[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 1.55 by root, Fri Aug 14 23:17:17 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		46	AnyEvent::MP::Intro - outdated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	=back
		203
		204	This function will block until all nodes have been resolved and, for slave
		205	nodes, until it has successfully established a connection to a master
		206	server.
		207
		208	Example: become a public node listening on the guessed noderef, or the one
		209	specified via C<aemp> for the current node. This should be the most common
		210	form of invocation for "daemon"-type nodes.
		211
		212	initialise_node;
		213
		214	Example: become a slave node to any of the the seednodes specified via
		215	C<aemp>. This form is often used for commandline clients.
		216
		217	initialise_node "slave/";
		218
		219	Example: become a slave node to any of the specified master servers. This
		220	form is also often used for commandline clients.
		221
		222	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
		223
		224	Example: become a public node, and try to contact some well-known master
		225	servers to become part of the network.
		226
		227	initialise_node undef, "master1", "master2";
		228
		229	Example: become a public node listening on port C<4041>.
		230
		231	initialise_node 4041;
		232
		233	Example: become a public node, only visible on localhost port 4044.
		234
		235	initialise_node "localhost:4044";
131		236
132	=item $cv = resolve_node $noderef	237	=item $cv = resolve_node $noderef
133		238
134	Takes an unresolved node reference that may contain hostnames and	239	Takes an unresolved node reference that may contain hostnames and
135	abbreviated IDs, resolves all of them and returns a resolved node	240	abbreviated IDs, resolves all of them and returns a resolved node
…		…
167		272
168	Due to some quirks in how perl exports variables, it is impossible to	273	Due to some quirks in how perl exports variables, it is impossible to
169	just export C<$SELF>, all the symbols called C<SELF> are exported by this	274	just export C<$SELF>, all the symbols called C<SELF> are exported by this
170	module, but only C<$SELF> is currently used.	275	module, but only C<$SELF> is currently used.
171		276
172	=item snd $portid, type => @data	277	=item snd $port, type => @data
173		278
174	=item snd $portid, @msg	279	=item snd $port, @msg
175		280
176	Send the given message to the given port ID, which can identify either	281	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	282	a local or a remote port, and must be a port ID.
178	stringifies a sa port ID (such as a port object :).
179		283
180	While the message can be about anything, it is highly recommended to use a	284	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	285	string as first element (a port ID, or some word that indicates a request
182	type etc.).	286	type etc.).
183		287
184	The message data effectively becomes read-only after a call to this	288	The message data effectively becomes read-only after a call to this
185	function: modifying any argument is not allowed and can cause many	289	function: modifying any argument is not allowed and can cause many
186	problems.	290	problems.
…		…
189	JSON is used, then only strings, numbers and arrays and hashes consisting	293	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	294	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	295	that Storable can serialise and deserialise is allowed, and for the local
192	node, anything can be passed.	296	node, anything can be passed.
193		297
194	=item kil $portid[, @reason]	298	=item $local_port = port
195		299
196	Kill the specified port with the given C<@reason>.	300	Create a new local port object and returns its port ID. Initially it has
		301	no callbacks set and will throw an error when it receives messages.
197		302
198	If no C<@reason> is specified, then the port is killed "normally" (linked	303	=item $local_port = port { my @msg = @_ }
199	ports will not be kileld, or even notified).
200		304
201	Otherwise, linked ports get killed with the same reason (second form of	305	Creates a new local port, and returns its ID. Semantically the same as
202	C<mon>, see below).	306	creating a port and calling C<rcv $port, $callback> on it.
203		307
204	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	308	The block will be called for every message received on the port, with the
205	will be reported as reason C<< die => $@ >>.	309	global variable C<$SELF> set to the port ID. Runtime errors will cause the
		310	port to be C<kil>ed. The message will be passed as-is, no extra argument
		311	(i.e. no port ID) will be passed to the callback.
206		312
207	Transport/communication errors are reported as C<< transport_error =>	313	If you want to stop/destroy the port, simply C<kil> it:
208	$message >>.
209		314
		315	my $port = port {
		316	my @msg = @_;
		317	...
		318	kil $SELF;
		319	};
		320
		321	=cut
		322
		323	sub rcv($@);
		324
		325	sub _kilme {
		326	die "received message on port without callback";
		327	}
		328
		329	sub port(;&) {
		330	my $id = "$UNIQ." . $ID++;
		331	my $port = "$NODE#$id";
		332
		333	rcv $port, shift \|\| \&_kilme;
		334
		335	$port
		336	}
		337
		338	=item rcv $local_port, $callback->(@msg)
		339
		340	Replaces the default callback on the specified port. There is no way to
		341	remove the default callback: use C<sub { }> to disable it, or better
		342	C<kil> the port when it is no longer needed.
		343
		344	The global C<$SELF> (exported by this module) contains C<$port> while
		345	executing the callback. Runtime errors during callback execution will
		346	result in the port being C<kil>ed.
		347
		348	The default callback received all messages not matched by a more specific
		349	C<tag> match.
		350
		351	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
		352
		353	Register (or replace) callbacks to be called on messages starting with the
		354	given tag on the given port (and return the port), or unregister it (when
		355	C<$callback> is C<$undef> or missing). There can only be one callback
		356	registered for each tag.
		357
		358	The original message will be passed to the callback, after the first
		359	element (the tag) has been removed. The callback will use the same
		360	environment as the default callback (see above).
		361
		362	Example: create a port and bind receivers on it in one go.
		363
		364	my $port = rcv port,
		365	msg1 => sub { ... },
		366	msg2 => sub { ... },
		367	;
		368
		369	Example: create a port, bind receivers and send it in a message elsewhere
		370	in one go:
		371
		372	snd $otherport, reply =>
		373	rcv port,
		374	msg1 => sub { ... },
		375	...
		376	;
		377
		378	Example: temporarily register a rcv callback for a tag matching some port
		379	(e.g. for a rpc reply) and unregister it after a message was received.
		380
		381	rcv $port, $otherport => sub {
		382	my @reply = @_;
		383
		384	rcv $SELF, $otherport;
		385	};
		386
		387	=cut
		388
		389	sub rcv($@) {
		390	my $port = shift;
		391	my ($noderef, $portid) = split /#/, $port, 2;
		392
		393	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
		394	or Carp::croak "$port: rcv can only be called on local ports, caught";
		395
		396	while (@_) {
		397	if (ref $_[0]) {
		398	if (my $self = $PORT_DATA{$portid}) {
		399	"AnyEvent::MP::Port" eq ref $self
		400	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		401
		402	$self->[2] = shift;
		403	} else {
		404	my $cb = shift;
		405	$PORT{$portid} = sub {
		406	local $SELF = $port;
		407	eval { &$cb }; _self_die if $@;
		408	};
		409	}
		410	} elsif (defined $_[0]) {
		411	my $self = $PORT_DATA{$portid} \|\|= do {
		412	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
		413
		414	$PORT{$portid} = sub {
		415	local $SELF = $port;
		416
		417	if (my $cb = $self->[1]{$_[0]}) {
		418	shift;
		419	eval { &$cb }; _self_die if $@;
		420	} else {
		421	&{ $self->[0] };
		422	}
		423	};
		424
		425	$self
		426	};
		427
		428	"AnyEvent::MP::Port" eq ref $self
		429	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		430
		431	my ($tag, $cb) = splice @_, 0, 2;
		432
		433	if (defined $cb) {
		434	$self->[1]{$tag} = $cb;
		435	} else {
		436	delete $self->[1]{$tag};
		437	}
		438	}
		439	}
		440
		441	$port
		442	}
		443
		444	=item $closure = psub { BLOCK }
		445
		446	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
		447	closure is executed, sets up the environment in the same way as in C<rcv>
		448	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		449
		450	This is useful when you register callbacks from C<rcv> callbacks:
		451
		452	rcv delayed_reply => sub {
		453	my ($delay, @reply) = @_;
		454	my $timer = AE::timer $delay, 0, psub {
		455	snd @reply, $SELF;
		456	};
		457	};
		458
		459	=cut
		460
		461	sub psub(&) {
		462	my $cb = shift;
		463
		464	my $port = $SELF
		465	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
		466
		467	sub {
		468	local $SELF = $port;
		469
		470	if (wantarray) {
		471	my @res = eval { &$cb };
		472	_self_die if $@;
		473	@res
		474	} else {
		475	my $res = eval { &$cb };
		476	_self_die if $@;
		477	$res
		478	}
		479	}
		480	}
		481
210	=item $guard = mon $portid, $cb->(@reason)	482	=item $guard = mon $port, $cb->(@reason)
211		483
212	=item $guard = mon $portid, $otherport	484	=item $guard = mon $port, $rcvport
213		485
		486	=item $guard = mon $port
		487
214	=item $guard = mon $portid, $otherport, @msg	488	=item $guard = mon $port, $rcvport, @msg
215		489
216	Monitor the given port and do something when the port is killed.	490	Monitor the given port and do something when the port is killed or
		491	messages to it were lost, and optionally return a guard that can be used
		492	to stop monitoring again.
217		493
		494	C<mon> effectively guarantees that, in the absence of hardware failures,
		495	that after starting the monitor, either all messages sent to the port
		496	will arrive, or the monitoring action will be invoked after possible
		497	message loss has been detected. No messages will be lost "in between"
		498	(after the first lost message no further messages will be received by the
		499	port). After the monitoring action was invoked, further messages might get
		500	delivered again.
		501
218	In the first form, the callback is simply called with any number	502	In the first form (callback), the callback is simply called with any
219	of C<@reason> elements (no @reason means that the port was deleted	503	number of C<@reason> elements (no @reason means that the port was deleted
220	"normally"). Note also that I<< the callback B<must> never die >>, so use	504	"normally"). Note also that I<< the callback B<must> never die >>, so use
221	C<eval> if unsure.	505	C<eval> if unsure.
222		506
223	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	507	In the second form (another port given), the other port (C<$rcvport>)
224	a @reason was specified, i.e. on "normal" kils nothing happens, while	508	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.	509	"normal" kils nothing happens, while under all other conditions, the other
		510	port is killed with the same reason.
226		511
		512	The third form (kill self) is the same as the second form, except that
		513	C<$rvport> defaults to C<$SELF>.
		514
227	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	515	In the last form (message), a message of the form C<@msg, @reason> will be
		516	C<snd>.
		517
		518	As a rule of thumb, monitoring requests should always monitor a port from
		519	a local port (or callback). The reason is that kill messages might get
		520	lost, just like any other message. Another less obvious reason is that
		521	even monitoring requests can get lost (for exmaple, when the connection
		522	to the other node goes down permanently). When monitoring a port locally
		523	these problems do not exist.
228		524
229	Example: call a given callback when C<$port> is killed.	525	Example: call a given callback when C<$port> is killed.
230		526
231	mon $port, sub { warn "port died because of <@_>\n" };	527	mon $port, sub { warn "port died because of <@_>\n" };
232		528
233	Example: kill ourselves when C<$port> is killed abnormally.	529	Example: kill ourselves when C<$port> is killed abnormally.
234		530
235	mon $port, $self;	531	mon $port;
236		532
237	Example: send us a restart message another C<$port> is killed.	533	Example: send us a restart message when another C<$port> is killed.
238		534
239	mon $port, $self => "restart";	535	mon $port, $self => "restart";
240		536
241	=cut	537	=cut
242		538
243	sub mon {	539	sub mon {
244	my ($noderef, $port) = split /#/, shift, 2;	540	my ($noderef, $port) = split /#/, shift, 2;
245		541
246	my $node = $NODE{$noderef} \|\| add_node $noderef;	542	my $node = $NODE{$noderef} \|\| add_node $noderef;
247		543
248	my $cb = shift;	544	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
249		545
250	unless (ref $cb) {	546	unless (ref $cb) {
251	if (@_) {	547	if (@_) {
252	# send a kill info message	548	# send a kill info message
253	my (@msg) = ($cb, @_);	549	my (@msg) = ($cb, @_);
…		…
284	=cut	580	=cut
285		581
286	sub mon_guard {	582	sub mon_guard {
287	my ($port, @refs) = @_;	583	my ($port, @refs) = @_;
288		584
		585	#TODO: mon-less form?
		586
289	mon $port, sub { 0 && @refs }	587	mon $port, sub { 0 && @refs }
290	}	588	}
291		589
292	=item lnk $port1, $port2	590	=item kil $port[, @reason]
293		591
294	Link two ports. This is simply a shorthand for:	592	Kill the specified port with the given C<@reason>.
295		593
296	mon $port1, $port2;	594	If no C<@reason> is specified, then the port is killed "normally" (linked
297	mon $port2, $port1;	595	ports will not be kileld, or even notified).
298		596
299	It means that if either one is killed abnormally, the other one gets	597	Otherwise, linked ports get killed with the same reason (second form of
300	killed as well.	598	C<mon>, see below).
301		599
302	=item $local_port = port	600	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		601	will be reported as reason C<< die => $@ >>.
303		602
304	Create a new local port object that can be used either as a pattern	603	Transport/communication errors are reported as C<< transport_error =>
305	matching port ("full port") or a single-callback port ("miniport"),	604	$message >>.
306	depending on how C<rcv> callbacks are bound to the object.
307		605
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
326	=cut	606	=cut
327		607
328	sub port(;&) {	608	=item $port = spawn $node, $initfunc[, @initdata]
329	my $id = "$UNIQ." . $ID++;
330	my $port = "$NODE#$id";
331		609
332	if (@_) {	610	Creates a port on the node C<$node> (which can also be a port ID, in which
333	my $cb = shift;	611	case it's the node where that port resides).
334	$PORT{$id} = sub {	612
335	local $SELF = $port;	613	The port ID of the newly created port is return immediately, and it is
336	eval {	614	permissible to immediately start sending messages or monitor the port.
337	&$cb	615
338	and kil $id;	616	After the port has been created, the init function is
		617	called. This function must be a fully-qualified function name
		618	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		619	program, use C<::name>.
		620
		621	If the function doesn't exist, then the node tries to C<require>
		622	the package, then the package above the package and so on (e.g.
		623	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		624	exists or it runs out of package names.
		625
		626	The init function is then called with the newly-created port as context
		627	object (C<$SELF>) and the C<@initdata> values as arguments.
		628
		629	A common idiom is to pass your own port, monitor the spawned port, and
		630	in the init function, monitor the original port. This two-way monitoring
		631	ensures that both ports get cleaned up when there is a problem.
		632
		633	Example: spawn a chat server port on C<$othernode>.
		634
		635	# this node, executed from within a port context:
		636	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		637	mon $server;
		638
		639	# init function on C<$othernode>
		640	sub connect {
		641	my ($srcport) = @_;
		642
		643	mon $srcport;
		644
		645	rcv $SELF, sub {
339	};	646	...
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	};	647	};
371	}	648	}
372		649
373	$port	650	=cut
		651
		652	sub _spawn {
		653	my $port = shift;
		654	my $init = shift;
		655
		656	local $SELF = "$NODE#$port";
		657	eval {
		658	&{ load_func $init }
		659	};
		660	_self_die if $@;
374	}	661	}
375		662
376	=item reg $portid, $name	663	sub spawn(@) {
		664	my ($noderef, undef) = split /#/, shift, 2;
377		665
378	Registers the given port under the name C<$name>. If the name already	666	my $id = "$RUNIQ." . $ID++;
379	exists it is replaced.
380		667
381	A port can only be registered under one well known name.	668	$_[0] =~ /::/
		669	or Carp::croak "spawn init function must be a fully-qualified name, caught";
382		670
383	A port automatically becomes unregistered when it is killed.	671	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
384		672
385	=cut	673	"$noderef#$id"
386
387	sub reg(@) {
388	my ($portid, $name) = @_;
389
390	$REG{$name} = $portid;
391	}	674	}
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		675
517	=back	676	=back
518		677
519	=head1 NODE MESSAGES	678	=head1 NODE MESSAGES
520		679
…		…
562		721
563	=back	722	=back
564		723
565	=head1 AnyEvent::MP vs. Distributed Erlang	724	=head1 AnyEvent::MP vs. Distributed Erlang
566		725
567	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node	726	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	727	== 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	728	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
570	sample:	729	sample:
571		730
572	http://www.erlang.se/doc/programming_rules.shtml	731	http://www.Erlang.se/doc/programming_rules.shtml
573	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	732	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	733	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	734	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
576		735
577	Despite the similarities, there are also some important differences:	736	Despite the similarities, there are also some important differences:
578		737
579	=over 4	738	=over 4
580		739
…		…
585	convenience functionality.	744	convenience functionality.
586		745
587	This means that AEMP requires a less tightly controlled environment at the	746	This means that AEMP requires a less tightly controlled environment at the
588	cost of longer node references and a slightly higher management overhead.	747	cost of longer node references and a slightly higher management overhead.
589		748
		749	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
		750	uses "local ports are like remote ports".
		751
		752	The failure modes for local ports are quite different (runtime errors
		753	only) then for remote ports - when a local port dies, you I<know> it dies,
		754	when a connection to another node dies, you know nothing about the other
		755	port.
		756
		757	Erlang pretends remote ports are as reliable as local ports, even when
		758	they are not.
		759
		760	AEMP encourages a "treat remote ports differently" philosophy, with local
		761	ports being the special case/exception, where transport errors cannot
		762	occur.
		763
590	=item * Erlang uses processes and a mailbox, AEMP does not queue.	764	=item * Erlang uses processes and a mailbox, AEMP does not queue.
591		765
592	Erlang uses processes that selctively receive messages, and therefore	766	Erlang uses processes that selectively receive messages, and therefore
593	needs a queue. AEMP is event based, queuing messages would serve no useful	767	needs a queue. AEMP is event based, queuing messages would serve no
594	purpose.	768	useful purpose. For the same reason the pattern-matching abilities of
		769	AnyEvent::MP are more limited, as there is little need to be able to
		770	filter messages without dequeing them.
595		771
596	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	772	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
597		773
598	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	774	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
599		775
600	Sending messages in erlang is synchronous and blocks the process. AEMP	776	Sending messages in Erlang is synchronous and blocks the process (and
601	sends are immediate, connection establishment is handled in the	777	so does not need a queue that can overflow). AEMP sends are immediate,
602	background.	778	connection establishment is handled in the background.
603		779
604	=item * Erlang can silently lose messages, AEMP cannot.	780	=item * Erlang suffers from silent message loss, AEMP does not.
605		781
606	Erlang makes few guarantees on messages delivery - messages can get lost	782	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,	783	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).	784	and c, and the other side only receives messages a and c).
609		785
610	AEMP guarantees correct ordering, and the guarantee that there are no	786	AEMP guarantees correct ordering, and the guarantee that there are no
611	holes in the message sequence.	787	holes in the message sequence.
612		788
613	=item * In erlang, processes can be declared dead and later be found to be	789	=item * In Erlang, processes can be declared dead and later be found to be
614	alive.	790	alive.
615		791
616	In erlang it can happen that a monitored process is declared dead and	792	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	793	linked processes get killed, but later it turns out that the process is
618	still alive - and can receive messages.	794	still alive - and can receive messages.
619		795
620	In AEMP, when port monitoring detects a port as dead, then that port will	796	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	797	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.	798	and then later sends messages to it, finding it is still alive.
623		799
624	=item * Erlang can send messages to the wrong port, AEMP does not.	800	=item * Erlang can send messages to the wrong port, AEMP does not.
625		801
626	In erlang it is quite possible that a node that restarts reuses a process	802	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	803	known to other nodes for a completely different process, causing messages
628	messages destined for that process to end up in an unrelated process.	804	destined for that process to end up in an unrelated process.
629		805
630	AEMP never reuses port IDs, so old messages or old port IDs floating	806	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.	807	around in the network will not be sent to an unrelated port.
632		808
633	=item * Erlang uses unprotected connections, AEMP uses secure	809	=item * Erlang uses unprotected connections, AEMP uses secure
…		…
637	securely authenticate nodes.	813	securely authenticate nodes.
638		814
639	=item * The AEMP protocol is optimised for both text-based and binary	815	=item * The AEMP protocol is optimised for both text-based and binary
640	communications.	816	communications.
641		817
642	The AEMP protocol, unlike the erlang protocol, supports both	818	The AEMP protocol, unlike the Erlang protocol, supports both
643	language-independent text-only protocols (good for debugging) and binary,	819	language-independent text-only protocols (good for debugging) and binary,
644	language-specific serialisers (e.g. Storable).	820	language-specific serialisers (e.g. Storable).
645		821
646	It has also been carefully designed to be implementable in other languages	822	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	823	with a minimum of work while gracefully degrading fucntionality to make the
648	protocol simple.	824	protocol simple.
649		825
		826	=item * AEMP has more flexible monitoring options than Erlang.
		827
		828	In Erlang, you can chose to receive I<all> exit signals as messages
		829	or I<none>, there is no in-between, so monitoring single processes is
		830	difficult to implement. Monitoring in AEMP is more flexible than in
		831	Erlang, as one can choose between automatic kill, exit message or callback
		832	on a per-process basis.
		833
		834	=item * Erlang tries to hide remote/local connections, AEMP does not.
		835
		836	Monitoring in Erlang is not an indicator of process death/crashes,
		837	as linking is (except linking is unreliable in Erlang).
		838
		839	In AEMP, you don't "look up" registered port names or send to named ports
		840	that might or might not be persistent. Instead, you normally spawn a port
		841	on the remote node. The init function monitors the you, and you monitor
		842	the remote port. Since both monitors are local to the node, they are much
		843	more reliable.
		844
		845	This also saves round-trips and avoids sending messages to the wrong port
		846	(hard to do in Erlang).
		847
		848	=back
		849
		850	=head1 RATIONALE
		851
		852	=over 4
		853
		854	=item Why strings for ports and noderefs, why not objects?
		855
		856	We considered "objects", but found that the actual number of methods
		857	thatc an be called are very low. Since port IDs and noderefs travel over
		858	the network frequently, the serialising/deserialising would add lots of
		859	overhead, as well as having to keep a proxy object.
		860
		861	Strings can easily be printed, easily serialised etc. and need no special
		862	procedures to be "valid".
		863
		864	And a a miniport consists of a single closure stored in a global hash - it
		865	can't become much cheaper.
		866
		867	=item Why favour JSON, why not real serialising format such as Storable?
		868
		869	In fact, any AnyEvent::MP node will happily accept Storable as framing
		870	format, but currently there is no way to make a node use Storable by
		871	default.
		872
		873	The default framing protocol is JSON because a) JSON::XS is many times
		874	faster for small messages and b) most importantly, after years of
		875	experience we found that object serialisation is causing more problems
		876	than it gains: Just like function calls, objects simply do not travel
		877	easily over the network, mostly because they will always be a copy, so you
		878	always have to re-think your design.
		879
		880	Keeping your messages simple, concentrating on data structures rather than
		881	objects, will keep your messages clean, tidy and efficient.
		882
650	=back	883	=back
651		884
652	=head1 SEE ALSO	885	=head1 SEE ALSO
653		886
654	L<AnyEvent>.	887	L<AnyEvent>.

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Revision 1.55 by root, Fri Aug 14 23:17:17 2009 UTC