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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.34 by root, Wed Aug 5 23:50:46 2009 UTC vs.
Revision 1.85 by root, Tue Sep 8 01:54:13 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	34
		35	# monitoring
		36	mon $port, $cb->(@msg) # callback is invoked on death
		37	mon $port, $otherport # kill otherport on abnormal death
		38	mon $port, $otherport, @msg # send message on death
		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.
27		49
28	=head1 DESCRIPTION	50	=head1 DESCRIPTION
29		51
30	This module (-family) implements a simple message passing framework.	52	This module (-family) implements a simple message passing framework.
31		53
32	Despite its simplicity, you can securely message other processes running	54	Despite its simplicity, you can securely message other processes running
33	on the same or other hosts.	55	on the same or other hosts, and you can supervise entities remotely.
34		56
35	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>
36	manual page.	58	manual page and the examples under F<eg/>.
37
38	At the moment, this module family is severly broken and underdocumented,
39	so do not use. This was uploaded mainly to reserve the CPAN namespace -
40	stay tuned! The basic API should be finished, however.
41		59
42	=head1 CONCEPTS	60	=head1 CONCEPTS
43		61
44	=over 4	62	=over 4
45		63
46	=item port	64	=item port
47		65
48	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).
49		68
50	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
51	messages. All C<rcv> handlers will receive messages they match, messages	70	some messages. Messages send to ports will not be queued, regardless of
52	will not be queued.	71	anything was listening for them or not.
53		72
54	=item port id - C<noderef#portname>	73	=item port ID - C<nodeid#portname>
55		74
56	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
57	separator, and a port name (a printable string of unspecified format). An	76	separator, and a port name (a printable string of unspecified format).
58	exception is the the node port, whose ID is identical to its node
59	reference.
60		77
61	=item node	78	=item node
62		79
63	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,
64	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
65	create new ports, among other things.	82	ports.
66		83
67	Nodes are either private (single-process only), slaves (connected to a	84	Nodes are either public (have one or more listening ports) or private
68	master node only) or public nodes (connectable from unrelated nodes).	85	(no listening ports). Private nodes cannot talk to other private nodes
		86	currently.
69		87
70	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	88	=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*>
71		89
72	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
73	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
74	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.
75		94
76	This recipe is simply a comma-separated list of C<address:port> pairs (for	95	=item binds - C<ip:port>
77	TCP/IP, other protocols might look different).
78		96
79	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
80	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.
81		101
82	Before using an unresolved node reference in a message you first have to	102	=item seed nodes
83	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. 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.
84		129
85	=back	130	=back
86		131
87	=head1 VARIABLES/FUNCTIONS	132	=head1 VARIABLES/FUNCTIONS
88		133
…		…
90		135
91	=cut	136	=cut
92		137
93	package AnyEvent::MP;	138	package AnyEvent::MP;
94		139
95	use AnyEvent::MP::Base;	140	use AnyEvent::MP::Kernel;
96		141
97	use common::sense;	142	use common::sense;
98		143
99	use Carp ();	144	use Carp ();
100		145
101	use AE ();	146	use AE ();
102		147
103	use base "Exporter";	148	use base "Exporter";
104		149
105	our $VERSION = '0.1';	150	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		151
106	our @EXPORT = qw(	152	our @EXPORT = qw(
107	NODE $NODE *SELF node_of _any_	153	NODE $NODE *SELF node_of after
108	resolve_node initialise_node	154	configure
109	snd rcv mon kil reg psub	155	snd rcv mon mon_guard kil reg psub spawn
110	port	156	port
111	);	157	);
112		158
113	our $SELF;	159	our $SELF;
114		160
…		…
118	kil $SELF, die => $msg;	164	kil $SELF, die => $msg;
119	}	165	}
120		166
121	=item $thisnode = NODE / $NODE	167	=item $thisnode = NODE / $NODE
122		168
123	The C<NODE> function returns, and the C<$NODE> variable contains	169	The C<NODE> function returns, and the C<$NODE> variable contains, the node
124	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
125	to C<become_public> or C<become_slave>, after which all local port	171	a call to C<configure>.
126	identifiers become invalid.
127		172
128	=item $noderef = node_of $port	173	=item $nodeid = node_of $port
129		174
130	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.
131		176
132	=item initialise_node $noderef, $seednode, $seednode...	177	=item configure $profile, key => value...
133		178
134	=item initialise_node "slave/", $master, $master...	179	=item configure key => value...
135		180
136	Before a node can talk to other nodes on the network it has to initialise	181	Before a node can talk to other nodes on the network (i.e. enter
137	itself - the minimum a node needs to know is it's own name, and optionally	182	"distributed mode") it has to configure itself - the minimum a node needs
138	it should know the noderefs of some other nodes in the network.	183	to know is its own name, and optionally it should know the addresses of
		184	some other nodes in the network to discover other nodes.
139		185
140	This function initialises a node - it must be called exactly once (or	186	This function configures a node - it must be called exactly once (or
141	never) before calling other AnyEvent::MP functions.	187	never) before calling other AnyEvent::MP functions.
142		188
143	All arguments are noderefs, which can be either resolved or unresolved.
144
145	There are two types of networked nodes, public nodes and slave nodes:
146
147	=over 4	189	=over 4
148		190
149	=item public nodes	191	=item step 1, gathering configuration from profiles
150		192
151	For public nodes, C<$noderef> must either be a (possibly unresolved)	193	The function first looks up a profile in the aemp configuration (see the
152	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
153	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.
154		197
155	Afterwards, the node will bind itself on all endpoints and try to connect	198	The profile data is then gathered as follows:
156	to all additional C<$seednodes> that are specified. Seednodes are optional
157	and can be used to quickly bootstrap the node into an existing network.
158		199
159	=item slave nodes	200	First, all remaining key => value pairs (all of which are conveniently
		201	undocumented at the moment) will be interpreted as configuration
		202	data. Then they will be overwritten by any values specified in the global
		203	default configuration (see the F<aemp> utility), then the chain of
		204	profiles chosen by the profile name (and any C<parent> attributes).
160		205
161	When the C<$noderef> is the special string C<slave/>, then the node will	206	That means that the values specified in the profile have highest priority
162	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,
163	route most of their traffic to the master node that they attach to.	208	and can only be used to specify defaults.
164		209
165	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
166	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
167	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.
168		231
169	=back	232	=back
170		233
171	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.
172	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.
173	server.
174		236
175	Example: become a public node listening on the default node.	237	configure
176		238
177	initialise_node;	239	Example: become an anonymous node. This form is often used for commandline
		240	clients.
178		241
179	Example: become a public node, and try to contact some well-known master	242	configure nodeid => "anon/";
180	servers to become part of the network.
181		243
182	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).
183		247
184	Example: become a public node listening on port C<4041>.	248	# use the aemp commandline utility
		249	# aemp profile seed nodeid anon/ binds '*:4040'
185		250
186	initialise_node 4041;	251	# then use it
		252	configure profile => "seed";
187		253
188	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
189		256
190	initialise_node "locahost:4044";	257	# or provide a nicer-to-remember nodeid
191		258	# aemp run profile seed nodeid "$(hostname)"
192	Example: become a slave node to any of the specified master servers.
193
194	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
195
196	=item $cv = resolve_node $noderef
197
198	Takes an unresolved node reference that may contain hostnames and
199	abbreviated IDs, resolves all of them and returns a resolved node
200	reference.
201
202	In addition to C<address:port> pairs allowed in resolved noderefs, the
203	following forms are supported:
204
205	=over 4
206
207	=item the empty string
208
209	An empty-string component gets resolved as if the default port (4040) was
210	specified.
211
212	=item naked port numbers (e.g. C<1234>)
213
214	These are resolved by prepending the local nodename and a colon, to be
215	further resolved.
216
217	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
218
219	These are resolved by using AnyEvent::DNS to resolve them, optionally
220	looking up SRV records for the C<aemp=4040> port, if no port was
221	specified.
222
223	=back
224		259
225	=item $SELF	260	=item $SELF
226		261
227	Contains the current port id while executing C<rcv> callbacks or C<psub>	262	Contains the current port id while executing C<rcv> callbacks or C<psub>
228	blocks.	263	blocks.
229		264
230	=item SELF, %SELF, @SELF...	265	=item *SELF, SELF, %SELF, @SELF...
231		266
232	Due to some quirks in how perl exports variables, it is impossible to	267	Due to some quirks in how perl exports variables, it is impossible to
233	just export C<$SELF>, all the symbols called C<SELF> are exported by this	268	just export C<$SELF>, all the symbols named C<SELF> are exported by this
234	module, but only C<$SELF> is currently used.	269	module, but only C<$SELF> is currently used.
235		270
236	=item snd $port, type => @data	271	=item snd $port, type => @data
237		272
238	=item snd $port, @msg	273	=item snd $port, @msg
239		274
240	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
241	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.
242	stringifies a sa port ID (such as a port object :).
243		277
244	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
245	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
246	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.
247		282
248	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
249	function: modifying any argument is not allowed and can cause many	284	function: modifying any argument (or values referenced by them) is
250	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.
251		289
252	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
253	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
254	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
255	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
256	node, anything can be passed.	294	node, anything can be passed. Best rely only on the common denominator of
		295	these.
257		296
258	=item $local_port = port	297	=item $local_port = port
259		298
260	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
261	matching port ("full port") or a single-callback port ("miniport"),	300	no callbacks set and will throw an error when it receives messages.
262	depending on how C<rcv> callbacks are bound to the object.
263		301
264	=item $port = port { my @msg = @_; $finished }	302	=item $local_port = port { my @msg = @_ }
265		303
266	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
267	matching behind it, and returns its ID. Semantically the same as creating
268	a port and calling C<rcv $port, $callback> on it.	305	creating a port and calling C<rcv $port, $callback> on it.
269		306
270	The block will be called for every message received on the port. When the	307	The block will be called for every message received on the port, with the
271	callback returns a true value its job is considered "done" and the port	308	global variable C<$SELF> set to the port ID. Runtime errors will cause the
272	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.
273		311
274	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:
275	be passed to the callback.
276		313
277	If you need the local port id in the callback, this works nicely:	314	my $port = port {
278		315	my @msg = @_;
279	my $port; $port = port {	316	...
280	snd $otherport, reply => $port;	317	kil $SELF;
281	};	318	};
282		319
283	=cut	320	=cut
284		321
285	sub rcv($@);	322	sub rcv($@);
		323
		324	sub _kilme {
		325	die "received message on port without callback";
		326	}
286		327
287	sub port(;&) {	328	sub port(;&) {
288	my $id = "$UNIQ." . $ID++;	329	my $id = "$UNIQ." . $ID++;
289	my $port = "$NODE#$id";	330	my $port = "$NODE#$id";
290		331
291	if (@_) {	332	rcv $port, shift \|\| \&_kilme;
292	rcv $port, shift;
293	} else {
294	$PORT{$id} = sub { }; # nop
295	}
296		333
297	$port	334	$port
298	}	335	}
299		336
300	=item reg $port, $name
301
302	Registers the given port under the name C<$name>. If the name already
303	exists it is replaced.
304
305	A port can only be registered under one well known name.
306
307	A port automatically becomes unregistered when it is killed.
308
309	=cut
310
311	sub reg(@) {
312	my ($port, $name) = @_;
313
314	$REG{$name} = $port;
315	}
316
317	=item rcv $port, $callback->(@msg)	337	=item rcv $local_port, $callback->(@msg)
318		338
319	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
320	one if required).	340	remove the default callback: use C<sub { }> to disable it, or better
321		341	C<kil> the port when it is no longer needed.
322	=item rcv $port, tagstring => $callback->(@msg), ...
323
324	=item rcv $port, $smartmatch => $callback->(@msg), ...
325
326	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
327
328	Register callbacks to be called on matching messages on the given full
329	port (after converting it to one if required).
330
331	The callback has to return a true value when its work is done, after
332	which is will be removed, or a false value in which case it will stay
333	registered.
334		342
335	The global C<$SELF> (exported by this module) contains C<$port> while	343	The global C<$SELF> (exported by this module) contains C<$port> while
336	executing the callback.	344	executing the callback. Runtime errors during callback execution will
		345	result in the port being C<kil>ed.
337		346
338	Runtime errors wdurign callback execution will result in the port being	347	The default callback received all messages not matched by a more specific
339	C<kil>ed.	348	C<tag> match.
340		349
341	If the match is an array reference, then it will be matched against the	350	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
342	first elements of the message, otherwise only the first element is being
343	matched.
344		351
345	Any element in the match that is specified as C<_any_> (a function	352	Register (or replace) callbacks to be called on messages starting with the
346	exported by this module) matches any single element of the message.	353	given tag on the given port (and return the port), or unregister it (when
		354	C<$callback> is C<$undef> or missing). There can only be one callback
		355	registered for each tag.
347		356
348	While not required, it is highly recommended that the first matching	357	The original message will be passed to the callback, after the first
349	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
350	also the most efficient match (by far).	359	environment as the default callback (see above).
		360
		361	Example: create a port and bind receivers on it in one go.
		362
		363	my $port = rcv port,
		364	msg1 => sub { ... },
		365	msg2 => sub { ... },
		366	;
		367
		368	Example: create a port, bind receivers and send it in a message elsewhere
		369	in one go:
		370
		371	snd $otherport, reply =>
		372	rcv port,
		373	msg1 => sub { ... },
		374	...
		375	;
		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, $otherport;
		384	};
351		385
352	=cut	386	=cut
353		387
354	sub rcv($@) {	388	sub rcv($@) {
355	my $port = shift;	389	my $port = shift;
356	my ($noderef, $portid) = split /#/, $port, 2;	390	my ($nodeid, $portid) = split /#/, $port, 2;
357		391
358	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	392	$NODE{$nodeid} == $NODE{""}
359	or Carp::croak "$port: rcv can only be called on local ports, caught";	393	or Carp::croak "$port: rcv can only be called on local ports, caught";
360		394
361	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 {
362	my $cb = shift;	403	my $cb = shift;
363	delete $PORT_DATA{$portid};
364	$PORT{$portid} = sub {	404	$PORT{$portid} = sub {
365	local $SELF = $port;	405	local $SELF = $port;
366	eval {	406	eval { &$cb }; _self_die if $@;
367	&$cb	407	};
368	and kil $port;
369	};	408	}
370	_self_die if $@;	409	} elsif (defined $_[0]) {
371	};
372	} else {
373	my $self = $PORT_DATA{$portid} \|\|= do {	410	my $self = $PORT_DATA{$portid} \|\|= do {
374	my $self = bless {	411	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
375	id => $port,
376	}, "AnyEvent::MP::Port";
377		412
378	$PORT{$portid} = sub {	413	$PORT{$portid} = sub {
379	local $SELF = $port;	414	local $SELF = $port;
380		415
381	eval {
382	for (@{ $self->{rc0}{$_[0]} }) {	416	if (my $cb = $self->[1]{$_[0]}) {
383	$_ && &{$_->[0]}	417	shift;
384	&& undef $_;	418	eval { &$cb }; _self_die if $@;
385	}	419	} else {
386
387	for (@{ $self->{rcv}{$_[0]} }) {
388	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
389	&& &{$_->[0]}	420	&{ $self->[0] };
390	&& undef $_;
391	}
392
393	for (@{ $self->{any} }) {
394	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
395	&& &{$_->[0]}
396	&& undef $_;
397	}	421	}
398	};	422	};
399	_self_die if $@;	423
		424	$self
400	};	425	};
401		426
402	$self
403	};
404
405	"AnyEvent::MP::Port" eq ref $self	427	"AnyEvent::MP::Port" eq ref $self
406	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	428	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
407		429
408	while (@_) {
409	my ($match, $cb) = splice @_, 0, 2;	430	my ($tag, $cb) = splice @_, 0, 2;
410		431
411	if (!ref $match) {	432	if (defined $cb) {
412	push @{ $self->{rc0}{$match} }, [$cb];	433	$self->[1]{$tag} = $cb;
413	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
414	my ($type, @match) = @$match;
415	@match
416	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
417	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
418	} else {	434	} else {
419	push @{ $self->{any} }, [$cb, $match];	435	delete $self->[1]{$tag};
420	}	436	}
421	}	437	}
422	}	438	}
423		439
424	$port	440	$port
…		…
460	$res	476	$res
461	}	477	}
462	}	478	}
463	}	479	}
464		480
465	=item $guard = mon $port, $cb->(@reason)	481	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
466		482
467	=item $guard = mon $port, $otherport	483	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
468		484
469	=item $guard = mon $port, $otherport, @msg	485	=item $guard = mon $port # kill $SELF when $port dies
470		486
		487	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
		488
471	Monitor the given port and do something when the port is killed.	489	Monitor the given port and do something when the port is killed or
		490	messages to it were lost, and optionally return a guard that can be used
		491	to stop monitoring again.
472		492
473	In the first form, the callback is simply called with any number	493	In the first form (callback), the callback is simply called with any
474	of C<@reason> elements (no @reason means that the port was deleted	494	number of C<@reason> elements (no @reason means that the port was deleted
475	"normally"). Note also that I<< the callback B<must> never die >>, so use	495	"normally"). Note also that I<< the callback B<must> never die >>, so use
476	C<eval> if unsure.	496	C<eval> if unsure.
477		497
478	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	498	In the second form (another port given), the other port (C<$rcvport>)
479	a @reason was specified, i.e. on "normal" kils nothing happens, while	499	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
480	under all other conditions, the other port is killed with the same reason.	500	"normal" kils nothing happens, while under all other conditions, the other
		501	port is killed with the same reason.
481		502
		503	The third form (kill self) is the same as the second form, except that
		504	C<$rvport> defaults to C<$SELF>.
		505
482	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	506	In the last form (message), a message of the form C<@msg, @reason> will be
		507	C<snd>.
		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.
483		535
484	Example: call a given callback when C<$port> is killed.	536	Example: call a given callback when C<$port> is killed.
485		537
486	mon $port, sub { warn "port died because of <@_>\n" };	538	mon $port, sub { warn "port died because of <@_>\n" };
487		539
488	Example: kill ourselves when C<$port> is killed abnormally.	540	Example: kill ourselves when C<$port> is killed abnormally.
489		541
490	mon $port, $self;	542	mon $port;
491		543
492	Example: send us a restart message another C<$port> is killed.	544	Example: send us a restart message when another C<$port> is killed.
493		545
494	mon $port, $self => "restart";	546	mon $port, $self => "restart";
495		547
496	=cut	548	=cut
497		549
498	sub mon {	550	sub mon {
499	my ($noderef, $port) = split /#/, shift, 2;	551	my ($nodeid, $port) = split /#/, shift, 2;
500		552
501	my $node = $NODE{$noderef} \|\| add_node $noderef;	553	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
502		554
503	my $cb = shift;	555	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
504		556
505	unless (ref $cb) {	557	unless (ref $cb) {
506	if (@_) {	558	if (@_) {
507	# send a kill info message	559	# send a kill info message
508	my (@msg) = ($cb, @_);	560	my (@msg) = ($cb, @_);
…		…
526	is killed, the references will be freed.	578	is killed, the references will be freed.
527		579
528	Optionally returns a guard that will stop the monitoring.	580	Optionally returns a guard that will stop the monitoring.
529		581
530	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
531	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>):
532		584
533	$port->rcv (start => sub {	585	$port->rcv (start => sub {
534	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	586	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
535	undef $timer if 0.9 < rand;	587	undef $timer if 0.9 < rand;
536	});	588	});
537	});	589	});
538		590
539	=cut	591	=cut
540		592
541	sub mon_guard {	593	sub mon_guard {
542	my ($port, @refs) = @_;	594	my ($port, @refs) = @_;
543		595
		596	#TODO: mon-less form?
		597
544	mon $port, sub { 0 && @refs }	598	mon $port, sub { 0 && @refs }
545	}	599	}
546		600
547	=item lnk $port1, $port2
548
549	Link two ports. This is simply a shorthand for:
550
551	mon $port1, $port2;
552	mon $port2, $port1;
553
554	It means that if either one is killed abnormally, the other one gets
555	killed as well.
556
557	=item kil $port[, @reason]	601	=item kil $port[, @reason]
558		602
559	Kill the specified port with the given C<@reason>.	603	Kill the specified port with the given C<@reason>.
560		604
561	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
562	ports will not be kileld, or even notified).	606	monitoring other ports will not necessarily die because a port dies
		607	"normally").
563		608
564	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
565	C<mon>, see below).	610	C<mon>, see above).
566		611
567	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
568	will be reported as reason C<< die => $@ >>.	613	will be reported as reason C<< die => $@ >>.
569		614
570	Transport/communication errors are reported as C<< transport_error =>	615	Transport/communication errors are reported as C<< transport_error =>
571	$message >>.	616	$message >>.
572		617
		618	=cut
		619
		620	=item $port = spawn $node, $initfunc[, @initdata]
		621
		622	Creates a port on the node C<$node> (which can also be a port ID, in which
		623	case it's the node where that port resides).
		624
		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.
		627
		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>.
		632
		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.
		637
		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.
		642
		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.
		647
		648	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
		649	caller before C<spawn> returns (by delaying invocation when spawn is
		650	called for the local node).
		651
		652	Example: spawn a chat server port on C<$othernode>.
		653
		654	# this node, executed from within a port context:
		655	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		656	mon $server;
		657
		658	# init function on C<$othernode>
		659	sub connect {
		660	my ($srcport) = @_;
		661
		662	mon $srcport;
		663
		664	rcv $SELF, sub {
		665	...
		666	};
		667	}
		668
		669	=cut
		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	? $action[0]()
		716	: snd @action;
		717	};
		718	}
		719
573	=back	720	=back
574		721
575	=head1 NODE MESSAGES	722	=head1 AnyEvent::MP vs. Distributed Erlang
576		723
577	Nodes understand the following messages sent to them. Many of them take	724	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
578	arguments called C<@reply>, which will simply be used to compose a reply	725	== aemp node, Erlang process == aemp port), so many of the documents and
579	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and	726	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
580	the remaining arguments are simply the message data.	727	sample:
581		728
582	While other messages exist, they are not public and subject to change.	729	http://www.Erlang.se/doc/programming_rules.shtml
		730	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		731	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		732	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		733
		734	Despite the similarities, there are also some important differences:
583		735
584	=over 4	736	=over 4
585		737
586	=cut	738	=item * Node IDs are arbitrary strings in AEMP.
587		739
588	=item lookup => $name, @reply
589
590	Replies with the port ID of the specified well-known port, or C<undef>.
591
592	=item devnull => ...
593
594	Generic data sink/CPU heat conversion.
595
596	=item relay => $port, @msg
597
598	Simply forwards the message to the given port.
599
600	=item eval => $string[ @reply]
601
602	Evaluates the given string. If C<@reply> is given, then a message of the
603	form C<@reply, $@, @evalres> is sent.
604
605	Example: crash another node.
606
607	snd $othernode, eval => "exit";
608
609	=item time => @reply
610
611	Replies the the current node time to C<@reply>.
612
613	Example: tell the current node to send the current time to C<$myport> in a
614	C<timereply> message.
615
616	snd $NODE, time => $myport, timereply => 1, 2;
617	# => snd $myport, timereply => 1, 2, <time>
618
619	=back
620
621	=head1 AnyEvent::MP vs. Distributed Erlang
622
623	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node
624	== aemp node, erlang process == aemp port), so many of the documents and
625	programming techniques employed by erlang apply to AnyEvent::MP. Here is a
626	sample:
627
628	http://www.erlang.se/doc/programming_rules.shtml
629	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
630	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6
631	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
632
633	Despite the similarities, there are also some important differences:
634
635	=over 4
636
637	=item * Node references contain the recipe on how to contact them.
638
639	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
640	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
641	convenience functionality.	742	configuration or DNS), but will otherwise discover other odes itself.
642		743
643	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
644	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.
645		758
646	=item * Erlang uses processes and a mailbox, AEMP does not queue.	759	=item * Erlang uses processes and a mailbox, AEMP does not queue.
647		760
648	Erlang uses processes that selctively receive messages, and therefore	761	Erlang uses processes that selectively receive messages, and therefore
649	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
650	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.
651		766
652	(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).
653		768
654	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	769	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
655		770
656	Sending messages in erlang is synchronous and blocks the process. AEMP	771	Sending messages in Erlang is synchronous and blocks the process (and
657	sends are immediate, connection establishment is handled in the	772	so does not need a queue that can overflow). AEMP sends are immediate,
658	background.	773	connection establishment is handled in the background.
659		774
660	=item * Erlang can silently lose messages, AEMP cannot.	775	=item * Erlang suffers from silent message loss, AEMP does not.
661		776
662	Erlang makes few guarantees on messages delivery - messages can get lost	777	Erlang makes few guarantees on messages delivery - messages can get lost
663	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,
664	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).
665		780
666	AEMP guarantees correct ordering, and the guarantee that there are no	781	AEMP guarantees correct ordering, and the guarantee that after one message
667	holes in the message sequence.	782	is lost, all following ones sent to the same port are lost as well, until
668		783	monitoring raises an error, so there are no silent "holes" in the message
669	=item * In erlang, processes can be declared dead and later be found to be	784	sequence.
670	alive.
671
672	In erlang it can happen that a monitored process is declared dead and
673	linked processes get killed, but later it turns out that the process is
674	still alive - and can receive messages.
675
676	In AEMP, when port monitoring detects a port as dead, then that port will
677	eventually be killed - it cannot happen that a node detects a port as dead
678	and then later sends messages to it, finding it is still alive.
679		785
680	=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.
681		787
682	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
683	ID known to other nodes for a completely different process, causing	789	known to other nodes for a completely different process, causing messages
684	messages destined for that process to end up in an unrelated process.	790	destined for that process to end up in an unrelated process.
685		791
686	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
687	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.
688		794
689	=item * Erlang uses unprotected connections, AEMP uses secure	795	=item * Erlang uses unprotected connections, AEMP uses secure
690	authentication and can use TLS.	796	authentication and can use TLS.
691		797
692	AEMP can use a proven protocol - SSL/TLS - to protect connections and	798	AEMP can use a proven protocol - TLS - to protect connections and
693	securely authenticate nodes.	799	securely authenticate nodes.
694		800
695	=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
696	communications.	802	communications.
697		803
698	The AEMP protocol, unlike the erlang protocol, supports both	804	The AEMP protocol, unlike the Erlang protocol, supports both programming
699	language-independent text-only protocols (good for debugging) and binary,	805	language independent text-only protocols (good for debugging) and binary,
700	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.
701		808
702	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
703	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
704	protocol simple.	811	protocol simple.
705		812
		813	=item * AEMP has more flexible monitoring options than Erlang.
		814
		815	In Erlang, you can chose to receive I<all> exit signals as messages
		816	or I<none>, there is no in-between, so monitoring single processes is
		817	difficult to implement. Monitoring in AEMP is more flexible than in
		818	Erlang, as one can choose between automatic kill, exit message or callback
		819	on a per-process basis.
		820
		821	=item * Erlang tries to hide remote/local connections, AEMP does not.
		822
		823	Monitoring in Erlang is not an indicator of process death/crashes, in the
		824	same way as linking is (except linking is unreliable in Erlang).
		825
		826	In AEMP, you don't "look up" registered port names or send to named ports
		827	that might or might not be persistent. Instead, you normally spawn a port
		828	on the remote node. The init function monitors 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).
		834
706	=back	835	=back
707		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
708	=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.
709		883
710	L<AnyEvent>.	884	L<AnyEvent>.
711		885
712	=head1 AUTHOR	886	=head1 AUTHOR
713		887

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.34 by root, Wed Aug 5 23:50:46 2009 UTC vs. Revision 1.85 by root, Tue Sep 8 01:54:13 2009 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.34 by root, Wed Aug 5 23:50:46 2009 UTC vs.
Revision 1.85 by root, Tue Sep 8 01:54:13 2009 UTC