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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.37 by root, Fri Aug 7 16:47:23 2009 UTC vs.
Revision 1.84 by root, Tue Sep 8 01:42:14 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		34
28	# monitoring	35	# monitoring
29	mon $port, $cb->(@msg) # callback is invoked on death	36	mon $port, $cb->(@msg) # callback is invoked on death
30	mon $port, $otherport # kill otherport on abnormal death	37	mon $port, $otherport # kill otherport on abnormal death
31	mon $port, $otherport, @msg # send message on death	38	mon $port, $otherport, @msg # send message on death
32		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
33	=head1 DESCRIPTION	50	=head1 DESCRIPTION
34		51
35	This module (-family) implements a simple message passing framework.	52	This module (-family) implements a simple message passing framework.
36		53
37	Despite its simplicity, you can securely message other processes running	54	Despite its simplicity, you can securely message other processes running
38	on the same or other hosts.	55	on the same or other hosts, and you can supervise entities remotely.
39		56
40	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>
41	manual page.	58	manual page and the examples under F<eg/>.
42
43	At the moment, this module family is severly broken and underdocumented,
44	so do not use. This was uploaded mainly to reserve the CPAN namespace -
45	stay tuned! The basic API should be finished, however.
46		59
47	=head1 CONCEPTS	60	=head1 CONCEPTS
48		61
49	=over 4	62	=over 4
50		63
51	=item port	64	=item port
52		65
53	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).
54		68
55	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
56	messages. All C<rcv> handlers will receive messages they match, messages	70	some messages. Messages send to ports will not be queued, regardless of
57	will not be queued.	71	anything was listening for them or not.
58		72
59	=item port id - C<noderef#portname>	73	=item port ID - C<nodeid#portname>
60		74
61	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
62	separator, and a port name (a printable string of unspecified format). An	76	separator, and a port name (a printable string of unspecified format).
63	exception is the the node port, whose ID is identical to its node
64	reference.
65		77
66	=item node	78	=item node
67		79
68	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,
69	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
70	create new ports, among other things.	82	ports.
71		83
72	Nodes are either private (single-process only), slaves (connected to a	84	Nodes are either public (have one or more listening ports) or private
73	master node only) or public nodes (connectable from unrelated nodes).	85	(no listening ports). Private nodes cannot talk to other private nodes
		86	currently.
74		87
75	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	88	=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*>
76		89
77	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
78	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
79	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.
80		94
81	This recipe is simply a comma-separated list of C<address:port> pairs (for	95	=item binds - C<ip:port>
82	TCP/IP, other protocols might look different).
83		96
84	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
85	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.
86		101
87	Before using an unresolved node reference in a message you first have to	102	=item seed nodes
88	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 the AnyEvent::MP network.
		115
		116	Seed nodes are expected to be long-running, and at least one seed node
		117	should always be available.
		118
		119	=item seeds - C<host:port>
		120
		121	Seeds are transport endpoint(s) (usually a hostname/IP address and a
		122	TCP port) of nodes thta should be used as seed nodes.
		123
		124	The nodes listening on those endpoints are expected to be long-running,
		125	and at least one of those should always be available. When nodes run out
		126	of connections (e.g. due to a network error), they try to re-establish
		127	connections to some seednodes again to join the network.
89		128
90	=back	129	=back
91		130
92	=head1 VARIABLES/FUNCTIONS	131	=head1 VARIABLES/FUNCTIONS
93		132
…		…
95		134
96	=cut	135	=cut
97		136
98	package AnyEvent::MP;	137	package AnyEvent::MP;
99		138
100	use AnyEvent::MP::Base;	139	use AnyEvent::MP::Kernel;
101		140
102	use common::sense;	141	use common::sense;
103		142
104	use Carp ();	143	use Carp ();
105		144
106	use AE ();	145	use AE ();
107		146
108	use base "Exporter";	147	use base "Exporter";
109		148
110	our $VERSION = '0.1';	149	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		150
111	our @EXPORT = qw(	151	our @EXPORT = qw(
112	NODE $NODE *SELF node_of _any_	152	NODE $NODE *SELF node_of after
113	resolve_node initialise_node	153	configure
114	snd rcv mon kil reg psub	154	snd rcv mon mon_guard kil reg psub spawn
115	port	155	port
116	);	156	);
117		157
118	our $SELF;	158	our $SELF;
119		159
…		…
123	kil $SELF, die => $msg;	163	kil $SELF, die => $msg;
124	}	164	}
125		165
126	=item $thisnode = NODE / $NODE	166	=item $thisnode = NODE / $NODE
127		167
128	The C<NODE> function returns, and the C<$NODE> variable contains	168	The C<NODE> function returns, and the C<$NODE> variable contains, the node
129	the noderef of the local node. The value is initialised by a call	169	ID of the node running in the current process. This value is initialised by
130	to C<become_public> or C<become_slave>, after which all local port	170	a call to C<configure>.
131	identifiers become invalid.
132		171
133	=item $noderef = node_of $port	172	=item $nodeid = node_of $port
134		173
135	Extracts and returns the noderef from a portid or a noderef.	174	Extracts and returns the node ID from a port ID or a node ID.
136		175
137	=item initialise_node $noderef, $seednode, $seednode...	176	=item configure $profile, key => value...
138		177
139	=item initialise_node "slave/", $master, $master...	178	=item configure key => value...
140		179
141	Before a node can talk to other nodes on the network it has to initialise	180	Before a node can talk to other nodes on the network (i.e. enter
142	itself - the minimum a node needs to know is it's own name, and optionally	181	"distributed mode") it has to configure itself - the minimum a node needs
143	it should know the noderefs of some other nodes in the network.	182	to know is its own name, and optionally it should know the addresses of
		183	some other nodes in the network to discover other nodes.
144		184
145	This function initialises a node - it must be called exactly once (or	185	This function configures a node - it must be called exactly once (or
146	never) before calling other AnyEvent::MP functions.	186	never) before calling other AnyEvent::MP functions.
147		187
148	All arguments are noderefs, which can be either resolved or unresolved.
149
150	There are two types of networked nodes, public nodes and slave nodes:
151
152	=over 4	188	=over 4
153		189
154	=item public nodes	190	=item step 1, gathering configuration from profiles
155		191
156	For public nodes, C<$noderef> must either be a (possibly unresolved)	192	The function first looks up a profile in the aemp configuration (see the
157	noderef, in which case it will be resolved, or C<undef> (or missing), in	193	L<aemp> commandline utility). The profile name can be specified via the
158	which case the noderef will be guessed.	194	named C<profile> parameter or can simply be the first parameter). If it is
		195	missing, then the nodename (F<uname -n>) will be used as profile name.
159		196
160	Afterwards, the node will bind itself on all endpoints and try to connect	197	The profile data is then gathered as follows:
161	to all additional C<$seednodes> that are specified. Seednodes are optional
162	and can be used to quickly bootstrap the node into an existing network.
163		198
164	=item slave nodes	199	First, all remaining key => value pairs (all of which are conveniently
		200	undocumented at the moment) will be interpreted as configuration
		201	data. Then they will be overwritten by any values specified in the global
		202	default configuration (see the F<aemp> utility), then the chain of
		203	profiles chosen by the profile name (and any C<parent> attributes).
165		204
166	When the C<$noderef> is the special string C<slave/>, then the node will	205	That means that the values specified in the profile have highest priority
167	become a slave node. Slave nodes cannot be contacted from outside and will	206	and the values specified directly via C<configure> have lowest priority,
168	route most of their traffic to the master node that they attach to.	207	and can only be used to specify defaults.
169		208
170	At least one additional noderef is required: The node will try to connect	209	If the profile specifies a node ID, then this will become the node ID of
171	to all of them and will become a slave attached to the first node it can	210	this process. If not, then the profile name will be used as node ID. The
172	successfully connect to.	211	special node ID of C<anon/> will be replaced by a random node ID.
		212
		213	=item step 2, bind listener sockets
		214
		215	The next step is to look up the binds in the profile, followed by binding
		216	aemp protocol listeners on all binds specified (it is possible and valid
		217	to have no binds, meaning that the node cannot be contacted form the
		218	outside. This means the node cannot talk to other nodes that also have no
		219	binds, but it can still talk to all "normal" nodes).
		220
		221	If the profile does not specify a binds list, then a default of C<*> is
		222	used, meaning the node will bind on a dynamically-assigned port on every
		223	local IP address it finds.
		224
		225	=item step 3, connect to seed nodes
		226
		227	As the last step, the seeds list from the profile is passed to the
		228	L<AnyEvent::MP::Global> module, which will then use it to keep
		229	connectivity with at least one node at any point in time.
173		230
174	=back	231	=back
175		232
176	This function will block until all nodes have been resolved and, for slave	233	Example: become a distributed node using the locla node name as profile.
177	nodes, until it has successfully established a connection to a master	234	This should be the most common form of invocation for "daemon"-type nodes.
178	server.
179		235
180	Example: become a public node listening on the default node.	236	configure
181		237
182	initialise_node;	238	Example: become an anonymous node. This form is often used for commandline
		239	clients.
183		240
184	Example: become a public node, and try to contact some well-known master	241	configure nodeid => "anon/";
185	servers to become part of the network.
186		242
187	initialise_node undef, "master1", "master2";	243	Example: configure a node using a profile called seed, which si suitable
		244	for a seed node as it binds on all local addresses on a fixed port (4040,
		245	customary for aemp).
188		246
189	Example: become a public node listening on port C<4041>.	247	# use the aemp commandline utility
		248	# aemp profile seed nodeid anon/ binds '*:4040'
190		249
191	initialise_node 4041;	250	# then use it
		251	configure profile => "seed";
192		252
193	Example: become a public node, only visible on localhost port 4044.	253	# or simply use aemp from the shell again:
		254	# aemp run profile seed
194		255
195	initialise_node "locahost:4044";	256	# or provide a nicer-to-remember nodeid
196		257	# aemp run profile seed nodeid "$(hostname)"
197	Example: become a slave node to any of the specified master servers.
198
199	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
200
201	=item $cv = resolve_node $noderef
202
203	Takes an unresolved node reference that may contain hostnames and
204	abbreviated IDs, resolves all of them and returns a resolved node
205	reference.
206
207	In addition to C<address:port> pairs allowed in resolved noderefs, the
208	following forms are supported:
209
210	=over 4
211
212	=item the empty string
213
214	An empty-string component gets resolved as if the default port (4040) was
215	specified.
216
217	=item naked port numbers (e.g. C<1234>)
218
219	These are resolved by prepending the local nodename and a colon, to be
220	further resolved.
221
222	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
223
224	These are resolved by using AnyEvent::DNS to resolve them, optionally
225	looking up SRV records for the C<aemp=4040> port, if no port was
226	specified.
227
228	=back
229		258
230	=item $SELF	259	=item $SELF
231		260
232	Contains the current port id while executing C<rcv> callbacks or C<psub>	261	Contains the current port id while executing C<rcv> callbacks or C<psub>
233	blocks.	262	blocks.
234		263
235	=item SELF, %SELF, @SELF...	264	=item *SELF, SELF, %SELF, @SELF...
236		265
237	Due to some quirks in how perl exports variables, it is impossible to	266	Due to some quirks in how perl exports variables, it is impossible to
238	just export C<$SELF>, all the symbols called C<SELF> are exported by this	267	just export C<$SELF>, all the symbols named C<SELF> are exported by this
239	module, but only C<$SELF> is currently used.	268	module, but only C<$SELF> is currently used.
240		269
241	=item snd $port, type => @data	270	=item snd $port, type => @data
242		271
243	=item snd $port, @msg	272	=item snd $port, @msg
244		273
245	Send the given message to the given port ID, which can identify either	274	Send the given message to the given port, which can identify either a
246	a local or a remote port, and can be either a string or soemthignt hat	275	local or a remote port, and must be a port ID.
247	stringifies a sa port ID (such as a port object :).
248		276
249	While the message can be about anything, it is highly recommended to use a	277	While the message can be almost anything, it is highly recommended to
250	string as first element (a portid, or some word that indicates a request	278	use a string as first element (a port ID, or some word that indicates a
251	type etc.).	279	request type etc.) and to consist if only simple perl values (scalars,
		280	arrays, hashes) - if you think you need to pass an object, think again.
252		281
253	The message data effectively becomes read-only after a call to this	282	The message data logically becomes read-only after a call to this
254	function: modifying any argument is not allowed and can cause many	283	function: modifying any argument (or values referenced by them) is
255	problems.	284	forbidden, as there can be considerable time between the call to C<snd>
		285	and the time the message is actually being serialised - in fact, it might
		286	never be copied as within the same process it is simply handed to the
		287	receiving port.
256		288
257	The type of data you can transfer depends on the transport protocol: when	289	The type of data you can transfer depends on the transport protocol: when
258	JSON is used, then only strings, numbers and arrays and hashes consisting	290	JSON is used, then only strings, numbers and arrays and hashes consisting
259	of those are allowed (no objects). When Storable is used, then anything	291	of those are allowed (no objects). When Storable is used, then anything
260	that Storable can serialise and deserialise is allowed, and for the local	292	that Storable can serialise and deserialise is allowed, and for the local
261	node, anything can be passed.	293	node, anything can be passed. Best rely only on the common denominator of
		294	these.
262		295
263	=item $local_port = port	296	=item $local_port = port
264		297
265	Create a new local port object that can be used either as a pattern	298	Create a new local port object and returns its port ID. Initially it has
266	matching port ("full port") or a single-callback port ("miniport"),	299	no callbacks set and will throw an error when it receives messages.
267	depending on how C<rcv> callbacks are bound to the object.
268		300
269	=item $port = port { my @msg = @_; $finished }	301	=item $local_port = port { my @msg = @_ }
270		302
271	Creates a "miniport", that is, a very lightweight port without any pattern	303	Creates a new local port, and returns its ID. Semantically the same as
272	matching behind it, and returns its ID. Semantically the same as creating
273	a port and calling C<rcv $port, $callback> on it.	304	creating a port and calling C<rcv $port, $callback> on it.
274		305
275	The block will be called for every message received on the port. When the	306	The block will be called for every message received on the port, with the
276	callback returns a true value its job is considered "done" and the port	307	global variable C<$SELF> set to the port ID. Runtime errors will cause the
277	will be destroyed. Otherwise it will stay alive.	308	port to be C<kil>ed. The message will be passed as-is, no extra argument
		309	(i.e. no port ID) will be passed to the callback.
278		310
279	The message will be passed as-is, no extra argument (i.e. no port id) will	311	If you want to stop/destroy the port, simply C<kil> it:
280	be passed to the callback.
281		312
282	If you need the local port id in the callback, this works nicely:	313	my $port = port {
283		314	my @msg = @_;
284	my $port; $port = port {	315	...
285	snd $otherport, reply => $port;	316	kil $SELF;
286	};	317	};
287		318
288	=cut	319	=cut
289		320
290	sub rcv($@);	321	sub rcv($@);
		322
		323	sub _kilme {
		324	die "received message on port without callback";
		325	}
291		326
292	sub port(;&) {	327	sub port(;&) {
293	my $id = "$UNIQ." . $ID++;	328	my $id = "$UNIQ." . $ID++;
294	my $port = "$NODE#$id";	329	my $port = "$NODE#$id";
295		330
296	if (@_) {	331	rcv $port, shift \|\| \&_kilme;
297	rcv $port, shift;
298	} else {
299	$PORT{$id} = sub { }; # nop
300	}
301		332
302	$port	333	$port
303	}	334	}
304		335
305	=item reg $port, $name
306
307	=item reg $name
308
309	Registers the given port (or C<$SELF><<< if missing) under the name
310	C<$name>. If the name already exists it is replaced.
311
312	A port can only be registered under one well known name.
313
314	A port automatically becomes unregistered when it is killed.
315
316	=cut
317
318	sub reg(@) {
319	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
320
321	$REG{$_[0]} = $port;
322	}
323
324	=item rcv $port, $callback->(@msg)	336	=item rcv $local_port, $callback->(@msg)
325		337
326	Replaces the callback on the specified miniport (after converting it to	338	Replaces the default callback on the specified port. There is no way to
327	one if required).	339	remove the default callback: use C<sub { }> to disable it, or better
328		340	C<kil> the port when it is no longer needed.
329	=item rcv $port, tagstring => $callback->(@msg), ...
330
331	=item rcv $port, $smartmatch => $callback->(@msg), ...
332
333	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
334
335	Register callbacks to be called on matching messages on the given full
336	port (after converting it to one if required) and return the port.
337
338	The callback has to return a true value when its work is done, after
339	which is will be removed, or a false value in which case it will stay
340	registered.
341		341
342	The global C<$SELF> (exported by this module) contains C<$port> while	342	The global C<$SELF> (exported by this module) contains C<$port> while
343	executing the callback.	343	executing the callback. Runtime errors during callback execution will
		344	result in the port being C<kil>ed.
344		345
345	Runtime errors wdurign callback execution will result in the port being	346	The default callback received all messages not matched by a more specific
346	C<kil>ed.	347	C<tag> match.
347		348
348	If the match is an array reference, then it will be matched against the	349	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
349	first elements of the message, otherwise only the first element is being
350	matched.
351		350
352	Any element in the match that is specified as C<_any_> (a function	351	Register (or replace) callbacks to be called on messages starting with the
353	exported by this module) matches any single element of the message.	352	given tag on the given port (and return the port), or unregister it (when
		353	C<$callback> is C<$undef> or missing). There can only be one callback
		354	registered for each tag.
354		355
355	While not required, it is highly recommended that the first matching	356	The original message will be passed to the callback, after the first
356	element is a string identifying the message. The one-string-only match is	357	element (the tag) has been removed. The callback will use the same
357	also the most efficient match (by far).	358	environment as the default callback (see above).
358		359
359	Example: create a port and bind receivers on it in one go.	360	Example: create a port and bind receivers on it in one go.
360		361
361	my $port = rcv port,	362	my $port = rcv port,
362	msg1 => sub { ...; 0 },	363	msg1 => sub { ... },
363	msg2 => sub { ...; 0 },	364	msg2 => sub { ... },
364	;	365	;
365		366
366	Example: create a port, bind receivers and send it in a message elsewhere	367	Example: create a port, bind receivers and send it in a message elsewhere
367	in one go:	368	in one go:
368		369
369	snd $otherport, reply =>	370	snd $otherport, reply =>
370	rcv port,	371	rcv port,
371	msg1 => sub { ...; 0 },	372	msg1 => sub { ... },
372	...	373	...
373	;	374	;
374		375
		376	Example: temporarily register a rcv callback for a tag matching some port
		377	(e.g. for a rpc reply) and unregister it after a message was received.
		378
		379	rcv $port, $otherport => sub {
		380	my @reply = @_;
		381
		382	rcv $SELF, $otherport;
		383	};
		384
375	=cut	385	=cut
376		386
377	sub rcv($@) {	387	sub rcv($@) {
378	my $port = shift;	388	my $port = shift;
379	my ($noderef, $portid) = split /#/, $port, 2;	389	my ($nodeid, $portid) = split /#/, $port, 2;
380		390
381	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	391	$NODE{$nodeid} == $NODE{""}
382	or Carp::croak "$port: rcv can only be called on local ports, caught";	392	or Carp::croak "$port: rcv can only be called on local ports, caught";
383		393
384	if (@_ == 1) {	394	while (@_) {
		395	if (ref $_[0]) {
		396	if (my $self = $PORT_DATA{$portid}) {
		397	"AnyEvent::MP::Port" eq ref $self
		398	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		399
		400	$self->[2] = shift;
		401	} else {
385	my $cb = shift;	402	my $cb = shift;
386	delete $PORT_DATA{$portid};
387	$PORT{$portid} = sub {	403	$PORT{$portid} = sub {
388	local $SELF = $port;	404	local $SELF = $port;
389	eval {	405	eval { &$cb }; _self_die if $@;
390	&$cb	406	};
391	and kil $port;
392	};	407	}
393	_self_die if $@;	408	} elsif (defined $_[0]) {
394	};
395	} else {
396	my $self = $PORT_DATA{$portid} \|\|= do {	409	my $self = $PORT_DATA{$portid} \|\|= do {
397	my $self = bless {	410	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
398	id => $port,
399	}, "AnyEvent::MP::Port";
400		411
401	$PORT{$portid} = sub {	412	$PORT{$portid} = sub {
402	local $SELF = $port;	413	local $SELF = $port;
403		414
404	eval {
405	for (@{ $self->{rc0}{$_[0]} }) {	415	if (my $cb = $self->[1]{$_[0]}) {
406	$_ && &{$_->[0]}	416	shift;
407	&& undef $_;	417	eval { &$cb }; _self_die if $@;
408	}	418	} else {
409
410	for (@{ $self->{rcv}{$_[0]} }) {
411	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
412	&& &{$_->[0]}	419	&{ $self->[0] };
413	&& undef $_;
414	}
415
416	for (@{ $self->{any} }) {
417	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
418	&& &{$_->[0]}
419	&& undef $_;
420	}	420	}
421	};	421	};
422	_self_die if $@;	422
		423	$self
423	};	424	};
424		425
425	$self
426	};
427
428	"AnyEvent::MP::Port" eq ref $self	426	"AnyEvent::MP::Port" eq ref $self
429	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	427	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
430		428
431	while (@_) {
432	my ($match, $cb) = splice @_, 0, 2;	429	my ($tag, $cb) = splice @_, 0, 2;
433		430
434	if (!ref $match) {	431	if (defined $cb) {
435	push @{ $self->{rc0}{$match} }, [$cb];	432	$self->[1]{$tag} = $cb;
436	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
437	my ($type, @match) = @$match;
438	@match
439	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
440	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
441	} else {	433	} else {
442	push @{ $self->{any} }, [$cb, $match];	434	delete $self->[1]{$tag};
443	}	435	}
444	}	436	}
445	}	437	}
446		438
447	$port	439	$port
…		…
483	$res	475	$res
484	}	476	}
485	}	477	}
486	}	478	}
487		479
488	=item $guard = mon $port, $cb->(@reason)	480	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
489		481
490	=item $guard = mon $port, $rcvport	482	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
491		483
492	=item $guard = mon $port	484	=item $guard = mon $port # kill $SELF when $port dies
493		485
494	=item $guard = mon $port, $rcvport, @msg	486	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
495		487
496	Monitor the given port and do something when the port is killed, and	488	Monitor the given port and do something when the port is killed or
497	optionally return a guard that can be used to stop monitoring again.	489	messages to it were lost, and optionally return a guard that can be used
		490	to stop monitoring again.
498		491
499	In the first form (callback), the callback is simply called with any	492	In the first form (callback), the callback is simply called with any
500	number of C<@reason> elements (no @reason means that the port was deleted	493	number of C<@reason> elements (no @reason means that the port was deleted
501	"normally"). Note also that I<< the callback B<must> never die >>, so use	494	"normally"). Note also that I<< the callback B<must> never die >>, so use
502	C<eval> if unsure.	495	C<eval> if unsure.
503		496
504	In the second form (another port given), the other port (C<$rcvport)	497	In the second form (another port given), the other port (C<$rcvport>)
505	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on	498	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
506	"normal" kils nothing happens, while under all other conditions, the other	499	"normal" kils nothing happens, while under all other conditions, the other
507	port is killed with the same reason.	500	port is killed with the same reason.
508		501
509	The third form (kill self) is the same as the second form, except that	502	The third form (kill self) is the same as the second form, except that
510	C<$rvport> defaults to C<$SELF>.	503	C<$rvport> defaults to C<$SELF>.
511		504
512	In the last form (message), a message of the form C<@msg, @reason> will be	505	In the last form (message), a message of the form C<@msg, @reason> will be
513	C<snd>.	506	C<snd>.
		507
		508	Monitoring-actions are one-shot: once messages are lost (and a monitoring
		509	alert was raised), they are removed and will not trigger again.
514		510
515	As a rule of thumb, monitoring requests should always monitor a port from	511	As a rule of thumb, monitoring requests should always monitor a port from
516	a local port (or callback). The reason is that kill messages might get	512	a local port (or callback). The reason is that kill messages might get
517	lost, just like any other message. Another less obvious reason is that	513	lost, just like any other message. Another less obvious reason is that
518	even monitoring requests can get lost (for exmaple, when the connection	514	even monitoring requests can get lost (for example, when the connection
519	to the other node goes down permanently). When monitoring a port locally	515	to the other node goes down permanently). When monitoring a port locally
520	these problems do not exist.	516	these problems do not exist.
521		517
		518	C<mon> effectively guarantees that, in the absence of hardware failures,
		519	after starting the monitor, either all messages sent to the port will
		520	arrive, or the monitoring action will be invoked after possible message
		521	loss has been detected. No messages will be lost "in between" (after
		522	the first lost message no further messages will be received by the
		523	port). After the monitoring action was invoked, further messages might get
		524	delivered again.
		525
		526	Inter-host-connection timeouts and monitoring depend on the transport
		527	used. The only transport currently implemented is TCP, and AnyEvent::MP
		528	relies on TCP to detect node-downs (this can take 10-15 minutes on a
		529	non-idle connection, and usually around two hours for idle conenctions).
		530
		531	This means that monitoring is good for program errors and cleaning up
		532	stuff eventually, but they are no replacement for a timeout when you need
		533	to ensure some maximum latency.
		534
522	Example: call a given callback when C<$port> is killed.	535	Example: call a given callback when C<$port> is killed.
523		536
524	mon $port, sub { warn "port died because of <@_>\n" };	537	mon $port, sub { warn "port died because of <@_>\n" };
525		538
526	Example: kill ourselves when C<$port> is killed abnormally.	539	Example: kill ourselves when C<$port> is killed abnormally.
…		…
532	mon $port, $self => "restart";	545	mon $port, $self => "restart";
533		546
534	=cut	547	=cut
535		548
536	sub mon {	549	sub mon {
537	my ($noderef, $port) = split /#/, shift, 2;	550	my ($nodeid, $port) = split /#/, shift, 2;
538		551
539	my $node = $NODE{$noderef} \|\| add_node $noderef;	552	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
540		553
541	my $cb = @_ ? $_[0] : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	554	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
542		555
543	unless (ref $cb) {	556	unless (ref $cb) {
544	if (@_) {	557	if (@_) {
545	# send a kill info message	558	# send a kill info message
546	my (@msg) = @_;	559	my (@msg) = ($cb, @_);
547	$cb = sub { snd @msg, @_ };	560	$cb = sub { snd @msg, @_ };
548	} else {	561	} else {
549	# simply kill other port	562	# simply kill other port
550	my $port = $cb;	563	my $port = $cb;
551	$cb = sub { kil $port, @_ if @_ };	564	$cb = sub { kil $port, @_ if @_ };
…		…
564	is killed, the references will be freed.	577	is killed, the references will be freed.
565		578
566	Optionally returns a guard that will stop the monitoring.	579	Optionally returns a guard that will stop the monitoring.
567		580
568	This function is useful when you create e.g. timers or other watchers and	581	This function is useful when you create e.g. timers or other watchers and
569	want to free them when the port gets killed:	582	want to free them when the port gets killed (note the use of C<psub>):
570		583
571	$port->rcv (start => sub {	584	$port->rcv (start => sub {
572	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	585	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
573	undef $timer if 0.9 < rand;	586	undef $timer if 0.9 < rand;
574	});	587	});
575	});	588	});
576		589
577	=cut	590	=cut
…		…
586		599
587	=item kil $port[, @reason]	600	=item kil $port[, @reason]
588		601
589	Kill the specified port with the given C<@reason>.	602	Kill the specified port with the given C<@reason>.
590		603
591	If no C<@reason> is specified, then the port is killed "normally" (linked	604	If no C<@reason> is specified, then the port is killed "normally" (ports
592	ports will not be kileld, or even notified).	605	monitoring other ports will not necessarily die because a port dies
		606	"normally").
593		607
594	Otherwise, linked ports get killed with the same reason (second form of	608	Otherwise, linked ports get killed with the same reason (second form of
595	C<mon>, see below).	609	C<mon>, see above).
596		610
597	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	611	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
598	will be reported as reason C<< die => $@ >>.	612	will be reported as reason C<< die => $@ >>.
599		613
600	Transport/communication errors are reported as C<< transport_error =>	614	Transport/communication errors are reported as C<< transport_error =>
601	$message >>.	615	$message >>.
602		616
603	=back
604
605	=head1 NODE MESSAGES
606
607	Nodes understand the following messages sent to them. Many of them take
608	arguments called C<@reply>, which will simply be used to compose a reply
609	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
610	the remaining arguments are simply the message data.
611
612	While other messages exist, they are not public and subject to change.
613
614	=over 4
615
616	=cut	617	=cut
617		618
618	=item lookup => $name, @reply	619	=item $port = spawn $node, $initfunc[, @initdata]
619		620
620	Replies with the port ID of the specified well-known port, or C<undef>.	621	Creates a port on the node C<$node> (which can also be a port ID, in which
		622	case it's the node where that port resides).
621		623
622	=item devnull => ...	624	The port ID of the newly created port is returned immediately, and it is
		625	possible to immediately start sending messages or to monitor the port.
623		626
624	Generic data sink/CPU heat conversion.	627	After the port has been created, the init function is called on the remote
		628	node, in the same context as a C<rcv> callback. This function must be a
		629	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
		630	specify a function in the main program, use C<::name>.
625		631
626	=item relay => $port, @msg	632	If the function doesn't exist, then the node tries to C<require>
		633	the package, then the package above the package and so on (e.g.
		634	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		635	exists or it runs out of package names.
627		636
628	Simply forwards the message to the given port.	637	The init function is then called with the newly-created port as context
		638	object (C<$SELF>) and the C<@initdata> values as arguments. It I<must>
		639	call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise
		640	the port might not get created.
629		641
630	=item eval => $string[ @reply]	642	A common idiom is to pass a local port, immediately monitor the spawned
		643	port, and in the remote init function, immediately monitor the passed
		644	local port. This two-way monitoring ensures that both ports get cleaned up
		645	when there is a problem.
631		646
632	Evaluates the given string. If C<@reply> is given, then a message of the	647	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
633	form C<@reply, $@, @evalres> is sent.	648	caller before C<spawn> returns (by delaying invocation when spawn is
		649	called for the local node).
634		650
635	Example: crash another node.	651	Example: spawn a chat server port on C<$othernode>.
636		652
637	snd $othernode, eval => "exit";	653	# this node, executed from within a port context:
		654	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		655	mon $server;
638		656
639	=item time => @reply	657	# init function on C<$othernode>
		658	sub connect {
		659	my ($srcport) = @_;
640		660
641	Replies the the current node time to C<@reply>.	661	mon $srcport;
642		662
643	Example: tell the current node to send the current time to C<$myport> in a	663	rcv $SELF, sub {
644	C<timereply> message.	664	...
		665	};
		666	}
645		667
646	snd $NODE, time => $myport, timereply => 1, 2;	668	=cut
647	# => snd $myport, timereply => 1, 2, <time>	669
		670	sub _spawn {
		671	my $port = shift;
		672	my $init = shift;
		673
		674	# rcv will create the actual port
		675	local $SELF = "$NODE#$port";
		676	eval {
		677	&{ load_func $init }
		678	};
		679	_self_die if $@;
		680	}
		681
		682	sub spawn(@) {
		683	my ($nodeid, undef) = split /#/, shift, 2;
		684
		685	my $id = "$RUNIQ." . $ID++;
		686
		687	$_[0] =~ /::/
		688	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		689
		690	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
		691
		692	"$nodeid#$id"
		693	}
		694
		695	=item after $timeout, @msg
		696
		697	=item after $timeout, $callback
		698
		699	Either sends the given message, or call the given callback, after the
		700	specified number of seconds.
		701
		702	This is simply a utility function that comes in handy at times - the
		703	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		704	so it may go away in the future.
		705
		706	=cut
		707
		708	sub after($@) {
		709	my ($timeout, @action) = @_;
		710
		711	my $t; $t = AE::timer $timeout, 0, sub {
		712	undef $t;
		713	ref $action[0]
		714	? $action[0]()
		715	: snd @action;
		716	};
		717	}
648		718
649	=back	719	=back
650		720
651	=head1 AnyEvent::MP vs. Distributed Erlang	721	=head1 AnyEvent::MP vs. Distributed Erlang
652		722
…		…
662		732
663	Despite the similarities, there are also some important differences:	733	Despite the similarities, there are also some important differences:
664		734
665	=over 4	735	=over 4
666		736
667	=item * Node references contain the recipe on how to contact them.	737	=item * Node IDs are arbitrary strings in AEMP.
668		738
669	Erlang relies on special naming and DNS to work everywhere in the	739	Erlang relies on special naming and DNS to work everywhere in the same
670	same way. AEMP relies on each node knowing it's own address(es), with	740	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
671	convenience functionality.	741	configuration or DNS), but will otherwise discover other odes itself.
672		742
673	This means that AEMP requires a less tightly controlled environment at the	743	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
674	cost of longer node references and a slightly higher management overhead.	744	uses "local ports are like remote ports".
		745
		746	The failure modes for local ports are quite different (runtime errors
		747	only) then for remote ports - when a local port dies, you I<know> it dies,
		748	when a connection to another node dies, you know nothing about the other
		749	port.
		750
		751	Erlang pretends remote ports are as reliable as local ports, even when
		752	they are not.
		753
		754	AEMP encourages a "treat remote ports differently" philosophy, with local
		755	ports being the special case/exception, where transport errors cannot
		756	occur.
675		757
676	=item * Erlang uses processes and a mailbox, AEMP does not queue.	758	=item * Erlang uses processes and a mailbox, AEMP does not queue.
677		759
678	Erlang uses processes that selctively receive messages, and therefore	760	Erlang uses processes that selectively receive messages, and therefore
679	needs a queue. AEMP is event based, queuing messages would serve no useful	761	needs a queue. AEMP is event based, queuing messages would serve no
680	purpose.	762	useful purpose. For the same reason the pattern-matching abilities of
		763	AnyEvent::MP are more limited, as there is little need to be able to
		764	filter messages without dequeuing them.
681		765
682	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	766	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
683		767
684	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	768	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
685		769
686	Sending messages in Erlang is synchronous and blocks the process. AEMP	770	Sending messages in Erlang is synchronous and blocks the process (and
687	sends are immediate, connection establishment is handled in the	771	so does not need a queue that can overflow). AEMP sends are immediate,
688	background.	772	connection establishment is handled in the background.
689		773
690	=item * Erlang can silently lose messages, AEMP cannot.	774	=item * Erlang suffers from silent message loss, AEMP does not.
691		775
692	Erlang makes few guarantees on messages delivery - messages can get lost	776	Erlang makes few guarantees on messages delivery - messages can get lost
693	without any of the processes realising it (i.e. you send messages a, b,	777	without any of the processes realising it (i.e. you send messages a, b,
694	and c, and the other side only receives messages a and c).	778	and c, and the other side only receives messages a and c).
695		779
696	AEMP guarantees correct ordering, and the guarantee that there are no	780	AEMP guarantees correct ordering, and the guarantee that after one message
697	holes in the message sequence.	781	is lost, all following ones sent to the same port are lost as well, until
698		782	monitoring raises an error, so there are no silent "holes" in the message
699	=item * In Erlang, processes can be declared dead and later be found to be	783	sequence.
700	alive.
701
702	In Erlang it can happen that a monitored process is declared dead and
703	linked processes get killed, but later it turns out that the process is
704	still alive - and can receive messages.
705
706	In AEMP, when port monitoring detects a port as dead, then that port will
707	eventually be killed - it cannot happen that a node detects a port as dead
708	and then later sends messages to it, finding it is still alive.
709		784
710	=item * Erlang can send messages to the wrong port, AEMP does not.	785	=item * Erlang can send messages to the wrong port, AEMP does not.
711		786
712	In Erlang it is quite possible that a node that restarts reuses a process	787	In Erlang it is quite likely that a node that restarts reuses a process ID
713	ID known to other nodes for a completely different process, causing	788	known to other nodes for a completely different process, causing messages
714	messages destined for that process to end up in an unrelated process.	789	destined for that process to end up in an unrelated process.
715		790
716	AEMP never reuses port IDs, so old messages or old port IDs floating	791	AEMP never reuses port IDs, so old messages or old port IDs floating
717	around in the network will not be sent to an unrelated port.	792	around in the network will not be sent to an unrelated port.
718		793
719	=item * Erlang uses unprotected connections, AEMP uses secure	794	=item * Erlang uses unprotected connections, AEMP uses secure
720	authentication and can use TLS.	795	authentication and can use TLS.
721		796
722	AEMP can use a proven protocol - SSL/TLS - to protect connections and	797	AEMP can use a proven protocol - TLS - to protect connections and
723	securely authenticate nodes.	798	securely authenticate nodes.
724		799
725	=item * The AEMP protocol is optimised for both text-based and binary	800	=item * The AEMP protocol is optimised for both text-based and binary
726	communications.	801	communications.
727		802
728	The AEMP protocol, unlike the Erlang protocol, supports both	803	The AEMP protocol, unlike the Erlang protocol, supports both programming
729	language-independent text-only protocols (good for debugging) and binary,	804	language independent text-only protocols (good for debugging) and binary,
730	language-specific serialisers (e.g. Storable).	805	language-specific serialisers (e.g. Storable). By default, unless TLS is
		806	used, the protocol is actually completely text-based.
731		807
732	It has also been carefully designed to be implementable in other languages	808	It has also been carefully designed to be implementable in other languages
733	with a minimum of work while gracefully degrading fucntionality to make the	809	with a minimum of work while gracefully degrading functionality to make the
734	protocol simple.	810	protocol simple.
735		811
736	=item * AEMP has more flexible monitoring options than Erlang.	812	=item * AEMP has more flexible monitoring options than Erlang.
737		813
738	In Erlang, you can chose to receive I<all> exit signals as messages	814	In Erlang, you can chose to receive I<all> exit signals as messages
…		…
741	Erlang, as one can choose between automatic kill, exit message or callback	817	Erlang, as one can choose between automatic kill, exit message or callback
742	on a per-process basis.	818	on a per-process basis.
743		819
744	=item * Erlang tries to hide remote/local connections, AEMP does not.	820	=item * Erlang tries to hide remote/local connections, AEMP does not.
745		821
746	Monitoring in Erlang is not an indicator of process death/crashes,	822	Monitoring in Erlang is not an indicator of process death/crashes, in the
747	as linking is (except linking is unreliable in Erlang).	823	same way as linking is (except linking is unreliable in Erlang).
748		824
749	In AEMP, you don't "look up" registered port names or send to named ports	825	In AEMP, you don't "look up" registered port names or send to named ports
750	that might or might not be persistent. Instead, you normally spawn a port	826	that might or might not be persistent. Instead, you normally spawn a port
751	on the remote node. The init function monitors the you, and you monitor	827	on the remote node. The init function monitors you, and you monitor the
752	the remote port. Since both monitors are local to the node, they are much	828	remote port. Since both monitors are local to the node, they are much more
753	more reliable.	829	reliable (no need for C<spawn_link>).
754		830
755	This also saves round-trips and avoids sending messages to the wrong port	831	This also saves round-trips and avoids sending messages to the wrong port
756	(hard to do in Erlang).	832	(hard to do in Erlang).
757		833
758	=back	834	=back
759		835
		836	=head1 RATIONALE
		837
		838	=over 4
		839
		840	=item Why strings for port and node IDs, why not objects?
		841
		842	We considered "objects", but found that the actual number of methods
		843	that can be called are quite low. Since port and node IDs travel over
		844	the network frequently, the serialising/deserialising would add lots of
		845	overhead, as well as having to keep a proxy object everywhere.
		846
		847	Strings can easily be printed, easily serialised etc. and need no special
		848	procedures to be "valid".
		849
		850	And as a result, a miniport consists of a single closure stored in a
		851	global hash - it can't become much cheaper.
		852
		853	=item Why favour JSON, why not a real serialising format such as Storable?
		854
		855	In fact, any AnyEvent::MP node will happily accept Storable as framing
		856	format, but currently there is no way to make a node use Storable by
		857	default (although all nodes will accept it).
		858
		859	The default framing protocol is JSON because a) JSON::XS is many times
		860	faster for small messages and b) most importantly, after years of
		861	experience we found that object serialisation is causing more problems
		862	than it solves: Just like function calls, objects simply do not travel
		863	easily over the network, mostly because they will always be a copy, so you
		864	always have to re-think your design.
		865
		866	Keeping your messages simple, concentrating on data structures rather than
		867	objects, will keep your messages clean, tidy and efficient.
		868
		869	=back
		870
760	=head1 SEE ALSO	871	=head1 SEE ALSO
		872
		873	L<AnyEvent::MP::Intro> - a gentle introduction.
		874
		875	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		876
		877	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		878	your applications.
		879
		880	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
		881	all nodes.
761		882
762	L<AnyEvent>.	883	L<AnyEvent>.
763		884
764	=head1 AUTHOR	885	=head1 AUTHOR
765		886

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.37 by root, Fri Aug 7 16:47:23 2009 UTC vs. Revision 1.84 by root, Tue Sep 8 01:42:14 2009 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.37 by root, Fri Aug 7 16:47:23 2009 UTC vs.
Revision 1.84 by root, Tue Sep 8 01:42:14 2009 UTC