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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.22 by root, Tue Aug 4 18:33:30 2009 UTC vs.
Revision 1.60 by root, Mon Aug 24 08:04:52 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; # -OR-
		17	initialise_node "localhost:4040"; # -OR-
		18	initialise_node "slave/", "localhost:4040"
		19
		20	# ports are message endpoints
		21
		22	# sending messages
13	snd $port, type => data...;	23	snd $port, type => data...;
		24	snd $port, @msg;
		25	snd @msg_with_first_element_being_a_port;
14		26
15	$SELF # receiving/own port id in rcv callbacks	27	# creating/using ports, the simple way
		28	my $simple_port = port { my @msg = @_; 0 };
16		29
17	rcv $port, smartmatch => $cb->($port, @msg);	30	# creating/using ports, tagged message matching
18		31	my $port = port;
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	32	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
21	rcv $port1, pong => sub { warn "pong received\n" };	33	rcv $port, pong => sub { warn "pong received\n"; 0 };
22	snd $port2, ping => $port1;
23		34
24	# more, smarter, matches (_any_ is exported by this module)	35	# create a port on another node
25	rcv $port, [child_died => $pid] => sub { ...	36	my $port = spawn $node, $initfunc, @initdata;
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	37
		38	# monitoring
		39	mon $port, $cb->(@msg) # callback is invoked on death
		40	mon $port, $otherport # kill otherport on abnormal death
		41	mon $port, $otherport, @msg # send message on death
		42
		43	=head1 CURRENT STATUS
		44
		45	AnyEvent::MP - stable API, should work
		46	AnyEvent::MP::Intro - outdated
		47	AnyEvent::MP::Kernel - WIP
		48	AnyEvent::MP::Transport - mostly stable
		49
		50	stay tuned.
27		51
28	=head1 DESCRIPTION	52	=head1 DESCRIPTION
29		53
30	This module (-family) implements a simple message passing framework.	54	This module (-family) implements a simple message passing framework.
31		55
32	Despite its simplicity, you can securely message other processes running	56	Despite its simplicity, you can securely message other processes running
33	on the same or other hosts.	57	on the same or other hosts.
34		58
		59	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
		60	manual page.
		61
35	At the moment, this module family is severly brokena nd underdocumented,	62	At the moment, this module family is severly broken and underdocumented,
36	so do not use. This was uploaded mainly to reserve the CPAN namespace -	63	so do not use. This was uploaded mainly to reserve the CPAN namespace -
37	stay tuned!	64	stay tuned!
38		65
39	=head1 CONCEPTS	66	=head1 CONCEPTS
40		67
41	=over 4	68	=over 4
42		69
43	=item port	70	=item port
44		71
45	A port is something you can send messages to with the C<snd> function, and	72	A port is something you can send messages to (with the C<snd> function).
46	you can register C<rcv> handlers with. All C<rcv> handlers will receive	73
		74	Ports allow you to register C<rcv> handlers that can match all or just
47	messages they match, messages will not be queued.	75	some messages. Messages will not be queued.
48		76
49	=item port id - C<noderef#portname>	77	=item port id - C<noderef#portname>
50		78
51	A port id is always the noderef, a hash-mark (C<#>) as separator, followed	79	A port ID is the concatenation of a noderef, a hash-mark (C<#>) as
52	by a port name (a printable string of unspecified format).	80	separator, and a port name (a printable string of unspecified format). An
		81	exception is the the node port, whose ID is identical to its node
		82	reference.
53		83
54	=item node	84	=item node
55		85
56	A node is a single process containing at least one port - the node	86	A node is a single process containing at least one port - the node port,
57	port. You can send messages to node ports to let them create new ports,	87	which provides nodes to manage each other remotely, and to create new
58	among other things.	88	ports.
59		89
60	Initially, nodes are either private (single-process only) or hidden	90	Nodes are either private (single-process only), slaves (connected to a
61	(connected to a master node only). Only when they epxlicitly "become	91	master node only) or public nodes (connectable from unrelated nodes).
62	public" can you send them messages from unrelated other nodes.
63		92
64	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	93	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>
65		94
66	A noderef is a string that either uniquely identifies a given node (for	95	A node reference is a string that either simply identifies the node (for
67	private and hidden nodes), or contains a recipe on how to reach a given	96	private and slave nodes), or contains a recipe on how to reach a given
68	node (for public nodes).	97	node (for public nodes).
69		98
		99	This recipe is simply a comma-separated list of C<address:port> pairs (for
		100	TCP/IP, other protocols might look different).
		101
		102	Node references come in two flavours: resolved (containing only numerical
		103	addresses) or unresolved (where hostnames are used instead of addresses).
		104
		105	Before using an unresolved node reference in a message you first have to
		106	resolve it.
		107
70	=back	108	=back
71		109
72	=head1 VARIABLES/FUNCTIONS	110	=head1 VARIABLES/FUNCTIONS
73		111
74	=over 4	112	=over 4
75		113
76	=cut	114	=cut
77		115
78	package AnyEvent::MP;	116	package AnyEvent::MP;
79		117
80	use AnyEvent::MP::Base;	118	use AnyEvent::MP::Kernel;
81		119
82	use common::sense;	120	use common::sense;
83		121
84	use Carp ();	122	use Carp ();
85		123
86	use AE ();	124	use AE ();
87		125
88	use base "Exporter";	126	use base "Exporter";
89		127
90	our $VERSION = '0.02';	128	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		129
91	our @EXPORT = qw(	130	our @EXPORT = qw(
92	NODE $NODE *SELF node_of _any_	131	NODE $NODE *SELF node_of after
93	become_slave become_public	132	resolve_node initialise_node
94	snd rcv mon kil reg psub	133	snd rcv mon mob_guard kil reg psub spawn
95	port	134	port
96	);	135	);
97		136
98	our $SELF;	137	our $SELF;
99		138
…		…
103	kil $SELF, die => $msg;	142	kil $SELF, die => $msg;
104	}	143	}
105		144
106	=item $thisnode = NODE / $NODE	145	=item $thisnode = NODE / $NODE
107		146
108	The C<NODE> function returns, and the C<$NODE> variable contains	147	The C<NODE> function returns, and the C<$NODE> variable contains the
109	the noderef of the local node. The value is initialised by a call	148	noderef of the local node. The value is initialised by a call to
110	to C<become_public> or C<become_slave>, after which all local port	149	C<initialise_node>.
111	identifiers become invalid.
112		150
113	=item $noderef = node_of $portid	151	=item $noderef = node_of $port
114		152
115	Extracts and returns the noderef from a portid or a noderef.	153	Extracts and returns the noderef from a port ID or a noderef.
		154
		155	=item initialise_node $noderef, $seednode, $seednode...
		156
		157	=item initialise_node "slave/", $master, $master...
		158
		159	Before a node can talk to other nodes on the network it has to initialise
		160	itself - the minimum a node needs to know is it's own name, and optionally
		161	it should know the noderefs of some other nodes in the network.
		162
		163	This function initialises a node - it must be called exactly once (or
		164	never) before calling other AnyEvent::MP functions.
		165
		166	All arguments (optionally except for the first) are noderefs, which can be
		167	either resolved or unresolved.
		168
		169	The first argument will be looked up in the configuration database first
		170	(if it is C<undef> then the current nodename will be used instead) to find
		171	the relevant configuration profile (see L<aemp>). If none is found then
		172	the default configuration is used. The configuration supplies additional
		173	seed/master nodes and can override the actual noderef.
		174
		175	There are two types of networked nodes, public nodes and slave nodes:
		176
		177	=over 4
		178
		179	=item public nodes
		180
		181	For public nodes, C<$noderef> (supplied either directly to
		182	C<initialise_node> or indirectly via a profile or the nodename) must be a
		183	noderef (possibly unresolved, in which case it will be resolved).
		184
		185	After resolving, the node will bind itself on all endpoints and try to
		186	connect to all additional C<$seednodes> that are specified. Seednodes are
		187	optional and can be used to quickly bootstrap the node into an existing
		188	network.
		189
		190	=item slave nodes
		191
		192	When the C<$noderef> (either as given or overriden by the config file)
		193	is the special string C<slave/>, then the node will become a slave
		194	node. Slave nodes cannot be contacted from outside and will route most of
		195	their traffic to the master node that they attach to.
		196
		197	At least one additional noderef is required (either by specifying it
		198	directly or because it is part of the configuration profile): The node
		199	will try to connect to all of them and will become a slave attached to the
		200	first node it can successfully connect to.
		201
		202	Note that slave nodes cannot change their name, and consequently, their
		203	master, so if the master goes down, the slave node will not function well
		204	anymore until it can re-establish conenciton to its master. This makes
		205	slave nodes unsuitable for long-term nodes or fault-tolerant networks.
		206
		207	=back
		208
		209	This function will block until all nodes have been resolved and, for slave
		210	nodes, until it has successfully established a connection to a master
		211	server.
		212
		213	All the seednodes will also be specially marked to automatically retry
		214	connecting to them infinitely.
		215
		216	Example: become a public node listening on the guessed noderef, or the one
		217	specified via C<aemp> for the current node. This should be the most common
		218	form of invocation for "daemon"-type nodes.
		219
		220	initialise_node;
		221
		222	Example: become a slave node to any of the the seednodes specified via
		223	C<aemp>. This form is often used for commandline clients.
		224
		225	initialise_node "slave/";
		226
		227	Example: become a slave node to any of the specified master servers. This
		228	form is also often used for commandline clients.
		229
		230	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
		231
		232	Example: become a public node, and try to contact some well-known master
		233	servers to become part of the network.
		234
		235	initialise_node undef, "master1", "master2";
		236
		237	Example: become a public node listening on port C<4041>.
		238
		239	initialise_node 4041;
		240
		241	Example: become a public node, only visible on localhost port 4044.
		242
		243	initialise_node "localhost:4044";
		244
		245	=item $cv = resolve_node $noderef
		246
		247	Takes an unresolved node reference that may contain hostnames and
		248	abbreviated IDs, resolves all of them and returns a resolved node
		249	reference.
		250
		251	In addition to C<address:port> pairs allowed in resolved noderefs, the
		252	following forms are supported:
		253
		254	=over 4
		255
		256	=item the empty string
		257
		258	An empty-string component gets resolved as if the default port (4040) was
		259	specified.
		260
		261	=item naked port numbers (e.g. C<1234>)
		262
		263	These are resolved by prepending the local nodename and a colon, to be
		264	further resolved.
		265
		266	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
		267
		268	These are resolved by using AnyEvent::DNS to resolve them, optionally
		269	looking up SRV records for the C<aemp=4040> port, if no port was
		270	specified.
		271
		272	=back
116		273
117	=item $SELF	274	=item $SELF
118		275
119	Contains the current port id while executing C<rcv> callbacks or C<psub>	276	Contains the current port id while executing C<rcv> callbacks or C<psub>
120	blocks.	277	blocks.
…		…
123		280
124	Due to some quirks in how perl exports variables, it is impossible to	281	Due to some quirks in how perl exports variables, it is impossible to
125	just export C<$SELF>, all the symbols called C<SELF> are exported by this	282	just export C<$SELF>, all the symbols called C<SELF> are exported by this
126	module, but only C<$SELF> is currently used.	283	module, but only C<$SELF> is currently used.
127		284
128	=item snd $portid, type => @data	285	=item snd $port, type => @data
129		286
130	=item snd $portid, @msg	287	=item snd $port, @msg
131		288
132	Send the given message to the given port ID, which can identify either	289	Send the given message to the given port ID, which can identify either
133	a local or a remote port, and can be either a string or soemthignt hat	290	a local or a remote port, and must be a port ID.
134	stringifies a sa port ID (such as a port object :).
135		291
136	While the message can be about anything, it is highly recommended to use a	292	While the message can be about anything, it is highly recommended to use a
137	string as first element (a portid, or some word that indicates a request	293	string as first element (a port ID, or some word that indicates a request
138	type etc.).	294	type etc.).
139		295
140	The message data effectively becomes read-only after a call to this	296	The message data effectively becomes read-only after a call to this
141	function: modifying any argument is not allowed and can cause many	297	function: modifying any argument is not allowed and can cause many
142	problems.	298	problems.
…		…
145	JSON is used, then only strings, numbers and arrays and hashes consisting	301	JSON is used, then only strings, numbers and arrays and hashes consisting
146	of those are allowed (no objects). When Storable is used, then anything	302	of those are allowed (no objects). When Storable is used, then anything
147	that Storable can serialise and deserialise is allowed, and for the local	303	that Storable can serialise and deserialise is allowed, and for the local
148	node, anything can be passed.	304	node, anything can be passed.
149		305
150	=item kil $portid[, @reason]	306	=item $local_port = port
151		307
152	Kill the specified port with the given C<@reason>.	308	Create a new local port object and returns its port ID. Initially it has
		309	no callbacks set and will throw an error when it receives messages.
153		310
154	If no C<@reason> is specified, then the port is killed "normally" (linked	311	=item $local_port = port { my @msg = @_ }
155	ports will not be kileld, or even notified).
156		312
157	Otherwise, linked ports get killed with the same reason (second form of	313	Creates a new local port, and returns its ID. Semantically the same as
158	C<mon>, see below).	314	creating a port and calling C<rcv $port, $callback> on it.
159		315
160	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	316	The block will be called for every message received on the port, with the
161	will be reported as reason C<< die => $@ >>.	317	global variable C<$SELF> set to the port ID. Runtime errors will cause the
		318	port to be C<kil>ed. The message will be passed as-is, no extra argument
		319	(i.e. no port ID) will be passed to the callback.
162		320
163	Transport/communication errors are reported as C<< transport_error =>	321	If you want to stop/destroy the port, simply C<kil> it:
164	$message >>.
165		322
		323	my $port = port {
		324	my @msg = @_;
		325	...
		326	kil $SELF;
		327	};
		328
		329	=cut
		330
		331	sub rcv($@);
		332
		333	sub _kilme {
		334	die "received message on port without callback";
		335	}
		336
		337	sub port(;&) {
		338	my $id = "$UNIQ." . $ID++;
		339	my $port = "$NODE#$id";
		340
		341	rcv $port, shift \|\| \&_kilme;
		342
		343	$port
		344	}
		345
		346	=item rcv $local_port, $callback->(@msg)
		347
		348	Replaces the default callback on the specified port. There is no way to
		349	remove the default callback: use C<sub { }> to disable it, or better
		350	C<kil> the port when it is no longer needed.
		351
		352	The global C<$SELF> (exported by this module) contains C<$port> while
		353	executing the callback. Runtime errors during callback execution will
		354	result in the port being C<kil>ed.
		355
		356	The default callback received all messages not matched by a more specific
		357	C<tag> match.
		358
		359	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
		360
		361	Register (or replace) callbacks to be called on messages starting with the
		362	given tag on the given port (and return the port), or unregister it (when
		363	C<$callback> is C<$undef> or missing). There can only be one callback
		364	registered for each tag.
		365
		366	The original message will be passed to the callback, after the first
		367	element (the tag) has been removed. The callback will use the same
		368	environment as the default callback (see above).
		369
		370	Example: create a port and bind receivers on it in one go.
		371
		372	my $port = rcv port,
		373	msg1 => sub { ... },
		374	msg2 => sub { ... },
		375	;
		376
		377	Example: create a port, bind receivers and send it in a message elsewhere
		378	in one go:
		379
		380	snd $otherport, reply =>
		381	rcv port,
		382	msg1 => sub { ... },
		383	...
		384	;
		385
		386	Example: temporarily register a rcv callback for a tag matching some port
		387	(e.g. for a rpc reply) and unregister it after a message was received.
		388
		389	rcv $port, $otherport => sub {
		390	my @reply = @_;
		391
		392	rcv $SELF, $otherport;
		393	};
		394
		395	=cut
		396
		397	sub rcv($@) {
		398	my $port = shift;
		399	my ($noderef, $portid) = split /#/, $port, 2;
		400
		401	$NODE{$noderef} == $NODE{""}
		402	or Carp::croak "$port: rcv can only be called on local ports, caught";
		403
		404	while (@_) {
		405	if (ref $_[0]) {
		406	if (my $self = $PORT_DATA{$portid}) {
		407	"AnyEvent::MP::Port" eq ref $self
		408	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		409
		410	$self->[2] = shift;
		411	} else {
		412	my $cb = shift;
		413	$PORT{$portid} = sub {
		414	local $SELF = $port;
		415	eval { &$cb }; _self_die if $@;
		416	};
		417	}
		418	} elsif (defined $_[0]) {
		419	my $self = $PORT_DATA{$portid} \|\|= do {
		420	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
		421
		422	$PORT{$portid} = sub {
		423	local $SELF = $port;
		424
		425	if (my $cb = $self->[1]{$_[0]}) {
		426	shift;
		427	eval { &$cb }; _self_die if $@;
		428	} else {
		429	&{ $self->[0] };
		430	}
		431	};
		432
		433	$self
		434	};
		435
		436	"AnyEvent::MP::Port" eq ref $self
		437	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		438
		439	my ($tag, $cb) = splice @_, 0, 2;
		440
		441	if (defined $cb) {
		442	$self->[1]{$tag} = $cb;
		443	} else {
		444	delete $self->[1]{$tag};
		445	}
		446	}
		447	}
		448
		449	$port
		450	}
		451
		452	=item $closure = psub { BLOCK }
		453
		454	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
		455	closure is executed, sets up the environment in the same way as in C<rcv>
		456	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		457
		458	This is useful when you register callbacks from C<rcv> callbacks:
		459
		460	rcv delayed_reply => sub {
		461	my ($delay, @reply) = @_;
		462	my $timer = AE::timer $delay, 0, psub {
		463	snd @reply, $SELF;
		464	};
		465	};
		466
		467	=cut
		468
		469	sub psub(&) {
		470	my $cb = shift;
		471
		472	my $port = $SELF
		473	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
		474
		475	sub {
		476	local $SELF = $port;
		477
		478	if (wantarray) {
		479	my @res = eval { &$cb };
		480	_self_die if $@;
		481	@res
		482	} else {
		483	my $res = eval { &$cb };
		484	_self_die if $@;
		485	$res
		486	}
		487	}
		488	}
		489
166	=item $guard = mon $portid, $cb->(@reason)	490	=item $guard = mon $port, $cb->(@reason)
167		491
168	=item $guard = mon $portid, $otherport	492	=item $guard = mon $port, $rcvport
169		493
		494	=item $guard = mon $port
		495
170	=item $guard = mon $portid, $otherport, @msg	496	=item $guard = mon $port, $rcvport, @msg
171		497
172	Monitor the given port and do something when the port is killed.	498	Monitor the given port and do something when the port is killed or
		499	messages to it were lost, and optionally return a guard that can be used
		500	to stop monitoring again.
173		501
		502	C<mon> effectively guarantees that, in the absence of hardware failures,
		503	that after starting the monitor, either all messages sent to the port
		504	will arrive, or the monitoring action will be invoked after possible
		505	message loss has been detected. No messages will be lost "in between"
		506	(after the first lost message no further messages will be received by the
		507	port). After the monitoring action was invoked, further messages might get
		508	delivered again.
		509
		510	Note that monitoring-actions are one-shot: once released, they are removed
		511	and will not trigger again.
		512
174	In the first form, the callback is simply called with any number	513	In the first form (callback), the callback is simply called with any
175	of C<@reason> elements (no @reason means that the port was deleted	514	number of C<@reason> elements (no @reason means that the port was deleted
176	"normally"). Note also that I<< the callback B<must> never die >>, so use	515	"normally"). Note also that I<< the callback B<must> never die >>, so use
177	C<eval> if unsure.	516	C<eval> if unsure.
178		517
179	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	518	In the second form (another port given), the other port (C<$rcvport>)
180	a @reason was specified, i.e. on "normal" kils nothing happens, while	519	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
181	under all other conditions, the other port is killed with the same reason.	520	"normal" kils nothing happens, while under all other conditions, the other
		521	port is killed with the same reason.
182		522
		523	The third form (kill self) is the same as the second form, except that
		524	C<$rvport> defaults to C<$SELF>.
		525
183	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	526	In the last form (message), a message of the form C<@msg, @reason> will be
		527	C<snd>.
		528
		529	As a rule of thumb, monitoring requests should always monitor a port from
		530	a local port (or callback). The reason is that kill messages might get
		531	lost, just like any other message. Another less obvious reason is that
		532	even monitoring requests can get lost (for exmaple, when the connection
		533	to the other node goes down permanently). When monitoring a port locally
		534	these problems do not exist.
184		535
185	Example: call a given callback when C<$port> is killed.	536	Example: call a given callback when C<$port> is killed.
186		537
187	mon $port, sub { warn "port died because of <@_>\n" };	538	mon $port, sub { warn "port died because of <@_>\n" };
188		539
189	Example: kill ourselves when C<$port> is killed abnormally.	540	Example: kill ourselves when C<$port> is killed abnormally.
190		541
191	mon $port, $self;	542	mon $port;
192		543
193	Example: send us a restart message another C<$port> is killed.	544	Example: send us a restart message when another C<$port> is killed.
194		545
195	mon $port, $self => "restart";	546	mon $port, $self => "restart";
196		547
197	=cut	548	=cut
198		549
199	sub mon {	550	sub mon {
200	my ($noderef, $port, $cb) = ((split /#/, shift, 2), shift);	551	my ($noderef, $port) = split /#/, shift, 2;
201		552
202	my $node = $NODE{$noderef} \|\| add_node $noderef;	553	my $node = $NODE{$noderef} \|\| add_node $noderef;
203		554
204	#TODO: ports must not be references	555	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
205	if (!ref $cb or "AnyEvent::MP::Port" eq ref $cb) {	556
		557	unless (ref $cb) {
206	if (@_) {	558	if (@_) {
207	# send a kill info message	559	# send a kill info message
208	my (@msg) = ($cb, @_);	560	my (@msg) = ($cb, @_);
209	$cb = sub { snd @msg, @_ };	561	$cb = sub { snd @msg, @_ };
210	} else {	562	} else {
…		…
239	=cut	591	=cut
240		592
241	sub mon_guard {	593	sub mon_guard {
242	my ($port, @refs) = @_;	594	my ($port, @refs) = @_;
243		595
		596	#TODO: mon-less form?
		597
244	mon $port, sub { 0 && @refs }	598	mon $port, sub { 0 && @refs }
245	}	599	}
246		600
247	=item $local_port = port	601	=item kil $port[, @reason]
248		602
249	Create a new local port object that supports message matching.	603	Kill the specified port with the given C<@reason>.
250		604
251	=item $portid = port { my @msg = @_; $finished }	605	If no C<@reason> is specified, then the port is killed "normally" (linked
		606	ports will not be kileld, or even notified).
252		607
253	Creates a "mini port", that is, a very lightweight port without any	608	Otherwise, linked ports get killed with the same reason (second form of
254	pattern matching behind it, and returns its ID.	609	C<mon>, see below).
255		610
256	The block will be called for every message received on the port. When the	611	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
257	callback returns a true value its job is considered "done" and the port	612	will be reported as reason C<< die => $@ >>.
258	will be destroyed. Otherwise it will stay alive.
259		613
260	The message will be passed as-is, no extra argument (i.e. no port id) will	614	Transport/communication errors are reported as C<< transport_error =>
261	be passed to the callback.	615	$message >>.
262		616
263	If you need the local port id in the callback, this works nicely:
264
265	my $port; $port = miniport {
266	snd $otherport, reply => $port;
267	};
268
269	=cut	617	=cut
270		618
271	sub port(;&) {	619	=item $port = spawn $node, $initfunc[, @initdata]
272	my $id = "$UNIQ." . $ID++;
273	my $port = "$NODE#$id";
274		620
275	if (@_) {	621	Creates a port on the node C<$node> (which can also be a port ID, in which
276	my $cb = shift;	622	case it's the node where that port resides).
277	$PORT{$id} = sub {	623
278	local $SELF = $port;	624	The port ID of the newly created port is return immediately, and it is
279	eval {	625	permissible to immediately start sending messages or monitor the port.
280	&$cb	626
281	and kil $id;	627	After the port has been created, the init function is
		628	called. This function must be a fully-qualified function name
		629	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		630	program, use C<::name>.
		631
		632	If the function doesn't exist, then the node tries to C<require>
		633	the package, then the package above the package and so on (e.g.
		634	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		635	exists or it runs out of package names.
		636
		637	The init function is then called with the newly-created port as context
		638	object (C<$SELF>) and the C<@initdata> values as arguments.
		639
		640	A common idiom is to pass your own port, monitor the spawned port, and
		641	in the init function, monitor the original port. This two-way monitoring
		642	ensures that both ports get cleaned up when there is a problem.
		643
		644	Example: spawn a chat server port on C<$othernode>.
		645
		646	# this node, executed from within a port context:
		647	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		648	mon $server;
		649
		650	# init function on C<$othernode>
		651	sub connect {
		652	my ($srcport) = @_;
		653
		654	mon $srcport;
		655
		656	rcv $SELF, sub {
282	};	657	...
283	_self_die if $@;
284	};
285	} else {
286	my $self = bless {
287	id => "$NODE#$id",
288	}, "AnyEvent::MP::Port";
289
290	$PORT_DATA{$id} = $self;
291	$PORT{$id} = sub {
292	local $SELF = $port;
293
294	eval {
295	for (@{ $self->{rc0}{$_[0]} }) {
296	$_ && &{$_->[0]}
297	&& undef $_;
298	}
299
300	for (@{ $self->{rcv}{$_[0]} }) {
301	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
302	&& &{$_->[0]}
303	&& undef $_;
304	}
305
306	for (@{ $self->{any} }) {
307	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
308	&& &{$_->[0]}
309	&& undef $_;
310	}
311	};
312	_self_die if $@;
313	};	658	};
314	}	659	}
315		660
316	$port
317	}
318
319	=item reg $portid, $name
320
321	Registers the given port under the name C<$name>. If the name already
322	exists it is replaced.
323
324	A port can only be registered under one well known name.
325
326	A port automatically becomes unregistered when it is killed.
327
328	=cut	661	=cut
329		662
330	sub reg(@) {	663	sub _spawn {
331	my ($portid, $name) = @_;	664	my $port = shift;
		665	my $init = shift;
332		666
333	$REG{$name} = $portid;	667	local $SELF = "$NODE#$port";
334	}	668	eval {
335		669	&{ load_func $init }
336	=item rcv $portid, tagstring => $callback->(@msg), ...
337
338	=item rcv $portid, $smartmatch => $callback->(@msg), ...
339
340	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
341
342	Register callbacks to be called on matching messages on the given port.
343
344	The callback has to return a true value when its work is done, after
345	which is will be removed, or a false value in which case it will stay
346	registered.
347
348	The global C<$SELF> (exported by this module) contains C<$portid> while
349	executing the callback.
350
351	Runtime errors wdurign callback execution will result in the port being
352	C<kil>ed.
353
354	If the match is an array reference, then it will be matched against the
355	first elements of the message, otherwise only the first element is being
356	matched.
357
358	Any element in the match that is specified as C<_any_> (a function
359	exported by this module) matches any single element of the message.
360
361	While not required, it is highly recommended that the first matching
362	element is a string identifying the message. The one-string-only match is
363	also the most efficient match (by far).
364
365	=cut
366
367	sub rcv($@) {
368	my ($noderef, $port) = split /#/, shift, 2;
369
370	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
371	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";
372
373	my $self = $PORT_DATA{$port}
374	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
375
376	"AnyEvent::MP::Port" eq ref $self
377	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
378
379	while (@_) {
380	my ($match, $cb) = splice @_, 0, 2;
381
382	if (!ref $match) {
383	push @{ $self->{rc0}{$match} }, [$cb];
384	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
385	my ($type, @match) = @$match;
386	@match
387	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
388	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
389	} else {
390	push @{ $self->{any} }, [$cb, $match];
391	}
392	}
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	};	670	};
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 $@;	671	_self_die if $@;
424	@res	672	}
425	} else {	673
426	my $res = eval { &$cb };	674	sub spawn(@) {
427	_self_die if $@;	675	my ($noderef, undef) = split /#/, shift, 2;
428	$res	676
429	}	677	my $id = "$RUNIQ." . $ID++;
		678
		679	$_[0] =~ /::/
		680	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		681
		682	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
		683
		684	"$noderef#$id"
		685	}
		686
		687	=item after $timeout, @msg
		688
		689	=item after $timeout, $callback
		690
		691	Either sends the given message, or call the given callback, after the
		692	specified number of seconds.
		693
		694	This is simply a utility function that come sin handy at times.
		695
		696	=cut
		697
		698	sub after($@) {
		699	my ($timeout, @action) = @_;
		700
		701	my $t; $t = AE::timer $timeout, 0, sub {
		702	undef $t;
		703	ref $action[0]
		704	? $action[0]()
		705	: snd @action;
430	}	706	};
431	}	707	}
432		708
433	=back	709	=back
434		710
435	=head1 FUNCTIONS FOR NODES	711	=head1 AnyEvent::MP vs. Distributed Erlang
		712
		713	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
		714	== aemp node, Erlang process == aemp port), so many of the documents and
		715	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		716	sample:
		717
		718	http://www.Erlang.se/doc/programming_rules.shtml
		719	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		720	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		721	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		722
		723	Despite the similarities, there are also some important differences:
436		724
437	=over 4	725	=over 4
438		726
439	=item become_public endpoint...	727	=item * Node references contain the recipe on how to contact them.
440		728
441	Tells the node to become a public node, i.e. reachable from other nodes.	729	Erlang relies on special naming and DNS to work everywhere in the
		730	same way. AEMP relies on each node knowing it's own address(es), with
		731	convenience functionality.
442		732
443	If no arguments are given, or the first argument is C<undef>, then	733	This means that AEMP requires a less tightly controlled environment at the
444	AnyEvent::MP tries to bind on port C<4040> on all IP addresses that the	734	cost of longer node references and a slightly higher management overhead.
445	local nodename resolves to.
446		735
447	Otherwise the first argument must be an array-reference with transport	736	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
448	endpoints ("ip:port", "hostname:port") or port numbers (in which case the	737	uses "local ports are like remote ports".
449	local nodename is used as hostname). The endpoints are all resolved and
450	will become the node reference.
451		738
452	=cut	739	The failure modes for local ports are quite different (runtime errors
		740	only) then for remote ports - when a local port dies, you I<know> it dies,
		741	when a connection to another node dies, you know nothing about the other
		742	port.
		743
		744	Erlang pretends remote ports are as reliable as local ports, even when
		745	they are not.
		746
		747	AEMP encourages a "treat remote ports differently" philosophy, with local
		748	ports being the special case/exception, where transport errors cannot
		749	occur.
		750
		751	=item * Erlang uses processes and a mailbox, AEMP does not queue.
		752
		753	Erlang uses processes that selectively receive messages, and therefore
		754	needs a queue. AEMP is event based, queuing messages would serve no
		755	useful purpose. For the same reason the pattern-matching abilities of
		756	AnyEvent::MP are more limited, as there is little need to be able to
		757	filter messages without dequeing them.
		758
		759	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
		760
		761	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
		762
		763	Sending messages in Erlang is synchronous and blocks the process (and
		764	so does not need a queue that can overflow). AEMP sends are immediate,
		765	connection establishment is handled in the background.
		766
		767	=item * Erlang suffers from silent message loss, AEMP does not.
		768
		769	Erlang makes few guarantees on messages delivery - messages can get lost
		770	without any of the processes realising it (i.e. you send messages a, b,
		771	and c, and the other side only receives messages a and c).
		772
		773	AEMP guarantees correct ordering, and the guarantee that there are no
		774	holes in the message sequence.
		775
		776	=item * In Erlang, processes can be declared dead and later be found to be
		777	alive.
		778
		779	In Erlang it can happen that a monitored process is declared dead and
		780	linked processes get killed, but later it turns out that the process is
		781	still alive - and can receive messages.
		782
		783	In AEMP, when port monitoring detects a port as dead, then that port will
		784	eventually be killed - it cannot happen that a node detects a port as dead
		785	and then later sends messages to it, finding it is still alive.
		786
		787	=item * Erlang can send messages to the wrong port, AEMP does not.
		788
		789	In Erlang it is quite likely that a node that restarts reuses a process ID
		790	known to other nodes for a completely different process, causing messages
		791	destined for that process to end up in an unrelated process.
		792
		793	AEMP never reuses port IDs, so old messages or old port IDs floating
		794	around in the network will not be sent to an unrelated port.
		795
		796	=item * Erlang uses unprotected connections, AEMP uses secure
		797	authentication and can use TLS.
		798
		799	AEMP can use a proven protocol - SSL/TLS - to protect connections and
		800	securely authenticate nodes.
		801
		802	=item * The AEMP protocol is optimised for both text-based and binary
		803	communications.
		804
		805	The AEMP protocol, unlike the Erlang protocol, supports both
		806	language-independent text-only protocols (good for debugging) and binary,
		807	language-specific serialisers (e.g. Storable).
		808
		809	It has also been carefully designed to be implementable in other languages
		810	with a minimum of work while gracefully degrading fucntionality to make the
		811	protocol simple.
		812
		813	=item * AEMP has more flexible monitoring options than Erlang.
		814
		815	In Erlang, you can chose to receive I<all> exit signals as messages
		816	or I<none>, there is no in-between, so monitoring single processes is
		817	difficult to implement. Monitoring in AEMP is more flexible than in
		818	Erlang, as one can choose between automatic kill, exit message or callback
		819	on a per-process basis.
		820
		821	=item * Erlang tries to hide remote/local connections, AEMP does not.
		822
		823	Monitoring in Erlang is not an indicator of process death/crashes,
		824	as linking is (except linking is unreliable in Erlang).
		825
		826	In AEMP, you don't "look up" registered port names or send to named ports
		827	that might or might not be persistent. Instead, you normally spawn a port
		828	on the remote node. The init function monitors the you, and you monitor
		829	the remote port. Since both monitors are local to the node, they are much
		830	more reliable.
		831
		832	This also saves round-trips and avoids sending messages to the wrong port
		833	(hard to do in Erlang).
453		834
454	=back	835	=back
455		836
456	=head1 NODE MESSAGES	837	=head1 RATIONALE
457
458	Nodes understand the following messages sent to them. Many of them take
459	arguments called C<@reply>, which will simply be used to compose a reply
460	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
461	the remaining arguments are simply the message data.
462		838
463	=over 4	839	=over 4
464		840
465	=cut	841	=item Why strings for ports and noderefs, why not objects?
466		842
467	=item lookup => $name, @reply	843	We considered "objects", but found that the actual number of methods
		844	thatc an be called are very low. Since port IDs and noderefs travel over
		845	the network frequently, the serialising/deserialising would add lots of
		846	overhead, as well as having to keep a proxy object.
468		847
469	Replies with the port ID of the specified well-known port, or C<undef>.	848	Strings can easily be printed, easily serialised etc. and need no special
		849	procedures to be "valid".
470		850
471	=item devnull => ...	851	And a a miniport consists of a single closure stored in a global hash - it
		852	can't become much cheaper.
472		853
473	Generic data sink/CPU heat conversion.	854	=item Why favour JSON, why not real serialising format such as Storable?
474		855
475	=item relay => $port, @msg	856	In fact, any AnyEvent::MP node will happily accept Storable as framing
		857	format, but currently there is no way to make a node use Storable by
		858	default.
476		859
477	Simply forwards the message to the given port.	860	The default framing protocol is JSON because a) JSON::XS is many times
		861	faster for small messages and b) most importantly, after years of
		862	experience we found that object serialisation is causing more problems
		863	than it gains: Just like function calls, objects simply do not travel
		864	easily over the network, mostly because they will always be a copy, so you
		865	always have to re-think your design.
478		866
479	=item eval => $string[ @reply]	867	Keeping your messages simple, concentrating on data structures rather than
480		868	objects, will keep your messages clean, tidy and efficient.
481	Evaluates the given string. If C<@reply> is given, then a message of the
482	form C<@reply, $@, @evalres> is sent.
483
484	Example: crash another node.
485
486	snd $othernode, eval => "exit";
487
488	=item time => @reply
489
490	Replies the the current node time to C<@reply>.
491
492	Example: tell the current node to send the current time to C<$myport> in a
493	C<timereply> message.
494
495	snd $NODE, time => $myport, timereply => 1, 2;
496	# => snd $myport, timereply => 1, 2, <time>
497		869
498	=back	870	=back
499		871
500	=head1 SEE ALSO	872	=head1 SEE ALSO
501		873

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Revision 1.60 by root, Mon Aug 24 08:04:52 2009 UTC