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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.35 by root, Thu Aug 6 10:21:48 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
28	# linking two ports, so they both crash together
29	lnk $port1, $port2;
30		34
31	# monitoring	35	# monitoring
32	mon $port, $cb->(@msg) # callback is invoked on death	36	mon $port, $cb->(@msg) # callback is invoked on death
33	mon $port, $otherport # kill otherport on abnormal death	37	mon $port, $otherport # kill otherport on abnormal death
34	mon $port, $otherport, @msg # send message on death	38	mon $port, $otherport, @msg # send message on death
35		39
		40	=head1 CURRENT STATUS
		41
		42	bin/aemp - stable.
		43	AnyEvent::MP - stable API, should work.
		44	AnyEvent::MP::Intro - explains most concepts.
		45	AnyEvent::MP::Kernel - mostly stable.
		46	AnyEvent::MP::Global - stable but incomplete, protocol not yet final.
		47
		48	stay tuned.
		49
36	=head1 DESCRIPTION	50	=head1 DESCRIPTION
37		51
38	This module (-family) implements a simple message passing framework.	52	This module (-family) implements a simple message passing framework.
39		53
40	Despite its simplicity, you can securely message other processes running	54	Despite its simplicity, you can securely message other processes running
41	on the same or other hosts.	55	on the same or other hosts, and you can supervise entities remotely.
42		56
43	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	57	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
44	manual page.	58	manual page and the examples under F<eg/>.
45
46	At the moment, this module family is severly broken and underdocumented,
47	so do not use. This was uploaded mainly to reserve the CPAN namespace -
48	stay tuned! The basic API should be finished, however.
49		59
50	=head1 CONCEPTS	60	=head1 CONCEPTS
51		61
52	=over 4	62	=over 4
53		63
54	=item port	64	=item port
55		65
56	A port is something you can send messages to (with the C<snd> function).	66	Not to be confused with a TCP port, a "port" is something you can send
		67	messages to (with the C<snd> function).
57		68
58	Some ports allow you to register C<rcv> handlers that can match specific	69	Ports allow you to register C<rcv> handlers that can match all or just
59	messages. All C<rcv> handlers will receive messages they match, messages	70	some messages. Messages send to ports will not be queued, regardless of
60	will not be queued.	71	anything was listening for them or not.
61		72
62	=item port id - C<noderef#portname>	73	=item port ID - C<nodeid#portname>
63		74
64	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	75	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as
65	separator, and a port name (a printable string of unspecified format). An	76	separator, and a port name (a printable string of unspecified format).
66	exception is the the node port, whose ID is identical to its node
67	reference.
68		77
69	=item node	78	=item node
70		79
71	A node is a single process containing at least one port - the node	80	A node is a single process containing at least one port - the node port,
72	port. You can send messages to node ports to find existing ports or to	81	which enables nodes to manage each other remotely, and to create new
73	create new ports, among other things.	82	ports.
74		83
75	Nodes are either private (single-process only), slaves (connected to a	84	Nodes are either public (have one or more listening ports) or private
76	master node only) or public nodes (connectable from unrelated nodes).	85	(no listening ports). Private nodes cannot talk to other private nodes
		86	currently.
77		87
78	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	88	=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*>
79		89
80	A node reference is a string that either simply identifies the node (for	90	A node ID is a string that uniquely identifies the node within a
81	private and slave nodes), or contains a recipe on how to reach a given	91	network. Depending on the configuration used, node IDs can look like a
82	node (for public nodes).	92	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
		93	doesn't interpret node IDs in any way.
83		94
84	This recipe is simply a comma-separated list of C<address:port> pairs (for	95	=item binds - C<ip:port>
85	TCP/IP, other protocols might look different).
86		96
87	Node references come in two flavours: resolved (containing only numerical	97	Nodes can only talk to each other by creating some kind of connection to
88	addresses) or unresolved (where hostnames are used instead of addresses).	98	each other. To do this, nodes should listen on one or more local transport
		99	endpoints - binds. Currently, only standard C<ip:port> specifications can
		100	be used, which specify TCP ports to listen on.
89		101
90	Before using an unresolved node reference in a message you first have to	102	=item seed nodes
91	resolve it.	103
		104	When a node starts, it knows nothing about the network. To teach the node
		105	about the network it first has to contact some other node within the
		106	network. This node is called a seed.
		107
		108	Apart from the fact that other nodes know them as seed nodes and they have
		109	to have fixed listening addresses, seed nodes are perfectly normal nodes -
		110	any node can function as a seed node for others.
		111
		112	In addition to discovering the network, seed nodes are also used to
		113	maintain the network and to connect nodes that otherwise would have
		114	trouble connecting. They form the backbone of 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.
92		128
93	=back	129	=back
94		130
95	=head1 VARIABLES/FUNCTIONS	131	=head1 VARIABLES/FUNCTIONS
96		132
…		…
98		134
99	=cut	135	=cut
100		136
101	package AnyEvent::MP;	137	package AnyEvent::MP;
102		138
103	use AnyEvent::MP::Base;	139	use AnyEvent::MP::Kernel;
104		140
105	use common::sense;	141	use common::sense;
106		142
107	use Carp ();	143	use Carp ();
108		144
109	use AE ();	145	use AE ();
110		146
111	use base "Exporter";	147	use base "Exporter";
112		148
113	our $VERSION = '0.1';	149	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		150
114	our @EXPORT = qw(	151	our @EXPORT = qw(
115	NODE $NODE *SELF node_of _any_	152	NODE $NODE *SELF node_of after
116	resolve_node initialise_node	153	configure
117	snd rcv mon kil reg psub	154	snd rcv mon mon_guard kil reg psub spawn
118	port	155	port
119	);	156	);
120		157
121	our $SELF;	158	our $SELF;
122		159
…		…
126	kil $SELF, die => $msg;	163	kil $SELF, die => $msg;
127	}	164	}
128		165
129	=item $thisnode = NODE / $NODE	166	=item $thisnode = NODE / $NODE
130		167
131	The C<NODE> function returns, and the C<$NODE> variable contains	168	The C<NODE> function returns, and the C<$NODE> variable contains, the node
132	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
133	to C<become_public> or C<become_slave>, after which all local port	170	a call to C<configure>.
134	identifiers become invalid.
135		171
136	=item $noderef = node_of $port	172	=item $nodeid = node_of $port
137		173
138	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.
139		175
140	=item initialise_node $noderef, $seednode, $seednode...	176	=item configure $profile, key => value...
141		177
142	=item initialise_node "slave/", $master, $master...	178	=item configure key => value...
143		179
144	Before a node can talk to other nodes on the network it has to initialise	180	Before a node can talk to other nodes on the network (i.e. enter
145	itself - the minimum a node needs to know is it's own name, and optionally	181	"distributed mode") it has to configure itself - the minimum a node needs
146	it should know the noderefs of some other nodes in the network.	182	to know is its own name, and optionally it should know the addresses of
		183	some other nodes in the network to discover other nodes.
147		184
148	This function initialises a node - it must be called exactly once (or	185	This function configures a node - it must be called exactly once (or
149	never) before calling other AnyEvent::MP functions.	186	never) before calling other AnyEvent::MP functions.
150		187
151	All arguments are noderefs, which can be either resolved or unresolved.
152
153	There are two types of networked nodes, public nodes and slave nodes:
154
155	=over 4	188	=over 4
156		189
157	=item public nodes	190	=item step 1, gathering configuration from profiles
158		191
159	For public nodes, C<$noderef> must either be a (possibly unresolved)	192	The function first looks up a profile in the aemp configuration (see the
160	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
161	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.
162		196
163	Afterwards, the node will bind itself on all endpoints and try to connect	197	The profile data is then gathered as follows:
164	to all additional C<$seednodes> that are specified. Seednodes are optional
165	and can be used to quickly bootstrap the node into an existing network.
166		198
167	=item slave nodes	199	First, all remaining key => value pairs (all of which are conveniently
		200	undocumented at the moment) will be interpreted as configuration
		201	data. Then they will be overwritten by any values specified in the global
		202	default configuration (see the F<aemp> utility), then the chain of
		203	profiles chosen by the profile name (and any C<parent> attributes).
168		204
169	When the C<$noderef> is the special string C<slave/>, then the node will	205	That means that the values specified in the profile have highest priority
170	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,
171	route most of their traffic to the master node that they attach to.	207	and can only be used to specify defaults.
172		208
173	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
174	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
175	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.
176		230
177	=back	231	=back
178		232
179	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.
180	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.
181	server.
182		235
183	Example: become a public node listening on the default node.	236	configure
184		237
185	initialise_node;	238	Example: become an anonymous node. This form is often used for commandline
		239	clients.
186		240
187	Example: become a public node, and try to contact some well-known master	241	configure nodeid => "anon/";
188	servers to become part of the network.
189		242
190	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).
191		246
192	Example: become a public node listening on port C<4041>.	247	# use the aemp commandline utility
		248	# aemp profile seed nodeid anon/ binds '*:4040'
193		249
194	initialise_node 4041;	250	# then use it
		251	configure profile => "seed";
195		252
196	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
197		255
198	initialise_node "locahost:4044";	256	# or provide a nicer-to-remember nodeid
199		257	# aemp run profile seed nodeid "$(hostname)"
200	Example: become a slave node to any of the specified master servers.
201
202	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
203
204	=item $cv = resolve_node $noderef
205
206	Takes an unresolved node reference that may contain hostnames and
207	abbreviated IDs, resolves all of them and returns a resolved node
208	reference.
209
210	In addition to C<address:port> pairs allowed in resolved noderefs, the
211	following forms are supported:
212
213	=over 4
214
215	=item the empty string
216
217	An empty-string component gets resolved as if the default port (4040) was
218	specified.
219
220	=item naked port numbers (e.g. C<1234>)
221
222	These are resolved by prepending the local nodename and a colon, to be
223	further resolved.
224
225	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
226
227	These are resolved by using AnyEvent::DNS to resolve them, optionally
228	looking up SRV records for the C<aemp=4040> port, if no port was
229	specified.
230
231	=back
232		258
233	=item $SELF	259	=item $SELF
234		260
235	Contains the current port id while executing C<rcv> callbacks or C<psub>	261	Contains the current port id while executing C<rcv> callbacks or C<psub>
236	blocks.	262	blocks.
237		263
238	=item SELF, %SELF, @SELF...	264	=item *SELF, SELF, %SELF, @SELF...
239		265
240	Due to some quirks in how perl exports variables, it is impossible to	266	Due to some quirks in how perl exports variables, it is impossible to
241	just export C<$SELF>, all the symbols called C<SELF> are exported by this	267	just export C<$SELF>, all the symbols named C<SELF> are exported by this
242	module, but only C<$SELF> is currently used.	268	module, but only C<$SELF> is currently used.
243		269
244	=item snd $port, type => @data	270	=item snd $port, type => @data
245		271
246	=item snd $port, @msg	272	=item snd $port, @msg
247		273
248	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
249	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.
250	stringifies a sa port ID (such as a port object :).
251		276
252	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
253	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
254	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.
255		281
256	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
257	function: modifying any argument is not allowed and can cause many	283	function: modifying any argument (or values referenced by them) is
258	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.
259		288
260	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
261	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
262	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
263	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
264	node, anything can be passed.	293	node, anything can be passed. Best rely only on the common denominator of
		294	these.
265		295
266	=item $local_port = port	296	=item $local_port = port
267		297
268	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
269	matching port ("full port") or a single-callback port ("miniport"),	299	no callbacks set and will throw an error when it receives messages.
270	depending on how C<rcv> callbacks are bound to the object.
271		300
272	=item $port = port { my @msg = @_; $finished }	301	=item $local_port = port { my @msg = @_ }
273		302
274	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
275	matching behind it, and returns its ID. Semantically the same as creating
276	a port and calling C<rcv $port, $callback> on it.	304	creating a port and calling C<rcv $port, $callback> on it.
277		305
278	The block will be called for every message received on the port. When the	306	The block will be called for every message received on the port, with the
279	callback returns a true value its job is considered "done" and the port	307	global variable C<$SELF> set to the port ID. Runtime errors will cause the
280	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.
281		310
282	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:
283	be passed to the callback.
284		312
285	If you need the local port id in the callback, this works nicely:	313	my $port = port {
286		314	my @msg = @_;
287	my $port; $port = port {	315	...
288	snd $otherport, reply => $port;	316	kil $SELF;
289	};	317	};
290		318
291	=cut	319	=cut
292		320
293	sub rcv($@);	321	sub rcv($@);
		322
		323	sub _kilme {
		324	die "received message on port without callback";
		325	}
294		326
295	sub port(;&) {	327	sub port(;&) {
296	my $id = "$UNIQ." . $ID++;	328	my $id = "$UNIQ." . $ID++;
297	my $port = "$NODE#$id";	329	my $port = "$NODE#$id";
298		330
299	if (@_) {	331	rcv $port, shift \|\| \&_kilme;
300	rcv $port, shift;
301	} else {
302	$PORT{$id} = sub { }; # nop
303	}
304		332
305	$port	333	$port
306	}	334	}
307		335
308	=item reg $port, $name
309
310	Registers the given port under the name C<$name>. If the name already
311	exists it is replaced.
312
313	A port can only be registered under one well known name.
314
315	A port automatically becomes unregistered when it is killed.
316
317	=cut
318
319	sub reg(@) {
320	my ($port, $name) = @_;
321
322	$REG{$name} = $port;
323	}
324
325	=item rcv $port, $callback->(@msg)	336	=item rcv $local_port, $callback->(@msg)
326		337
327	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
328	one if required).	339	remove the default callback: use C<sub { }> to disable it, or better
329		340	C<kil> the port when it is no longer needed.
330	=item rcv $port, tagstring => $callback->(@msg), ...
331
332	=item rcv $port, $smartmatch => $callback->(@msg), ...
333
334	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
335
336	Register callbacks to be called on matching messages on the given full
337	port (after converting it to one if required).
338
339	The callback has to return a true value when its work is done, after
340	which is will be removed, or a false value in which case it will stay
341	registered.
342		341
343	The global C<$SELF> (exported by this module) contains C<$port> while	342	The global C<$SELF> (exported by this module) contains C<$port> while
344	executing the callback.	343	executing the callback. Runtime errors during callback execution will
		344	result in the port being C<kil>ed.
345		345
346	Runtime errors wdurign callback execution will result in the port being	346	The default callback received all messages not matched by a more specific
347	C<kil>ed.	347	C<tag> match.
348		348
349	If the match is an array reference, then it will be matched against the	349	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
350	first elements of the message, otherwise only the first element is being
351	matched.
352		350
353	Any element in the match that is specified as C<_any_> (a function	351	Register (or replace) callbacks to be called on messages starting with the
354	exported by this module) matches any single element of the message.	352	given tag on the given port (and return the port), or unregister it (when
		353	C<$callback> is C<$undef> or missing). There can only be one callback
		354	registered for each tag.
355		355
356	While not required, it is highly recommended that the first matching	356	The original message will be passed to the callback, after the first
357	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
358	also the most efficient match (by far).	358	environment as the default callback (see above).
		359
		360	Example: create a port and bind receivers on it in one go.
		361
		362	my $port = rcv port,
		363	msg1 => sub { ... },
		364	msg2 => sub { ... },
		365	;
		366
		367	Example: create a port, bind receivers and send it in a message elsewhere
		368	in one go:
		369
		370	snd $otherport, reply =>
		371	rcv port,
		372	msg1 => sub { ... },
		373	...
		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, $otherport;
		383	};
359		384
360	=cut	385	=cut
361		386
362	sub rcv($@) {	387	sub rcv($@) {
363	my $port = shift;	388	my $port = shift;
364	my ($noderef, $portid) = split /#/, $port, 2;	389	my ($nodeid, $portid) = split /#/, $port, 2;
365		390
366	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	391	$NODE{$nodeid} == $NODE{""}
367	or Carp::croak "$port: rcv can only be called on local ports, caught";	392	or Carp::croak "$port: rcv can only be called on local ports, caught";
368		393
369	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 {
370	my $cb = shift;	402	my $cb = shift;
371	delete $PORT_DATA{$portid};
372	$PORT{$portid} = sub {	403	$PORT{$portid} = sub {
373	local $SELF = $port;	404	local $SELF = $port;
374	eval {	405	eval { &$cb }; _self_die if $@;
375	&$cb	406	};
376	and kil $port;
377	};	407	}
378	_self_die if $@;	408	} elsif (defined $_[0]) {
379	};
380	} else {
381	my $self = $PORT_DATA{$portid} \|\|= do {	409	my $self = $PORT_DATA{$portid} \|\|= do {
382	my $self = bless {	410	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
383	id => $port,
384	}, "AnyEvent::MP::Port";
385		411
386	$PORT{$portid} = sub {	412	$PORT{$portid} = sub {
387	local $SELF = $port;	413	local $SELF = $port;
388		414
389	eval {
390	for (@{ $self->{rc0}{$_[0]} }) {	415	if (my $cb = $self->[1]{$_[0]}) {
391	$_ && &{$_->[0]}	416	shift;
392	&& undef $_;	417	eval { &$cb }; _self_die if $@;
393	}	418	} else {
394
395	for (@{ $self->{rcv}{$_[0]} }) {
396	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
397	&& &{$_->[0]}	419	&{ $self->[0] };
398	&& undef $_;
399	}
400
401	for (@{ $self->{any} }) {
402	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
403	&& &{$_->[0]}
404	&& undef $_;
405	}	420	}
406	};	421	};
407	_self_die if $@;	422
		423	$self
408	};	424	};
409		425
410	$self
411	};
412
413	"AnyEvent::MP::Port" eq ref $self	426	"AnyEvent::MP::Port" eq ref $self
414	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	427	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
415		428
416	while (@_) {
417	my ($match, $cb) = splice @_, 0, 2;	429	my ($tag, $cb) = splice @_, 0, 2;
418		430
419	if (!ref $match) {	431	if (defined $cb) {
420	push @{ $self->{rc0}{$match} }, [$cb];	432	$self->[1]{$tag} = $cb;
421	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
422	my ($type, @match) = @$match;
423	@match
424	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
425	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
426	} else {	433	} else {
427	push @{ $self->{any} }, [$cb, $match];	434	delete $self->[1]{$tag};
428	}	435	}
429	}	436	}
430	}	437	}
431		438
432	$port	439	$port
…		…
468	$res	475	$res
469	}	476	}
470	}	477	}
471	}	478	}
472		479
473	=item $guard = mon $port, $cb->(@reason)	480	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
474		481
475	=item $guard = mon $port, $otherport	482	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
476		483
477	=item $guard = mon $port, $otherport, @msg	484	=item $guard = mon $port # kill $SELF when $port dies
478		485
		486	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
		487
479	Monitor the given port and do something when the port is killed.	488	Monitor the given port and do something when the port is killed or
		489	messages to it were lost, and optionally return a guard that can be used
		490	to stop monitoring again.
480		491
481	In the first form, the callback is simply called with any number	492	In the first form (callback), the callback is simply called with any
482	of C<@reason> elements (no @reason means that the port was deleted	493	number of C<@reason> elements (no @reason means that the port was deleted
483	"normally"). Note also that I<< the callback B<must> never die >>, so use	494	"normally"). Note also that I<< the callback B<must> never die >>, so use
484	C<eval> if unsure.	495	C<eval> if unsure.
485		496
486	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	497	In the second form (another port given), the other port (C<$rcvport>)
487	a @reason was specified, i.e. on "normal" kils nothing happens, while	498	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
488	under all other conditions, the other port is killed with the same reason.	499	"normal" kils nothing happens, while under all other conditions, the other
		500	port is killed with the same reason.
489		501
		502	The third form (kill self) is the same as the second form, except that
		503	C<$rvport> defaults to C<$SELF>.
		504
490	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	505	In the last form (message), a message of the form C<@msg, @reason> will be
		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.
		510
		511	As a rule of thumb, monitoring requests should always monitor a port from
		512	a local port (or callback). The reason is that kill messages might get
		513	lost, just like any other message. Another less obvious reason is that
		514	even monitoring requests can get lost (for example, when the connection
		515	to the other node goes down permanently). When monitoring a port locally
		516	these problems do not exist.
		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.
491		534
492	Example: call a given callback when C<$port> is killed.	535	Example: call a given callback when C<$port> is killed.
493		536
494	mon $port, sub { warn "port died because of <@_>\n" };	537	mon $port, sub { warn "port died because of <@_>\n" };
495		538
496	Example: kill ourselves when C<$port> is killed abnormally.	539	Example: kill ourselves when C<$port> is killed abnormally.
497		540
498	mon $port, $self;	541	mon $port;
499		542
500	Example: send us a restart message another C<$port> is killed.	543	Example: send us a restart message when another C<$port> is killed.
501		544
502	mon $port, $self => "restart";	545	mon $port, $self => "restart";
503		546
504	=cut	547	=cut
505		548
506	sub mon {	549	sub mon {
507	my ($noderef, $port) = split /#/, shift, 2;	550	my ($nodeid, $port) = split /#/, shift, 2;
508		551
509	my $node = $NODE{$noderef} \|\| add_node $noderef;	552	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
510		553
511	my $cb = shift;	554	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
512		555
513	unless (ref $cb) {	556	unless (ref $cb) {
514	if (@_) {	557	if (@_) {
515	# send a kill info message	558	# send a kill info message
516	my (@msg) = ($cb, @_);	559	my (@msg) = ($cb, @_);
…		…
534	is killed, the references will be freed.	577	is killed, the references will be freed.
535		578
536	Optionally returns a guard that will stop the monitoring.	579	Optionally returns a guard that will stop the monitoring.
537		580
538	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
539	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>):
540		583
541	$port->rcv (start => sub {	584	$port->rcv (start => sub {
542	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	585	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
543	undef $timer if 0.9 < rand;	586	undef $timer if 0.9 < rand;
544	});	587	});
545	});	588	});
546		589
547	=cut	590	=cut
548		591
549	sub mon_guard {	592	sub mon_guard {
550	my ($port, @refs) = @_;	593	my ($port, @refs) = @_;
551		594
		595	#TODO: mon-less form?
		596
552	mon $port, sub { 0 && @refs }	597	mon $port, sub { 0 && @refs }
553	}	598	}
554		599
555	=item lnk $port1, $port2
556
557	Link two ports. This is simply a shorthand for:
558
559	mon $port1, $port2;
560	mon $port2, $port1;
561
562	It means that if either one is killed abnormally, the other one gets
563	killed as well.
564
565	=item kil $port[, @reason]	600	=item kil $port[, @reason]
566		601
567	Kill the specified port with the given C<@reason>.	602	Kill the specified port with the given C<@reason>.
568		603
569	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
570	ports will not be kileld, or even notified).	605	monitoring other ports will not necessarily die because a port dies
		606	"normally").
571		607
572	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
573	C<mon>, see below).	609	C<mon>, see above).
574		610
575	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
576	will be reported as reason C<< die => $@ >>.	612	will be reported as reason C<< die => $@ >>.
577		613
578	Transport/communication errors are reported as C<< transport_error =>	614	Transport/communication errors are reported as C<< transport_error =>
579	$message >>.	615	$message >>.
580		616
581	=back
582
583	=head1 NODE MESSAGES
584
585	Nodes understand the following messages sent to them. Many of them take
586	arguments called C<@reply>, which will simply be used to compose a reply
587	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
588	the remaining arguments are simply the message data.
589
590	While other messages exist, they are not public and subject to change.
591
592	=over 4
593
594	=cut	617	=cut
595		618
596	=item lookup => $name, @reply	619	=item $port = spawn $node, $initfunc[, @initdata]
597		620
598	Replies with the port ID of the specified well-known port, or C<undef>.	621	Creates a port on the node C<$node> (which can also be a port ID, in which
		622	case it's the node where that port resides).
599		623
600	=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.
601		626
602	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>.
603		631
604	=item relay => $port, @msg	632	If the function doesn't exist, then the node tries to C<require>
		633	the package, then the package above the package and so on (e.g.
		634	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		635	exists or it runs out of package names.
605		636
606	Simply forwards the message to the given port.	637	The init function is then called with the newly-created port as context
		638	object (C<$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.
607		641
608	=item eval => $string[ @reply]	642	A common idiom is to pass a local port, immediately monitor the spawned
		643	port, and in the remote init function, immediately monitor the passed
		644	local port. This two-way monitoring ensures that both ports get cleaned up
		645	when there is a problem.
609		646
610	Evaluates the given string. If C<@reply> is given, then a message of the	647	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
611	form C<@reply, $@, @evalres> is sent.	648	caller before C<spawn> returns (by delaying invocation when spawn is
		649	called for the local node).
612		650
613	Example: crash another node.	651	Example: spawn a chat server port on C<$othernode>.
614		652
615	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 $server;
616		656
617	=item time => @reply	657	# init function on C<$othernode>
		658	sub connect {
		659	my ($srcport) = @_;
618		660
619	Replies the the current node time to C<@reply>.	661	mon $srcport;
620		662
621	Example: tell the current node to send the current time to C<$myport> in a	663	rcv $SELF, sub {
622	C<timereply> message.	664	...
		665	};
		666	}
623		667
624	snd $NODE, time => $myport, timereply => 1, 2;	668	=cut
625	# => 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	}
626		718
627	=back	719	=back
628		720
629	=head1 AnyEvent::MP vs. Distributed Erlang	721	=head1 AnyEvent::MP vs. Distributed Erlang
630		722
…		…
640		732
641	Despite the similarities, there are also some important differences:	733	Despite the similarities, there are also some important differences:
642		734
643	=over 4	735	=over 4
644		736
645	=item * Node references contain the recipe on how to contact them.	737	=item * Node IDs are arbitrary strings in AEMP.
646		738
647	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
648	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
649	convenience functionality.	741	configuration or DNS), but will otherwise discover other odes itself.
650		742
651	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
652	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.
653		757
654	=item * Erlang uses processes and a mailbox, AEMP does not queue.	758	=item * Erlang uses processes and a mailbox, AEMP does not queue.
655		759
656	Erlang uses processes that selctively receive messages, and therefore	760	Erlang uses processes that selectively receive messages, and therefore
657	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
658	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.
659		765
660	(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).
661		767
662	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	768	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
663		769
664	Sending messages in Erlang is synchronous and blocks the process. AEMP	770	Sending messages in Erlang is synchronous and blocks the process (and
665	sends are immediate, connection establishment is handled in the	771	so does not need a queue that can overflow). AEMP sends are immediate,
666	background.	772	connection establishment is handled in the background.
667		773
668	=item * Erlang can silently lose messages, AEMP cannot.	774	=item * Erlang suffers from silent message loss, AEMP does not.
669		775
670	Erlang makes few guarantees on messages delivery - messages can get lost	776	Erlang makes few guarantees on messages delivery - messages can get lost
671	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,
672	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).
673		779
674	AEMP guarantees correct ordering, and the guarantee that there are no	780	AEMP guarantees correct ordering, and the guarantee that after one message
675	holes in the message sequence.	781	is lost, all following ones sent to the same port are lost as well, until
676		782	monitoring raises an error, so there are no silent "holes" in the message
677	=item * In Erlang, processes can be declared dead and later be found to be	783	sequence.
678	alive.
679
680	In Erlang it can happen that a monitored process is declared dead and
681	linked processes get killed, but later it turns out that the process is
682	still alive - and can receive messages.
683
684	In AEMP, when port monitoring detects a port as dead, then that port will
685	eventually be killed - it cannot happen that a node detects a port as dead
686	and then later sends messages to it, finding it is still alive.
687		784
688	=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.
689		786
690	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
691	ID known to other nodes for a completely different process, causing	788	known to other nodes for a completely different process, causing messages
692	messages destined for that process to end up in an unrelated process.	789	destined for that process to end up in an unrelated process.
693		790
694	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
695	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.
696		793
697	=item * Erlang uses unprotected connections, AEMP uses secure	794	=item * Erlang uses unprotected connections, AEMP uses secure
698	authentication and can use TLS.	795	authentication and can use TLS.
699		796
700	AEMP can use a proven protocol - SSL/TLS - to protect connections and	797	AEMP can use a proven protocol - TLS - to protect connections and
701	securely authenticate nodes.	798	securely authenticate nodes.
702		799
703	=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
704	communications.	801	communications.
705		802
706	The AEMP protocol, unlike the Erlang protocol, supports both	803	The AEMP protocol, unlike the Erlang protocol, supports both programming
707	language-independent text-only protocols (good for debugging) and binary,	804	language independent text-only protocols (good for debugging) and binary,
708	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.
709		807
710	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
711	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
712	protocol simple.	810	protocol simple.
713		811
714	=item * AEMP has more flexible monitoring options than Erlang.	812	=item * AEMP has more flexible monitoring options than Erlang.
715		813
716	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
717	or I<none>, there is no in-between, so monitoring single processes is	815	or I<none>, there is no in-between, so monitoring single processes is
718	difficult to implement. Monitoring in AEMP is more flexible than in	816	difficult to implement. Monitoring in AEMP is more flexible than in
719	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
720	on a per-process basis.	818	on a per-process basis.
721		819
722	=item * Erlang has different semantics for monitoring and linking, AEMP has the same.	820	=item * Erlang tries to hide remote/local connections, AEMP does not.
723		821
724	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
725	as linking is (except linking is unreliable in Erlang). In AEMP, the	823	same way as linking is (except linking is unreliable in Erlang).
726	semantics of monitoring and linking are identical, linking is simply	824
727	two-way monitoring with automatic kill.	825	In AEMP, you don't "look up" registered port names or send to named ports
		826	that might or might not be persistent. Instead, you normally spawn a port
		827	on the remote node. The init function monitors you, and you monitor the
		828	remote port. Since both monitors are local to the node, they are much more
		829	reliable (no need for C<spawn_link>).
		830
		831	This also saves round-trips and avoids sending messages to the wrong port
		832	(hard to do in Erlang).
728		833
729	=back	834	=back
730		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
731	=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.
732		882
733	L<AnyEvent>.	883	L<AnyEvent>.
734		884
735	=head1 AUTHOR	885	=head1 AUTHOR
736		886

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.35 by root, Thu Aug 6 10:21:48 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 1.35 by root, Thu Aug 6 10:21:48 2009 UTC vs.
Revision 1.84 by root, Tue Sep 8 01:42:14 2009 UTC