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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.37 by root, Fri Aug 7 16:47:23 2009 UTC vs.
Revision 1.70 by root, Sun Aug 30 19:49:47 2009 UTC

…		…
8		8
9	$NODE # contains this node's noderef	9	$NODE # contains this node's noderef
10	NODE # returns this node's noderef	10	NODE # returns this node's noderef
11	NODE $port # returns the noderef of the port	11	NODE $port # returns the noderef of the port
12		12
		13	$SELF # receiving/own port id in rcv callbacks
		14
		15	# initialise the node so it can send/receive messages
		16	initialise_node;
		17
		18	# ports are message endpoints
		19
		20	# sending messages
13	snd $port, type => data...;	21	snd $port, type => data...;
		22	snd $port, @msg;
		23	snd @msg_with_first_element_being_a_port;
14		24
15	$SELF # receiving/own port id in rcv callbacks	25	# creating/using ports, the simple way
		26	my $simple_port = port { my @msg = @_; 0 };
16		27
17	rcv $port, smartmatch => $cb->($port, @msg);	28	# creating/using ports, tagged message matching
18		29	my $port = port;
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	30	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
21	rcv $port1, pong => sub { warn "pong received\n" };	31	rcv $port, pong => sub { warn "pong received\n"; 0 };
22	snd $port2, ping => $port1;
23		32
24	# more, smarter, matches (_any_ is exported by this module)	33	# create a port on another node
25	rcv $port, [child_died => $pid] => sub { ...	34	my $port = spawn $node, $initfunc, @initdata;
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
27		35
28	# monitoring	36	# monitoring
29	mon $port, $cb->(@msg) # callback is invoked on death	37	mon $port, $cb->(@msg) # callback is invoked on death
30	mon $port, $otherport # kill otherport on abnormal death	38	mon $port, $otherport # kill otherport on abnormal death
31	mon $port, $otherport, @msg # send message on death	39	mon $port, $otherport, @msg # send message on death
32		40
		41	=head1 CURRENT STATUS
		42
		43	AnyEvent::MP - stable API, should work
		44	AnyEvent::MP::Intro - outdated
		45	AnyEvent::MP::Kernel - mostly stable
		46	AnyEvent::MP::Global - mostly stable
		47	AnyEvent::MP::Node - mostly stable, but internal anyways
		48	AnyEvent::MP::Transport - mostly stable, but internal anyways
		49
		50	stay tuned.
		51
33	=head1 DESCRIPTION	52	=head1 DESCRIPTION
34		53
35	This module (-family) implements a simple message passing framework.	54	This module (-family) implements a simple message passing framework.
36		55
37	Despite its simplicity, you can securely message other processes running	56	Despite its simplicity, you can securely message other processes running
38	on the same or other hosts.	57	on the same or other hosts, and you can supervise entities remotely.
39		58
40	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	59	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
41	manual page.	60	manual page and the examples under F<eg/>.
42		61
43	At the moment, this module family is severly broken and underdocumented,	62	At the moment, this module family is a bit underdocumented.
44	so do not use. This was uploaded mainly to reserve the CPAN namespace -
45	stay tuned! The basic API should be finished, however.
46		63
47	=head1 CONCEPTS	64	=head1 CONCEPTS
48		65
49	=over 4	66	=over 4
50		67
51	=item port	68	=item port
52		69
53	A port is something you can send messages to (with the C<snd> function).	70	A port is something you can send messages to (with the C<snd> function).
54		71
55	Some ports allow you to register C<rcv> handlers that can match specific	72	Ports allow you to register C<rcv> handlers that can match all or just
56	messages. All C<rcv> handlers will receive messages they match, messages	73	some messages. Messages send to ports will not be queued, regardless of
57	will not be queued.	74	anything was listening for them or not.
58		75
59	=item port id - C<noderef#portname>	76	=item port ID - C<nodeid#portname>
60		77
61	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	78	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as
62	separator, and a port name (a printable string of unspecified format). An	79	separator, and a port name (a printable string of unspecified format).
63	exception is the the node port, whose ID is identical to its node
64	reference.
65		80
66	=item node	81	=item node
67		82
68	A node is a single process containing at least one port - the node	83	A node is a single process containing at least one port - the node port,
69	port. You can send messages to node ports to find existing ports or to	84	which enables nodes to manage each other remotely, and to create new
70	create new ports, among other things.	85	ports.
71		86
72	Nodes are either private (single-process only), slaves (connected to a	87	Nodes are either public (have one or more listening ports) or private
73	master node only) or public nodes (connectable from unrelated nodes).	88	(no listening ports). Private nodes cannot talk to other private nodes
		89	currently.
74		90
75	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	91	=item node ID - C<[a-za-Z0-9_\-.:]+>
76		92
77	A node reference is a string that either simply identifies the node (for	93	A node ID is a string that uniquely identifies the node within a
78	private and slave nodes), or contains a recipe on how to reach a given	94	network. Depending on the configuration used, node IDs can look like a
79	node (for public nodes).	95	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
		96	doesn't interpret node IDs in any way.
80		97
81	This recipe is simply a comma-separated list of C<address:port> pairs (for	98	=item binds - C<ip:port>
82	TCP/IP, other protocols might look different).
83		99
84	Node references come in two flavours: resolved (containing only numerical	100	Nodes can only talk to each other by creating some kind of connection to
85	addresses) or unresolved (where hostnames are used instead of addresses).	101	each other. To do this, nodes should listen on one or more local transport
		102	endpoints - binds. Currently, only standard C<ip:port> specifications can
		103	be used, which specify TCP ports to listen on.
86		104
87	Before using an unresolved node reference in a message you first have to	105	=item seeds - C<host:port>
88	resolve it.	106
		107	When a node starts, it knows nothing about the network. To teach the node
		108	about the network it first has to contact some other node within the
		109	network. This node is called a seed.
		110
		111	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes
		112	are expected to be long-running, and at least one of those should always
		113	be available. When nodes run out of connections (e.g. due to a network
		114	error), they try to re-establish connections to some seednodes again to
		115	join the network.
		116
		117	Apart from being sued for seeding, seednodes are not special in any way -
		118	every public node can be a seednode.
89		119
90	=back	120	=back
91		121
92	=head1 VARIABLES/FUNCTIONS	122	=head1 VARIABLES/FUNCTIONS
93		123
…		…
95		125
96	=cut	126	=cut
97		127
98	package AnyEvent::MP;	128	package AnyEvent::MP;
99		129
100	use AnyEvent::MP::Base;	130	use AnyEvent::MP::Kernel;
101		131
102	use common::sense;	132	use common::sense;
103		133
104	use Carp ();	134	use Carp ();
105		135
106	use AE ();	136	use AE ();
107		137
108	use base "Exporter";	138	use base "Exporter";
109		139
110	our $VERSION = '0.1';	140	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		141
111	our @EXPORT = qw(	142	our @EXPORT = qw(
112	NODE $NODE *SELF node_of _any_	143	NODE $NODE *SELF node_of after
113	resolve_node initialise_node	144	initialise_node
114	snd rcv mon kil reg psub	145	snd rcv mon mon_guard kil reg psub spawn
115	port	146	port
116	);	147	);
117		148
118	our $SELF;	149	our $SELF;
119		150
…		…
123	kil $SELF, die => $msg;	154	kil $SELF, die => $msg;
124	}	155	}
125		156
126	=item $thisnode = NODE / $NODE	157	=item $thisnode = NODE / $NODE
127		158
128	The C<NODE> function returns, and the C<$NODE> variable contains	159	The C<NODE> function returns, and the C<$NODE> variable contains, the node
129	the noderef of the local node. The value is initialised by a call	160	ID of the node running in the current process. This value is initialised by
130	to C<become_public> or C<become_slave>, after which all local port	161	a call to C<initialise_node>.
131	identifiers become invalid.
132		162
133	=item $noderef = node_of $port	163	=item $nodeid = node_of $port
134		164
135	Extracts and returns the noderef from a portid or a noderef.	165	Extracts and returns the node ID from a port ID or a node ID.
136		166
137	=item initialise_node $noderef, $seednode, $seednode...	167	=item initialise_node $profile_name, key => value...
138		168
139	=item initialise_node "slave/", $master, $master...
140
141	Before a node can talk to other nodes on the network it has to initialise	169	Before a node can talk to other nodes on the network (i.e. enter
142	itself - the minimum a node needs to know is it's own name, and optionally	170	"distributed mode") it has to initialise itself - the minimum a node needs
143	it should know the noderefs of some other nodes in the network.	171	to know is its own name, and optionally it should know the addresses of
		172	some other nodes in the network to discover other nodes.
144		173
145	This function initialises a node - it must be called exactly once (or	174	This function initialises a node - it must be called exactly once (or
146	never) before calling other AnyEvent::MP functions.	175	never) before calling other AnyEvent::MP functions.
147		176
148	All arguments are noderefs, which can be either resolved or unresolved.	177	The first argument is a profile name. If it is C<undef> or missing, then
		178	the current nodename will be used instead (i.e. F<uname -n>).
149		179
150	There are two types of networked nodes, public nodes and slave nodes:	180	The function first looks up the profile in the aemp configuration (see the
		181	L<aemp> commandline utility). the profile is calculated as follows:
151		182
152	=over 4	183	First, all remaining key => value pairs (all of which are conviniently
		184	undocumented at the moment) will be used. Then they will be overwritten by
		185	any values specified in the global default configuration (see the F<aemp>
		186	utility), then the chain of profiles selected, if any. That means that
		187	the values specified in the profile have highest priority and the values
		188	specified via C<initialise_node> have lowest priority.
153		189
154	=item public nodes	190	If the profile specifies a node ID, then this will become the node ID of
		191	this process. If not, then the profile name will be used as node ID. The
		192	special node ID of C<anon/> will be replaced by a random node ID.
155		193
156	For public nodes, C<$noderef> must either be a (possibly unresolved)	194	The next step is to look up the binds in the profile, followed by binding
157	noderef, in which case it will be resolved, or C<undef> (or missing), in	195	aemp protocol listeners on all binds specified (it is possible and valid
158	which case the noderef will be guessed.	196	to have no binds, meaning that the node cannot be contacted form the
		197	outside. This means the node cannot talk to other nodes that also have no
		198	binds, but it can still talk to all "normal" nodes).
159		199
160	Afterwards, the node will bind itself on all endpoints and try to connect	200	If the profile does not specify a binds list, then a default of C<*> is
161	to all additional C<$seednodes> that are specified. Seednodes are optional	201	used.
162	and can be used to quickly bootstrap the node into an existing network.
163		202
164	=item slave nodes	203	Lastly, the seeds list from the profile is passed to the
		204	L<AnyEvent::MP::Global> module, which will then use it to keep
		205	connectivity with at least on of those seed nodes at any point in time.
165		206
166	When the C<$noderef> is the special string C<slave/>, then the node will	207	Example: become a distributed node listening on the guessed noderef, or
167	become a slave node. Slave nodes cannot be contacted from outside and will	208	the one specified via C<aemp> for the current node. This should be the
168	route most of their traffic to the master node that they attach to.	209	most common form of invocation for "daemon"-type nodes.
169
170	At least one additional noderef is required: The node will try to connect
171	to all of them and will become a slave attached to the first node it can
172	successfully connect to.
173
174	=back
175
176	This function will block until all nodes have been resolved and, for slave
177	nodes, until it has successfully established a connection to a master
178	server.
179
180	Example: become a public node listening on the default node.
181		210
182	initialise_node;	211	initialise_node;
183		212
184	Example: become a public node, and try to contact some well-known master	213	Example: become an anonymous node. This form is often used for commandline
185	servers to become part of the network.	214	clients.
186		215
187	initialise_node undef, "master1", "master2";
188
189	Example: become a public node listening on port C<4041>.
190
191	initialise_node 4041;	216	initialise_node "anon/";
192		217
193	Example: become a public node, only visible on localhost port 4044.	218	Example: become a distributed node. If there is no profile of the given
		219	name, or no binds list was specified, resolve C<localhost:4044> and bind
		220	on the resulting addresses.
194		221
195	initialise_node "locahost:4044";	222	initialise_node "localhost:4044";
196
197	Example: become a slave node to any of the specified master servers.
198
199	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
200
201	=item $cv = resolve_node $noderef
202
203	Takes an unresolved node reference that may contain hostnames and
204	abbreviated IDs, resolves all of them and returns a resolved node
205	reference.
206
207	In addition to C<address:port> pairs allowed in resolved noderefs, the
208	following forms are supported:
209
210	=over 4
211
212	=item the empty string
213
214	An empty-string component gets resolved as if the default port (4040) was
215	specified.
216
217	=item naked port numbers (e.g. C<1234>)
218
219	These are resolved by prepending the local nodename and a colon, to be
220	further resolved.
221
222	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
223
224	These are resolved by using AnyEvent::DNS to resolve them, optionally
225	looking up SRV records for the C<aemp=4040> port, if no port was
226	specified.
227
228	=back
229		223
230	=item $SELF	224	=item $SELF
231		225
232	Contains the current port id while executing C<rcv> callbacks or C<psub>	226	Contains the current port id while executing C<rcv> callbacks or C<psub>
233	blocks.	227	blocks.
234		228
235	=item SELF, %SELF, @SELF...	229	=item *SELF, SELF, %SELF, @SELF...
236		230
237	Due to some quirks in how perl exports variables, it is impossible to	231	Due to some quirks in how perl exports variables, it is impossible to
238	just export C<$SELF>, all the symbols called C<SELF> are exported by this	232	just export C<$SELF>, all the symbols named C<SELF> are exported by this
239	module, but only C<$SELF> is currently used.	233	module, but only C<$SELF> is currently used.
240		234
241	=item snd $port, type => @data	235	=item snd $port, type => @data
242		236
243	=item snd $port, @msg	237	=item snd $port, @msg
244		238
245	Send the given message to the given port ID, which can identify either	239	Send the given message to the given port, which can identify either a
246	a local or a remote port, and can be either a string or soemthignt hat	240	local or a remote port, and must be a port ID.
247	stringifies a sa port ID (such as a port object :).
248		241
249	While the message can be about anything, it is highly recommended to use a	242	While the message can be almost anything, it is highly recommended to
250	string as first element (a portid, or some word that indicates a request	243	use a string as first element (a port ID, or some word that indicates a
251	type etc.).	244	request type etc.) and to consist if only simple perl values (scalars,
		245	arrays, hashes) - if you think you need to pass an object, think again.
252		246
253	The message data effectively becomes read-only after a call to this	247	The message data logically becomes read-only after a call to this
254	function: modifying any argument is not allowed and can cause many	248	function: modifying any argument (or values referenced by them) is
255	problems.	249	forbidden, as there can be considerable time between the call to C<snd>
		250	and the time the message is actually being serialised - in fact, it might
		251	never be copied as within the same process it is simply handed to the
		252	receiving port.
256		253
257	The type of data you can transfer depends on the transport protocol: when	254	The type of data you can transfer depends on the transport protocol: when
258	JSON is used, then only strings, numbers and arrays and hashes consisting	255	JSON is used, then only strings, numbers and arrays and hashes consisting
259	of those are allowed (no objects). When Storable is used, then anything	256	of those are allowed (no objects). When Storable is used, then anything
260	that Storable can serialise and deserialise is allowed, and for the local	257	that Storable can serialise and deserialise is allowed, and for the local
261	node, anything can be passed.	258	node, anything can be passed. Best rely only on the common denominator of
		259	these.
262		260
263	=item $local_port = port	261	=item $local_port = port
264		262
265	Create a new local port object that can be used either as a pattern	263	Create a new local port object and returns its port ID. Initially it has
266	matching port ("full port") or a single-callback port ("miniport"),	264	no callbacks set and will throw an error when it receives messages.
267	depending on how C<rcv> callbacks are bound to the object.
268		265
269	=item $port = port { my @msg = @_; $finished }	266	=item $local_port = port { my @msg = @_ }
270		267
271	Creates a "miniport", that is, a very lightweight port without any pattern	268	Creates a new local port, and returns its ID. Semantically the same as
272	matching behind it, and returns its ID. Semantically the same as creating
273	a port and calling C<rcv $port, $callback> on it.	269	creating a port and calling C<rcv $port, $callback> on it.
274		270
275	The block will be called for every message received on the port. When the	271	The block will be called for every message received on the port, with the
276	callback returns a true value its job is considered "done" and the port	272	global variable C<$SELF> set to the port ID. Runtime errors will cause the
277	will be destroyed. Otherwise it will stay alive.	273	port to be C<kil>ed. The message will be passed as-is, no extra argument
		274	(i.e. no port ID) will be passed to the callback.
278		275
279	The message will be passed as-is, no extra argument (i.e. no port id) will	276	If you want to stop/destroy the port, simply C<kil> it:
280	be passed to the callback.
281		277
282	If you need the local port id in the callback, this works nicely:	278	my $port = port {
283		279	my @msg = @_;
284	my $port; $port = port {	280	...
285	snd $otherport, reply => $port;	281	kil $SELF;
286	};	282	};
287		283
288	=cut	284	=cut
289		285
290	sub rcv($@);	286	sub rcv($@);
		287
		288	sub _kilme {
		289	die "received message on port without callback";
		290	}
291		291
292	sub port(;&) {	292	sub port(;&) {
293	my $id = "$UNIQ." . $ID++;	293	my $id = "$UNIQ." . $ID++;
294	my $port = "$NODE#$id";	294	my $port = "$NODE#$id";
295		295
296	if (@_) {	296	rcv $port, shift \|\| \&_kilme;
297	rcv $port, shift;
298	} else {
299	$PORT{$id} = sub { }; # nop
300	}
301		297
302	$port	298	$port
303	}	299	}
304		300
305	=item reg $port, $name
306
307	=item reg $name
308
309	Registers the given port (or C<$SELF><<< if missing) under the name
310	C<$name>. If the name already exists it is replaced.
311
312	A port can only be registered under one well known name.
313
314	A port automatically becomes unregistered when it is killed.
315
316	=cut
317
318	sub reg(@) {
319	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
320
321	$REG{$_[0]} = $port;
322	}
323
324	=item rcv $port, $callback->(@msg)	301	=item rcv $local_port, $callback->(@msg)
325		302
326	Replaces the callback on the specified miniport (after converting it to	303	Replaces the default callback on the specified port. There is no way to
327	one if required).	304	remove the default callback: use C<sub { }> to disable it, or better
328		305	C<kil> the port when it is no longer needed.
329	=item rcv $port, tagstring => $callback->(@msg), ...
330
331	=item rcv $port, $smartmatch => $callback->(@msg), ...
332
333	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
334
335	Register callbacks to be called on matching messages on the given full
336	port (after converting it to one if required) and return the port.
337
338	The callback has to return a true value when its work is done, after
339	which is will be removed, or a false value in which case it will stay
340	registered.
341		306
342	The global C<$SELF> (exported by this module) contains C<$port> while	307	The global C<$SELF> (exported by this module) contains C<$port> while
343	executing the callback.	308	executing the callback. Runtime errors during callback execution will
		309	result in the port being C<kil>ed.
344		310
345	Runtime errors wdurign callback execution will result in the port being	311	The default callback received all messages not matched by a more specific
346	C<kil>ed.	312	C<tag> match.
347		313
348	If the match is an array reference, then it will be matched against the	314	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
349	first elements of the message, otherwise only the first element is being
350	matched.
351		315
352	Any element in the match that is specified as C<_any_> (a function	316	Register (or replace) callbacks to be called on messages starting with the
353	exported by this module) matches any single element of the message.	317	given tag on the given port (and return the port), or unregister it (when
		318	C<$callback> is C<$undef> or missing). There can only be one callback
		319	registered for each tag.
354		320
355	While not required, it is highly recommended that the first matching	321	The original message will be passed to the callback, after the first
356	element is a string identifying the message. The one-string-only match is	322	element (the tag) has been removed. The callback will use the same
357	also the most efficient match (by far).	323	environment as the default callback (see above).
358		324
359	Example: create a port and bind receivers on it in one go.	325	Example: create a port and bind receivers on it in one go.
360		326
361	my $port = rcv port,	327	my $port = rcv port,
362	msg1 => sub { ...; 0 },	328	msg1 => sub { ... },
363	msg2 => sub { ...; 0 },	329	msg2 => sub { ... },
364	;	330	;
365		331
366	Example: create a port, bind receivers and send it in a message elsewhere	332	Example: create a port, bind receivers and send it in a message elsewhere
367	in one go:	333	in one go:
368		334
369	snd $otherport, reply =>	335	snd $otherport, reply =>
370	rcv port,	336	rcv port,
371	msg1 => sub { ...; 0 },	337	msg1 => sub { ... },
372	...	338	...
373	;	339	;
		340
		341	Example: temporarily register a rcv callback for a tag matching some port
		342	(e.g. for a rpc reply) and unregister it after a message was received.
		343
		344	rcv $port, $otherport => sub {
		345	my @reply = @_;
		346
		347	rcv $SELF, $otherport;
		348	};
374		349
375	=cut	350	=cut
376		351
377	sub rcv($@) {	352	sub rcv($@) {
378	my $port = shift;	353	my $port = shift;
379	my ($noderef, $portid) = split /#/, $port, 2;	354	my ($noderef, $portid) = split /#/, $port, 2;
380		355
381	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	356	$NODE{$noderef} == $NODE{""}
382	or Carp::croak "$port: rcv can only be called on local ports, caught";	357	or Carp::croak "$port: rcv can only be called on local ports, caught";
383		358
384	if (@_ == 1) {	359	while (@_) {
		360	if (ref $_[0]) {
		361	if (my $self = $PORT_DATA{$portid}) {
		362	"AnyEvent::MP::Port" eq ref $self
		363	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		364
		365	$self->[2] = shift;
		366	} else {
385	my $cb = shift;	367	my $cb = shift;
386	delete $PORT_DATA{$portid};
387	$PORT{$portid} = sub {	368	$PORT{$portid} = sub {
388	local $SELF = $port;	369	local $SELF = $port;
389	eval {	370	eval { &$cb }; _self_die if $@;
390	&$cb	371	};
391	and kil $port;
392	};	372	}
393	_self_die if $@;	373	} elsif (defined $_[0]) {
394	};
395	} else {
396	my $self = $PORT_DATA{$portid} \|\|= do {	374	my $self = $PORT_DATA{$portid} \|\|= do {
397	my $self = bless {	375	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
398	id => $port,
399	}, "AnyEvent::MP::Port";
400		376
401	$PORT{$portid} = sub {	377	$PORT{$portid} = sub {
402	local $SELF = $port;	378	local $SELF = $port;
403		379
404	eval {
405	for (@{ $self->{rc0}{$_[0]} }) {	380	if (my $cb = $self->[1]{$_[0]}) {
406	$_ && &{$_->[0]}	381	shift;
407	&& undef $_;	382	eval { &$cb }; _self_die if $@;
408	}	383	} else {
409
410	for (@{ $self->{rcv}{$_[0]} }) {
411	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
412	&& &{$_->[0]}	384	&{ $self->[0] };
413	&& undef $_;
414	}
415
416	for (@{ $self->{any} }) {
417	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
418	&& &{$_->[0]}
419	&& undef $_;
420	}	385	}
421	};	386	};
422	_self_die if $@;	387
		388	$self
423	};	389	};
424		390
425	$self
426	};
427
428	"AnyEvent::MP::Port" eq ref $self	391	"AnyEvent::MP::Port" eq ref $self
429	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	392	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
430		393
431	while (@_) {
432	my ($match, $cb) = splice @_, 0, 2;	394	my ($tag, $cb) = splice @_, 0, 2;
433		395
434	if (!ref $match) {	396	if (defined $cb) {
435	push @{ $self->{rc0}{$match} }, [$cb];	397	$self->[1]{$tag} = $cb;
436	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
437	my ($type, @match) = @$match;
438	@match
439	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
440	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
441	} else {	398	} else {
442	push @{ $self->{any} }, [$cb, $match];	399	delete $self->[1]{$tag};
443	}	400	}
444	}	401	}
445	}	402	}
446		403
447	$port	404	$port
…		…
483	$res	440	$res
484	}	441	}
485	}	442	}
486	}	443	}
487		444
488	=item $guard = mon $port, $cb->(@reason)	445	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
489		446
490	=item $guard = mon $port, $rcvport	447	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
491		448
492	=item $guard = mon $port	449	=item $guard = mon $port # kill $SELF when $port dies
493		450
494	=item $guard = mon $port, $rcvport, @msg	451	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
495		452
496	Monitor the given port and do something when the port is killed, and	453	Monitor the given port and do something when the port is killed or
497	optionally return a guard that can be used to stop monitoring again.	454	messages to it were lost, and optionally return a guard that can be used
		455	to stop monitoring again.
		456
		457	C<mon> effectively guarantees that, in the absence of hardware failures,
		458	after starting the monitor, either all messages sent to the port will
		459	arrive, or the monitoring action will be invoked after possible message
		460	loss has been detected. No messages will be lost "in between" (after
		461	the first lost message no further messages will be received by the
		462	port). After the monitoring action was invoked, further messages might get
		463	delivered again.
		464
		465	Note that monitoring-actions are one-shot: once messages are lost (and a
		466	monitoring alert was raised), they are removed and will not trigger again.
498		467
499	In the first form (callback), the callback is simply called with any	468	In the first form (callback), the callback is simply called with any
500	number of C<@reason> elements (no @reason means that the port was deleted	469	number of C<@reason> elements (no @reason means that the port was deleted
501	"normally"). Note also that I<< the callback B<must> never die >>, so use	470	"normally"). Note also that I<< the callback B<must> never die >>, so use
502	C<eval> if unsure.	471	C<eval> if unsure.
503		472
504	In the second form (another port given), the other port (C<$rcvport)	473	In the second form (another port given), the other port (C<$rcvport>)
505	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on	474	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
506	"normal" kils nothing happens, while under all other conditions, the other	475	"normal" kils nothing happens, while under all other conditions, the other
507	port is killed with the same reason.	476	port is killed with the same reason.
508		477
509	The third form (kill self) is the same as the second form, except that	478	The third form (kill self) is the same as the second form, except that
…		…
536	sub mon {	505	sub mon {
537	my ($noderef, $port) = split /#/, shift, 2;	506	my ($noderef, $port) = split /#/, shift, 2;
538		507
539	my $node = $NODE{$noderef} \|\| add_node $noderef;	508	my $node = $NODE{$noderef} \|\| add_node $noderef;
540		509
541	my $cb = @_ ? $_[0] : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	510	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
542		511
543	unless (ref $cb) {	512	unless (ref $cb) {
544	if (@_) {	513	if (@_) {
545	# send a kill info message	514	# send a kill info message
546	my (@msg) = @_;	515	my (@msg) = ($cb, @_);
547	$cb = sub { snd @msg, @_ };	516	$cb = sub { snd @msg, @_ };
548	} else {	517	} else {
549	# simply kill other port	518	# simply kill other port
550	my $port = $cb;	519	my $port = $cb;
551	$cb = sub { kil $port, @_ if @_ };	520	$cb = sub { kil $port, @_ if @_ };
…		…
564	is killed, the references will be freed.	533	is killed, the references will be freed.
565		534
566	Optionally returns a guard that will stop the monitoring.	535	Optionally returns a guard that will stop the monitoring.
567		536
568	This function is useful when you create e.g. timers or other watchers and	537	This function is useful when you create e.g. timers or other watchers and
569	want to free them when the port gets killed:	538	want to free them when the port gets killed (note the use of C<psub>):
570		539
571	$port->rcv (start => sub {	540	$port->rcv (start => sub {
572	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	541	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
573	undef $timer if 0.9 < rand;	542	undef $timer if 0.9 < rand;
574	});	543	});
575	});	544	});
576		545
577	=cut	546	=cut
…		…
586		555
587	=item kil $port[, @reason]	556	=item kil $port[, @reason]
588		557
589	Kill the specified port with the given C<@reason>.	558	Kill the specified port with the given C<@reason>.
590		559
591	If no C<@reason> is specified, then the port is killed "normally" (linked	560	If no C<@reason> is specified, then the port is killed "normally" (ports
592	ports will not be kileld, or even notified).	561	monitoring other ports will not necessarily die because a port dies
		562	"normally").
593		563
594	Otherwise, linked ports get killed with the same reason (second form of	564	Otherwise, linked ports get killed with the same reason (second form of
595	C<mon>, see below).	565	C<mon>, see above).
596		566
597	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	567	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
598	will be reported as reason C<< die => $@ >>.	568	will be reported as reason C<< die => $@ >>.
599		569
600	Transport/communication errors are reported as C<< transport_error =>	570	Transport/communication errors are reported as C<< transport_error =>
601	$message >>.	571	$message >>.
602		572
603	=back
604
605	=head1 NODE MESSAGES
606
607	Nodes understand the following messages sent to them. Many of them take
608	arguments called C<@reply>, which will simply be used to compose a reply
609	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
610	the remaining arguments are simply the message data.
611
612	While other messages exist, they are not public and subject to change.
613
614	=over 4
615
616	=cut	573	=cut
617		574
618	=item lookup => $name, @reply	575	=item $port = spawn $node, $initfunc[, @initdata]
619		576
620	Replies with the port ID of the specified well-known port, or C<undef>.	577	Creates a port on the node C<$node> (which can also be a port ID, in which
		578	case it's the node where that port resides).
621		579
622	=item devnull => ...	580	The port ID of the newly created port is returned immediately, and it is
		581	possible to immediately start sending messages or to monitor the port.
623		582
624	Generic data sink/CPU heat conversion.	583	After the port has been created, the init function is called on the remote
		584	node, in the same context as a C<rcv> callback. This function must be a
		585	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
		586	specify a function in the main program, use C<::name>.
625		587
626	=item relay => $port, @msg	588	If the function doesn't exist, then the node tries to C<require>
		589	the package, then the package above the package and so on (e.g.
		590	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		591	exists or it runs out of package names.
627		592
628	Simply forwards the message to the given port.	593	The init function is then called with the newly-created port as context
		594	object (C<$SELF>) and the C<@initdata> values as arguments.
629		595
630	=item eval => $string[ @reply]	596	A common idiom is to pass a local port, immediately monitor the spawned
		597	port, and in the remote init function, immediately monitor the passed
		598	local port. This two-way monitoring ensures that both ports get cleaned up
		599	when there is a problem.
631		600
632	Evaluates the given string. If C<@reply> is given, then a message of the	601	Example: spawn a chat server port on C<$othernode>.
633	form C<@reply, $@, @evalres> is sent.
634		602
635	Example: crash another node.	603	# this node, executed from within a port context:
		604	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		605	mon $server;
636		606
637	snd $othernode, eval => "exit";	607	# init function on C<$othernode>
		608	sub connect {
		609	my ($srcport) = @_;
638		610
639	=item time => @reply	611	mon $srcport;
640		612
641	Replies the the current node time to C<@reply>.	613	rcv $SELF, sub {
		614	...
		615	};
		616	}
642		617
643	Example: tell the current node to send the current time to C<$myport> in a	618	=cut
644	C<timereply> message.
645		619
646	snd $NODE, time => $myport, timereply => 1, 2;	620	sub _spawn {
647	# => snd $myport, timereply => 1, 2, <time>	621	my $port = shift;
		622	my $init = shift;
		623
		624	local $SELF = "$NODE#$port";
		625	eval {
		626	&{ load_func $init }
		627	};
		628	_self_die if $@;
		629	}
		630
		631	sub spawn(@) {
		632	my ($noderef, undef) = split /#/, shift, 2;
		633
		634	my $id = "$RUNIQ." . $ID++;
		635
		636	$_[0] =~ /::/
		637	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		638
		639	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
		640
		641	"$noderef#$id"
		642	}
		643
		644	=item after $timeout, @msg
		645
		646	=item after $timeout, $callback
		647
		648	Either sends the given message, or call the given callback, after the
		649	specified number of seconds.
		650
		651	This is simply a utility function that comes in handy at times - the
		652	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		653	so it may go away in the future.
		654
		655	=cut
		656
		657	sub after($@) {
		658	my ($timeout, @action) = @_;
		659
		660	my $t; $t = AE::timer $timeout, 0, sub {
		661	undef $t;
		662	ref $action[0]
		663	? $action[0]()
		664	: snd @action;
		665	};
		666	}
648		667
649	=back	668	=back
650		669
651	=head1 AnyEvent::MP vs. Distributed Erlang	670	=head1 AnyEvent::MP vs. Distributed Erlang
652		671
…		…
662		681
663	Despite the similarities, there are also some important differences:	682	Despite the similarities, there are also some important differences:
664		683
665	=over 4	684	=over 4
666		685
667	=item * Node references contain the recipe on how to contact them.	686	=item * Node IDs are arbitrary strings in AEMP.
668		687
669	Erlang relies on special naming and DNS to work everywhere in the	688	Erlang relies on special naming and DNS to work everywhere in the same
670	same way. AEMP relies on each node knowing it's own address(es), with	689	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
671	convenience functionality.	690	configuraiton or DNS), but will otherwise discover other odes itself.
672		691
673	This means that AEMP requires a less tightly controlled environment at the	692	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
674	cost of longer node references and a slightly higher management overhead.	693	uses "local ports are like remote ports".
		694
		695	The failure modes for local ports are quite different (runtime errors
		696	only) then for remote ports - when a local port dies, you I<know> it dies,
		697	when a connection to another node dies, you know nothing about the other
		698	port.
		699
		700	Erlang pretends remote ports are as reliable as local ports, even when
		701	they are not.
		702
		703	AEMP encourages a "treat remote ports differently" philosophy, with local
		704	ports being the special case/exception, where transport errors cannot
		705	occur.
675		706
676	=item * Erlang uses processes and a mailbox, AEMP does not queue.	707	=item * Erlang uses processes and a mailbox, AEMP does not queue.
677		708
678	Erlang uses processes that selctively receive messages, and therefore	709	Erlang uses processes that selectively receive messages, and therefore
679	needs a queue. AEMP is event based, queuing messages would serve no useful	710	needs a queue. AEMP is event based, queuing messages would serve no
680	purpose.	711	useful purpose. For the same reason the pattern-matching abilities of
		712	AnyEvent::MP are more limited, as there is little need to be able to
		713	filter messages without dequeing them.
681		714
682	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	715	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
683		716
684	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	717	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
685		718
686	Sending messages in Erlang is synchronous and blocks the process. AEMP	719	Sending messages in Erlang is synchronous and blocks the process (and
687	sends are immediate, connection establishment is handled in the	720	so does not need a queue that can overflow). AEMP sends are immediate,
688	background.	721	connection establishment is handled in the background.
689		722
690	=item * Erlang can silently lose messages, AEMP cannot.	723	=item * Erlang suffers from silent message loss, AEMP does not.
691		724
692	Erlang makes few guarantees on messages delivery - messages can get lost	725	Erlang makes few guarantees on messages delivery - messages can get lost
693	without any of the processes realising it (i.e. you send messages a, b,	726	without any of the processes realising it (i.e. you send messages a, b,
694	and c, and the other side only receives messages a and c).	727	and c, and the other side only receives messages a and c).
695		728
696	AEMP guarantees correct ordering, and the guarantee that there are no	729	AEMP guarantees correct ordering, and the guarantee that after one message
697	holes in the message sequence.	730	is lost, all following ones sent to the same port are lost as well, until
698		731	monitoring raises an error, so there are no silent "holes" in the message
699	=item * In Erlang, processes can be declared dead and later be found to be	732	sequence.
700	alive.
701
702	In Erlang it can happen that a monitored process is declared dead and
703	linked processes get killed, but later it turns out that the process is
704	still alive - and can receive messages.
705
706	In AEMP, when port monitoring detects a port as dead, then that port will
707	eventually be killed - it cannot happen that a node detects a port as dead
708	and then later sends messages to it, finding it is still alive.
709		733
710	=item * Erlang can send messages to the wrong port, AEMP does not.	734	=item * Erlang can send messages to the wrong port, AEMP does not.
711		735
712	In Erlang it is quite possible that a node that restarts reuses a process	736	In Erlang it is quite likely that a node that restarts reuses a process ID
713	ID known to other nodes for a completely different process, causing	737	known to other nodes for a completely different process, causing messages
714	messages destined for that process to end up in an unrelated process.	738	destined for that process to end up in an unrelated process.
715		739
716	AEMP never reuses port IDs, so old messages or old port IDs floating	740	AEMP never reuses port IDs, so old messages or old port IDs floating
717	around in the network will not be sent to an unrelated port.	741	around in the network will not be sent to an unrelated port.
718		742
719	=item * Erlang uses unprotected connections, AEMP uses secure	743	=item * Erlang uses unprotected connections, AEMP uses secure
720	authentication and can use TLS.	744	authentication and can use TLS.
721		745
722	AEMP can use a proven protocol - SSL/TLS - to protect connections and	746	AEMP can use a proven protocol - TLS - to protect connections and
723	securely authenticate nodes.	747	securely authenticate nodes.
724		748
725	=item * The AEMP protocol is optimised for both text-based and binary	749	=item * The AEMP protocol is optimised for both text-based and binary
726	communications.	750	communications.
727		751
728	The AEMP protocol, unlike the Erlang protocol, supports both	752	The AEMP protocol, unlike the Erlang protocol, supports both programming
729	language-independent text-only protocols (good for debugging) and binary,	753	language independent text-only protocols (good for debugging) and binary,
730	language-specific serialisers (e.g. Storable).	754	language-specific serialisers (e.g. Storable). By default, unless TLS is
		755	used, the protocol is actually completely text-based.
731		756
732	It has also been carefully designed to be implementable in other languages	757	It has also been carefully designed to be implementable in other languages
733	with a minimum of work while gracefully degrading fucntionality to make the	758	with a minimum of work while gracefully degrading functionality to make the
734	protocol simple.	759	protocol simple.
735		760
736	=item * AEMP has more flexible monitoring options than Erlang.	761	=item * AEMP has more flexible monitoring options than Erlang.
737		762
738	In Erlang, you can chose to receive I<all> exit signals as messages	763	In Erlang, you can chose to receive I<all> exit signals as messages
…		…
741	Erlang, as one can choose between automatic kill, exit message or callback	766	Erlang, as one can choose between automatic kill, exit message or callback
742	on a per-process basis.	767	on a per-process basis.
743		768
744	=item * Erlang tries to hide remote/local connections, AEMP does not.	769	=item * Erlang tries to hide remote/local connections, AEMP does not.
745		770
746	Monitoring in Erlang is not an indicator of process death/crashes,	771	Monitoring in Erlang is not an indicator of process death/crashes, in the
747	as linking is (except linking is unreliable in Erlang).	772	same way as linking is (except linking is unreliable in Erlang).
748		773
749	In AEMP, you don't "look up" registered port names or send to named ports	774	In AEMP, you don't "look up" registered port names or send to named ports
750	that might or might not be persistent. Instead, you normally spawn a port	775	that might or might not be persistent. Instead, you normally spawn a port
751	on the remote node. The init function monitors the you, and you monitor	776	on the remote node. The init function monitors you, and you monitor the
752	the remote port. Since both monitors are local to the node, they are much	777	remote port. Since both monitors are local to the node, they are much more
753	more reliable.	778	reliable (no need for C<spawn_link>).
754		779
755	This also saves round-trips and avoids sending messages to the wrong port	780	This also saves round-trips and avoids sending messages to the wrong port
756	(hard to do in Erlang).	781	(hard to do in Erlang).
757		782
758	=back	783	=back
759		784
		785	=head1 RATIONALE
		786
		787	=over 4
		788
		789	=item Why strings for port and node IDs, why not objects?
		790
		791	We considered "objects", but found that the actual number of methods
		792	that can be called are quite low. Since port and node IDs travel over
		793	the network frequently, the serialising/deserialising would add lots of
		794	overhead, as well as having to keep a proxy object everywhere.
		795
		796	Strings can easily be printed, easily serialised etc. and need no special
		797	procedures to be "valid".
		798
		799	And as a result, a miniport consists of a single closure stored in a
		800	global hash - it can't become much cheaper.
		801
		802	=item Why favour JSON, why not a real serialising format such as Storable?
		803
		804	In fact, any AnyEvent::MP node will happily accept Storable as framing
		805	format, but currently there is no way to make a node use Storable by
		806	default (although all nodes will accept it).
		807
		808	The default framing protocol is JSON because a) JSON::XS is many times
		809	faster for small messages and b) most importantly, after years of
		810	experience we found that object serialisation is causing more problems
		811	than it solves: Just like function calls, objects simply do not travel
		812	easily over the network, mostly because they will always be a copy, so you
		813	always have to re-think your design.
		814
		815	Keeping your messages simple, concentrating on data structures rather than
		816	objects, will keep your messages clean, tidy and efficient.
		817
		818	=back
		819
760	=head1 SEE ALSO	820	=head1 SEE ALSO
		821
		822	L<AnyEvent::MP::Intro> - a gentle introduction.
		823
		824	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		825
		826	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		827	your applications.
761		828
762	L<AnyEvent>.	829	L<AnyEvent>.
763		830
764	=head1 AUTHOR	831	=head1 AUTHOR
765		832

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Revision 1.70 by root, Sun Aug 30 19:49:47 2009 UTC