	650	}
445		651
446	=back	652	=back
447		653
448	=head1 FUNCTIONS FOR NODES
449
450	=over 4
451
452	=item become_public endpoint...
453
454	Tells the node to become a public node, i.e. reachable from other nodes.
455
456	If no arguments are given, or the first argument is C<undef>, then
457	AnyEvent::MP tries to bind on port C<4040> on all IP addresses that the
458	local nodename resolves to.
459
460	Otherwise the first argument must be an array-reference with transport
461	endpoints ("ip:port", "hostname:port") or port numbers (in which case the
462	local nodename is used as hostname). The endpoints are all resolved and
463	will become the node reference.
464
465	=cut
466
467	=back
468
469	=head1 NODE MESSAGES
470
471	Nodes understand the following messages sent to them. Many of them take
472	arguments called C<@reply>, which will simply be used to compose a reply
473	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
474	the remaining arguments are simply the message data.
475
476	=over 4
477
478	=cut
479
480	=item lookup => $name, @reply
481
482	Replies with the port ID of the specified well-known port, or C<undef>.
483
484	=item devnull => ...
485
486	Generic data sink/CPU heat conversion.
487
488	=item relay => $port, @msg
489
490	Simply forwards the message to the given port.
491
492	=item eval => $string[ @reply]
493
494	Evaluates the given string. If C<@reply> is given, then a message of the
495	form C<@reply, $@, @evalres> is sent.
496
497	Example: crash another node.
498
499	snd $othernode, eval => "exit";
500
501	=item time => @reply
502
503	Replies the the current node time to C<@reply>.
504
505	Example: tell the current node to send the current time to C<$myport> in a
506	C<timereply> message.
507
508	snd $NODE, time => $myport, timereply => 1, 2;
509	# => snd $myport, timereply => 1, 2, <time>
510
511	=back
512
513	=head1 AnyEvent::MP vs. Distributed Erlang	654	=head1 AnyEvent::MP vs. Distributed Erlang
514		655
515	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node	656	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
516	== aemp node, erlang process == aemp port), so many of the documents and	657	== aemp node, Erlang process == aemp port), so many of the documents and
517	programming techniques employed by erlang apply to AnyEvent::MP. Here is a	658	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
518	sample:	659	sample:
519		660
520	http://www.erlang.se/doc/programming_rules.shtml	661	http://www.Erlang.se/doc/programming_rules.shtml
521	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	662	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
522	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6	663	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
523	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5	664	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
524		665
525	Despite the similarities, there are also some important differences:	666	Despite the similarities, there are also some important differences:
526		667
527	=over 4	668	=over 4
528		669
…		…
533	convenience functionality.	674	convenience functionality.
534		675
535	This means that AEMP requires a less tightly controlled environment at the	676	This means that AEMP requires a less tightly controlled environment at the
536	cost of longer node references and a slightly higher management overhead.	677	cost of longer node references and a slightly higher management overhead.
537		678
		679	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
		680	uses "local ports are like remote ports".
		681
		682	The failure modes for local ports are quite different (runtime errors
		683	only) then for remote ports - when a local port dies, you I<know> it dies,
		684	when a connection to another node dies, you know nothing about the other
		685	port.
		686
		687	Erlang pretends remote ports are as reliable as local ports, even when
		688	they are not.
		689
		690	AEMP encourages a "treat remote ports differently" philosophy, with local
		691	ports being the special case/exception, where transport errors cannot
		692	occur.
		693
538	=item * Erlang uses processes and a mailbox, AEMP does not queue.	694	=item * Erlang uses processes and a mailbox, AEMP does not queue.
539		695
540	Erlang uses processes that selctively receive messages, and therefore	696	Erlang uses processes that selectively receive messages, and therefore
541	needs a queue. AEMP is event based, queuing messages would serve no useful	697	needs a queue. AEMP is event based, queuing messages would serve no
542	purpose.	698	useful purpose. For the same reason the pattern-matching abilities of
		699	AnyEvent::MP are more limited, as there is little need to be able to
		700	filter messages without dequeing them.
543		701
544	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	702	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
545		703
546	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	704	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
547		705
548	Sending messages in erlang is synchronous and blocks the process. AEMP	706	Sending messages in Erlang is synchronous and blocks the process (and
549	sends are immediate, connection establishment is handled in the	707	so does not need a queue that can overflow). AEMP sends are immediate,
550	background.	708	connection establishment is handled in the background.
551		709
552	=item * Erlang can silently lose messages, AEMP cannot.	710	=item * Erlang suffers from silent message loss, AEMP does not.
553		711
554	Erlang makes few guarantees on messages delivery - messages can get lost	712	Erlang makes few guarantees on messages delivery - messages can get lost
555	without any of the processes realising it (i.e. you send messages a, b,	713	without any of the processes realising it (i.e. you send messages a, b,
556	and c, and the other side only receives messages a and c).	714	and c, and the other side only receives messages a and c).
557		715
558	AEMP guarantees correct ordering, and the guarantee that there are no	716	AEMP guarantees correct ordering, and the guarantee that there are no
559	holes in the message sequence.	717	holes in the message sequence.
560		718
561	=item * In erlang, processes can be declared dead and later be found to be	719	=item * In Erlang, processes can be declared dead and later be found to be
562	alive.	720	alive.
563		721
564	In erlang it can happen that a monitored process is declared dead and	722	In Erlang it can happen that a monitored process is declared dead and
565	linked processes get killed, but later it turns out that the process is	723	linked processes get killed, but later it turns out that the process is
566	still alive - and can receive messages.	724	still alive - and can receive messages.
567		725
568	In AEMP, when port monitoring detects a port as dead, then that port will	726	In AEMP, when port monitoring detects a port as dead, then that port will
569	eventually be killed - it cannot happen that a node detects a port as dead	727	eventually be killed - it cannot happen that a node detects a port as dead
570	and then later sends messages to it, finding it is still alive.	728	and then later sends messages to it, finding it is still alive.
571		729
572	=item * Erlang can send messages to the wrong port, AEMP does not.	730	=item * Erlang can send messages to the wrong port, AEMP does not.
573		731
574	In erlang it is quite possible that a node that restarts reuses a process	732	In Erlang it is quite likely that a node that restarts reuses a process ID
575	ID known to other nodes for a completely different process, causing	733	known to other nodes for a completely different process, causing messages
576	messages destined for that process to end up in an unrelated process.	734	destined for that process to end up in an unrelated process.
577		735
578	AEMP never reuses port IDs, so old messages or old port IDs floating	736	AEMP never reuses port IDs, so old messages or old port IDs floating
579	around in the network will not be sent to an unrelated port.	737	around in the network will not be sent to an unrelated port.
580		738
581	=item * Erlang uses unprotected connections, AEMP uses secure	739	=item * Erlang uses unprotected connections, AEMP uses secure
582	authentication and can use TLS.	740	authentication and can use TLS.
583		741
584	AEMP can use a proven protocol - SSL/TLS - to protect connections and	742	AEMP can use a proven protocol - SSL/TLS - to protect connections and
585	securely authenticate nodes.	743	securely authenticate nodes.
586		744
		745	=item * The AEMP protocol is optimised for both text-based and binary
		746	communications.
		747
		748	The AEMP protocol, unlike the Erlang protocol, supports both
		749	language-independent text-only protocols (good for debugging) and binary,
		750	language-specific serialisers (e.g. Storable).
		751
		752	It has also been carefully designed to be implementable in other languages
		753	with a minimum of work while gracefully degrading fucntionality to make the
		754	protocol simple.
		755
		756	=item * AEMP has more flexible monitoring options than Erlang.
		757
		758	In Erlang, you can chose to receive I<all> exit signals as messages
		759	or I<none>, there is no in-between, so monitoring single processes is
		760	difficult to implement. Monitoring in AEMP is more flexible than in
		761	Erlang, as one can choose between automatic kill, exit message or callback
		762	on a per-process basis.
		763
		764	=item * Erlang tries to hide remote/local connections, AEMP does not.
		765
		766	Monitoring in Erlang is not an indicator of process death/crashes,
		767	as linking is (except linking is unreliable in Erlang).
		768
		769	In AEMP, you don't "look up" registered port names or send to named ports
		770	that might or might not be persistent. Instead, you normally spawn a port
		771	on the remote node. The init function monitors the you, and you monitor
		772	the remote port. Since both monitors are local to the node, they are much
		773	more reliable.
		774
		775	This also saves round-trips and avoids sending messages to the wrong port
		776	(hard to do in Erlang).
		777
		778	=back
		779
		780	=head1 RATIONALE
		781
		782	=over 4
		783
		784	=item Why strings for ports and noderefs, why not objects?
		785
		786	We considered "objects", but found that the actual number of methods
		787	thatc an be called are very low. Since port IDs and noderefs travel over
		788	the network frequently, the serialising/deserialising would add lots of
		789	overhead, as well as having to keep a proxy object.
		790
		791	Strings can easily be printed, easily serialised etc. and need no special
		792	procedures to be "valid".
		793
		794	And a a miniport consists of a single closure stored in a global hash - it
		795	can't become much cheaper.
		796
		797	=item Why favour JSON, why not real serialising format such as Storable?
		798
		799	In fact, any AnyEvent::MP node will happily accept Storable as framing
		800	format, but currently there is no way to make a node use Storable by
		801	default.
		802
		803	The default framing protocol is JSON because a) JSON::XS is many times
		804	faster for small messages and b) most importantly, after years of
		805	experience we found that object serialisation is causing more problems
		806	than it gains: Just like function calls, objects simply do not travel
		807	easily over the network, mostly because they will always be a copy, so you
		808	always have to re-think your design.
		809
		810	Keeping your messages simple, concentrating on data structures rather than
		811	objects, will keep your messages clean, tidy and efficient.
		812
587	=back	813	=back
588		814
589	=head1 SEE ALSO	815	=head1 SEE ALSO
590		816
591	L<AnyEvent>.	817	L<AnyEvent>.

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Revision 1.64 by root, Fri Aug 28 00:58:44 2009 UTC