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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.30 by root, Tue Aug 4 23:35:51 2009 UTC vs.
Revision 1.61 by root, Mon Aug 24 08:06:49 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		46	AnyEvent::MP::Intro - outdated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
…		…
35	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	59	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
36	manual page.	60	manual page.
37		61
38	At the moment, this module family is severly broken and underdocumented,	62	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 -	63	so do not use. This was uploaded mainly to reserve the CPAN namespace -
40	stay tuned! The basic API should be finished, however.	64	stay tuned!
41		65
42	=head1 CONCEPTS	66	=head1 CONCEPTS
43		67
44	=over 4	68	=over 4
45		69
46	=item port	70	=item port
47		71
48	A port is something you can send messages to (with the C<snd> function).	72	A port is something you can send messages to (with the C<snd> function).
49		73
50	Some ports allow you to register C<rcv> handlers that can match specific	74	Ports allow you to register C<rcv> handlers that can match all or just
51	messages. All C<rcv> handlers will receive messages they match, messages	75	some messages. Messages will not be queued.
52	will not be queued.
53		76
54	=item port id - C<noderef#portname>	77	=item port id - C<noderef#portname>
55		78
56	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	79	A port ID is the concatenation of a noderef, a hash-mark (C<#>) as
57	separator, and a port name (a printable string of unspecified format). An	80	separator, and a port name (a printable string of unspecified format). An
58	exception is the the node port, whose ID is identical to its node	81	exception is the the node port, whose ID is identical to its node
59	reference.	82	reference.
60		83
61	=item node	84	=item node
62		85
63	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,
64	port. You can send messages to node ports to find existing ports or to	87	which provides nodes to manage each other remotely, and to create new
65	create new ports, among other things.	88	ports.
66		89
67	Nodes are either private (single-process only), slaves (connected to a	90	Nodes are either private (single-process only), slaves (connected to a
68	master node only) or public nodes (connectable from unrelated nodes).	91	master node only) or public nodes (connectable from unrelated nodes).
69		92
70	=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>
…		…
90		113
91	=cut	114	=cut
92		115
93	package AnyEvent::MP;	116	package AnyEvent::MP;
94		117
95	use AnyEvent::MP::Base;	118	use AnyEvent::MP::Kernel;
96		119
97	use common::sense;	120	use common::sense;
98		121
99	use Carp ();	122	use Carp ();
100		123
101	use AE ();	124	use AE ();
102		125
103	use base "Exporter";	126	use base "Exporter";
104		127
105	our $VERSION = '0.1';	128	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		129
106	our @EXPORT = qw(	130	our @EXPORT = qw(
107	NODE $NODE *SELF node_of _any_	131	NODE $NODE *SELF node_of after
108	resolve_node	132	resolve_node initialise_node
109	become_slave become_public
110	snd rcv mon kil reg psub	133	snd rcv mon mon_guard kil reg psub spawn
111	port	134	port
112	);	135	);
113		136
114	our $SELF;	137	our $SELF;
115		138
…		…
119	kil $SELF, die => $msg;	142	kil $SELF, die => $msg;
120	}	143	}
121		144
122	=item $thisnode = NODE / $NODE	145	=item $thisnode = NODE / $NODE
123		146
124	The C<NODE> function returns, and the C<$NODE> variable contains	147	The C<NODE> function returns, and the C<$NODE> variable contains the
125	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
126	to C<become_public> or C<become_slave>, after which all local port	149	C<initialise_node>.
127	identifiers become invalid.
128		150
129	=item $noderef = node_of $portid	151	=item $noderef = node_of $port
130		152
131	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";
132		244
133	=item $cv = resolve_node $noderef	245	=item $cv = resolve_node $noderef
134		246
135	Takes an unresolved node reference that may contain hostnames and	247	Takes an unresolved node reference that may contain hostnames and
136	abbreviated IDs, resolves all of them and returns a resolved node	248	abbreviated IDs, resolves all of them and returns a resolved node
…		…
168		280
169	Due to some quirks in how perl exports variables, it is impossible to	281	Due to some quirks in how perl exports variables, it is impossible to
170	just export C<$SELF>, all the symbols called C<SELF> are exported by this	282	just export C<$SELF>, all the symbols called C<SELF> are exported by this
171	module, but only C<$SELF> is currently used.	283	module, but only C<$SELF> is currently used.
172		284
173	=item snd $portid, type => @data	285	=item snd $port, type => @data
174		286
175	=item snd $portid, @msg	287	=item snd $port, @msg
176		288
177	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
178	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.
179	stringifies a sa port ID (such as a port object :).
180		291
181	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
182	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
183	type etc.).	294	type etc.).
184		295
185	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
186	function: modifying any argument is not allowed and can cause many	297	function: modifying any argument is not allowed and can cause many
187	problems.	298	problems.
…		…
190	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
191	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
192	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
193	node, anything can be passed.	304	node, anything can be passed.
194		305
195	=item kil $portid[, @reason]	306	=item $local_port = port
196		307
197	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.
198		310
199	If no C<@reason> is specified, then the port is killed "normally" (linked	311	=item $local_port = port { my @msg = @_ }
200	ports will not be kileld, or even notified).
201		312
202	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
203	C<mon>, see below).	314	creating a port and calling C<rcv $port, $callback> on it.
204		315
205	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
206	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.
207		320
208	Transport/communication errors are reported as C<< transport_error =>	321	If you want to stop/destroy the port, simply C<kil> it:
209	$message >>.
210		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
211	=item $guard = mon $portid, $cb->(@reason)	490	=item $guard = mon $port, $cb->(@reason)
212		491
213	=item $guard = mon $portid, $otherport	492	=item $guard = mon $port, $rcvport
214		493
		494	=item $guard = mon $port
		495
215	=item $guard = mon $portid, $otherport, @msg	496	=item $guard = mon $port, $rcvport, @msg
216		497
217	Monitor the given port and do something when the port is killed.	498	Monitor the given port and do something when the port is killed or
		499	messages to it were lost, and optionally return a guard that can be used
		500	to stop monitoring again.
218		501
		502	C<mon> effectively guarantees that, in the absence of hardware failures,
		503	that after starting the monitor, either all messages sent to the port
		504	will arrive, or the monitoring action will be invoked after possible
		505	message loss has been detected. No messages will be lost "in between"
		506	(after the first lost message no further messages will be received by the
		507	port). After the monitoring action was invoked, further messages might get
		508	delivered again.
		509
		510	Note that monitoring-actions are one-shot: once released, they are removed
		511	and will not trigger again.
		512
219	In the first form, the callback is simply called with any number	513	In the first form (callback), the callback is simply called with any
220	of C<@reason> elements (no @reason means that the port was deleted	514	number of C<@reason> elements (no @reason means that the port was deleted
221	"normally"). Note also that I<< the callback B<must> never die >>, so use	515	"normally"). Note also that I<< the callback B<must> never die >>, so use
222	C<eval> if unsure.	516	C<eval> if unsure.
223		517
224	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	518	In the second form (another port given), the other port (C<$rcvport>)
225	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
226	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.
227		522
		523	The third form (kill self) is the same as the second form, except that
		524	C<$rvport> defaults to C<$SELF>.
		525
228	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.
229		535
230	Example: call a given callback when C<$port> is killed.	536	Example: call a given callback when C<$port> is killed.
231		537
232	mon $port, sub { warn "port died because of <@_>\n" };	538	mon $port, sub { warn "port died because of <@_>\n" };
233		539
234	Example: kill ourselves when C<$port> is killed abnormally.	540	Example: kill ourselves when C<$port> is killed abnormally.
235		541
236	mon $port, $self;	542	mon $port;
237		543
238	Example: send us a restart message another C<$port> is killed.	544	Example: send us a restart message when another C<$port> is killed.
239		545
240	mon $port, $self => "restart";	546	mon $port, $self => "restart";
241		547
242	=cut	548	=cut
243		549
244	sub mon {	550	sub mon {
245	my ($noderef, $port) = split /#/, shift, 2;	551	my ($noderef, $port) = split /#/, shift, 2;
246		552
247	my $node = $NODE{$noderef} \|\| add_node $noderef;	553	my $node = $NODE{$noderef} \|\| add_node $noderef;
248		554
249	my $cb = shift;	555	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
250		556
251	unless (ref $cb) {	557	unless (ref $cb) {
252	if (@_) {	558	if (@_) {
253	# send a kill info message	559	# send a kill info message
254	my (@msg) = ($cb, @_);	560	my (@msg) = ($cb, @_);
…		…
285	=cut	591	=cut
286		592
287	sub mon_guard {	593	sub mon_guard {
288	my ($port, @refs) = @_;	594	my ($port, @refs) = @_;
289		595
		596	#TODO: mon-less form?
		597
290	mon $port, sub { 0 && @refs }	598	mon $port, sub { 0 && @refs }
291	}	599	}
292		600
293	=item lnk $port1, $port2	601	=item kil $port[, @reason]
294		602
295	Link two ports. This is simply a shorthand for:	603	Kill the specified port with the given C<@reason>.
296		604
297	mon $port1, $port2;	605	If no C<@reason> is specified, then the port is killed "normally" (linked
298	mon $port2, $port1;	606	ports will not be kileld, or even notified).
299		607
300	It means that if either one is killed abnormally, the other one gets	608	Otherwise, linked ports get killed with the same reason (second form of
301	killed as well.	609	C<mon>, see below).
302		610
303	=item $local_port = port	611	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		612	will be reported as reason C<< die => $@ >>.
304		613
305	Create a new local port object that supports message matching.	614	Transport/communication errors are reported as C<< transport_error =>
		615	$message >>.
306		616
307	=item $portid = port { my @msg = @_; $finished }
308
309	Creates a "mini port", that is, a very lightweight port without any
310	pattern matching behind it, and returns its ID.
311
312	The block will be called for every message received on the port. When the
313	callback returns a true value its job is considered "done" and the port
314	will be destroyed. Otherwise it will stay alive.
315
316	The message will be passed as-is, no extra argument (i.e. no port id) will
317	be passed to the callback.
318
319	If you need the local port id in the callback, this works nicely:
320
321	my $port; $port = miniport {
322	snd $otherport, reply => $port;
323	};
324
325	=cut	617	=cut
326		618
327	sub port(;&) {	619	=item $port = spawn $node, $initfunc[, @initdata]
328	my $id = "$UNIQ." . $ID++;
329	my $port = "$NODE#$id";
330		620
331	if (@_) {	621	Creates a port on the node C<$node> (which can also be a port ID, in which
332	my $cb = shift;	622	case it's the node where that port resides).
333	$PORT{$id} = sub {	623
334	local $SELF = $port;	624	The port ID of the newly created port is return immediately, and it is
335	eval {	625	permissible to immediately start sending messages or monitor the port.
336	&$cb	626
337	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 {
338	};	657	...
339	_self_die if $@;
340	};
341	} else {
342	my $self = bless {
343	id => "$NODE#$id",
344	}, "AnyEvent::MP::Port";
345
346	$PORT_DATA{$id} = $self;
347	$PORT{$id} = sub {
348	local $SELF = $port;
349
350	eval {
351	for (@{ $self->{rc0}{$_[0]} }) {
352	$_ && &{$_->[0]}
353	&& undef $_;
354	}
355
356	for (@{ $self->{rcv}{$_[0]} }) {
357	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
358	&& &{$_->[0]}
359	&& undef $_;
360	}
361
362	for (@{ $self->{any} }) {
363	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
364	&& &{$_->[0]}
365	&& undef $_;
366	}
367	};
368	_self_die if $@;
369	};	658	};
370	}	659	}
371		660
372	$port
373	}
374
375	=item reg $portid, $name
376
377	Registers the given port under the name C<$name>. If the name already
378	exists it is replaced.
379
380	A port can only be registered under one well known name.
381
382	A port automatically becomes unregistered when it is killed.
383
384	=cut	661	=cut
385		662
386	sub reg(@) {	663	sub _spawn {
387	my ($portid, $name) = @_;	664	my $port = shift;
		665	my $init = shift;
388		666
389	$REG{$name} = $portid;	667	local $SELF = "$NODE#$port";
390	}	668	eval {
391		669	&{ load_func $init }
392	=item rcv $portid, tagstring => $callback->(@msg), ...
393
394	=item rcv $portid, $smartmatch => $callback->(@msg), ...
395
396	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
397
398	Register callbacks to be called on matching messages on the given port.
399
400	The callback has to return a true value when its work is done, after
401	which is will be removed, or a false value in which case it will stay
402	registered.
403
404	The global C<$SELF> (exported by this module) contains C<$portid> while
405	executing the callback.
406
407	Runtime errors wdurign callback execution will result in the port being
408	C<kil>ed.
409
410	If the match is an array reference, then it will be matched against the
411	first elements of the message, otherwise only the first element is being
412	matched.
413
414	Any element in the match that is specified as C<_any_> (a function
415	exported by this module) matches any single element of the message.
416
417	While not required, it is highly recommended that the first matching
418	element is a string identifying the message. The one-string-only match is
419	also the most efficient match (by far).
420
421	=cut
422
423	sub rcv($@) {
424	my ($noderef, $port) = split /#/, shift, 2;
425
426	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
427	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";
428
429	my $self = $PORT_DATA{$port}
430	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
431
432	"AnyEvent::MP::Port" eq ref $self
433	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
434
435	while (@_) {
436	my ($match, $cb) = splice @_, 0, 2;
437
438	if (!ref $match) {
439	push @{ $self->{rc0}{$match} }, [$cb];
440	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
441	my ($type, @match) = @$match;
442	@match
443	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
444	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
445	} else {
446	push @{ $self->{any} }, [$cb, $match];
447	}
448	}
449	}
450
451	=item $closure = psub { BLOCK }
452
453	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
454	closure is executed, sets up the environment in the same way as in C<rcv>
455	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
456
457	This is useful when you register callbacks from C<rcv> callbacks:
458
459	rcv delayed_reply => sub {
460	my ($delay, @reply) = @_;
461	my $timer = AE::timer $delay, 0, psub {
462	snd @reply, $SELF;
463	};
464	};	670	};
465
466	=cut
467
468	sub psub(&) {
469	my $cb = shift;
470
471	my $port = $SELF
472	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
473
474	sub {
475	local $SELF = $port;
476
477	if (wantarray) {
478	my @res = eval { &$cb };
479	_self_die if $@;	671	_self_die if $@;
480	@res	672	}
481	} else {	673
482	my $res = eval { &$cb };	674	sub spawn(@) {
483	_self_die if $@;	675	my ($noderef, undef) = split /#/, shift, 2;
484	$res	676
485	}	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;
486	}	706	};
487	}	707	}
488		708
489	=back	709	=back
490		710
491	=head1 FUNCTIONS FOR NODES
492
493	=over 4
494
495	=item become_public $noderef
496
497	Tells the node to become a public node, i.e. reachable from other nodes.
498
499	The first argument is the (unresolved) node reference of the local node
500	(if missing then the empty string is used).
501
502	It is quite common to not specify anything, in which case the local node
503	tries to listen on the default port, or to only specify a port number, in
504	which case AnyEvent::MP tries to guess the local addresses.
505
506	=cut
507
508	=back
509
510	=head1 NODE MESSAGES
511
512	Nodes understand the following messages sent to them. Many of them take
513	arguments called C<@reply>, which will simply be used to compose a reply
514	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
515	the remaining arguments are simply the message data.
516
517	While other messages exist, they are not public and subject to change.
518
519	=over 4
520
521	=cut
522
523	=item lookup => $name, @reply
524
525	Replies with the port ID of the specified well-known port, or C<undef>.
526
527	=item devnull => ...
528
529	Generic data sink/CPU heat conversion.
530
531	=item relay => $port, @msg
532
533	Simply forwards the message to the given port.
534
535	=item eval => $string[ @reply]
536
537	Evaluates the given string. If C<@reply> is given, then a message of the
538	form C<@reply, $@, @evalres> is sent.
539
540	Example: crash another node.
541
542	snd $othernode, eval => "exit";
543
544	=item time => @reply
545
546	Replies the the current node time to C<@reply>.
547
548	Example: tell the current node to send the current time to C<$myport> in a
549	C<timereply> message.
550
551	snd $NODE, time => $myport, timereply => 1, 2;
552	# => snd $myport, timereply => 1, 2, <time>
553
554	=back
555
556	=head1 AnyEvent::MP vs. Distributed Erlang	711	=head1 AnyEvent::MP vs. Distributed Erlang
557		712
558	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node	713	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
559	== aemp node, erlang process == aemp port), so many of the documents and	714	== aemp node, Erlang process == aemp port), so many of the documents and
560	programming techniques employed by erlang apply to AnyEvent::MP. Here is a	715	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
561	sample:	716	sample:
562		717
563	http://www.erlang.se/doc/programming_rules.shtml	718	http://www.Erlang.se/doc/programming_rules.shtml
564	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	719	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
565	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6	720	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
566	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5	721	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
567		722
568	Despite the similarities, there are also some important differences:	723	Despite the similarities, there are also some important differences:
569		724
570	=over 4	725	=over 4
571		726
…		…
576	convenience functionality.	731	convenience functionality.
577		732
578	This means that AEMP requires a less tightly controlled environment at the	733	This means that AEMP requires a less tightly controlled environment at the
579	cost of longer node references and a slightly higher management overhead.	734	cost of longer node references and a slightly higher management overhead.
580		735
		736	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
		737	uses "local ports are like remote ports".
		738
		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
581	=item * Erlang uses processes and a mailbox, AEMP does not queue.	751	=item * Erlang uses processes and a mailbox, AEMP does not queue.
582		752
583	Erlang uses processes that selctively receive messages, and therefore	753	Erlang uses processes that selectively receive messages, and therefore
584	needs a queue. AEMP is event based, queuing messages would serve no useful	754	needs a queue. AEMP is event based, queuing messages would serve no
585	purpose.	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.
586		758
587	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	759	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
588		760
589	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	761	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
590		762
591	Sending messages in erlang is synchronous and blocks the process. AEMP	763	Sending messages in Erlang is synchronous and blocks the process (and
592	sends are immediate, connection establishment is handled in the	764	so does not need a queue that can overflow). AEMP sends are immediate,
593	background.	765	connection establishment is handled in the background.
594		766
595	=item * Erlang can silently lose messages, AEMP cannot.	767	=item * Erlang suffers from silent message loss, AEMP does not.
596		768
597	Erlang makes few guarantees on messages delivery - messages can get lost	769	Erlang makes few guarantees on messages delivery - messages can get lost
598	without any of the processes realising it (i.e. you send messages a, b,	770	without any of the processes realising it (i.e. you send messages a, b,
599	and c, and the other side only receives messages a and c).	771	and c, and the other side only receives messages a and c).
600		772
601	AEMP guarantees correct ordering, and the guarantee that there are no	773	AEMP guarantees correct ordering, and the guarantee that there are no
602	holes in the message sequence.	774	holes in the message sequence.
603		775
604	=item * In erlang, processes can be declared dead and later be found to be	776	=item * In Erlang, processes can be declared dead and later be found to be
605	alive.	777	alive.
606		778
607	In erlang it can happen that a monitored process is declared dead and	779	In Erlang it can happen that a monitored process is declared dead and
608	linked processes get killed, but later it turns out that the process is	780	linked processes get killed, but later it turns out that the process is
609	still alive - and can receive messages.	781	still alive - and can receive messages.
610		782
611	In AEMP, when port monitoring detects a port as dead, then that port will	783	In AEMP, when port monitoring detects a port as dead, then that port will
612	eventually be killed - it cannot happen that a node detects a port as dead	784	eventually be killed - it cannot happen that a node detects a port as dead
613	and then later sends messages to it, finding it is still alive.	785	and then later sends messages to it, finding it is still alive.
614		786
615	=item * Erlang can send messages to the wrong port, AEMP does not.	787	=item * Erlang can send messages to the wrong port, AEMP does not.
616		788
617	In erlang it is quite possible that a node that restarts reuses a process	789	In Erlang it is quite likely that a node that restarts reuses a process ID
618	ID known to other nodes for a completely different process, causing	790	known to other nodes for a completely different process, causing messages
619	messages destined for that process to end up in an unrelated process.	791	destined for that process to end up in an unrelated process.
620		792
621	AEMP never reuses port IDs, so old messages or old port IDs floating	793	AEMP never reuses port IDs, so old messages or old port IDs floating
622	around in the network will not be sent to an unrelated port.	794	around in the network will not be sent to an unrelated port.
623		795
624	=item * Erlang uses unprotected connections, AEMP uses secure	796	=item * Erlang uses unprotected connections, AEMP uses secure
…		…
628	securely authenticate nodes.	800	securely authenticate nodes.
629		801
630	=item * The AEMP protocol is optimised for both text-based and binary	802	=item * The AEMP protocol is optimised for both text-based and binary
631	communications.	803	communications.
632		804
633	The AEMP protocol, unlike the erlang protocol, supports both	805	The AEMP protocol, unlike the Erlang protocol, supports both
634	language-independent text-only protocols (good for debugging) and binary,	806	language-independent text-only protocols (good for debugging) and binary,
635	language-specific serialisers (e.g. Storable).	807	language-specific serialisers (e.g. Storable).
636		808
637	It has also been carefully designed to be implementable in other languages	809	It has also been carefully designed to be implementable in other languages
638	with a minimum of work while gracefully degrading fucntionality to make the	810	with a minimum of work while gracefully degrading fucntionality to make the
639	protocol simple.	811	protocol simple.
640		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).
		834
		835	=back
		836
		837	=head1 RATIONALE
		838
		839	=over 4
		840
		841	=item Why strings for ports and noderefs, why not objects?
		842
		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.
		847
		848	Strings can easily be printed, easily serialised etc. and need no special
		849	procedures to be "valid".
		850
		851	And a a miniport consists of a single closure stored in a global hash - it
		852	can't become much cheaper.
		853
		854	=item Why favour JSON, why not real serialising format such as Storable?
		855
		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.
		859
		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.
		866
		867	Keeping your messages simple, concentrating on data structures rather than
		868	objects, will keep your messages clean, tidy and efficient.
		869
641	=back	870	=back
642		871
643	=head1 SEE ALSO	872	=head1 SEE ALSO
644		873
645	L<AnyEvent>.	874	L<AnyEvent>.

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Revision 1.61 by root, Mon Aug 24 08:06:49 2009 UTC