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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.36 by root, Thu Aug 6 10:46:48 2009 UTC vs.
Revision 1.86 by root, Wed Sep 9 01:47:01 2009 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use AnyEvent::MP;	7	use AnyEvent::MP;
8		8
9	$NODE # contains this node's noderef	9	$NODE # contains this node's node ID
10	NODE # returns this node's noderef	10	NODE # returns this node's node ID
11	NODE $port # returns the noderef of the port
12		11
		12	$SELF # receiving/own port id in rcv callbacks
		13
		14	# initialise the node so it can send/receive messages
		15	configure;
		16
		17	# ports are message destinations
		18
		19	# sending messages
13	snd $port, type => data...;	20	snd $port, type => data...;
		21	snd $port, @msg;
		22	snd @msg_with_first_element_being_a_port;
14		23
15	$SELF # receiving/own port id in rcv callbacks	24	# creating/using ports, the simple way
		25	my $simple_port = port { my @msg = @_ };
16		26
17	rcv $port, smartmatch => $cb->($port, @msg);	27	# creating/using ports, tagged message matching
18		28	my $port = port;
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	29	rcv $port, ping => sub { snd $_[0], "pong" };
21	rcv $port1, pong => sub { warn "pong received\n" };	30	rcv $port, pong => sub { warn "pong received\n" };
22	snd $port2, ping => $port1;
23		31
24	# more, smarter, matches (_any_ is exported by this module)	32	# create a port on another node
25	rcv $port, [child_died => $pid] => sub { ...	33	my $port = spawn $node, $initfunc, @initdata;
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
27
28	# linking two ports, so they both crash together
29	lnk $port1, $port2;
30		34
31	# monitoring	35	# monitoring
32	mon $port, $cb->(@msg) # callback is invoked on death	36	mon $port, $cb->(@msg) # callback is invoked on death
33	mon $port, $otherport # kill otherport on abnormal death	37	mon $port, $otherport # kill otherport on abnormal death
34	mon $port, $otherport, @msg # send message on death	38	mon $port, $otherport, @msg # send message on death
35		39
		40	=head1 CURRENT STATUS
		41
		42	bin/aemp - stable.
		43	AnyEvent::MP - stable API, should work.
		44	AnyEvent::MP::Intro - explains most concepts.
		45	AnyEvent::MP::Kernel - mostly stable.
		46	AnyEvent::MP::Global - stable but incomplete, protocol not yet final.
		47
		48	stay tuned.
		49
36	=head1 DESCRIPTION	50	=head1 DESCRIPTION
37		51
38	This module (-family) implements a simple message passing framework.	52	This module (-family) implements a simple message passing framework.
39		53
40	Despite its simplicity, you can securely message other processes running	54	Despite its simplicity, you can securely message other processes running
41	on the same or other hosts.	55	on the same or other hosts, and you can supervise entities remotely.
42		56
43	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	57	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
44	manual page.	58	manual page and the examples under F<eg/>.
45
46	At the moment, this module family is severly broken and underdocumented,
47	so do not use. This was uploaded mainly to reserve the CPAN namespace -
48	stay tuned! The basic API should be finished, however.
49		59
50	=head1 CONCEPTS	60	=head1 CONCEPTS
51		61
52	=over 4	62	=over 4
53		63
54	=item port	64	=item port
55		65
56	A port is something you can send messages to (with the C<snd> function).	66	Not to be confused with a TCP port, a "port" is something you can send
		67	messages to (with the C<snd> function).
57		68
58	Some ports allow you to register C<rcv> handlers that can match specific	69	Ports allow you to register C<rcv> handlers that can match all or just
59	messages. All C<rcv> handlers will receive messages they match, messages	70	some messages. Messages send to ports will not be queued, regardless of
60	will not be queued.	71	anything was listening for them or not.
61		72
62	=item port id - C<noderef#portname>	73	=item port ID - C<nodeid#portname>
63		74
64	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	75	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as
65	separator, and a port name (a printable string of unspecified format). An	76	separator, and a port name (a printable string of unspecified format).
66	exception is the the node port, whose ID is identical to its node
67	reference.
68		77
69	=item node	78	=item node
70		79
71	A node is a single process containing at least one port - the node	80	A node is a single process containing at least one port - the node port,
72	port. You can send messages to node ports to find existing ports or to	81	which enables nodes to manage each other remotely, and to create new
73	create new ports, among other things.	82	ports.
74		83
75	Nodes are either private (single-process only), slaves (connected to a	84	Nodes are either public (have one or more listening ports) or private
76	master node only) or public nodes (connectable from unrelated nodes).	85	(no listening ports). Private nodes cannot talk to other private nodes
		86	currently.
77		87
78	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	88	=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*>
79		89
80	A node reference is a string that either simply identifies the node (for	90	A node ID is a string that uniquely identifies the node within a
81	private and slave nodes), or contains a recipe on how to reach a given	91	network. Depending on the configuration used, node IDs can look like a
82	node (for public nodes).	92	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
		93	doesn't interpret node IDs in any way.
83		94
84	This recipe is simply a comma-separated list of C<address:port> pairs (for	95	=item binds - C<ip:port>
85	TCP/IP, other protocols might look different).
86		96
87	Node references come in two flavours: resolved (containing only numerical	97	Nodes can only talk to each other by creating some kind of connection to
88	addresses) or unresolved (where hostnames are used instead of addresses).	98	each other. To do this, nodes should listen on one or more local transport
		99	endpoints - binds. Currently, only standard C<ip:port> specifications can
		100	be used, which specify TCP ports to listen on.
89		101
90	Before using an unresolved node reference in a message you first have to	102	=item seed nodes
91	resolve it.	103
		104	When a node starts, it knows nothing about the network. To teach the node
		105	about the network it first has to contact some other node within the
		106	network. This node is called a seed.
		107
		108	Apart from the fact that other nodes know them as seed nodes and they have
		109	to have fixed listening addresses, seed nodes are perfectly normal nodes -
		110	any node can function as a seed node for others.
		111
		112	In addition to discovering the network, seed nodes are also used to
		113	maintain the network and to connect nodes that otherwise would have
		114	trouble connecting. They form the backbone of an AnyEvent::MP network.
		115
		116	Seed nodes are expected to be long-running, and at least one seed node
		117	should always be available. They should also be relatively responsive - a
		118	seed node that blocks for long periods will slow down everybody else.
		119
		120	=item seeds - C<host:port>
		121
		122	Seeds are transport endpoint(s) (usually a hostname/IP address and a
		123	TCP port) of nodes thta should be used as seed nodes.
		124
		125	The nodes listening on those endpoints are expected to be long-running,
		126	and at least one of those should always be available. When nodes run out
		127	of connections (e.g. due to a network error), they try to re-establish
		128	connections to some seednodes again to join the network.
92		129
93	=back	130	=back
94		131
95	=head1 VARIABLES/FUNCTIONS	132	=head1 VARIABLES/FUNCTIONS
96		133
…		…
98		135
99	=cut	136	=cut
100		137
101	package AnyEvent::MP;	138	package AnyEvent::MP;
102		139
103	use AnyEvent::MP::Base;	140	use AnyEvent::MP::Kernel;
104		141
105	use common::sense;	142	use common::sense;
106		143
107	use Carp ();	144	use Carp ();
108		145
109	use AE ();	146	use AE ();
110		147
111	use base "Exporter";	148	use base "Exporter";
112		149
113	our $VERSION = '0.1';	150	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		151
114	our @EXPORT = qw(	152	our @EXPORT = qw(
115	NODE $NODE *SELF node_of _any_	153	NODE $NODE *SELF node_of after
116	resolve_node initialise_node	154	configure
117	snd rcv mon kil reg psub	155	snd rcv mon mon_guard kil reg psub spawn
118	port	156	port
119	);	157	);
120		158
121	our $SELF;	159	our $SELF;
122		160
…		…
126	kil $SELF, die => $msg;	164	kil $SELF, die => $msg;
127	}	165	}
128		166
129	=item $thisnode = NODE / $NODE	167	=item $thisnode = NODE / $NODE
130		168
131	The C<NODE> function returns, and the C<$NODE> variable contains	169	The C<NODE> function returns, and the C<$NODE> variable contains, the node
132	the noderef of the local node. The value is initialised by a call	170	ID of the node running in the current process. This value is initialised by
133	to C<become_public> or C<become_slave>, after which all local port	171	a call to C<configure>.
134	identifiers become invalid.
135		172
136	=item $noderef = node_of $port	173	=item $nodeid = node_of $port
137		174
138	Extracts and returns the noderef from a portid or a noderef.	175	Extracts and returns the node ID from a port ID or a node ID.
139		176
140	=item initialise_node $noderef, $seednode, $seednode...	177	=item configure $profile, key => value...
141		178
142	=item initialise_node "slave/", $master, $master...	179	=item configure key => value...
143		180
144	Before a node can talk to other nodes on the network it has to initialise	181	Before a node can talk to other nodes on the network (i.e. enter
145	itself - the minimum a node needs to know is it's own name, and optionally	182	"distributed mode") it has to configure itself - the minimum a node needs
146	it should know the noderefs of some other nodes in the network.	183	to know is its own name, and optionally it should know the addresses of
		184	some other nodes in the network to discover other nodes.
147		185
148	This function initialises a node - it must be called exactly once (or	186	This function configures a node - it must be called exactly once (or
149	never) before calling other AnyEvent::MP functions.	187	never) before calling other AnyEvent::MP functions.
150		188
151	All arguments are noderefs, which can be either resolved or unresolved.
152
153	There are two types of networked nodes, public nodes and slave nodes:
154
155	=over 4	189	=over 4
156		190
157	=item public nodes	191	=item step 1, gathering configuration from profiles
158		192
159	For public nodes, C<$noderef> must either be a (possibly unresolved)	193	The function first looks up a profile in the aemp configuration (see the
160	noderef, in which case it will be resolved, or C<undef> (or missing), in	194	L<aemp> commandline utility). The profile name can be specified via the
161	which case the noderef will be guessed.	195	named C<profile> parameter or can simply be the first parameter). If it is
		196	missing, then the nodename (F<uname -n>) will be used as profile name.
162		197
163	Afterwards, the node will bind itself on all endpoints and try to connect	198	The profile data is then gathered as follows:
164	to all additional C<$seednodes> that are specified. Seednodes are optional
165	and can be used to quickly bootstrap the node into an existing network.
166		199
167	=item slave nodes	200	First, all remaining key => value pairs (all of which are conveniently
		201	undocumented at the moment) will be interpreted as configuration
		202	data. Then they will be overwritten by any values specified in the global
		203	default configuration (see the F<aemp> utility), then the chain of
		204	profiles chosen by the profile name (and any C<parent> attributes).
168		205
169	When the C<$noderef> is the special string C<slave/>, then the node will	206	That means that the values specified in the profile have highest priority
170	become a slave node. Slave nodes cannot be contacted from outside and will	207	and the values specified directly via C<configure> have lowest priority,
171	route most of their traffic to the master node that they attach to.	208	and can only be used to specify defaults.
172		209
173	At least one additional noderef is required: The node will try to connect	210	If the profile specifies a node ID, then this will become the node ID of
174	to all of them and will become a slave attached to the first node it can	211	this process. If not, then the profile name will be used as node ID. The
175	successfully connect to.	212	special node ID of C<anon/> will be replaced by a random node ID.
		213
		214	=item step 2, bind listener sockets
		215
		216	The next step is to look up the binds in the profile, followed by binding
		217	aemp protocol listeners on all binds specified (it is possible and valid
		218	to have no binds, meaning that the node cannot be contacted form the
		219	outside. This means the node cannot talk to other nodes that also have no
		220	binds, but it can still talk to all "normal" nodes).
		221
		222	If the profile does not specify a binds list, then a default of C<*> is
		223	used, meaning the node will bind on a dynamically-assigned port on every
		224	local IP address it finds.
		225
		226	=item step 3, connect to seed nodes
		227
		228	As the last step, the seeds list from the profile is passed to the
		229	L<AnyEvent::MP::Global> module, which will then use it to keep
		230	connectivity with at least one node at any point in time.
176		231
177	=back	232	=back
178		233
179	This function will block until all nodes have been resolved and, for slave	234	Example: become a distributed node using the locla node name as profile.
180	nodes, until it has successfully established a connection to a master	235	This should be the most common form of invocation for "daemon"-type nodes.
181	server.
182		236
183	Example: become a public node listening on the default node.	237	configure
184		238
185	initialise_node;	239	Example: become an anonymous node. This form is often used for commandline
		240	clients.
186		241
187	Example: become a public node, and try to contact some well-known master	242	configure nodeid => "anon/";
188	servers to become part of the network.
189		243
190	initialise_node undef, "master1", "master2";	244	Example: configure a node using a profile called seed, which si suitable
		245	for a seed node as it binds on all local addresses on a fixed port (4040,
		246	customary for aemp).
191		247
192	Example: become a public node listening on port C<4041>.	248	# use the aemp commandline utility
		249	# aemp profile seed nodeid anon/ binds '*:4040'
193		250
194	initialise_node 4041;	251	# then use it
		252	configure profile => "seed";
195		253
196	Example: become a public node, only visible on localhost port 4044.	254	# or simply use aemp from the shell again:
		255	# aemp run profile seed
197		256
198	initialise_node "locahost:4044";	257	# or provide a nicer-to-remember nodeid
199		258	# aemp run profile seed nodeid "$(hostname)"
200	Example: become a slave node to any of the specified master servers.
201
202	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
203
204	=item $cv = resolve_node $noderef
205
206	Takes an unresolved node reference that may contain hostnames and
207	abbreviated IDs, resolves all of them and returns a resolved node
208	reference.
209
210	In addition to C<address:port> pairs allowed in resolved noderefs, the
211	following forms are supported:
212
213	=over 4
214
215	=item the empty string
216
217	An empty-string component gets resolved as if the default port (4040) was
218	specified.
219
220	=item naked port numbers (e.g. C<1234>)
221
222	These are resolved by prepending the local nodename and a colon, to be
223	further resolved.
224
225	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
226
227	These are resolved by using AnyEvent::DNS to resolve them, optionally
228	looking up SRV records for the C<aemp=4040> port, if no port was
229	specified.
230
231	=back
232		259
233	=item $SELF	260	=item $SELF
234		261
235	Contains the current port id while executing C<rcv> callbacks or C<psub>	262	Contains the current port id while executing C<rcv> callbacks or C<psub>
236	blocks.	263	blocks.
237		264
238	=item SELF, %SELF, @SELF...	265	=item *SELF, SELF, %SELF, @SELF...
239		266
240	Due to some quirks in how perl exports variables, it is impossible to	267	Due to some quirks in how perl exports variables, it is impossible to
241	just export C<$SELF>, all the symbols called C<SELF> are exported by this	268	just export C<$SELF>, all the symbols named C<SELF> are exported by this
242	module, but only C<$SELF> is currently used.	269	module, but only C<$SELF> is currently used.
243		270
244	=item snd $port, type => @data	271	=item snd $port, type => @data
245		272
246	=item snd $port, @msg	273	=item snd $port, @msg
247		274
248	Send the given message to the given port ID, which can identify either	275	Send the given message to the given port, which can identify either a
249	a local or a remote port, and can be either a string or soemthignt hat	276	local or a remote port, and must be a port ID.
250	stringifies a sa port ID (such as a port object :).
251		277
252	While the message can be about anything, it is highly recommended to use a	278	While the message can be almost anything, it is highly recommended to
253	string as first element (a portid, or some word that indicates a request	279	use a string as first element (a port ID, or some word that indicates a
254	type etc.).	280	request type etc.) and to consist if only simple perl values (scalars,
		281	arrays, hashes) - if you think you need to pass an object, think again.
255		282
256	The message data effectively becomes read-only after a call to this	283	The message data logically becomes read-only after a call to this
257	function: modifying any argument is not allowed and can cause many	284	function: modifying any argument (or values referenced by them) is
258	problems.	285	forbidden, as there can be considerable time between the call to C<snd>
		286	and the time the message is actually being serialised - in fact, it might
		287	never be copied as within the same process it is simply handed to the
		288	receiving port.
259		289
260	The type of data you can transfer depends on the transport protocol: when	290	The type of data you can transfer depends on the transport protocol: when
261	JSON is used, then only strings, numbers and arrays and hashes consisting	291	JSON is used, then only strings, numbers and arrays and hashes consisting
262	of those are allowed (no objects). When Storable is used, then anything	292	of those are allowed (no objects). When Storable is used, then anything
263	that Storable can serialise and deserialise is allowed, and for the local	293	that Storable can serialise and deserialise is allowed, and for the local
264	node, anything can be passed.	294	node, anything can be passed. Best rely only on the common denominator of
		295	these.
265		296
266	=item $local_port = port	297	=item $local_port = port
267		298
268	Create a new local port object that can be used either as a pattern	299	Create a new local port object and returns its port ID. Initially it has
269	matching port ("full port") or a single-callback port ("miniport"),	300	no callbacks set and will throw an error when it receives messages.
270	depending on how C<rcv> callbacks are bound to the object.
271		301
272	=item $port = port { my @msg = @_; $finished }	302	=item $local_port = port { my @msg = @_ }
273		303
274	Creates a "miniport", that is, a very lightweight port without any pattern	304	Creates a new local port, and returns its ID. Semantically the same as
275	matching behind it, and returns its ID. Semantically the same as creating
276	a port and calling C<rcv $port, $callback> on it.	305	creating a port and calling C<rcv $port, $callback> on it.
277		306
278	The block will be called for every message received on the port. When the	307	The block will be called for every message received on the port, with the
279	callback returns a true value its job is considered "done" and the port	308	global variable C<$SELF> set to the port ID. Runtime errors will cause the
280	will be destroyed. Otherwise it will stay alive.	309	port to be C<kil>ed. The message will be passed as-is, no extra argument
		310	(i.e. no port ID) will be passed to the callback.
281		311
282	The message will be passed as-is, no extra argument (i.e. no port id) will	312	If you want to stop/destroy the port, simply C<kil> it:
283	be passed to the callback.
284		313
285	If you need the local port id in the callback, this works nicely:	314	my $port = port {
286		315	my @msg = @_;
287	my $port; $port = port {	316	...
288	snd $otherport, reply => $port;	317	kil $SELF;
289	};	318	};
290		319
291	=cut	320	=cut
292		321
293	sub rcv($@);	322	sub rcv($@);
		323
		324	sub _kilme {
		325	die "received message on port without callback";
		326	}
294		327
295	sub port(;&) {	328	sub port(;&) {
296	my $id = "$UNIQ." . $ID++;	329	my $id = "$UNIQ." . $ID++;
297	my $port = "$NODE#$id";	330	my $port = "$NODE#$id";
298		331
299	if (@_) {	332	rcv $port, shift \|\| \&_kilme;
300	rcv $port, shift;
301	} else {
302	$PORT{$id} = sub { }; # nop
303	}
304		333
305	$port	334	$port
306	}	335	}
307		336
308	=item reg $port, $name
309
310	=item reg $name
311
312	Registers the given port (or C<$SELF><<< if missing) under the name
313	C<$name>. If the name already exists it is replaced.
314
315	A port can only be registered under one well known name.
316
317	A port automatically becomes unregistered when it is killed.
318
319	=cut
320
321	sub reg(@) {
322	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
323
324	$REG{$_[0]} = $port;
325	}
326
327	=item rcv $port, $callback->(@msg)	337	=item rcv $local_port, $callback->(@msg)
328		338
329	Replaces the callback on the specified miniport (after converting it to	339	Replaces the default callback on the specified port. There is no way to
330	one if required).	340	remove the default callback: use C<sub { }> to disable it, or better
331		341	C<kil> the port when it is no longer needed.
332	=item rcv $port, tagstring => $callback->(@msg), ...
333
334	=item rcv $port, $smartmatch => $callback->(@msg), ...
335
336	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
337
338	Register callbacks to be called on matching messages on the given full
339	port (after converting it to one if required) and return the port.
340
341	The callback has to return a true value when its work is done, after
342	which is will be removed, or a false value in which case it will stay
343	registered.
344		342
345	The global C<$SELF> (exported by this module) contains C<$port> while	343	The global C<$SELF> (exported by this module) contains C<$port> while
346	executing the callback.	344	executing the callback. Runtime errors during callback execution will
		345	result in the port being C<kil>ed.
347		346
348	Runtime errors wdurign callback execution will result in the port being	347	The default callback received all messages not matched by a more specific
349	C<kil>ed.	348	C<tag> match.
350		349
351	If the match is an array reference, then it will be matched against the	350	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
352	first elements of the message, otherwise only the first element is being
353	matched.
354		351
355	Any element in the match that is specified as C<_any_> (a function	352	Register (or replace) callbacks to be called on messages starting with the
356	exported by this module) matches any single element of the message.	353	given tag on the given port (and return the port), or unregister it (when
		354	C<$callback> is C<$undef> or missing). There can only be one callback
		355	registered for each tag.
357		356
358	While not required, it is highly recommended that the first matching	357	The original message will be passed to the callback, after the first
359	element is a string identifying the message. The one-string-only match is	358	element (the tag) has been removed. The callback will use the same
360	also the most efficient match (by far).	359	environment as the default callback (see above).
361		360
362	Example: create a port and bind receivers on it in one go.	361	Example: create a port and bind receivers on it in one go.
363		362
364	my $port = rcv port,	363	my $port = rcv port,
365	msg1 => sub { ...; 0 },	364	msg1 => sub { ... },
366	msg2 => sub { ...; 0 },	365	msg2 => sub { ... },
367	;	366	;
368		367
369	Example: create a port, bind receivers and send it in a message elsewhere	368	Example: create a port, bind receivers and send it in a message elsewhere
370	in one go:	369	in one go:
371		370
372	snd $otherport, reply =>	371	snd $otherport, reply =>
373	rcv port,	372	rcv port,
374	msg1 => sub { ...; 0 },	373	msg1 => sub { ... },
375	...	374	...
376	;	375	;
377		376
		377	Example: temporarily register a rcv callback for a tag matching some port
		378	(e.g. for a rpc reply) and unregister it after a message was received.
		379
		380	rcv $port, $otherport => sub {
		381	my @reply = @_;
		382
		383	rcv $SELF, $otherport;
		384	};
		385
378	=cut	386	=cut
379		387
380	sub rcv($@) {	388	sub rcv($@) {
381	my $port = shift;	389	my $port = shift;
382	my ($noderef, $portid) = split /#/, $port, 2;	390	my ($nodeid, $portid) = split /#/, $port, 2;
383		391
384	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	392	$NODE{$nodeid} == $NODE{""}
385	or Carp::croak "$port: rcv can only be called on local ports, caught";	393	or Carp::croak "$port: rcv can only be called on local ports, caught";
386		394
387	if (@_ == 1) {	395	while (@_) {
		396	if (ref $_[0]) {
		397	if (my $self = $PORT_DATA{$portid}) {
		398	"AnyEvent::MP::Port" eq ref $self
		399	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		400
		401	$self->[2] = shift;
		402	} else {
388	my $cb = shift;	403	my $cb = shift;
389	delete $PORT_DATA{$portid};
390	$PORT{$portid} = sub {	404	$PORT{$portid} = sub {
391	local $SELF = $port;	405	local $SELF = $port;
392	eval {	406	eval { &$cb }; _self_die if $@;
393	&$cb	407	};
394	and kil $port;
395	};	408	}
396	_self_die if $@;	409	} elsif (defined $_[0]) {
397	};
398	} else {
399	my $self = $PORT_DATA{$portid} \|\|= do {	410	my $self = $PORT_DATA{$portid} \|\|= do {
400	my $self = bless {	411	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
401	id => $port,
402	}, "AnyEvent::MP::Port";
403		412
404	$PORT{$portid} = sub {	413	$PORT{$portid} = sub {
405	local $SELF = $port;	414	local $SELF = $port;
406		415
407	eval {
408	for (@{ $self->{rc0}{$_[0]} }) {	416	if (my $cb = $self->[1]{$_[0]}) {
409	$_ && &{$_->[0]}	417	shift;
410	&& undef $_;	418	eval { &$cb }; _self_die if $@;
411	}	419	} else {
412
413	for (@{ $self->{rcv}{$_[0]} }) {
414	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
415	&& &{$_->[0]}	420	&{ $self->[0] };
416	&& undef $_;
417	}
418
419	for (@{ $self->{any} }) {
420	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
421	&& &{$_->[0]}
422	&& undef $_;
423	}	421	}
424	};	422	};
425	_self_die if $@;	423
		424	$self
426	};	425	};
427		426
428	$self
429	};
430
431	"AnyEvent::MP::Port" eq ref $self	427	"AnyEvent::MP::Port" eq ref $self
432	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	428	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
433		429
434	while (@_) {
435	my ($match, $cb) = splice @_, 0, 2;	430	my ($tag, $cb) = splice @_, 0, 2;
436		431
437	if (!ref $match) {	432	if (defined $cb) {
438	push @{ $self->{rc0}{$match} }, [$cb];	433	$self->[1]{$tag} = $cb;
439	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
440	my ($type, @match) = @$match;
441	@match
442	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
443	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
444	} else {	434	} else {
445	push @{ $self->{any} }, [$cb, $match];	435	delete $self->[1]{$tag};
446	}	436	}
447	}	437	}
448	}	438	}
449		439
450	$port	440	$port
…		…
486	$res	476	$res
487	}	477	}
488	}	478	}
489	}	479	}
490		480
491	=item $guard = mon $port, $cb->(@reason)	481	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
492		482
493	=item $guard = mon $port, $rcvport	483	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
494		484
495	=item $guard = mon $port	485	=item $guard = mon $port # kill $SELF when $port dies
496		486
497	=item $guard = mon $port, $rcvport, @msg	487	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
498		488
499	Monitor the given port and do something when the port is killed, and	489	Monitor the given port and do something when the port is killed or
500	optionally return a guard that can be used to stop monitoring again.	490	messages to it were lost, and optionally return a guard that can be used
		491	to stop monitoring again.
501		492
502	In the first form (callback), the callback is simply called with any	493	In the first form (callback), the callback is simply called with any
503	number of C<@reason> elements (no @reason means that the port was deleted	494	number of C<@reason> elements (no @reason means that the port was deleted
504	"normally"). Note also that I<< the callback B<must> never die >>, so use	495	"normally"). Note also that I<< the callback B<must> never die >>, so use
505	C<eval> if unsure.	496	C<eval> if unsure.
506		497
507	In the second form (another port given), the other port (C<$rcvport)	498	In the second form (another port given), the other port (C<$rcvport>)
508	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on	499	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
509	"normal" kils nothing happens, while under all other conditions, the other	500	"normal" kils nothing happens, while under all other conditions, the other
510	port is killed with the same reason.	501	port is killed with the same reason.
511		502
512	The third form (kill self) is the same as the second form, except that	503	The third form (kill self) is the same as the second form, except that
513	C<$rvport> defaults to C<$SELF>.	504	C<$rvport> defaults to C<$SELF>.
514		505
515	In the last form (message), a message of the form C<@msg, @reason> will be	506	In the last form (message), a message of the form C<@msg, @reason> will be
516	C<snd>.	507	C<snd>.
517		508
		509	Monitoring-actions are one-shot: once messages are lost (and a monitoring
		510	alert was raised), they are removed and will not trigger again.
		511
		512	As a rule of thumb, monitoring requests should always monitor a port from
		513	a local port (or callback). The reason is that kill messages might get
		514	lost, just like any other message. Another less obvious reason is that
		515	even monitoring requests can get lost (for example, when the connection
		516	to the other node goes down permanently). When monitoring a port locally
		517	these problems do not exist.
		518
		519	C<mon> effectively guarantees that, in the absence of hardware failures,
		520	after starting the monitor, either all messages sent to the port will
		521	arrive, or the monitoring action will be invoked after possible message
		522	loss has been detected. No messages will be lost "in between" (after
		523	the first lost message no further messages will be received by the
		524	port). After the monitoring action was invoked, further messages might get
		525	delivered again.
		526
		527	Inter-host-connection timeouts and monitoring depend on the transport
		528	used. The only transport currently implemented is TCP, and AnyEvent::MP
		529	relies on TCP to detect node-downs (this can take 10-15 minutes on a
		530	non-idle connection, and usually around two hours for idle conenctions).
		531
		532	This means that monitoring is good for program errors and cleaning up
		533	stuff eventually, but they are no replacement for a timeout when you need
		534	to ensure some maximum latency.
		535
518	Example: call a given callback when C<$port> is killed.	536	Example: call a given callback when C<$port> is killed.
519		537
520	mon $port, sub { warn "port died because of <@_>\n" };	538	mon $port, sub { warn "port died because of <@_>\n" };
521		539
522	Example: kill ourselves when C<$port> is killed abnormally.	540	Example: kill ourselves when C<$port> is killed abnormally.
…		…
528	mon $port, $self => "restart";	546	mon $port, $self => "restart";
529		547
530	=cut	548	=cut
531		549
532	sub mon {	550	sub mon {
533	my ($noderef, $port) = split /#/, shift, 2;	551	my ($nodeid, $port) = split /#/, shift, 2;
534		552
535	my $node = $NODE{$noderef} \|\| add_node $noderef;	553	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
536		554
537	my $cb = @_ ? $_[0] : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	555	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
538		556
539	unless (ref $cb) {	557	unless (ref $cb) {
540	if (@_) {	558	if (@_) {
541	# send a kill info message	559	# send a kill info message
542	my (@msg) = @_;	560	my (@msg) = ($cb, @_);
543	$cb = sub { snd @msg, @_ };	561	$cb = sub { snd @msg, @_ };
544	} else {	562	} else {
545	# simply kill other port	563	# simply kill other port
546	my $port = $cb;	564	my $port = $cb;
547	$cb = sub { kil $port, @_ if @_ };	565	$cb = sub { kil $port, @_ if @_ };
…		…
560	is killed, the references will be freed.	578	is killed, the references will be freed.
561		579
562	Optionally returns a guard that will stop the monitoring.	580	Optionally returns a guard that will stop the monitoring.
563		581
564	This function is useful when you create e.g. timers or other watchers and	582	This function is useful when you create e.g. timers or other watchers and
565	want to free them when the port gets killed:	583	want to free them when the port gets killed (note the use of C<psub>):
566		584
567	$port->rcv (start => sub {	585	$port->rcv (start => sub {
568	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	586	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
569	undef $timer if 0.9 < rand;	587	undef $timer if 0.9 < rand;
570	});	588	});
571	});	589	});
572		590
573	=cut	591	=cut
…		…
578	#TODO: mon-less form?	596	#TODO: mon-less form?
579		597
580	mon $port, sub { 0 && @refs }	598	mon $port, sub { 0 && @refs }
581	}	599	}
582		600
583	=item lnk $port1, $port2
584
585	=item lnk $otherport
586
587	Link two ports. This is simply a shorthand for:
588
589	mon $port1, $port2;
590	mon $port2, $port1;
591
592	It means that if either one is killed abnormally, the other one gets
593	killed as well.
594
595	The one-argument form assumes that one port is C<$SELF>.
596
597	=cut
598
599	sub lnk {
600	my $port1 = shift;
601	my $port2 = @_ ? shift : $SELF \|\| Carp::croak 'lnk: called with one argument only, but $SELF not set,';
602
603	mon $port1, $port2;
604	mon $port2, $port1;
605	}
606
607	=item kil $port[, @reason]	601	=item kil $port[, @reason]
608		602
609	Kill the specified port with the given C<@reason>.	603	Kill the specified port with the given C<@reason>.
610		604
611	If no C<@reason> is specified, then the port is killed "normally" (linked	605	If no C<@reason> is specified, then the port is killed "normally" (ports
612	ports will not be kileld, or even notified).	606	monitoring other ports will not necessarily die because a port dies
		607	"normally").
613		608
614	Otherwise, linked ports get killed with the same reason (second form of	609	Otherwise, linked ports get killed with the same reason (second form of
615	C<mon>, see below).	610	C<mon>, see above).
616		611
617	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	612	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
618	will be reported as reason C<< die => $@ >>.	613	will be reported as reason C<< die => $@ >>.
619		614
620	Transport/communication errors are reported as C<< transport_error =>	615	Transport/communication errors are reported as C<< transport_error =>
621	$message >>.	616	$message >>.
622		617
623	=back
624
625	=head1 NODE MESSAGES
626
627	Nodes understand the following messages sent to them. Many of them take
628	arguments called C<@reply>, which will simply be used to compose a reply
629	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
630	the remaining arguments are simply the message data.
631
632	While other messages exist, they are not public and subject to change.
633
634	=over 4
635
636	=cut	618	=cut
637		619
638	=item lookup => $name, @reply	620	=item $port = spawn $node, $initfunc[, @initdata]
639		621
640	Replies with the port ID of the specified well-known port, or C<undef>.	622	Creates a port on the node C<$node> (which can also be a port ID, in which
		623	case it's the node where that port resides).
641		624
642	=item devnull => ...	625	The port ID of the newly created port is returned immediately, and it is
		626	possible to immediately start sending messages or to monitor the port.
643		627
644	Generic data sink/CPU heat conversion.	628	After the port has been created, the init function is called on the remote
		629	node, in the same context as a C<rcv> callback. This function must be a
		630	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
		631	specify a function in the main program, use C<::name>.
645		632
646	=item relay => $port, @msg	633	If the function doesn't exist, then the node tries to C<require>
		634	the package, then the package above the package and so on (e.g.
		635	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		636	exists or it runs out of package names.
647		637
648	Simply forwards the message to the given port.	638	The init function is then called with the newly-created port as context
		639	object (C<$SELF>) and the C<@initdata> values as arguments. It I<must>
		640	call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise
		641	the port might not get created.
649		642
650	=item eval => $string[ @reply]	643	A common idiom is to pass a local port, immediately monitor the spawned
		644	port, and in the remote init function, immediately monitor the passed
		645	local port. This two-way monitoring ensures that both ports get cleaned up
		646	when there is a problem.
651		647
652	Evaluates the given string. If C<@reply> is given, then a message of the	648	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
653	form C<@reply, $@, @evalres> is sent.	649	caller before C<spawn> returns (by delaying invocation when spawn is
		650	called for the local node).
654		651
655	Example: crash another node.	652	Example: spawn a chat server port on C<$othernode>.
656		653
657	snd $othernode, eval => "exit";	654	# this node, executed from within a port context:
		655	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		656	mon $server;
658		657
659	=item time => @reply	658	# init function on C<$othernode>
		659	sub connect {
		660	my ($srcport) = @_;
660		661
661	Replies the the current node time to C<@reply>.	662	mon $srcport;
662		663
663	Example: tell the current node to send the current time to C<$myport> in a	664	rcv $SELF, sub {
664	C<timereply> message.	665	...
		666	};
		667	}
665		668
666	snd $NODE, time => $myport, timereply => 1, 2;	669	=cut
667	# => snd $myport, timereply => 1, 2, <time>	670
		671	sub _spawn {
		672	my $port = shift;
		673	my $init = shift;
		674
		675	# rcv will create the actual port
		676	local $SELF = "$NODE#$port";
		677	eval {
		678	&{ load_func $init }
		679	};
		680	_self_die if $@;
		681	}
		682
		683	sub spawn(@) {
		684	my ($nodeid, undef) = split /#/, shift, 2;
		685
		686	my $id = "$RUNIQ." . $ID++;
		687
		688	$_[0] =~ /::/
		689	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		690
		691	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
		692
		693	"$nodeid#$id"
		694	}
		695
		696	=item after $timeout, @msg
		697
		698	=item after $timeout, $callback
		699
		700	Either sends the given message, or call the given callback, after the
		701	specified number of seconds.
		702
		703	This is simply a utility function that comes in handy at times - the
		704	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		705	so it may go away in the future.
		706
		707	=cut
		708
		709	sub after($@) {
		710	my ($timeout, @action) = @_;
		711
		712	my $t; $t = AE::timer $timeout, 0, sub {
		713	undef $t;
		714	ref $action[0]
		715	? $action[0]()
		716	: snd @action;
		717	};
		718	}
668		719
669	=back	720	=back
670		721
671	=head1 AnyEvent::MP vs. Distributed Erlang	722	=head1 AnyEvent::MP vs. Distributed Erlang
672		723
…		…
682		733
683	Despite the similarities, there are also some important differences:	734	Despite the similarities, there are also some important differences:
684		735
685	=over 4	736	=over 4
686		737
687	=item * Node references contain the recipe on how to contact them.	738	=item * Node IDs are arbitrary strings in AEMP.
688		739
689	Erlang relies on special naming and DNS to work everywhere in the	740	Erlang relies on special naming and DNS to work everywhere in the same
690	same way. AEMP relies on each node knowing it's own address(es), with	741	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
691	convenience functionality.	742	configuration or DNS), but will otherwise discover other odes itself.
692		743
693	This means that AEMP requires a less tightly controlled environment at the	744	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
694	cost of longer node references and a slightly higher management overhead.	745	uses "local ports are like remote ports".
		746
		747	The failure modes for local ports are quite different (runtime errors
		748	only) then for remote ports - when a local port dies, you I<know> it dies,
		749	when a connection to another node dies, you know nothing about the other
		750	port.
		751
		752	Erlang pretends remote ports are as reliable as local ports, even when
		753	they are not.
		754
		755	AEMP encourages a "treat remote ports differently" philosophy, with local
		756	ports being the special case/exception, where transport errors cannot
		757	occur.
695		758
696	=item * Erlang uses processes and a mailbox, AEMP does not queue.	759	=item * Erlang uses processes and a mailbox, AEMP does not queue.
697		760
698	Erlang uses processes that selctively receive messages, and therefore	761	Erlang uses processes that selectively receive messages, and therefore
699	needs a queue. AEMP is event based, queuing messages would serve no useful	762	needs a queue. AEMP is event based, queuing messages would serve no
700	purpose.	763	useful purpose. For the same reason the pattern-matching abilities of
		764	AnyEvent::MP are more limited, as there is little need to be able to
		765	filter messages without dequeuing them.
701		766
702	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	767	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
703		768
704	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	769	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
705		770
706	Sending messages in Erlang is synchronous and blocks the process. AEMP	771	Sending messages in Erlang is synchronous and blocks the process (and
707	sends are immediate, connection establishment is handled in the	772	so does not need a queue that can overflow). AEMP sends are immediate,
708	background.	773	connection establishment is handled in the background.
709		774
710	=item * Erlang can silently lose messages, AEMP cannot.	775	=item * Erlang suffers from silent message loss, AEMP does not.
711		776
712	Erlang makes few guarantees on messages delivery - messages can get lost	777	Erlang makes few guarantees on messages delivery - messages can get lost
713	without any of the processes realising it (i.e. you send messages a, b,	778	without any of the processes realising it (i.e. you send messages a, b,
714	and c, and the other side only receives messages a and c).	779	and c, and the other side only receives messages a and c).
715		780
716	AEMP guarantees correct ordering, and the guarantee that there are no	781	AEMP guarantees correct ordering, and the guarantee that after one message
717	holes in the message sequence.	782	is lost, all following ones sent to the same port are lost as well, until
718		783	monitoring raises an error, so there are no silent "holes" in the message
719	=item * In Erlang, processes can be declared dead and later be found to be	784	sequence.
720	alive.
721
722	In Erlang it can happen that a monitored process is declared dead and
723	linked processes get killed, but later it turns out that the process is
724	still alive - and can receive messages.
725
726	In AEMP, when port monitoring detects a port as dead, then that port will
727	eventually be killed - it cannot happen that a node detects a port as dead
728	and then later sends messages to it, finding it is still alive.
729		785
730	=item * Erlang can send messages to the wrong port, AEMP does not.	786	=item * Erlang can send messages to the wrong port, AEMP does not.
731		787
732	In Erlang it is quite possible that a node that restarts reuses a process	788	In Erlang it is quite likely that a node that restarts reuses a process ID
733	ID known to other nodes for a completely different process, causing	789	known to other nodes for a completely different process, causing messages
734	messages destined for that process to end up in an unrelated process.	790	destined for that process to end up in an unrelated process.
735		791
736	AEMP never reuses port IDs, so old messages or old port IDs floating	792	AEMP never reuses port IDs, so old messages or old port IDs floating
737	around in the network will not be sent to an unrelated port.	793	around in the network will not be sent to an unrelated port.
738		794
739	=item * Erlang uses unprotected connections, AEMP uses secure	795	=item * Erlang uses unprotected connections, AEMP uses secure
740	authentication and can use TLS.	796	authentication and can use TLS.
741		797
742	AEMP can use a proven protocol - SSL/TLS - to protect connections and	798	AEMP can use a proven protocol - TLS - to protect connections and
743	securely authenticate nodes.	799	securely authenticate nodes.
744		800
745	=item * The AEMP protocol is optimised for both text-based and binary	801	=item * The AEMP protocol is optimised for both text-based and binary
746	communications.	802	communications.
747		803
748	The AEMP protocol, unlike the Erlang protocol, supports both	804	The AEMP protocol, unlike the Erlang protocol, supports both programming
749	language-independent text-only protocols (good for debugging) and binary,	805	language independent text-only protocols (good for debugging) and binary,
750	language-specific serialisers (e.g. Storable).	806	language-specific serialisers (e.g. Storable). By default, unless TLS is
		807	used, the protocol is actually completely text-based.
751		808
752	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
753	with a minimum of work while gracefully degrading fucntionality to make the	810	with a minimum of work while gracefully degrading functionality to make the
754	protocol simple.	811	protocol simple.
755		812
756	=item * AEMP has more flexible monitoring options than Erlang.	813	=item * AEMP has more flexible monitoring options than Erlang.
757		814
758	In Erlang, you can chose to receive I<all> exit signals as messages	815	In Erlang, you can chose to receive I<all> exit signals as messages
759	or I<none>, there is no in-between, so monitoring single processes is	816	or I<none>, there is no in-between, so monitoring single processes is
760	difficult to implement. Monitoring in AEMP is more flexible than in	817	difficult to implement. Monitoring in AEMP is more flexible than in
761	Erlang, as one can choose between automatic kill, exit message or callback	818	Erlang, as one can choose between automatic kill, exit message or callback
762	on a per-process basis.	819	on a per-process basis.
763		820
764	=item * Erlang has different semantics for monitoring and linking, AEMP has the same.	821	=item * Erlang tries to hide remote/local connections, AEMP does not.
765		822
766	Monitoring in Erlang is not an indicator of process death/crashes,	823	Monitoring in Erlang is not an indicator of process death/crashes, in the
767	as linking is (except linking is unreliable in Erlang). In AEMP, the	824	same way as linking is (except linking is unreliable in Erlang).
768	semantics of monitoring and linking are identical, linking is simply	825
769	two-way monitoring with automatic kill.	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 you, and you monitor the
		829	remote port. Since both monitors are local to the node, they are much more
		830	reliable (no need for C<spawn_link>).
		831
		832	This also saves round-trips and avoids sending messages to the wrong port
		833	(hard to do in Erlang).
770		834
771	=back	835	=back
772		836
		837	=head1 RATIONALE
		838
		839	=over 4
		840
		841	=item Why strings for port and node IDs, why not objects?
		842
		843	We considered "objects", but found that the actual number of methods
		844	that can be called are quite low. Since port and node IDs travel over
		845	the network frequently, the serialising/deserialising would add lots of
		846	overhead, as well as having to keep a proxy object everywhere.
		847
		848	Strings can easily be printed, easily serialised etc. and need no special
		849	procedures to be "valid".
		850
		851	And as a result, a miniport consists of a single closure stored in a
		852	global hash - it can't become much cheaper.
		853
		854	=item Why favour JSON, why not a 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 (although all nodes will accept it).
		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 solves: 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
		870	=back
		871
773	=head1 SEE ALSO	872	=head1 SEE ALSO
		873
		874	L<AnyEvent::MP::Intro> - a gentle introduction.
		875
		876	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		877
		878	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		879	your applications.
		880
		881	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
		882	all nodes.
774		883
775	L<AnyEvent>.	884	L<AnyEvent>.
776		885
777	=head1 AUTHOR	886	=head1 AUTHOR
778		887

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.36 by root, Thu Aug 6 10:46:48 2009 UTC vs. Revision 1.86 by root, Wed Sep 9 01:47:01 2009 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.36 by root, Thu Aug 6 10:46:48 2009 UTC vs.
Revision 1.86 by root, Wed Sep 9 01:47:01 2009 UTC