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

…		…
8		8
9	$NODE # contains this node's noderef	9	$NODE # contains this node's noderef
10	NODE # returns this node's noderef	10	NODE # returns this node's noderef
11	NODE $port # returns the noderef of the port	11	NODE $port # returns the noderef of the port
12		12
		13	$SELF # receiving/own port id in rcv callbacks
		14
		15	# initialise the node so it can send/receive messages
		16	initialise_node;
		17
		18	# ports are message endpoints
		19
		20	# sending messages
13	snd $port, type => data...;	21	snd $port, type => data...;
		22	snd $port, @msg;
		23	snd @msg_with_first_element_being_a_port;
14		24
15	$SELF # receiving/own port id in rcv callbacks	25	# creating/using ports, the simple way
		26	my $simple_port = port { my @msg = @_; 0 };
16		27
17	rcv $port, smartmatch => $cb->($port, @msg);	28	# creating/using ports, tagged message matching
18		29	my $port = port;
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	30	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
21	rcv $port1, pong => sub { warn "pong received\n" };	31	rcv $port, pong => sub { warn "pong received\n"; 0 };
22	snd $port2, ping => $port1;
23		32
24	# more, smarter, matches (_any_ is exported by this module)	33	# create a port on another node
25	rcv $port, [child_died => $pid] => sub { ...	34	my $port = spawn $node, $initfunc, @initdata;
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	35
		36	# monitoring
		37	mon $port, $cb->(@msg) # callback is invoked on death
		38	mon $port, $otherport # kill otherport on abnormal death
		39	mon $port, $otherport, @msg # send message on death
		40
		41	=head1 CURRENT STATUS
		42
		43	AnyEvent::MP - stable API, should work
		44	AnyEvent::MP::Intro - outdated
		45	AnyEvent::MP::Kernel - WIP
		46	AnyEvent::MP::Transport - mostly stable
		47
		48	stay tuned.
27		49
28	=head1 DESCRIPTION	50	=head1 DESCRIPTION
29		51
30	This module (-family) implements a simple message passing framework.	52	This module (-family) implements a simple message passing framework.
31		53
…		…
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	71
		72	Ports allow you to register C<rcv> handlers that can match all or just
50	messages they match, messages will not be queued.	73	some messages. Messages will not be queued.
51		74
52	=item port id - C<noderef#portname>	75	=item port ID - C<noderef#portname>
53		76
54	A port id is always the noderef, a hash-mark (C<#>) as separator, followed	77	A port ID is the concatenation of a noderef, a hash-mark (C<#>) as
55	by a port name (a printable string of unspecified format).	78	separator, and a port name (a printable string of unspecified format). An
		79	exception is the the node port, whose ID is identical to its node
		80	reference.
56		81
57	=item node	82	=item node
58		83
59	A node is a single process containing at least one port - the node	84	A node is a single process containing at least one port - the node port,
60	port. You can send messages to node ports to let them create new ports,	85	which provides nodes to manage each other remotely, and to create new
61	among other things.	86	ports.
62		87
63	Initially, nodes are either private (single-process only) or hidden	88	Nodes are either private (single-process only), slaves (can only talk to
64	(connected to a master node only). Only when they epxlicitly "become	89	public nodes, but do not need an open port) or public nodes (connectable
65	public" can you send them messages from unrelated other nodes.	90	from any other node).
66		91
67	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	92	=item node ID - C<[a-za-Z0-9_\-.:]+>
68		93
69	A noderef is a string that either uniquely identifies a given node (for	94	A node ID is a string that either simply identifies the node (for
70	private and hidden nodes), or contains a recipe on how to reach a given	95	private and slave nodes), or contains a recipe on how to reach a given
71	node (for public nodes).	96	node (for public nodes).
72		97
		98	This recipe is simply a comma-separated list of C<address:port> pairs (for
		99	TCP/IP, other protocols might look different).
		100
		101	Node references come in two flavours: resolved (containing only numerical
		102	addresses) or unresolved (where hostnames are used instead of addresses).
		103
		104	Before using an unresolved node reference in a message you first have to
		105	resolve it.
		106
73	=back	107	=back
74		108
75	=head1 VARIABLES/FUNCTIONS	109	=head1 VARIABLES/FUNCTIONS
76		110
77	=over 4	111	=over 4
78		112
79	=cut	113	=cut
80		114
81	package AnyEvent::MP;	115	package AnyEvent::MP;
82		116
83	use AnyEvent::MP::Base;	117	use AnyEvent::MP::Kernel;
84		118
85	use common::sense;	119	use common::sense;
86		120
87	use Carp ();	121	use Carp ();
88		122
89	use AE ();	123	use AE ();
90		124
91	use base "Exporter";	125	use base "Exporter";
92		126
93	our $VERSION = '0.1';	127	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		128
94	our @EXPORT = qw(	129	our @EXPORT = qw(
95	NODE $NODE *SELF node_of _any_	130	NODE $NODE *SELF node_of after
96	become_slave become_public	131	resolve_node initialise_node
97	snd rcv mon kil reg psub	132	snd rcv mon mon_guard kil reg psub spawn
98	port	133	port
99	);	134	);
100		135
101	our $SELF;	136	our $SELF;
102		137
…		…
106	kil $SELF, die => $msg;	141	kil $SELF, die => $msg;
107	}	142	}
108		143
109	=item $thisnode = NODE / $NODE	144	=item $thisnode = NODE / $NODE
110		145
111	The C<NODE> function returns, and the C<$NODE> variable contains	146	The C<NODE> function returns, and the C<$NODE> variable contains the
112	the noderef of the local node. The value is initialised by a call	147	node id of the local node. The value is initialised by a call to
113	to C<become_public> or C<become_slave>, after which all local port	148	C<initialise_node>.
114	identifiers become invalid.
115		149
116	=item $noderef = node_of $portid	150	=item $nodeid = node_of $port
117		151
118	Extracts and returns the noderef from a portid or a noderef.	152	Extracts and returns the noderef from a port ID or a node ID.
		153
		154	=item initialise_node $profile_name
		155
		156	Before a node can talk to other nodes on the network it has to initialise
		157	itself - the minimum a node needs to know is it's own name, and optionally
		158	it should know the noderefs of some other nodes in the network.
		159
		160	This function initialises a node - it must be called exactly once (or
		161	never) before calling other AnyEvent::MP functions.
		162
		163	All arguments (optionally except for the first) are noderefs, which can be
		164	either resolved or unresolved.
		165
		166	The first argument will be looked up in the configuration database first
		167	(if it is C<undef> then the current nodename will be used instead) to find
		168	the relevant configuration profile (see L<aemp>). If none is found then
		169	the default configuration is used. The configuration supplies additional
		170	seed/master nodes and can override the actual noderef.
		171
		172	There are two types of networked nodes, public nodes and slave nodes:
		173
		174	=over 4
		175
		176	=item public nodes
		177
		178	For public nodes, C<$noderef> (supplied either directly to
		179	C<initialise_node> or indirectly via a profile or the nodename) must be a
		180	noderef (possibly unresolved, in which case it will be resolved).
		181
		182	After resolving, the node will bind itself on all endpoints.
		183
		184	=item slave nodes
		185
		186	When the C<$noderef> (either as given or overriden by the config file)
		187	is the special string C<slave/>, then the node will become a slave
		188	node. Slave nodes cannot be contacted from outside, and cannot talk to
		189	each other (at least in this version of AnyEvent::MP).
		190
		191	Slave nodes work by creating connections to all public nodes, using the
		192	L<AnyEvent::MP::Global> service.
		193
		194	=back
		195
		196	After initialising itself, the node will connect to all additional
		197	C<$seednodes> that are specified diretcly or via a profile. Seednodes are
		198	optional and can be used to quickly bootstrap the node into an existing
		199	network.
		200
		201	All the seednodes will also be specially marked to automatically retry
		202	connecting to them indefinitely, so make sure that seednodes are really
		203	reliable and up (this might also change in the future).
		204
		205	Example: become a public node listening on the guessed noderef, or the one
		206	specified via C<aemp> for the current node. This should be the most common
		207	form of invocation for "daemon"-type nodes.
		208
		209	initialise_node;
		210
		211	Example: become a slave node to any of the the seednodes specified via
		212	C<aemp>. This form is often used for commandline clients.
		213
		214	initialise_node "slave/";
		215
		216	Example: become a public node, and try to contact some well-known master
		217	servers to become part of the network.
		218
		219	initialise_node undef, "master1", "master2";
		220
		221	Example: become a public node listening on port C<4041>.
		222
		223	initialise_node 4041;
		224
		225	Example: become a public node, only visible on localhost port 4044.
		226
		227	initialise_node "localhost:4044";
		228
		229	=item $cv = resolve_node $noderef
		230
		231	Takes an unresolved node reference that may contain hostnames and
		232	abbreviated IDs, resolves all of them and returns a resolved node
		233	reference.
		234
		235	In addition to C<address:port> pairs allowed in resolved noderefs, the
		236	following forms are supported:
		237
		238	=over 4
		239
		240	=item the empty string
		241
		242	An empty-string component gets resolved as if the default port (4040) was
		243	specified.
		244
		245	=item naked port numbers (e.g. C<1234>)
		246
		247	These are resolved by prepending the local nodename and a colon, to be
		248	further resolved.
		249
		250	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
		251
		252	These are resolved by using AnyEvent::DNS to resolve them, optionally
		253	looking up SRV records for the C<aemp=4040> port, if no port was
		254	specified.
		255
		256	=back
119		257
120	=item $SELF	258	=item $SELF
121		259
122	Contains the current port id while executing C<rcv> callbacks or C<psub>	260	Contains the current port id while executing C<rcv> callbacks or C<psub>
123	blocks.	261	blocks.
…		…
126		264
127	Due to some quirks in how perl exports variables, it is impossible to	265	Due to some quirks in how perl exports variables, it is impossible to
128	just export C<$SELF>, all the symbols called C<SELF> are exported by this	266	just export C<$SELF>, all the symbols called C<SELF> are exported by this
129	module, but only C<$SELF> is currently used.	267	module, but only C<$SELF> is currently used.
130		268
131	=item snd $portid, type => @data	269	=item snd $port, type => @data
132		270
133	=item snd $portid, @msg	271	=item snd $port, @msg
134		272
135	Send the given message to the given port ID, which can identify either	273	Send the given message to the given port ID, which can identify either
136	a local or a remote port, and can be either a string or soemthignt hat	274	a local or a remote port, and must be a port ID.
137	stringifies a sa port ID (such as a port object :).
138		275
139	While the message can be about anything, it is highly recommended to use a	276	While the message can be about anything, it is highly recommended to use a
140	string as first element (a portid, or some word that indicates a request	277	string as first element (a port ID, or some word that indicates a request
141	type etc.).	278	type etc.).
142		279
143	The message data effectively becomes read-only after a call to this	280	The message data effectively becomes read-only after a call to this
144	function: modifying any argument is not allowed and can cause many	281	function: modifying any argument is not allowed and can cause many
145	problems.	282	problems.
…		…
148	JSON is used, then only strings, numbers and arrays and hashes consisting	285	JSON is used, then only strings, numbers and arrays and hashes consisting
149	of those are allowed (no objects). When Storable is used, then anything	286	of those are allowed (no objects). When Storable is used, then anything
150	that Storable can serialise and deserialise is allowed, and for the local	287	that Storable can serialise and deserialise is allowed, and for the local
151	node, anything can be passed.	288	node, anything can be passed.
152		289
153	=item kil $portid[, @reason]	290	=item $local_port = port
154		291
155	Kill the specified port with the given C<@reason>.	292	Create a new local port object and returns its port ID. Initially it has
		293	no callbacks set and will throw an error when it receives messages.
156		294
157	If no C<@reason> is specified, then the port is killed "normally" (linked	295	=item $local_port = port { my @msg = @_ }
158	ports will not be kileld, or even notified).
159		296
160	Otherwise, linked ports get killed with the same reason (second form of	297	Creates a new local port, and returns its ID. Semantically the same as
161	C<mon>, see below).	298	creating a port and calling C<rcv $port, $callback> on it.
162		299
163	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	300	The block will be called for every message received on the port, with the
164	will be reported as reason C<< die => $@ >>.	301	global variable C<$SELF> set to the port ID. Runtime errors will cause the
		302	port to be C<kil>ed. The message will be passed as-is, no extra argument
		303	(i.e. no port ID) will be passed to the callback.
165		304
166	Transport/communication errors are reported as C<< transport_error =>	305	If you want to stop/destroy the port, simply C<kil> it:
167	$message >>.
168		306
		307	my $port = port {
		308	my @msg = @_;
		309	...
		310	kil $SELF;
		311	};
		312
		313	=cut
		314
		315	sub rcv($@);
		316
		317	sub _kilme {
		318	die "received message on port without callback";
		319	}
		320
		321	sub port(;&) {
		322	my $id = "$UNIQ." . $ID++;
		323	my $port = "$NODE#$id";
		324
		325	rcv $port, shift \|\| \&_kilme;
		326
		327	$port
		328	}
		329
		330	=item rcv $local_port, $callback->(@msg)
		331
		332	Replaces the default callback on the specified port. There is no way to
		333	remove the default callback: use C<sub { }> to disable it, or better
		334	C<kil> the port when it is no longer needed.
		335
		336	The global C<$SELF> (exported by this module) contains C<$port> while
		337	executing the callback. Runtime errors during callback execution will
		338	result in the port being C<kil>ed.
		339
		340	The default callback received all messages not matched by a more specific
		341	C<tag> match.
		342
		343	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
		344
		345	Register (or replace) callbacks to be called on messages starting with the
		346	given tag on the given port (and return the port), or unregister it (when
		347	C<$callback> is C<$undef> or missing). There can only be one callback
		348	registered for each tag.
		349
		350	The original message will be passed to the callback, after the first
		351	element (the tag) has been removed. The callback will use the same
		352	environment as the default callback (see above).
		353
		354	Example: create a port and bind receivers on it in one go.
		355
		356	my $port = rcv port,
		357	msg1 => sub { ... },
		358	msg2 => sub { ... },
		359	;
		360
		361	Example: create a port, bind receivers and send it in a message elsewhere
		362	in one go:
		363
		364	snd $otherport, reply =>
		365	rcv port,
		366	msg1 => sub { ... },
		367	...
		368	;
		369
		370	Example: temporarily register a rcv callback for a tag matching some port
		371	(e.g. for a rpc reply) and unregister it after a message was received.
		372
		373	rcv $port, $otherport => sub {
		374	my @reply = @_;
		375
		376	rcv $SELF, $otherport;
		377	};
		378
		379	=cut
		380
		381	sub rcv($@) {
		382	my $port = shift;
		383	my ($noderef, $portid) = split /#/, $port, 2;
		384
		385	$NODE{$noderef} == $NODE{""}
		386	or Carp::croak "$port: rcv can only be called on local ports, caught";
		387
		388	while (@_) {
		389	if (ref $_[0]) {
		390	if (my $self = $PORT_DATA{$portid}) {
		391	"AnyEvent::MP::Port" eq ref $self
		392	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		393
		394	$self->[2] = shift;
		395	} else {
		396	my $cb = shift;
		397	$PORT{$portid} = sub {
		398	local $SELF = $port;
		399	eval { &$cb }; _self_die if $@;
		400	};
		401	}
		402	} elsif (defined $_[0]) {
		403	my $self = $PORT_DATA{$portid} \|\|= do {
		404	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
		405
		406	$PORT{$portid} = sub {
		407	local $SELF = $port;
		408
		409	if (my $cb = $self->[1]{$_[0]}) {
		410	shift;
		411	eval { &$cb }; _self_die if $@;
		412	} else {
		413	&{ $self->[0] };
		414	}
		415	};
		416
		417	$self
		418	};
		419
		420	"AnyEvent::MP::Port" eq ref $self
		421	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		422
		423	my ($tag, $cb) = splice @_, 0, 2;
		424
		425	if (defined $cb) {
		426	$self->[1]{$tag} = $cb;
		427	} else {
		428	delete $self->[1]{$tag};
		429	}
		430	}
		431	}
		432
		433	$port
		434	}
		435
		436	=item $closure = psub { BLOCK }
		437
		438	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
		439	closure is executed, sets up the environment in the same way as in C<rcv>
		440	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		441
		442	This is useful when you register callbacks from C<rcv> callbacks:
		443
		444	rcv delayed_reply => sub {
		445	my ($delay, @reply) = @_;
		446	my $timer = AE::timer $delay, 0, psub {
		447	snd @reply, $SELF;
		448	};
		449	};
		450
		451	=cut
		452
		453	sub psub(&) {
		454	my $cb = shift;
		455
		456	my $port = $SELF
		457	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
		458
		459	sub {
		460	local $SELF = $port;
		461
		462	if (wantarray) {
		463	my @res = eval { &$cb };
		464	_self_die if $@;
		465	@res
		466	} else {
		467	my $res = eval { &$cb };
		468	_self_die if $@;
		469	$res
		470	}
		471	}
		472	}
		473
169	=item $guard = mon $portid, $cb->(@reason)	474	=item $guard = mon $port, $cb->(@reason)
170		475
171	=item $guard = mon $portid, $otherport	476	=item $guard = mon $port, $rcvport
172		477
		478	=item $guard = mon $port
		479
173	=item $guard = mon $portid, $otherport, @msg	480	=item $guard = mon $port, $rcvport, @msg
174		481
175	Monitor the given port and do something when the port is killed.	482	Monitor the given port and do something when the port is killed or
		483	messages to it were lost, and optionally return a guard that can be used
		484	to stop monitoring again.
176		485
		486	C<mon> effectively guarantees that, in the absence of hardware failures,
		487	that after starting the monitor, either all messages sent to the port
		488	will arrive, or the monitoring action will be invoked after possible
		489	message loss has been detected. No messages will be lost "in between"
		490	(after the first lost message no further messages will be received by the
		491	port). After the monitoring action was invoked, further messages might get
		492	delivered again.
		493
		494	Note that monitoring-actions are one-shot: once released, they are removed
		495	and will not trigger again.
		496
177	In the first form, the callback is simply called with any number	497	In the first form (callback), the callback is simply called with any
178	of C<@reason> elements (no @reason means that the port was deleted	498	number of C<@reason> elements (no @reason means that the port was deleted
179	"normally"). Note also that I<< the callback B<must> never die >>, so use	499	"normally"). Note also that I<< the callback B<must> never die >>, so use
180	C<eval> if unsure.	500	C<eval> if unsure.
181		501
182	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	502	In the second form (another port given), the other port (C<$rcvport>)
183	a @reason was specified, i.e. on "normal" kils nothing happens, while	503	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
184	under all other conditions, the other port is killed with the same reason.	504	"normal" kils nothing happens, while under all other conditions, the other
		505	port is killed with the same reason.
185		506
		507	The third form (kill self) is the same as the second form, except that
		508	C<$rvport> defaults to C<$SELF>.
		509
186	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	510	In the last form (message), a message of the form C<@msg, @reason> will be
		511	C<snd>.
		512
		513	As a rule of thumb, monitoring requests should always monitor a port from
		514	a local port (or callback). The reason is that kill messages might get
		515	lost, just like any other message. Another less obvious reason is that
		516	even monitoring requests can get lost (for exmaple, when the connection
		517	to the other node goes down permanently). When monitoring a port locally
		518	these problems do not exist.
187		519
188	Example: call a given callback when C<$port> is killed.	520	Example: call a given callback when C<$port> is killed.
189		521
190	mon $port, sub { warn "port died because of <@_>\n" };	522	mon $port, sub { warn "port died because of <@_>\n" };
191		523
192	Example: kill ourselves when C<$port> is killed abnormally.	524	Example: kill ourselves when C<$port> is killed abnormally.
193		525
194	mon $port, $self;	526	mon $port;
195		527
196	Example: send us a restart message another C<$port> is killed.	528	Example: send us a restart message when another C<$port> is killed.
197		529
198	mon $port, $self => "restart";	530	mon $port, $self => "restart";
199		531
200	=cut	532	=cut
201		533
202	sub mon {	534	sub mon {
203	my ($noderef, $port, $cb) = ((split /#/, shift, 2), shift);	535	my ($noderef, $port) = split /#/, shift, 2;
204		536
205	my $node = $NODE{$noderef} \|\| add_node $noderef;	537	my $node = $NODE{$noderef} \|\| add_node $noderef;
206		538
207	#TODO: ports must not be references	539	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) {	540
		541	unless (ref $cb) {
209	if (@_) {	542	if (@_) {
210	# send a kill info message	543	# send a kill info message
211	my (@msg) = ($cb, @_);	544	my (@msg) = ($cb, @_);
212	$cb = sub { snd @msg, @_ };	545	$cb = sub { snd @msg, @_ };
213	} else {	546	} else {
…		…
242	=cut	575	=cut
243		576
244	sub mon_guard {	577	sub mon_guard {
245	my ($port, @refs) = @_;	578	my ($port, @refs) = @_;
246		579
		580	#TODO: mon-less form?
		581
247	mon $port, sub { 0 && @refs }	582	mon $port, sub { 0 && @refs }
248	}	583	}
249		584
250	=item lnk $port1, $port2	585	=item kil $port[, @reason]
251		586
252	Link two ports. This is simply a shorthand for:	587	Kill the specified port with the given C<@reason>.
253		588
254	mon $port1, $port2;	589	If no C<@reason> is specified, then the port is killed "normally" (linked
255	mon $port2, $port1;	590	ports will not be kileld, or even notified).
256		591
257	It means that if either one is killed abnormally, the other one gets	592	Otherwise, linked ports get killed with the same reason (second form of
258	killed as well.	593	C<mon>, see below).
259		594
260	=item $local_port = port	595	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		596	will be reported as reason C<< die => $@ >>.
261		597
262	Create a new local port object that supports message matching.	598	Transport/communication errors are reported as C<< transport_error =>
		599	$message >>.
263		600
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	601	=cut
283		602
284	sub port(;&) {	603	=item $port = spawn $node, $initfunc[, @initdata]
285	my $id = "$UNIQ." . $ID++;
286	my $port = "$NODE#$id";
287		604
288	if (@_) {	605	Creates a port on the node C<$node> (which can also be a port ID, in which
289	my $cb = shift;	606	case it's the node where that port resides).
290	$PORT{$id} = sub {	607
291	local $SELF = $port;	608	The port ID of the newly created port is return immediately, and it is
292	eval {	609	permissible to immediately start sending messages or monitor the port.
293	&$cb	610
294	and kil $id;	611	After the port has been created, the init function is
		612	called. This function must be a fully-qualified function name
		613	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		614	program, use C<::name>.
		615
		616	If the function doesn't exist, then the node tries to C<require>
		617	the package, then the package above the package and so on (e.g.
		618	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		619	exists or it runs out of package names.
		620
		621	The init function is then called with the newly-created port as context
		622	object (C<$SELF>) and the C<@initdata> values as arguments.
		623
		624	A common idiom is to pass your own port, monitor the spawned port, and
		625	in the init function, monitor the original port. This two-way monitoring
		626	ensures that both ports get cleaned up when there is a problem.
		627
		628	Example: spawn a chat server port on C<$othernode>.
		629
		630	# this node, executed from within a port context:
		631	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		632	mon $server;
		633
		634	# init function on C<$othernode>
		635	sub connect {
		636	my ($srcport) = @_;
		637
		638	mon $srcport;
		639
		640	rcv $SELF, sub {
295	};	641	...
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	};	642	};
327	}	643	}
328		644
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	645	=cut
342		646
343	sub reg(@) {	647	sub _spawn {
344	my ($portid, $name) = @_;	648	my $port = shift;
		649	my $init = shift;
345		650
346	$REG{$name} = $portid;	651	local $SELF = "$NODE#$port";
347	}	652	eval {
348		653	&{ 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	};	654	};
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 $@;	655	_self_die if $@;
437	@res	656	}
438	} else {	657
439	my $res = eval { &$cb };	658	sub spawn(@) {
440	_self_die if $@;	659	my ($noderef, undef) = split /#/, shift, 2;
441	$res	660
442	}	661	my $id = "$RUNIQ." . $ID++;
		662
		663	$_[0] =~ /::/
		664	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		665
		666	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
		667
		668	"$noderef#$id"
		669	}
		670
		671	=item after $timeout, @msg
		672
		673	=item after $timeout, $callback
		674
		675	Either sends the given message, or call the given callback, after the
		676	specified number of seconds.
		677
		678	This is simply a utility function that come sin handy at times.
		679
		680	=cut
		681
		682	sub after($@) {
		683	my ($timeout, @action) = @_;
		684
		685	my $t; $t = AE::timer $timeout, 0, sub {
		686	undef $t;
		687	ref $action[0]
		688	? $action[0]()
		689	: snd @action;
443	}	690	};
444	}	691	}
445		692
446	=back	693	=back
447		694
448	=head1 FUNCTIONS FOR NODES
449
450	=over 4
451
452	=item become_public endpoint...
453
454	Tells the node to become a public node, i.e. reachable from other nodes.
455
456	If no arguments are given, or the first argument is C<undef>, then
457	AnyEvent::MP tries to bind on port C<4040> on all IP addresses that the
458	local nodename resolves to.
459
460	Otherwise the first argument must be an array-reference with transport
461	endpoints ("ip:port", "hostname:port") or port numbers (in which case the
462	local nodename is used as hostname). The endpoints are all resolved and
463	will become the node reference.
464
465	=cut
466
467	=back
468
469	=head1 NODE MESSAGES
470
471	Nodes understand the following messages sent to them. Many of them take
472	arguments called C<@reply>, which will simply be used to compose a reply
473	message - C<$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	695	=head1 AnyEvent::MP vs. Distributed Erlang
514		696
515	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node	697	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	698	== 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	699	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
518	sample:	700	sample:
519		701
520	http://www.erlang.se/doc/programming_rules.shtml	702	http://www.Erlang.se/doc/programming_rules.shtml
521	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	703	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	704	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	705	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
524		706
525	Despite the similarities, there are also some important differences:	707	Despite the similarities, there are also some important differences:
526		708
527	=over 4	709	=over 4
528		710
…		…
533	convenience functionality.	715	convenience functionality.
534		716
535	This means that AEMP requires a less tightly controlled environment at the	717	This means that AEMP requires a less tightly controlled environment at the
536	cost of longer node references and a slightly higher management overhead.	718	cost of longer node references and a slightly higher management overhead.
537		719
		720	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
		721	uses "local ports are like remote ports".
		722
		723	The failure modes for local ports are quite different (runtime errors
		724	only) then for remote ports - when a local port dies, you I<know> it dies,
		725	when a connection to another node dies, you know nothing about the other
		726	port.
		727
		728	Erlang pretends remote ports are as reliable as local ports, even when
		729	they are not.
		730
		731	AEMP encourages a "treat remote ports differently" philosophy, with local
		732	ports being the special case/exception, where transport errors cannot
		733	occur.
		734
538	=item * Erlang uses processes and a mailbox, AEMP does not queue.	735	=item * Erlang uses processes and a mailbox, AEMP does not queue.
539		736
540	Erlang uses processes that selctively receive messages, and therefore	737	Erlang uses processes that selectively receive messages, and therefore
541	needs a queue. AEMP is event based, queuing messages would serve no useful	738	needs a queue. AEMP is event based, queuing messages would serve no
542	purpose.	739	useful purpose. For the same reason the pattern-matching abilities of
		740	AnyEvent::MP are more limited, as there is little need to be able to
		741	filter messages without dequeing them.
543		742
544	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	743	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
545		744
546	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	745	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
547		746
548	Sending messages in erlang is synchronous and blocks the process. AEMP	747	Sending messages in Erlang is synchronous and blocks the process (and
549	sends are immediate, connection establishment is handled in the	748	so does not need a queue that can overflow). AEMP sends are immediate,
550	background.	749	connection establishment is handled in the background.
551		750
552	=item * Erlang can silently lose messages, AEMP cannot.	751	=item * Erlang suffers from silent message loss, AEMP does not.
553		752
554	Erlang makes few guarantees on messages delivery - messages can get lost	753	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,	754	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).	755	and c, and the other side only receives messages a and c).
557		756
558	AEMP guarantees correct ordering, and the guarantee that there are no	757	AEMP guarantees correct ordering, and the guarantee that there are no
559	holes in the message sequence.	758	holes in the message sequence.
560		759
561	=item * In erlang, processes can be declared dead and later be found to be	760	=item * In Erlang, processes can be declared dead and later be found to be
562	alive.	761	alive.
563		762
564	In erlang it can happen that a monitored process is declared dead and	763	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	764	linked processes get killed, but later it turns out that the process is
566	still alive - and can receive messages.	765	still alive - and can receive messages.
567		766
568	In AEMP, when port monitoring detects a port as dead, then that port will	767	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	768	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.	769	and then later sends messages to it, finding it is still alive.
571		770
572	=item * Erlang can send messages to the wrong port, AEMP does not.	771	=item * Erlang can send messages to the wrong port, AEMP does not.
573		772
574	In erlang it is quite possible that a node that restarts reuses a process	773	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	774	known to other nodes for a completely different process, causing messages
576	messages destined for that process to end up in an unrelated process.	775	destined for that process to end up in an unrelated process.
577		776
578	AEMP never reuses port IDs, so old messages or old port IDs floating	777	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.	778	around in the network will not be sent to an unrelated port.
580		779
581	=item * Erlang uses unprotected connections, AEMP uses secure	780	=item * Erlang uses unprotected connections, AEMP uses secure
582	authentication and can use TLS.	781	authentication and can use TLS.
583		782
584	AEMP can use a proven protocol - SSL/TLS - to protect connections and	783	AEMP can use a proven protocol - SSL/TLS - to protect connections and
585	securely authenticate nodes.	784	securely authenticate nodes.
586		785
		786	=item * The AEMP protocol is optimised for both text-based and binary
		787	communications.
		788
		789	The AEMP protocol, unlike the Erlang protocol, supports both
		790	language-independent text-only protocols (good for debugging) and binary,
		791	language-specific serialisers (e.g. Storable).
		792
		793	It has also been carefully designed to be implementable in other languages
		794	with a minimum of work while gracefully degrading fucntionality to make the
		795	protocol simple.
		796
		797	=item * AEMP has more flexible monitoring options than Erlang.
		798
		799	In Erlang, you can chose to receive I<all> exit signals as messages
		800	or I<none>, there is no in-between, so monitoring single processes is
		801	difficult to implement. Monitoring in AEMP is more flexible than in
		802	Erlang, as one can choose between automatic kill, exit message or callback
		803	on a per-process basis.
		804
		805	=item * Erlang tries to hide remote/local connections, AEMP does not.
		806
		807	Monitoring in Erlang is not an indicator of process death/crashes,
		808	as linking is (except linking is unreliable in Erlang).
		809
		810	In AEMP, you don't "look up" registered port names or send to named ports
		811	that might or might not be persistent. Instead, you normally spawn a port
		812	on the remote node. The init function monitors the you, and you monitor
		813	the remote port. Since both monitors are local to the node, they are much
		814	more reliable.
		815
		816	This also saves round-trips and avoids sending messages to the wrong port
		817	(hard to do in Erlang).
		818
		819	=back
		820
		821	=head1 RATIONALE
		822
		823	=over 4
		824
		825	=item Why strings for ports and noderefs, why not objects?
		826
		827	We considered "objects", but found that the actual number of methods
		828	thatc an be called are very low. Since port IDs and noderefs travel over
		829	the network frequently, the serialising/deserialising would add lots of
		830	overhead, as well as having to keep a proxy object.
		831
		832	Strings can easily be printed, easily serialised etc. and need no special
		833	procedures to be "valid".
		834
		835	And a a miniport consists of a single closure stored in a global hash - it
		836	can't become much cheaper.
		837
		838	=item Why favour JSON, why not real serialising format such as Storable?
		839
		840	In fact, any AnyEvent::MP node will happily accept Storable as framing
		841	format, but currently there is no way to make a node use Storable by
		842	default.
		843
		844	The default framing protocol is JSON because a) JSON::XS is many times
		845	faster for small messages and b) most importantly, after years of
		846	experience we found that object serialisation is causing more problems
		847	than it gains: Just like function calls, objects simply do not travel
		848	easily over the network, mostly because they will always be a copy, so you
		849	always have to re-think your design.
		850
		851	Keeping your messages simple, concentrating on data structures rather than
		852	objects, will keep your messages clean, tidy and efficient.
		853
587	=back	854	=back
588		855
589	=head1 SEE ALSO	856	=head1 SEE ALSO
590		857
591	L<AnyEvent>.	858	L<AnyEvent>.

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