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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.31 by root, Wed Aug 5 19:55:58 2009 UTC vs.
Revision 1.56 by root, Sat Aug 15 04:12:38 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		46	AnyEvent::MP::Intro - outdated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 _any_
108	resolve_node initialise_node	132	resolve_node initialise_node
109	snd rcv mon kil reg psub	133	snd rcv mon kil reg psub spawn
110	port	134	port
111	);	135	);
112		136
113	our $SELF;	137	our $SELF;
114		138
…		…
118	kil $SELF, die => $msg;	142	kil $SELF, die => $msg;
119	}	143	}
120		144
121	=item $thisnode = NODE / $NODE	145	=item $thisnode = NODE / $NODE
122		146
123	The C<NODE> function returns, and the C<$NODE> variable contains	147	The C<NODE> function returns, and the C<$NODE> variable contains the
124	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
125	to C<become_public> or C<become_slave>, after which all local port	149	C<initialise_node>.
126	identifiers become invalid.
127		150
128	=item $noderef = node_of $portid	151	=item $noderef = node_of $port
129		152
130	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";
131		244
132	=item $cv = resolve_node $noderef	245	=item $cv = resolve_node $noderef
133		246
134	Takes an unresolved node reference that may contain hostnames and	247	Takes an unresolved node reference that may contain hostnames and
135	abbreviated IDs, resolves all of them and returns a resolved node	248	abbreviated IDs, resolves all of them and returns a resolved node
…		…
167		280
168	Due to some quirks in how perl exports variables, it is impossible to	281	Due to some quirks in how perl exports variables, it is impossible to
169	just export C<$SELF>, all the symbols called C<SELF> are exported by this	282	just export C<$SELF>, all the symbols called C<SELF> are exported by this
170	module, but only C<$SELF> is currently used.	283	module, but only C<$SELF> is currently used.
171		284
172	=item snd $portid, type => @data	285	=item snd $port, type => @data
173		286
174	=item snd $portid, @msg	287	=item snd $port, @msg
175		288
176	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
177	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.
178	stringifies a sa port ID (such as a port object :).
179		291
180	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
181	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
182	type etc.).	294	type etc.).
183		295
184	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
185	function: modifying any argument is not allowed and can cause many	297	function: modifying any argument is not allowed and can cause many
186	problems.	298	problems.
…		…
189	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
190	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
191	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
192	node, anything can be passed.	304	node, anything can be passed.
193		305
194	=item kil $portid[, @reason]	306	=item $local_port = port
195		307
196	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.
197		310
198	If no C<@reason> is specified, then the port is killed "normally" (linked	311	=item $local_port = port { my @msg = @_ }
199	ports will not be kileld, or even notified).
200		312
201	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
202	C<mon>, see below).	314	creating a port and calling C<rcv $port, $callback> on it.
203		315
204	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
205	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.
206		320
207	Transport/communication errors are reported as C<< transport_error =>	321	If you want to stop/destroy the port, simply C<kil> it:
208	$message >>.
209		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} \|\| add_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
210	=item $guard = mon $portid, $cb->(@reason)	490	=item $guard = mon $port, $cb->(@reason)
211		491
212	=item $guard = mon $portid, $otherport	492	=item $guard = mon $port, $rcvport
213		493
		494	=item $guard = mon $port
		495
214	=item $guard = mon $portid, $otherport, @msg	496	=item $guard = mon $port, $rcvport, @msg
215		497
216	Monitor the given port and do something when the port is killed.	498	Monitor the given port and do something when the port is killed or
		499	messages to it were lost, and optionally return a guard that can be used
		500	to stop monitoring again.
217		501
		502	C<mon> effectively guarantees that, in the absence of hardware failures,
		503	that after starting the monitor, either all messages sent to the port
		504	will arrive, or the monitoring action will be invoked after possible
		505	message loss has been detected. No messages will be lost "in between"
		506	(after the first lost message no further messages will be received by the
		507	port). After the monitoring action was invoked, further messages might get
		508	delivered again.
		509
218	In the first form, the callback is simply called with any number	510	In the first form (callback), the callback is simply called with any
219	of C<@reason> elements (no @reason means that the port was deleted	511	number of C<@reason> elements (no @reason means that the port was deleted
220	"normally"). Note also that I<< the callback B<must> never die >>, so use	512	"normally"). Note also that I<< the callback B<must> never die >>, so use
221	C<eval> if unsure.	513	C<eval> if unsure.
222		514
223	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	515	In the second form (another port given), the other port (C<$rcvport>)
224	a @reason was specified, i.e. on "normal" kils nothing happens, while	516	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
225	under all other conditions, the other port is killed with the same reason.	517	"normal" kils nothing happens, while under all other conditions, the other
		518	port is killed with the same reason.
226		519
		520	The third form (kill self) is the same as the second form, except that
		521	C<$rvport> defaults to C<$SELF>.
		522
227	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	523	In the last form (message), a message of the form C<@msg, @reason> will be
		524	C<snd>.
		525
		526	As a rule of thumb, monitoring requests should always monitor a port from
		527	a local port (or callback). The reason is that kill messages might get
		528	lost, just like any other message. Another less obvious reason is that
		529	even monitoring requests can get lost (for exmaple, when the connection
		530	to the other node goes down permanently). When monitoring a port locally
		531	these problems do not exist.
228		532
229	Example: call a given callback when C<$port> is killed.	533	Example: call a given callback when C<$port> is killed.
230		534
231	mon $port, sub { warn "port died because of <@_>\n" };	535	mon $port, sub { warn "port died because of <@_>\n" };
232		536
233	Example: kill ourselves when C<$port> is killed abnormally.	537	Example: kill ourselves when C<$port> is killed abnormally.
234		538
235	mon $port, $self;	539	mon $port;
236		540
237	Example: send us a restart message another C<$port> is killed.	541	Example: send us a restart message when another C<$port> is killed.
238		542
239	mon $port, $self => "restart";	543	mon $port, $self => "restart";
240		544
241	=cut	545	=cut
242		546
243	sub mon {	547	sub mon {
244	my ($noderef, $port) = split /#/, shift, 2;	548	my ($noderef, $port) = split /#/, shift, 2;
245		549
246	my $node = $NODE{$noderef} \|\| add_node $noderef;	550	my $node = $NODE{$noderef} \|\| add_node $noderef;
247		551
248	my $cb = shift;	552	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
249		553
250	unless (ref $cb) {	554	unless (ref $cb) {
251	if (@_) {	555	if (@_) {
252	# send a kill info message	556	# send a kill info message
253	my (@msg) = ($cb, @_);	557	my (@msg) = ($cb, @_);
…		…
284	=cut	588	=cut
285		589
286	sub mon_guard {	590	sub mon_guard {
287	my ($port, @refs) = @_;	591	my ($port, @refs) = @_;
288		592
		593	#TODO: mon-less form?
		594
289	mon $port, sub { 0 && @refs }	595	mon $port, sub { 0 && @refs }
290	}	596	}
291		597
292	=item lnk $port1, $port2	598	=item kil $port[, @reason]
293		599
294	Link two ports. This is simply a shorthand for:	600	Kill the specified port with the given C<@reason>.
295		601
296	mon $port1, $port2;	602	If no C<@reason> is specified, then the port is killed "normally" (linked
297	mon $port2, $port1;	603	ports will not be kileld, or even notified).
298		604
299	It means that if either one is killed abnormally, the other one gets	605	Otherwise, linked ports get killed with the same reason (second form of
300	killed as well.	606	C<mon>, see below).
301		607
302	=item $local_port = port	608	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		609	will be reported as reason C<< die => $@ >>.
303		610
304	Create a new local port object that can be used either as a pattern	611	Transport/communication errors are reported as C<< transport_error =>
305	matching port ("full port") or a single-callback port ("miniport"),	612	$message >>.
306	depending on how C<rcv> callbacks are bound to the object.
307
308	=item $portid = port { my @msg = @_; $finished }
309
310	Creates a "mini port", that is, a very lightweight port without any
311	pattern matching behind it, and returns its ID.
312
313	The block will be called for every message received on the port. When the
314	callback returns a true value its job is considered "done" and the port
315	will be destroyed. Otherwise it will stay alive.
316
317	The message will be passed as-is, no extra argument (i.e. no port id) will
318	be passed to the callback.
319
320	If you need the local port id in the callback, this works nicely:
321
322	my $port; $port = port {
323	snd $otherport, reply => $port;
324	};
325		613
326	=cut	614	=cut
327		615
328	sub port(;&) {	616	=item $port = spawn $node, $initfunc[, @initdata]
329	my $id = "$UNIQ." . $ID++;
330	my $port = "$NODE#$id";
331		617
332	if (@_) {	618	Creates a port on the node C<$node> (which can also be a port ID, in which
333	my $cb = shift;	619	case it's the node where that port resides).
334	$PORT{$id} = sub {	620
335	local $SELF = $port;	621	The port ID of the newly created port is return immediately, and it is
336	eval {	622	permissible to immediately start sending messages or monitor the port.
337	&$cb	623
338	and kil $id;	624	After the port has been created, the init function is
		625	called. This function must be a fully-qualified function name
		626	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		627	program, use C<::name>.
		628
		629	If the function doesn't exist, then the node tries to C<require>
		630	the package, then the package above the package and so on (e.g.
		631	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		632	exists or it runs out of package names.
		633
		634	The init function is then called with the newly-created port as context
		635	object (C<$SELF>) and the C<@initdata> values as arguments.
		636
		637	A common idiom is to pass your own port, monitor the spawned port, and
		638	in the init function, monitor the original port. This two-way monitoring
		639	ensures that both ports get cleaned up when there is a problem.
		640
		641	Example: spawn a chat server port on C<$othernode>.
		642
		643	# this node, executed from within a port context:
		644	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		645	mon $server;
		646
		647	# init function on C<$othernode>
		648	sub connect {
		649	my ($srcport) = @_;
		650
		651	mon $srcport;
		652
		653	rcv $SELF, sub {
339	};	654	...
340	_self_die if $@;
341	};
342	} else {
343	my $self = bless {
344	id => "$NODE#$id",
345	}, "AnyEvent::MP::Port";
346
347	$PORT_DATA{$id} = $self;
348	$PORT{$id} = sub {
349	local $SELF = $port;
350
351	eval {
352	for (@{ $self->{rc0}{$_[0]} }) {
353	$_ && &{$_->[0]}
354	&& undef $_;
355	}
356
357	for (@{ $self->{rcv}{$_[0]} }) {
358	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
359	&& &{$_->[0]}
360	&& undef $_;
361	}
362
363	for (@{ $self->{any} }) {
364	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
365	&& &{$_->[0]}
366	&& undef $_;
367	}
368	};
369	_self_die if $@;
370	};	655	};
371	}	656	}
372		657
373	$port	658	=cut
		659
		660	sub _spawn {
		661	my $port = shift;
		662	my $init = shift;
		663
		664	local $SELF = "$NODE#$port";
		665	eval {
		666	&{ load_func $init }
		667	};
		668	_self_die if $@;
374	}	669	}
375		670
376	=item reg $portid, $name	671	sub spawn(@) {
		672	my ($noderef, undef) = split /#/, shift, 2;
377		673
378	Registers the given port under the name C<$name>. If the name already	674	my $id = "$RUNIQ." . $ID++;
379	exists it is replaced.
380		675
381	A port can only be registered under one well known name.	676	$_[0] =~ /::/
		677	or Carp::croak "spawn init function must be a fully-qualified name, caught";
382		678
383	A port automatically becomes unregistered when it is killed.	679	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
384		680
385	=cut	681	"$noderef#$id"
386
387	sub reg(@) {
388	my ($portid, $name) = @_;
389
390	$REG{$name} = $portid;
391	}	682	}
392
393	=item rcv $portid, $callback->(@msg)
394
395	Replaces the callback on the specified miniport (or newly created port
396	object, see C<port>). Full ports are configured with the following calls:
397
398	=item rcv $portid, tagstring => $callback->(@msg), ...
399
400	=item rcv $portid, $smartmatch => $callback->(@msg), ...
401
402	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
403
404	Register callbacks to be called on matching messages on the given port.
405
406	The callback has to return a true value when its work is done, after
407	which is will be removed, or a false value in which case it will stay
408	registered.
409
410	The global C<$SELF> (exported by this module) contains C<$portid> while
411	executing the callback.
412
413	Runtime errors wdurign callback execution will result in the port being
414	C<kil>ed.
415
416	If the match is an array reference, then it will be matched against the
417	first elements of the message, otherwise only the first element is being
418	matched.
419
420	Any element in the match that is specified as C<_any_> (a function
421	exported by this module) matches any single element of the message.
422
423	While not required, it is highly recommended that the first matching
424	element is a string identifying the message. The one-string-only match is
425	also the most efficient match (by far).
426
427	=cut
428
429	sub rcv($@) {
430	my $portid = shift;
431	my ($noderef, $port) = split /#/, $port, 2;
432
433	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
434	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";
435
436	my $self = $PORT_DATA{$port}
437	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
438
439	"AnyEvent::MP::Port" eq ref $self
440	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
441
442	while (@_) {
443	my ($match, $cb) = splice @_, 0, 2;
444
445	if (!ref $match) {
446	push @{ $self->{rc0}{$match} }, [$cb];
447	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
448	my ($type, @match) = @$match;
449	@match
450	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
451	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
452	} else {
453	push @{ $self->{any} }, [$cb, $match];
454	}
455	}
456
457	$portid
458	}
459
460	=item $closure = psub { BLOCK }
461
462	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
463	closure is executed, sets up the environment in the same way as in C<rcv>
464	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
465
466	This is useful when you register callbacks from C<rcv> callbacks:
467
468	rcv delayed_reply => sub {
469	my ($delay, @reply) = @_;
470	my $timer = AE::timer $delay, 0, psub {
471	snd @reply, $SELF;
472	};
473	};
474
475	=cut
476
477	sub psub(&) {
478	my $cb = shift;
479
480	my $port = $SELF
481	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
482
483	sub {
484	local $SELF = $port;
485
486	if (wantarray) {
487	my @res = eval { &$cb };
488	_self_die if $@;
489	@res
490	} else {
491	my $res = eval { &$cb };
492	_self_die if $@;
493	$res
494	}
495	}
496	}
497
498	=back
499
500	=head1 FUNCTIONS FOR NODES
501
502	=over 4
503
504	=item become_public $noderef
505
506	Tells the node to become a public node, i.e. reachable from other nodes.
507
508	The first argument is the (unresolved) node reference of the local node
509	(if missing then the empty string is used).
510
511	It is quite common to not specify anything, in which case the local node
512	tries to listen on the default port, or to only specify a port number, in
513	which case AnyEvent::MP tries to guess the local addresses.
514
515	=cut
516		683
517	=back	684	=back
518		685
519	=head1 NODE MESSAGES	686	=head1 NODE MESSAGES
520		687
…		…
562		729
563	=back	730	=back
564		731
565	=head1 AnyEvent::MP vs. Distributed Erlang	732	=head1 AnyEvent::MP vs. Distributed Erlang
566		733
567	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node	734	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
568	== aemp node, erlang process == aemp port), so many of the documents and	735	== aemp node, Erlang process == aemp port), so many of the documents and
569	programming techniques employed by erlang apply to AnyEvent::MP. Here is a	736	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
570	sample:	737	sample:
571		738
572	http://www.erlang.se/doc/programming_rules.shtml	739	http://www.Erlang.se/doc/programming_rules.shtml
573	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	740	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
574	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6	741	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
575	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5	742	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
576		743
577	Despite the similarities, there are also some important differences:	744	Despite the similarities, there are also some important differences:
578		745
579	=over 4	746	=over 4
580		747
…		…
585	convenience functionality.	752	convenience functionality.
586		753
587	This means that AEMP requires a less tightly controlled environment at the	754	This means that AEMP requires a less tightly controlled environment at the
588	cost of longer node references and a slightly higher management overhead.	755	cost of longer node references and a slightly higher management overhead.
589		756
		757	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
		758	uses "local ports are like remote ports".
		759
		760	The failure modes for local ports are quite different (runtime errors
		761	only) then for remote ports - when a local port dies, you I<know> it dies,
		762	when a connection to another node dies, you know nothing about the other
		763	port.
		764
		765	Erlang pretends remote ports are as reliable as local ports, even when
		766	they are not.
		767
		768	AEMP encourages a "treat remote ports differently" philosophy, with local
		769	ports being the special case/exception, where transport errors cannot
		770	occur.
		771
590	=item * Erlang uses processes and a mailbox, AEMP does not queue.	772	=item * Erlang uses processes and a mailbox, AEMP does not queue.
591		773
592	Erlang uses processes that selctively receive messages, and therefore	774	Erlang uses processes that selectively receive messages, and therefore
593	needs a queue. AEMP is event based, queuing messages would serve no useful	775	needs a queue. AEMP is event based, queuing messages would serve no
594	purpose.	776	useful purpose. For the same reason the pattern-matching abilities of
		777	AnyEvent::MP are more limited, as there is little need to be able to
		778	filter messages without dequeing them.
595		779
596	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	780	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
597		781
598	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	782	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
599		783
600	Sending messages in erlang is synchronous and blocks the process. AEMP	784	Sending messages in Erlang is synchronous and blocks the process (and
601	sends are immediate, connection establishment is handled in the	785	so does not need a queue that can overflow). AEMP sends are immediate,
602	background.	786	connection establishment is handled in the background.
603		787
604	=item * Erlang can silently lose messages, AEMP cannot.	788	=item * Erlang suffers from silent message loss, AEMP does not.
605		789
606	Erlang makes few guarantees on messages delivery - messages can get lost	790	Erlang makes few guarantees on messages delivery - messages can get lost
607	without any of the processes realising it (i.e. you send messages a, b,	791	without any of the processes realising it (i.e. you send messages a, b,
608	and c, and the other side only receives messages a and c).	792	and c, and the other side only receives messages a and c).
609		793
610	AEMP guarantees correct ordering, and the guarantee that there are no	794	AEMP guarantees correct ordering, and the guarantee that there are no
611	holes in the message sequence.	795	holes in the message sequence.
612		796
613	=item * In erlang, processes can be declared dead and later be found to be	797	=item * In Erlang, processes can be declared dead and later be found to be
614	alive.	798	alive.
615		799
616	In erlang it can happen that a monitored process is declared dead and	800	In Erlang it can happen that a monitored process is declared dead and
617	linked processes get killed, but later it turns out that the process is	801	linked processes get killed, but later it turns out that the process is
618	still alive - and can receive messages.	802	still alive - and can receive messages.
619		803
620	In AEMP, when port monitoring detects a port as dead, then that port will	804	In AEMP, when port monitoring detects a port as dead, then that port will
621	eventually be killed - it cannot happen that a node detects a port as dead	805	eventually be killed - it cannot happen that a node detects a port as dead
622	and then later sends messages to it, finding it is still alive.	806	and then later sends messages to it, finding it is still alive.
623		807
624	=item * Erlang can send messages to the wrong port, AEMP does not.	808	=item * Erlang can send messages to the wrong port, AEMP does not.
625		809
626	In erlang it is quite possible that a node that restarts reuses a process	810	In Erlang it is quite likely that a node that restarts reuses a process ID
627	ID known to other nodes for a completely different process, causing	811	known to other nodes for a completely different process, causing messages
628	messages destined for that process to end up in an unrelated process.	812	destined for that process to end up in an unrelated process.
629		813
630	AEMP never reuses port IDs, so old messages or old port IDs floating	814	AEMP never reuses port IDs, so old messages or old port IDs floating
631	around in the network will not be sent to an unrelated port.	815	around in the network will not be sent to an unrelated port.
632		816
633	=item * Erlang uses unprotected connections, AEMP uses secure	817	=item * Erlang uses unprotected connections, AEMP uses secure
…		…
637	securely authenticate nodes.	821	securely authenticate nodes.
638		822
639	=item * The AEMP protocol is optimised for both text-based and binary	823	=item * The AEMP protocol is optimised for both text-based and binary
640	communications.	824	communications.
641		825
642	The AEMP protocol, unlike the erlang protocol, supports both	826	The AEMP protocol, unlike the Erlang protocol, supports both
643	language-independent text-only protocols (good for debugging) and binary,	827	language-independent text-only protocols (good for debugging) and binary,
644	language-specific serialisers (e.g. Storable).	828	language-specific serialisers (e.g. Storable).
645		829
646	It has also been carefully designed to be implementable in other languages	830	It has also been carefully designed to be implementable in other languages
647	with a minimum of work while gracefully degrading fucntionality to make the	831	with a minimum of work while gracefully degrading fucntionality to make the
648	protocol simple.	832	protocol simple.
649		833
		834	=item * AEMP has more flexible monitoring options than Erlang.
		835
		836	In Erlang, you can chose to receive I<all> exit signals as messages
		837	or I<none>, there is no in-between, so monitoring single processes is
		838	difficult to implement. Monitoring in AEMP is more flexible than in
		839	Erlang, as one can choose between automatic kill, exit message or callback
		840	on a per-process basis.
		841
		842	=item * Erlang tries to hide remote/local connections, AEMP does not.
		843
		844	Monitoring in Erlang is not an indicator of process death/crashes,
		845	as linking is (except linking is unreliable in Erlang).
		846
		847	In AEMP, you don't "look up" registered port names or send to named ports
		848	that might or might not be persistent. Instead, you normally spawn a port
		849	on the remote node. The init function monitors the you, and you monitor
		850	the remote port. Since both monitors are local to the node, they are much
		851	more reliable.
		852
		853	This also saves round-trips and avoids sending messages to the wrong port
		854	(hard to do in Erlang).
		855
		856	=back
		857
		858	=head1 RATIONALE
		859
		860	=over 4
		861
		862	=item Why strings for ports and noderefs, why not objects?
		863
		864	We considered "objects", but found that the actual number of methods
		865	thatc an be called are very low. Since port IDs and noderefs travel over
		866	the network frequently, the serialising/deserialising would add lots of
		867	overhead, as well as having to keep a proxy object.
		868
		869	Strings can easily be printed, easily serialised etc. and need no special
		870	procedures to be "valid".
		871
		872	And a a miniport consists of a single closure stored in a global hash - it
		873	can't become much cheaper.
		874
		875	=item Why favour JSON, why not real serialising format such as Storable?
		876
		877	In fact, any AnyEvent::MP node will happily accept Storable as framing
		878	format, but currently there is no way to make a node use Storable by
		879	default.
		880
		881	The default framing protocol is JSON because a) JSON::XS is many times
		882	faster for small messages and b) most importantly, after years of
		883	experience we found that object serialisation is causing more problems
		884	than it gains: Just like function calls, objects simply do not travel
		885	easily over the network, mostly because they will always be a copy, so you
		886	always have to re-think your design.
		887
		888	Keeping your messages simple, concentrating on data structures rather than
		889	objects, will keep your messages clean, tidy and efficient.
		890
650	=back	891	=back
651		892
652	=head1 SEE ALSO	893	=head1 SEE ALSO
653		894
654	L<AnyEvent>.	895	L<AnyEvent>.

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Revision 1.56 by root, Sat Aug 15 04:12:38 2009 UTC