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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.43 by root, Sun Aug 9 16:08:16 2009 UTC vs.
Revision 1.80 by root, Fri Sep 4 22:30:29 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
13	$SELF # receiving/own port id in rcv callbacks	12	$SELF # receiving/own port id in rcv callbacks
14		13
		14	# initialise the node so it can send/receive messages
		15	configure;
		16
15	# ports are message endpoints	17	# ports are message destinations
16		18
17	# sending messages	19	# sending messages
18	snd $port, type => data...;	20	snd $port, type => data...;
19	snd $port, @msg;	21	snd $port, @msg;
20	snd @msg_with_first_element_being_a_port;	22	snd @msg_with_first_element_being_a_port;
21		23
22	# miniports	24	# creating/using ports, the simple way
23	my $miniport = port { my @msg = @_; 0 };	25	my $simple_port = port { my @msg = @_ };
24		26
25	# full ports	27	# creating/using ports, tagged message matching
26	my $port = port;	28	my $port = port;
27	rcv $port, smartmatch => $cb->(@msg);
28	rcv $port, ping => sub { snd $_[0], "pong"; 0 };	29	rcv $port, ping => sub { snd $_[0], "pong" };
29	rcv $port, pong => sub { warn "pong received\n"; 0 };	30	rcv $port, pong => sub { warn "pong received\n" };
30		31
31	# remote ports	32	# create a port on another node
32	my $port = spawn $node, $initfunc, @initdata;	33	my $port = spawn $node, $initfunc, @initdata;
33
34	# more, smarter, matches (_any_ is exported by this module)
35	rcv $port, [child_died => $pid] => sub { ...
36	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
37		34
38	# monitoring	35	# monitoring
39	mon $port, $cb->(@msg) # callback is invoked on death	36	mon $port, $cb->(@msg) # callback is invoked on death
40	mon $port, $otherport # kill otherport on abnormal death	37	mon $port, $otherport # kill otherport on abnormal death
41	mon $port, $otherport, @msg # send message on death	38	mon $port, $otherport, @msg # send message on death
42		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
43	=head1 DESCRIPTION	50	=head1 DESCRIPTION
44		51
45	This module (-family) implements a simple message passing framework.	52	This module (-family) implements a simple message passing framework.
46		53
47	Despite its simplicity, you can securely message other processes running	54	Despite its simplicity, you can securely message other processes running
48	on the same or other hosts.	55	on the same or other hosts, and you can supervise entities remotely.
49		56
50	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>
51	manual page.	58	manual page and the examples under F<eg/>.
52
53	At the moment, this module family is severly broken and underdocumented,
54	so do not use. This was uploaded mainly to reserve the CPAN namespace -
55	stay tuned! The basic API should be finished, however.
56		59
57	=head1 CONCEPTS	60	=head1 CONCEPTS
58		61
59	=over 4	62	=over 4
60		63
61	=item port	64	=item port
62		65
63	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).
64		68
65	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
66	messages. All C<rcv> handlers will receive messages they match, messages	70	some messages. Messages send to ports will not be queued, regardless of
67	will not be queued.	71	anything was listening for them or not.
68		72
69	=item port id - C<noderef#portname>	73	=item port ID - C<nodeid#portname>
70		74
71	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
72	separator, and a port name (a printable string of unspecified format). An	76	separator, and a port name (a printable string of unspecified format).
73	exception is the the node port, whose ID is identical to its node
74	reference.
75		77
76	=item node	78	=item node
77		79
78	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,
79	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
80	create new ports, among other things.	82	ports.
81		83
82	Nodes are either private (single-process only), slaves (connected to a	84	Nodes are either public (have one or more listening ports) or private
83	master node only) or public nodes (connectable from unrelated nodes).	85	(no listening ports). Private nodes cannot talk to other private nodes
		86	currently.
84		87
85	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	88	=item node ID - C<[a-za-Z0-9_\-.:]+>
86		89
87	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
88	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
89	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.
90		94
91	This recipe is simply a comma-separated list of C<address:port> pairs (for	95	=item binds - C<ip:port>
92	TCP/IP, other protocols might look different).
93		96
94	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
95	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.
96		101
97	Before using an unresolved node reference in a message you first have to	102	=item seeds - C<host:port>
98	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	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes
		109	are expected to be long-running, and at least one of those should always
		110	be available. When nodes run out of connections (e.g. due to a network
		111	error), they try to re-establish connections to some seednodes again to
		112	join the network.
		113
		114	Apart from being sued for seeding, seednodes are not special in any way -
		115	every public node can be a seednode.
99		116
100	=back	117	=back
101		118
102	=head1 VARIABLES/FUNCTIONS	119	=head1 VARIABLES/FUNCTIONS
103		120
…		…
105		122
106	=cut	123	=cut
107		124
108	package AnyEvent::MP;	125	package AnyEvent::MP;
109		126
110	use AnyEvent::MP::Base;	127	use AnyEvent::MP::Kernel;
111		128
112	use common::sense;	129	use common::sense;
113		130
114	use Carp ();	131	use Carp ();
115		132
116	use AE ();	133	use AE ();
117		134
118	use base "Exporter";	135	use base "Exporter";
119		136
120	our $VERSION = $AnyEvent::MP::Base::VERSION;	137	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
121		138
122	our @EXPORT = qw(	139	our @EXPORT = qw(
123	NODE $NODE *SELF node_of _any_	140	NODE $NODE *SELF node_of after
124	resolve_node initialise_node	141	configure
125	snd rcv mon kil reg psub spawn	142	snd rcv mon mon_guard kil reg psub spawn
126	port	143	port
127	);	144	);
128		145
129	our $SELF;	146	our $SELF;
130		147
…		…
134	kil $SELF, die => $msg;	151	kil $SELF, die => $msg;
135	}	152	}
136		153
137	=item $thisnode = NODE / $NODE	154	=item $thisnode = NODE / $NODE
138		155
139	The C<NODE> function returns, and the C<$NODE> variable contains	156	The C<NODE> function returns, and the C<$NODE> variable contains, the node
140	the noderef of the local node. The value is initialised by a call	157	ID of the node running in the current process. This value is initialised by
141	to C<become_public> or C<become_slave>, after which all local port	158	a call to C<configure>.
142	identifiers become invalid.
143		159
144	=item $noderef = node_of $port	160	=item $nodeid = node_of $port
145		161
146	Extracts and returns the noderef from a portid or a noderef.	162	Extracts and returns the node ID from a port ID or a node ID.
147		163
148	=item initialise_node $noderef, $seednode, $seednode...	164	=item configure $profile, key => value...
149		165
150	=item initialise_node "slave/", $master, $master...	166	=item configure key => value...
151		167
152	Before a node can talk to other nodes on the network it has to initialise	168	Before a node can talk to other nodes on the network (i.e. enter
153	itself - the minimum a node needs to know is it's own name, and optionally	169	"distributed mode") it has to configure itself - the minimum a node needs
154	it should know the noderefs of some other nodes in the network.	170	to know is its own name, and optionally it should know the addresses of
		171	some other nodes in the network to discover other nodes.
155		172
156	This function initialises a node - it must be called exactly once (or	173	This function configures a node - it must be called exactly once (or
157	never) before calling other AnyEvent::MP functions.	174	never) before calling other AnyEvent::MP functions.
158		175
159	All arguments are noderefs, which can be either resolved or unresolved.
160
161	There are two types of networked nodes, public nodes and slave nodes:
162
163	=over 4	176	=over 4
164		177
165	=item public nodes	178	=item step 1, gathering configuration from profiles
166		179
167	For public nodes, C<$noderef> must either be a (possibly unresolved)	180	The function first looks up a profile in the aemp configuration (see the
168	noderef, in which case it will be resolved, or C<undef> (or missing), in	181	L<aemp> commandline utility). The profile name can be specified via the
169	which case the noderef will be guessed.	182	named C<profile> parameter or can simply be the first parameter). If it is
		183	missing, then the nodename (F<uname -n>) will be used as profile name.
170		184
171	Afterwards, the node will bind itself on all endpoints and try to connect	185	The profile data is then gathered as follows:
172	to all additional C<$seednodes> that are specified. Seednodes are optional
173	and can be used to quickly bootstrap the node into an existing network.
174		186
175	=item slave nodes	187	First, all remaining key => value pairs (all of which are conveniently
		188	undocumented at the moment) will be interpreted as configuration
		189	data. Then they will be overwritten by any values specified in the global
		190	default configuration (see the F<aemp> utility), then the chain of
		191	profiles chosen by the profile name (and any C<parent> attributes).
176		192
177	When the C<$noderef> is the special string C<slave/>, then the node will	193	That means that the values specified in the profile have highest priority
178	become a slave node. Slave nodes cannot be contacted from outside and will	194	and the values specified directly via C<configure> have lowest priority,
179	route most of their traffic to the master node that they attach to.	195	and can only be used to specify defaults.
180		196
181	At least one additional noderef is required: The node will try to connect	197	If the profile specifies a node ID, then this will become the node ID of
182	to all of them and will become a slave attached to the first node it can	198	this process. If not, then the profile name will be used as node ID. The
183	successfully connect to.	199	special node ID of C<anon/> will be replaced by a random node ID.
		200
		201	=item step 2, bind listener sockets
		202
		203	The next step is to look up the binds in the profile, followed by binding
		204	aemp protocol listeners on all binds specified (it is possible and valid
		205	to have no binds, meaning that the node cannot be contacted form the
		206	outside. This means the node cannot talk to other nodes that also have no
		207	binds, but it can still talk to all "normal" nodes).
		208
		209	If the profile does not specify a binds list, then a default of C<*> is
		210	used, meaning the node will bind on a dynamically-assigned port on every
		211	local IP address it finds.
		212
		213	=item step 3, connect to seed nodes
		214
		215	As the last step, the seeds list from the profile is passed to the
		216	L<AnyEvent::MP::Global> module, which will then use it to keep
		217	connectivity with at least one node at any point in time.
184		218
185	=back	219	=back
186		220
187	This function will block until all nodes have been resolved and, for slave	221	Example: become a distributed node using the locla node name as profile.
188	nodes, until it has successfully established a connection to a master	222	This should be the most common form of invocation for "daemon"-type nodes.
189	server.
190		223
191	Example: become a public node listening on the default node.	224	configure
192		225
193	initialise_node;	226	Example: become an anonymous node. This form is often used for commandline
		227	clients.
194		228
195	Example: become a public node, and try to contact some well-known master	229	configure nodeid => "anon/";
196	servers to become part of the network.
197		230
198	initialise_node undef, "master1", "master2";	231	Example: configure a node using a profile called seed, which si suitable
		232	for a seed node as it binds on all local addresses on a fixed port (4040,
		233	customary for aemp).
199		234
200	Example: become a public node listening on port C<4041>.	235	# use the aemp commandline utility
		236	# aemp profile seed nodeid anon/ binds '*:4040'
201		237
202	initialise_node 4041;	238	# then use it
		239	configure profile => "seed";
203		240
204	Example: become a public node, only visible on localhost port 4044.	241	# or simply use aemp from the shell again:
		242	# aemp run profile seed
205		243
206	initialise_node "locahost:4044";	244	# or provide a nicer-to-remember nodeid
207		245	# aemp run profile seed nodeid "$(hostname)"
208	Example: become a slave node to any of the specified master servers.
209
210	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
211
212	=item $cv = resolve_node $noderef
213
214	Takes an unresolved node reference that may contain hostnames and
215	abbreviated IDs, resolves all of them and returns a resolved node
216	reference.
217
218	In addition to C<address:port> pairs allowed in resolved noderefs, the
219	following forms are supported:
220
221	=over 4
222
223	=item the empty string
224
225	An empty-string component gets resolved as if the default port (4040) was
226	specified.
227
228	=item naked port numbers (e.g. C<1234>)
229
230	These are resolved by prepending the local nodename and a colon, to be
231	further resolved.
232
233	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
234
235	These are resolved by using AnyEvent::DNS to resolve them, optionally
236	looking up SRV records for the C<aemp=4040> port, if no port was
237	specified.
238
239	=back
240		246
241	=item $SELF	247	=item $SELF
242		248
243	Contains the current port id while executing C<rcv> callbacks or C<psub>	249	Contains the current port id while executing C<rcv> callbacks or C<psub>
244	blocks.	250	blocks.
245		251
246	=item SELF, %SELF, @SELF...	252	=item *SELF, SELF, %SELF, @SELF...
247		253
248	Due to some quirks in how perl exports variables, it is impossible to	254	Due to some quirks in how perl exports variables, it is impossible to
249	just export C<$SELF>, all the symbols called C<SELF> are exported by this	255	just export C<$SELF>, all the symbols named C<SELF> are exported by this
250	module, but only C<$SELF> is currently used.	256	module, but only C<$SELF> is currently used.
251		257
252	=item snd $port, type => @data	258	=item snd $port, type => @data
253		259
254	=item snd $port, @msg	260	=item snd $port, @msg
255		261
256	Send the given message to the given port ID, which can identify either	262	Send the given message to the given port, which can identify either a
257	a local or a remote port, and can be either a string or soemthignt hat	263	local or a remote port, and must be a port ID.
258	stringifies a sa port ID (such as a port object :).
259		264
260	While the message can be about anything, it is highly recommended to use a	265	While the message can be almost anything, it is highly recommended to
261	string as first element (a portid, or some word that indicates a request	266	use a string as first element (a port ID, or some word that indicates a
262	type etc.).	267	request type etc.) and to consist if only simple perl values (scalars,
		268	arrays, hashes) - if you think you need to pass an object, think again.
263		269
264	The message data effectively becomes read-only after a call to this	270	The message data logically becomes read-only after a call to this
265	function: modifying any argument is not allowed and can cause many	271	function: modifying any argument (or values referenced by them) is
266	problems.	272	forbidden, as there can be considerable time between the call to C<snd>
		273	and the time the message is actually being serialised - in fact, it might
		274	never be copied as within the same process it is simply handed to the
		275	receiving port.
267		276
268	The type of data you can transfer depends on the transport protocol: when	277	The type of data you can transfer depends on the transport protocol: when
269	JSON is used, then only strings, numbers and arrays and hashes consisting	278	JSON is used, then only strings, numbers and arrays and hashes consisting
270	of those are allowed (no objects). When Storable is used, then anything	279	of those are allowed (no objects). When Storable is used, then anything
271	that Storable can serialise and deserialise is allowed, and for the local	280	that Storable can serialise and deserialise is allowed, and for the local
272	node, anything can be passed.	281	node, anything can be passed. Best rely only on the common denominator of
		282	these.
273		283
274	=item $local_port = port	284	=item $local_port = port
275		285
276	Create a new local port object that can be used either as a pattern	286	Create a new local port object and returns its port ID. Initially it has
277	matching port ("full port") or a single-callback port ("miniport"),	287	no callbacks set and will throw an error when it receives messages.
278	depending on how C<rcv> callbacks are bound to the object.
279		288
280	=item $port = port { my @msg = @_; $finished }	289	=item $local_port = port { my @msg = @_ }
281		290
282	Creates a "miniport", that is, a very lightweight port without any pattern	291	Creates a new local port, and returns its ID. Semantically the same as
283	matching behind it, and returns its ID. Semantically the same as creating
284	a port and calling C<rcv $port, $callback> on it.	292	creating a port and calling C<rcv $port, $callback> on it.
285		293
286	The block will be called for every message received on the port. When the	294	The block will be called for every message received on the port, with the
287	callback returns a true value its job is considered "done" and the port	295	global variable C<$SELF> set to the port ID. Runtime errors will cause the
288	will be destroyed. Otherwise it will stay alive.	296	port to be C<kil>ed. The message will be passed as-is, no extra argument
		297	(i.e. no port ID) will be passed to the callback.
289		298
290	The message will be passed as-is, no extra argument (i.e. no port id) will	299	If you want to stop/destroy the port, simply C<kil> it:
291	be passed to the callback.
292		300
293	If you need the local port id in the callback, this works nicely:	301	my $port = port {
294		302	my @msg = @_;
295	my $port; $port = port {	303	...
296	snd $otherport, reply => $port;	304	kil $SELF;
297	};	305	};
298		306
299	=cut	307	=cut
300		308
301	sub rcv($@);	309	sub rcv($@);
		310
		311	sub _kilme {
		312	die "received message on port without callback";
		313	}
302		314
303	sub port(;&) {	315	sub port(;&) {
304	my $id = "$UNIQ." . $ID++;	316	my $id = "$UNIQ." . $ID++;
305	my $port = "$NODE#$id";	317	my $port = "$NODE#$id";
306		318
307	if (@_) {	319	rcv $port, shift \|\| \&_kilme;
308	rcv $port, shift;
309	} else {
310	$PORT{$id} = sub { }; # nop
311	}
312		320
313	$port	321	$port
314	}	322	}
315		323
316	=item reg $port, $name
317
318	=item reg $name
319
320	Registers the given port (or C<$SELF><<< if missing) under the name
321	C<$name>. If the name already exists it is replaced.
322
323	A port can only be registered under one well known name.
324
325	A port automatically becomes unregistered when it is killed.
326
327	=cut
328
329	sub reg(@) {
330	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
331
332	$REG{$_[0]} = $port;
333	}
334
335	=item rcv $port, $callback->(@msg)	324	=item rcv $local_port, $callback->(@msg)
336		325
337	Replaces the callback on the specified miniport (after converting it to	326	Replaces the default callback on the specified port. There is no way to
338	one if required).	327	remove the default callback: use C<sub { }> to disable it, or better
339		328	C<kil> the port when it is no longer needed.
340	=item rcv $port, tagstring => $callback->(@msg), ...
341
342	=item rcv $port, $smartmatch => $callback->(@msg), ...
343
344	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
345
346	Register callbacks to be called on matching messages on the given full
347	port (after converting it to one if required) and return the port.
348
349	The callback has to return a true value when its work is done, after
350	which is will be removed, or a false value in which case it will stay
351	registered.
352		329
353	The global C<$SELF> (exported by this module) contains C<$port> while	330	The global C<$SELF> (exported by this module) contains C<$port> while
354	executing the callback.	331	executing the callback. Runtime errors during callback execution will
		332	result in the port being C<kil>ed.
355		333
356	Runtime errors during callback execution will result in the port being	334	The default callback received all messages not matched by a more specific
357	C<kil>ed.	335	C<tag> match.
358		336
359	If the match is an array reference, then it will be matched against the	337	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
360	first elements of the message, otherwise only the first element is being
361	matched.
362		338
363	Any element in the match that is specified as C<_any_> (a function	339	Register (or replace) callbacks to be called on messages starting with the
364	exported by this module) matches any single element of the message.	340	given tag on the given port (and return the port), or unregister it (when
		341	C<$callback> is C<$undef> or missing). There can only be one callback
		342	registered for each tag.
365		343
366	While not required, it is highly recommended that the first matching	344	The original message will be passed to the callback, after the first
367	element is a string identifying the message. The one-string-only match is	345	element (the tag) has been removed. The callback will use the same
368	also the most efficient match (by far).	346	environment as the default callback (see above).
369		347
370	Example: create a port and bind receivers on it in one go.	348	Example: create a port and bind receivers on it in one go.
371		349
372	my $port = rcv port,	350	my $port = rcv port,
373	msg1 => sub { ...; 0 },	351	msg1 => sub { ... },
374	msg2 => sub { ...; 0 },	352	msg2 => sub { ... },
375	;	353	;
376		354
377	Example: create a port, bind receivers and send it in a message elsewhere	355	Example: create a port, bind receivers and send it in a message elsewhere
378	in one go:	356	in one go:
379		357
380	snd $otherport, reply =>	358	snd $otherport, reply =>
381	rcv port,	359	rcv port,
382	msg1 => sub { ...; 0 },	360	msg1 => sub { ... },
383	...	361	...
384	;	362	;
385		363
		364	Example: temporarily register a rcv callback for a tag matching some port
		365	(e.g. for a rpc reply) and unregister it after a message was received.
		366
		367	rcv $port, $otherport => sub {
		368	my @reply = @_;
		369
		370	rcv $SELF, $otherport;
		371	};
		372
386	=cut	373	=cut
387		374
388	sub rcv($@) {	375	sub rcv($@) {
389	my $port = shift;	376	my $port = shift;
390	my ($noderef, $portid) = split /#/, $port, 2;	377	my ($nodeid, $portid) = split /#/, $port, 2;
391		378
392	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	379	$NODE{$nodeid} == $NODE{""}
393	or Carp::croak "$port: rcv can only be called on local ports, caught";	380	or Carp::croak "$port: rcv can only be called on local ports, caught";
394		381
395	if (@_ == 1) {	382	while (@_) {
		383	if (ref $_[0]) {
		384	if (my $self = $PORT_DATA{$portid}) {
		385	"AnyEvent::MP::Port" eq ref $self
		386	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		387
		388	$self->[2] = shift;
		389	} else {
396	my $cb = shift;	390	my $cb = shift;
397	delete $PORT_DATA{$portid};
398	$PORT{$portid} = sub {	391	$PORT{$portid} = sub {
399	local $SELF = $port;	392	local $SELF = $port;
400	eval {	393	eval { &$cb }; _self_die if $@;
401	&$cb	394	};
402	and kil $port;
403	};	395	}
404	_self_die if $@;	396	} elsif (defined $_[0]) {
405	};
406	} else {
407	my $self = $PORT_DATA{$portid} \|\|= do {	397	my $self = $PORT_DATA{$portid} \|\|= do {
408	my $self = bless {	398	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
409	id => $port,
410	}, "AnyEvent::MP::Port";
411		399
412	$PORT{$portid} = sub {	400	$PORT{$portid} = sub {
413	local $SELF = $port;	401	local $SELF = $port;
414		402
415	eval {
416	for (@{ $self->{rc0}{$_[0]} }) {	403	if (my $cb = $self->[1]{$_[0]}) {
417	$_ && &{$_->[0]}	404	shift;
418	&& undef $_;	405	eval { &$cb }; _self_die if $@;
419	}	406	} else {
420
421	for (@{ $self->{rcv}{$_[0]} }) {
422	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
423	&& &{$_->[0]}	407	&{ $self->[0] };
424	&& undef $_;
425	}
426
427	for (@{ $self->{any} }) {
428	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
429	&& &{$_->[0]}
430	&& undef $_;
431	}	408	}
432	};	409	};
433	_self_die if $@;	410
		411	$self
434	};	412	};
435		413
436	$self
437	};
438
439	"AnyEvent::MP::Port" eq ref $self	414	"AnyEvent::MP::Port" eq ref $self
440	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	415	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
441		416
442	while (@_) {
443	my ($match, $cb) = splice @_, 0, 2;	417	my ($tag, $cb) = splice @_, 0, 2;
444		418
445	if (!ref $match) {	419	if (defined $cb) {
446	push @{ $self->{rc0}{$match} }, [$cb];	420	$self->[1]{$tag} = $cb;
447	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
448	my ($type, @match) = @$match;
449	@match
450	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
451	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
452	} else {	421	} else {
453	push @{ $self->{any} }, [$cb, $match];	422	delete $self->[1]{$tag};
454	}	423	}
455	}	424	}
456	}	425	}
457		426
458	$port	427	$port
…		…
494	$res	463	$res
495	}	464	}
496	}	465	}
497	}	466	}
498		467
499	=item $guard = mon $port, $cb->(@reason)	468	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
500		469
501	=item $guard = mon $port, $rcvport	470	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
502		471
503	=item $guard = mon $port	472	=item $guard = mon $port # kill $SELF when $port dies
504		473
505	=item $guard = mon $port, $rcvport, @msg	474	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
506		475
507	Monitor the given port and do something when the port is killed or	476	Monitor the given port and do something when the port is killed or
508	messages to it were lost, and optionally return a guard that can be used	477	messages to it were lost, and optionally return a guard that can be used
509	to stop monitoring again.	478	to stop monitoring again.
510
511	C<mon> effectively guarantees that, in the absence of hardware failures,
512	that after starting the monitor, either all messages sent to the port
513	will arrive, or the monitoring action will be invoked after possible
514	message loss has been detected. No messages will be lost "in between"
515	(after the first lost message no further messages will be received by the
516	port). After the monitoring action was invoked, further messages might get
517	delivered again.
518		479
519	In the first form (callback), the callback is simply called with any	480	In the first form (callback), the callback is simply called with any
520	number of C<@reason> elements (no @reason means that the port was deleted	481	number of C<@reason> elements (no @reason means that the port was deleted
521	"normally"). Note also that I<< the callback B<must> never die >>, so use	482	"normally"). Note also that I<< the callback B<must> never die >>, so use
522	C<eval> if unsure.	483	C<eval> if unsure.
523		484
524	In the second form (another port given), the other port (C<$rcvport>)	485	In the second form (another port given), the other port (C<$rcvport>)
525	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on	486	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
526	"normal" kils nothing happens, while under all other conditions, the other	487	"normal" kils nothing happens, while under all other conditions, the other
527	port is killed with the same reason.	488	port is killed with the same reason.
528		489
529	The third form (kill self) is the same as the second form, except that	490	The third form (kill self) is the same as the second form, except that
530	C<$rvport> defaults to C<$SELF>.	491	C<$rvport> defaults to C<$SELF>.
531		492
532	In the last form (message), a message of the form C<@msg, @reason> will be	493	In the last form (message), a message of the form C<@msg, @reason> will be
533	C<snd>.	494	C<snd>.
		495
		496	Monitoring-actions are one-shot: once messages are lost (and a monitoring
		497	alert was raised), they are removed and will not trigger again.
534		498
535	As a rule of thumb, monitoring requests should always monitor a port from	499	As a rule of thumb, monitoring requests should always monitor a port from
536	a local port (or callback). The reason is that kill messages might get	500	a local port (or callback). The reason is that kill messages might get
537	lost, just like any other message. Another less obvious reason is that	501	lost, just like any other message. Another less obvious reason is that
538	even monitoring requests can get lost (for exmaple, when the connection	502	even monitoring requests can get lost (for example, when the connection
539	to the other node goes down permanently). When monitoring a port locally	503	to the other node goes down permanently). When monitoring a port locally
540	these problems do not exist.	504	these problems do not exist.
541		505
		506	C<mon> effectively guarantees that, in the absence of hardware failures,
		507	after starting the monitor, either all messages sent to the port will
		508	arrive, or the monitoring action will be invoked after possible message
		509	loss has been detected. No messages will be lost "in between" (after
		510	the first lost message no further messages will be received by the
		511	port). After the monitoring action was invoked, further messages might get
		512	delivered again.
		513
		514	Inter-host-connection timeouts and monitoring depend on the transport
		515	used. The only transport currently implemented is TCP, and AnyEvent::MP
		516	relies on TCP to detect node-downs (this can take 10-15 minutes on a
		517	non-idle connection, and usually around two hours for idle conenctions).
		518
		519	This means that monitoring is good for program errors and cleaning up
		520	stuff eventually, but they are no replacement for a timeout when you need
		521	to ensure some maximum latency.
		522
542	Example: call a given callback when C<$port> is killed.	523	Example: call a given callback when C<$port> is killed.
543		524
544	mon $port, sub { warn "port died because of <@_>\n" };	525	mon $port, sub { warn "port died because of <@_>\n" };
545		526
546	Example: kill ourselves when C<$port> is killed abnormally.	527	Example: kill ourselves when C<$port> is killed abnormally.
…		…
552	mon $port, $self => "restart";	533	mon $port, $self => "restart";
553		534
554	=cut	535	=cut
555		536
556	sub mon {	537	sub mon {
557	my ($noderef, $port) = split /#/, shift, 2;	538	my ($nodeid, $port) = split /#/, shift, 2;
558		539
559	my $node = $NODE{$noderef} \|\| add_node $noderef;	540	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
560		541
561	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	542	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
562		543
563	unless (ref $cb) {	544	unless (ref $cb) {
564	if (@_) {	545	if (@_) {
…		…
584	is killed, the references will be freed.	565	is killed, the references will be freed.
585		566
586	Optionally returns a guard that will stop the monitoring.	567	Optionally returns a guard that will stop the monitoring.
587		568
588	This function is useful when you create e.g. timers or other watchers and	569	This function is useful when you create e.g. timers or other watchers and
589	want to free them when the port gets killed:	570	want to free them when the port gets killed (note the use of C<psub>):
590		571
591	$port->rcv (start => sub {	572	$port->rcv (start => sub {
592	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	573	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
593	undef $timer if 0.9 < rand;	574	undef $timer if 0.9 < rand;
594	});	575	});
595	});	576	});
596		577
597	=cut	578	=cut
…		…
606		587
607	=item kil $port[, @reason]	588	=item kil $port[, @reason]
608		589
609	Kill the specified port with the given C<@reason>.	590	Kill the specified port with the given C<@reason>.
610		591
611	If no C<@reason> is specified, then the port is killed "normally" (linked	592	If no C<@reason> is specified, then the port is killed "normally" (ports
612	ports will not be kileld, or even notified).	593	monitoring other ports will not necessarily die because a port dies
		594	"normally").
613		595
614	Otherwise, linked ports get killed with the same reason (second form of	596	Otherwise, linked ports get killed with the same reason (second form of
615	C<mon>, see below).	597	C<mon>, see above).
616		598
617	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	599	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
618	will be reported as reason C<< die => $@ >>.	600	will be reported as reason C<< die => $@ >>.
619		601
620	Transport/communication errors are reported as C<< transport_error =>	602	Transport/communication errors are reported as C<< transport_error =>
…		…
625	=item $port = spawn $node, $initfunc[, @initdata]	607	=item $port = spawn $node, $initfunc[, @initdata]
626		608
627	Creates a port on the node C<$node> (which can also be a port ID, in which	609	Creates a port on the node C<$node> (which can also be a port ID, in which
628	case it's the node where that port resides).	610	case it's the node where that port resides).
629		611
630	The port ID of the newly created port is return immediately, and it is	612	The port ID of the newly created port is returned immediately, and it is
631	permissible to immediately start sending messages or monitor the port.	613	possible to immediately start sending messages or to monitor the port.
632		614
633	After the port has been created, the init function is	615	After the port has been created, the init function is called on the remote
634	called. This function must be a fully-qualified function name	616	node, in the same context as a C<rcv> callback. This function must be a
635	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main	617	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
636	program, use C<::name>.	618	specify a function in the main program, use C<::name>.
637		619
638	If the function doesn't exist, then the node tries to C<require>	620	If the function doesn't exist, then the node tries to C<require>
639	the package, then the package above the package and so on (e.g.	621	the package, then the package above the package and so on (e.g.
640	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	622	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
641	exists or it runs out of package names.	623	exists or it runs out of package names.
642		624
643	The init function is then called with the newly-created port as context	625	The init function is then called with the newly-created port as context
644	object (C<$SELF>) and the C<@initdata> values as arguments.	626	object (C<$SELF>) and the C<@initdata> values as arguments.
645		627
646	A common idiom is to pass your own port, monitor the spawned port, and	628	A common idiom is to pass a local port, immediately monitor the spawned
647	in the init function, monitor the original port. This two-way monitoring	629	port, and in the remote init function, immediately monitor the passed
648	ensures that both ports get cleaned up when there is a problem.	630	local port. This two-way monitoring ensures that both ports get cleaned up
		631	when there is a problem.
		632
		633	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
		634	caller before C<spawn> returns (by delaying invocation when spawn is
		635	called for the local node).
649		636
650	Example: spawn a chat server port on C<$othernode>.	637	Example: spawn a chat server port on C<$othernode>.
651		638
652	# this node, executed from within a port context:	639	# this node, executed from within a port context:
653	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	640	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
…		…
676	};	663	};
677	_self_die if $@;	664	_self_die if $@;
678	}	665	}
679		666
680	sub spawn(@) {	667	sub spawn(@) {
681	my ($noderef, undef) = split /#/, shift, 2;	668	my ($nodeid, undef) = split /#/, shift, 2;
682		669
683	my $id = "$RUNIQ." . $ID++;	670	my $id = "$RUNIQ." . $ID++;
684		671
685	$_[0] =~ /::/	672	$_[0] =~ /::/
686	or Carp::croak "spawn init function must be a fully-qualified name, caught";	673	or Carp::croak "spawn init function must be a fully-qualified name, caught";
687		674
688	($NODE{$noderef} \|\| add_node $noderef)	675	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
689	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
690		676
691	"$noderef#$id"	677	"$nodeid#$id"
692	}	678	}
693		679
694	=back	680	=item after $timeout, @msg
695		681
696	=head1 NODE MESSAGES	682	=item after $timeout, $callback
697		683
698	Nodes understand the following messages sent to them. Many of them take	684	Either sends the given message, or call the given callback, after the
699	arguments called C<@reply>, which will simply be used to compose a reply	685	specified number of seconds.
700	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
701	the remaining arguments are simply the message data.
702		686
703	While other messages exist, they are not public and subject to change.	687	This is simply a utility function that comes in handy at times - the
		688	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		689	so it may go away in the future.
704		690
705	=over 4
706
707	=cut	691	=cut
708		692
709	=item lookup => $name, @reply	693	sub after($@) {
		694	my ($timeout, @action) = @_;
710		695
711	Replies with the port ID of the specified well-known port, or C<undef>.	696	my $t; $t = AE::timer $timeout, 0, sub {
712		697	undef $t;
713	=item devnull => ...	698	ref $action[0]
714		699	? $action[0]()
715	Generic data sink/CPU heat conversion.	700	: snd @action;
716		701	};
717	=item relay => $port, @msg	702	}
718
719	Simply forwards the message to the given port.
720
721	=item eval => $string[ @reply]
722
723	Evaluates the given string. If C<@reply> is given, then a message of the
724	form C<@reply, $@, @evalres> is sent.
725
726	Example: crash another node.
727
728	snd $othernode, eval => "exit";
729
730	=item time => @reply
731
732	Replies the the current node time to C<@reply>.
733
734	Example: tell the current node to send the current time to C<$myport> in a
735	C<timereply> message.
736
737	snd $NODE, time => $myport, timereply => 1, 2;
738	# => snd $myport, timereply => 1, 2, <time>
739		703
740	=back	704	=back
741		705
742	=head1 AnyEvent::MP vs. Distributed Erlang	706	=head1 AnyEvent::MP vs. Distributed Erlang
743		707
…		…
753		717
754	Despite the similarities, there are also some important differences:	718	Despite the similarities, there are also some important differences:
755		719
756	=over 4	720	=over 4
757		721
758	=item * Node references contain the recipe on how to contact them.	722	=item * Node IDs are arbitrary strings in AEMP.
759		723
760	Erlang relies on special naming and DNS to work everywhere in the	724	Erlang relies on special naming and DNS to work everywhere in the same
761	same way. AEMP relies on each node knowing it's own address(es), with	725	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
762	convenience functionality.	726	configuration or DNS), but will otherwise discover other odes itself.
763		727
764	This means that AEMP requires a less tightly controlled environment at the	728	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
765	cost of longer node references and a slightly higher management overhead.	729	uses "local ports are like remote ports".
		730
		731	The failure modes for local ports are quite different (runtime errors
		732	only) then for remote ports - when a local port dies, you I<know> it dies,
		733	when a connection to another node dies, you know nothing about the other
		734	port.
		735
		736	Erlang pretends remote ports are as reliable as local ports, even when
		737	they are not.
		738
		739	AEMP encourages a "treat remote ports differently" philosophy, with local
		740	ports being the special case/exception, where transport errors cannot
		741	occur.
766		742
767	=item * Erlang uses processes and a mailbox, AEMP does not queue.	743	=item * Erlang uses processes and a mailbox, AEMP does not queue.
768		744
769	Erlang uses processes that selctively receive messages, and therefore	745	Erlang uses processes that selectively receive messages, and therefore
770	needs a queue. AEMP is event based, queuing messages would serve no useful	746	needs a queue. AEMP is event based, queuing messages would serve no
771	purpose.	747	useful purpose. For the same reason the pattern-matching abilities of
		748	AnyEvent::MP are more limited, as there is little need to be able to
		749	filter messages without dequeuing them.
772		750
773	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	751	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
774		752
775	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	753	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
776		754
777	Sending messages in Erlang is synchronous and blocks the process. AEMP	755	Sending messages in Erlang is synchronous and blocks the process (and
778	sends are immediate, connection establishment is handled in the	756	so does not need a queue that can overflow). AEMP sends are immediate,
779	background.	757	connection establishment is handled in the background.
780		758
781	=item * Erlang can silently lose messages, AEMP cannot.	759	=item * Erlang suffers from silent message loss, AEMP does not.
782		760
783	Erlang makes few guarantees on messages delivery - messages can get lost	761	Erlang makes few guarantees on messages delivery - messages can get lost
784	without any of the processes realising it (i.e. you send messages a, b,	762	without any of the processes realising it (i.e. you send messages a, b,
785	and c, and the other side only receives messages a and c).	763	and c, and the other side only receives messages a and c).
786		764
787	AEMP guarantees correct ordering, and the guarantee that there are no	765	AEMP guarantees correct ordering, and the guarantee that after one message
788	holes in the message sequence.	766	is lost, all following ones sent to the same port are lost as well, until
789		767	monitoring raises an error, so there are no silent "holes" in the message
790	=item * In Erlang, processes can be declared dead and later be found to be	768	sequence.
791	alive.
792
793	In Erlang it can happen that a monitored process is declared dead and
794	linked processes get killed, but later it turns out that the process is
795	still alive - and can receive messages.
796
797	In AEMP, when port monitoring detects a port as dead, then that port will
798	eventually be killed - it cannot happen that a node detects a port as dead
799	and then later sends messages to it, finding it is still alive.
800		769
801	=item * Erlang can send messages to the wrong port, AEMP does not.	770	=item * Erlang can send messages to the wrong port, AEMP does not.
802		771
803	In Erlang it is quite possible that a node that restarts reuses a process	772	In Erlang it is quite likely that a node that restarts reuses a process ID
804	ID known to other nodes for a completely different process, causing	773	known to other nodes for a completely different process, causing messages
805	messages destined for that process to end up in an unrelated process.	774	destined for that process to end up in an unrelated process.
806		775
807	AEMP never reuses port IDs, so old messages or old port IDs floating	776	AEMP never reuses port IDs, so old messages or old port IDs floating
808	around in the network will not be sent to an unrelated port.	777	around in the network will not be sent to an unrelated port.
809		778
810	=item * Erlang uses unprotected connections, AEMP uses secure	779	=item * Erlang uses unprotected connections, AEMP uses secure
811	authentication and can use TLS.	780	authentication and can use TLS.
812		781
813	AEMP can use a proven protocol - SSL/TLS - to protect connections and	782	AEMP can use a proven protocol - TLS - to protect connections and
814	securely authenticate nodes.	783	securely authenticate nodes.
815		784
816	=item * The AEMP protocol is optimised for both text-based and binary	785	=item * The AEMP protocol is optimised for both text-based and binary
817	communications.	786	communications.
818		787
819	The AEMP protocol, unlike the Erlang protocol, supports both	788	The AEMP protocol, unlike the Erlang protocol, supports both programming
820	language-independent text-only protocols (good for debugging) and binary,	789	language independent text-only protocols (good for debugging) and binary,
821	language-specific serialisers (e.g. Storable).	790	language-specific serialisers (e.g. Storable). By default, unless TLS is
		791	used, the protocol is actually completely text-based.
822		792
823	It has also been carefully designed to be implementable in other languages	793	It has also been carefully designed to be implementable in other languages
824	with a minimum of work while gracefully degrading fucntionality to make the	794	with a minimum of work while gracefully degrading functionality to make the
825	protocol simple.	795	protocol simple.
826		796
827	=item * AEMP has more flexible monitoring options than Erlang.	797	=item * AEMP has more flexible monitoring options than Erlang.
828		798
829	In Erlang, you can chose to receive I<all> exit signals as messages	799	In Erlang, you can chose to receive I<all> exit signals as messages
…		…
832	Erlang, as one can choose between automatic kill, exit message or callback	802	Erlang, as one can choose between automatic kill, exit message or callback
833	on a per-process basis.	803	on a per-process basis.
834		804
835	=item * Erlang tries to hide remote/local connections, AEMP does not.	805	=item * Erlang tries to hide remote/local connections, AEMP does not.
836		806
837	Monitoring in Erlang is not an indicator of process death/crashes,	807	Monitoring in Erlang is not an indicator of process death/crashes, in the
838	as linking is (except linking is unreliable in Erlang).	808	same way as linking is (except linking is unreliable in Erlang).
839		809
840	In AEMP, you don't "look up" registered port names or send to named ports	810	In AEMP, you don't "look up" registered port names or send to named ports
841	that might or might not be persistent. Instead, you normally spawn a port	811	that might or might not be persistent. Instead, you normally spawn a port
842	on the remote node. The init function monitors the you, and you monitor	812	on the remote node. The init function monitors you, and you monitor the
843	the remote port. Since both monitors are local to the node, they are much	813	remote port. Since both monitors are local to the node, they are much more
844	more reliable.	814	reliable (no need for C<spawn_link>).
845		815
846	This also saves round-trips and avoids sending messages to the wrong port	816	This also saves round-trips and avoids sending messages to the wrong port
847	(hard to do in Erlang).	817	(hard to do in Erlang).
848		818
849	=back	819	=back
850		820
		821	=head1 RATIONALE
		822
		823	=over 4
		824
		825	=item Why strings for port and node IDs, why not objects?
		826
		827	We considered "objects", but found that the actual number of methods
		828	that can be called are quite low. Since port and node IDs travel over
		829	the network frequently, the serialising/deserialising would add lots of
		830	overhead, as well as having to keep a proxy object everywhere.
		831
		832	Strings can easily be printed, easily serialised etc. and need no special
		833	procedures to be "valid".
		834
		835	And as a result, a miniport consists of a single closure stored in a
		836	global hash - it can't become much cheaper.
		837
		838	=item Why favour JSON, why not a real serialising format such as Storable?
		839
		840	In fact, any AnyEvent::MP node will happily accept Storable as framing
		841	format, but currently there is no way to make a node use Storable by
		842	default (although all nodes will accept it).
		843
		844	The default framing protocol is JSON because a) JSON::XS is many times
		845	faster for small messages and b) most importantly, after years of
		846	experience we found that object serialisation is causing more problems
		847	than it solves: Just like function calls, objects simply do not travel
		848	easily over the network, mostly because they will always be a copy, so you
		849	always have to re-think your design.
		850
		851	Keeping your messages simple, concentrating on data structures rather than
		852	objects, will keep your messages clean, tidy and efficient.
		853
		854	=back
		855
851	=head1 SEE ALSO	856	=head1 SEE ALSO
		857
		858	L<AnyEvent::MP::Intro> - a gentle introduction.
		859
		860	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		861
		862	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		863	your applications.
852		864
853	L<AnyEvent>.	865	L<AnyEvent>.
854		866
855	=head1 AUTHOR	867	=head1 AUTHOR
856		868

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.43 by root, Sun Aug 9 16:08:16 2009 UTC vs. Revision 1.80 by root, Fri Sep 4 22:30:29 2009 UTC

Diff Legend

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.43 by root, Sun Aug 9 16:08:16 2009 UTC vs.
Revision 1.80 by root, Fri Sep 4 22:30:29 2009 UTC