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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.34 by root, Wed Aug 5 23:50:46 2009 UTC vs.
Revision 1.73 by root, Mon Aug 31 11:08:25 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	configure;
		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 = @_ };
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" };
21	rcv $port1, pong => sub { warn "pong received\n" };	31	rcv $port, pong => sub { warn "pong received\n" };
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	35
		36	# monitoring
		37	mon $port, $cb->(@msg) # callback is invoked on death
		38	mon $port, $otherport # kill otherport on abnormal death
		39	mon $port, $otherport, @msg # send message on death
		40
		41	=head1 CURRENT STATUS
		42
		43	bin/aemp - stable.
		44	AnyEvent::MP - stable API, should work.
		45	AnyEvent::MP::Intro - uptodate, but incomplete.
		46	AnyEvent::MP::Kernel - mostly stable.
		47	AnyEvent::MP::Global - stable API, protocol not yet final.
		48
		49	stay tuned.
27		50
28	=head1 DESCRIPTION	51	=head1 DESCRIPTION
29		52
30	This module (-family) implements a simple message passing framework.	53	This module (-family) implements a simple message passing framework.
31		54
32	Despite its simplicity, you can securely message other processes running	55	Despite its simplicity, you can securely message other processes running
33	on the same or other hosts.	56	on the same or other hosts, and you can supervise entities remotely.
34		57
35	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	58	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
36	manual page.	59	manual page and the examples under F<eg/>.
37		60
38	At the moment, this module family is severly broken and underdocumented,	61	At the moment, this module family is a bit underdocumented.
39	so do not use. This was uploaded mainly to reserve the CPAN namespace -
40	stay tuned! The basic API should be finished, however.
41		62
42	=head1 CONCEPTS	63	=head1 CONCEPTS
43		64
44	=over 4	65	=over 4
45		66
46	=item port	67	=item port
47		68
48	A port is something you can send messages to (with the C<snd> function).	69	A port is something you can send messages to (with the C<snd> function).
49		70
50	Some ports allow you to register C<rcv> handlers that can match specific	71	Ports allow you to register C<rcv> handlers that can match all or just
51	messages. All C<rcv> handlers will receive messages they match, messages	72	some messages. Messages send to ports will not be queued, regardless of
52	will not be queued.	73	anything was listening for them or not.
53		74
54	=item port id - C<noderef#portname>	75	=item port ID - C<nodeid#portname>
55		76
56	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	77	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as
57	separator, and a port name (a printable string of unspecified format). An	78	separator, and a port name (a printable string of unspecified format).
58	exception is the the node port, whose ID is identical to its node
59	reference.
60		79
61	=item node	80	=item node
62		81
63	A node is a single process containing at least one port - the node	82	A node is a single process containing at least one port - the node port,
64	port. You can send messages to node ports to find existing ports or to	83	which enables nodes to manage each other remotely, and to create new
65	create new ports, among other things.	84	ports.
66		85
67	Nodes are either private (single-process only), slaves (connected to a	86	Nodes are either public (have one or more listening ports) or private
68	master node only) or public nodes (connectable from unrelated nodes).	87	(no listening ports). Private nodes cannot talk to other private nodes
		88	currently.
69		89
70	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	90	=item node ID - C<[a-za-Z0-9_\-.:]+>
71		91
72	A node reference is a string that either simply identifies the node (for	92	A node ID is a string that uniquely identifies the node within a
73	private and slave nodes), or contains a recipe on how to reach a given	93	network. Depending on the configuration used, node IDs can look like a
74	node (for public nodes).	94	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
		95	doesn't interpret node IDs in any way.
75		96
76	This recipe is simply a comma-separated list of C<address:port> pairs (for	97	=item binds - C<ip:port>
77	TCP/IP, other protocols might look different).
78		98
79	Node references come in two flavours: resolved (containing only numerical	99	Nodes can only talk to each other by creating some kind of connection to
80	addresses) or unresolved (where hostnames are used instead of addresses).	100	each other. To do this, nodes should listen on one or more local transport
		101	endpoints - binds. Currently, only standard C<ip:port> specifications can
		102	be used, which specify TCP ports to listen on.
81		103
82	Before using an unresolved node reference in a message you first have to	104	=item seeds - C<host:port>
83	resolve it.	105
		106	When a node starts, it knows nothing about the network. To teach the node
		107	about the network it first has to contact some other node within the
		108	network. This node is called a seed.
		109
		110	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes
		111	are expected to be long-running, and at least one of those should always
		112	be available. When nodes run out of connections (e.g. due to a network
		113	error), they try to re-establish connections to some seednodes again to
		114	join the network.
		115
		116	Apart from being sued for seeding, seednodes are not special in any way -
		117	every public node can be a seednode.
84		118
85	=back	119	=back
86		120
87	=head1 VARIABLES/FUNCTIONS	121	=head1 VARIABLES/FUNCTIONS
88		122
…		…
90		124
91	=cut	125	=cut
92		126
93	package AnyEvent::MP;	127	package AnyEvent::MP;
94		128
95	use AnyEvent::MP::Base;	129	use AnyEvent::MP::Kernel;
96		130
97	use common::sense;	131	use common::sense;
98		132
99	use Carp ();	133	use Carp ();
100		134
101	use AE ();	135	use AE ();
102		136
103	use base "Exporter";	137	use base "Exporter";
104		138
105	our $VERSION = '0.1';	139	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		140
106	our @EXPORT = qw(	141	our @EXPORT = qw(
107	NODE $NODE *SELF node_of _any_	142	NODE $NODE *SELF node_of after
108	resolve_node initialise_node	143	configure
109	snd rcv mon kil reg psub	144	snd rcv mon mon_guard kil reg psub spawn
110	port	145	port
111	);	146	);
112		147
113	our $SELF;	148	our $SELF;
114		149
…		…
118	kil $SELF, die => $msg;	153	kil $SELF, die => $msg;
119	}	154	}
120		155
121	=item $thisnode = NODE / $NODE	156	=item $thisnode = NODE / $NODE
122		157
123	The C<NODE> function returns, and the C<$NODE> variable contains	158	The C<NODE> function returns, and the C<$NODE> variable contains, the node
124	the noderef of the local node. The value is initialised by a call	159	ID of the node running in the current process. This value is initialised by
125	to C<become_public> or C<become_slave>, after which all local port	160	a call to C<configure>.
126	identifiers become invalid.
127		161
128	=item $noderef = node_of $port	162	=item $nodeid = node_of $port
129		163
130	Extracts and returns the noderef from a portid or a noderef.	164	Extracts and returns the node ID from a port ID or a node ID.
131		165
132	=item initialise_node $noderef, $seednode, $seednode...	166	=item configure key => value...
133		167
134	=item initialise_node "slave/", $master, $master...
135
136	Before a node can talk to other nodes on the network it has to initialise	168	Before a node can talk to other nodes on the network (i.e. enter
137	itself - the minimum a node needs to know is it's own name, and optionally	169	"distributed mode") it has to configure itself - the minimum a node needs
138	it should know the noderefs of some other nodes in the network.	170	to know is its own name, and optionally it should know the addresses of
		171	some other nodes in the network to discover other nodes.
139		172
140	This function initialises a node - it must be called exactly once (or	173	This function configures a node - it must be called exactly once (or
141	never) before calling other AnyEvent::MP functions.	174	never) before calling other AnyEvent::MP functions.
142		175
143	All arguments are noderefs, which can be either resolved or unresolved.
144
145	There are two types of networked nodes, public nodes and slave nodes:
146
147	=over 4	176	=over 4
148		177
149	=item public nodes	178	=item step 1, gathering configuration from profiles
150		179
151	For public nodes, C<$noderef> must either be a (possibly unresolved)	180	The function first looks up a profile in the aemp configuration (see the
152	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
153	which case the noderef will be guessed.	182	named C<profile> parameter. If it is missing, then the nodename (F<uname
		183	-n>) will be used as profile name.
154		184
155	Afterwards, the node will bind itself on all endpoints and try to connect	185	The profile data is then gathered as follows:
156	to all additional C<$seednodes> that are specified. Seednodes are optional
157	and can be used to quickly bootstrap the node into an existing network.
158		186
159	=item slave nodes	187	First, all remaining key => value pairs (all of which are conviniently
		188	undocumented at the moment) will be interpreted as configuration
		189	data. Then they will be overwritten by any values specified in the global
		190	default configuration (see the F<aemp> utility), then the chain of
		191	profiles chosen by the profile name (and any C<parent> attributes).
160		192
161	When the C<$noderef> is the special string C<slave/>, then the node will	193	That means that the values specified in the profile have highest priority
162	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,
163	route most of their traffic to the master node that they attach to.	195	and can only be used to specify defaults.
164		196
165	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
166	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
167	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.
168		218
169	=back	219	=back
170		220
171	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.
172	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.
173	server.
174		223
175	Example: become a public node listening on the default node.	224	configure
176		225
177	initialise_node;	226	Example: become an anonymous node. This form is often used for commandline
		227	clients.
178		228
179	Example: become a public node, and try to contact some well-known master	229	configure nodeid => "anon/";
180	servers to become part of the network.
181		230
182	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).
183		234
184	Example: become a public node listening on port C<4041>.	235	# use the aemp commandline utility
		236	# aemp profile seed setnodeid anon/ setbinds '*:4040'
185		237
186	initialise_node 4041;	238	# then use it
		239	configure profile => "seed";
187		240
188	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
189		243
190	initialise_node "locahost:4044";	244	# or provide a nicer-to-remember nodeid
191		245	# aemp run profile seed nodeid "$(hostname)"
192	Example: become a slave node to any of the specified master servers.
193
194	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
195
196	=item $cv = resolve_node $noderef
197
198	Takes an unresolved node reference that may contain hostnames and
199	abbreviated IDs, resolves all of them and returns a resolved node
200	reference.
201
202	In addition to C<address:port> pairs allowed in resolved noderefs, the
203	following forms are supported:
204
205	=over 4
206
207	=item the empty string
208
209	An empty-string component gets resolved as if the default port (4040) was
210	specified.
211
212	=item naked port numbers (e.g. C<1234>)
213
214	These are resolved by prepending the local nodename and a colon, to be
215	further resolved.
216
217	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
218
219	These are resolved by using AnyEvent::DNS to resolve them, optionally
220	looking up SRV records for the C<aemp=4040> port, if no port was
221	specified.
222
223	=back
224		246
225	=item $SELF	247	=item $SELF
226		248
227	Contains the current port id while executing C<rcv> callbacks or C<psub>	249	Contains the current port id while executing C<rcv> callbacks or C<psub>
228	blocks.	250	blocks.
229		251
230	=item SELF, %SELF, @SELF...	252	=item *SELF, SELF, %SELF, @SELF...
231		253
232	Due to some quirks in how perl exports variables, it is impossible to	254	Due to some quirks in how perl exports variables, it is impossible to
233	just export C<$SELF>, all the symbols called C<SELF> are exported by this	255	just export C<$SELF>, all the symbols named C<SELF> are exported by this
234	module, but only C<$SELF> is currently used.	256	module, but only C<$SELF> is currently used.
235		257
236	=item snd $port, type => @data	258	=item snd $port, type => @data
237		259
238	=item snd $port, @msg	260	=item snd $port, @msg
239		261
240	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
241	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.
242	stringifies a sa port ID (such as a port object :).
243		264
244	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
245	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
246	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.
247		269
248	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
249	function: modifying any argument is not allowed and can cause many	271	function: modifying any argument (or values referenced by them) is
250	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.
251		276
252	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
253	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
254	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
255	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
256	node, anything can be passed.	281	node, anything can be passed. Best rely only on the common denominator of
		282	these.
257		283
258	=item $local_port = port	284	=item $local_port = port
259		285
260	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
261	matching port ("full port") or a single-callback port ("miniport"),	287	no callbacks set and will throw an error when it receives messages.
262	depending on how C<rcv> callbacks are bound to the object.
263		288
264	=item $port = port { my @msg = @_; $finished }	289	=item $local_port = port { my @msg = @_ }
265		290
266	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
267	matching behind it, and returns its ID. Semantically the same as creating
268	a port and calling C<rcv $port, $callback> on it.	292	creating a port and calling C<rcv $port, $callback> on it.
269		293
270	The block will be called for every message received on the port. When the	294	The block will be called for every message received on the port, with the
271	callback returns a true value its job is considered "done" and the port	295	global variable C<$SELF> set to the port ID. Runtime errors will cause the
272	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.
273		298
274	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:
275	be passed to the callback.
276		300
277	If you need the local port id in the callback, this works nicely:	301	my $port = port {
278		302	my @msg = @_;
279	my $port; $port = port {	303	...
280	snd $otherport, reply => $port;	304	kil $SELF;
281	};	305	};
282		306
283	=cut	307	=cut
284		308
285	sub rcv($@);	309	sub rcv($@);
		310
		311	sub _kilme {
		312	die "received message on port without callback";
		313	}
286		314
287	sub port(;&) {	315	sub port(;&) {
288	my $id = "$UNIQ." . $ID++;	316	my $id = "$UNIQ." . $ID++;
289	my $port = "$NODE#$id";	317	my $port = "$NODE#$id";
290		318
291	if (@_) {	319	rcv $port, shift \|\| \&_kilme;
292	rcv $port, shift;
293	} else {
294	$PORT{$id} = sub { }; # nop
295	}
296		320
297	$port	321	$port
298	}	322	}
299		323
300	=item reg $port, $name
301
302	Registers the given port under the name C<$name>. If the name already
303	exists it is replaced.
304
305	A port can only be registered under one well known name.
306
307	A port automatically becomes unregistered when it is killed.
308
309	=cut
310
311	sub reg(@) {
312	my ($port, $name) = @_;
313
314	$REG{$name} = $port;
315	}
316
317	=item rcv $port, $callback->(@msg)	324	=item rcv $local_port, $callback->(@msg)
318		325
319	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
320	one if required).	327	remove the default callback: use C<sub { }> to disable it, or better
321		328	C<kil> the port when it is no longer needed.
322	=item rcv $port, tagstring => $callback->(@msg), ...
323
324	=item rcv $port, $smartmatch => $callback->(@msg), ...
325
326	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
327
328	Register callbacks to be called on matching messages on the given full
329	port (after converting it to one if required).
330
331	The callback has to return a true value when its work is done, after
332	which is will be removed, or a false value in which case it will stay
333	registered.
334		329
335	The global C<$SELF> (exported by this module) contains C<$port> while	330	The global C<$SELF> (exported by this module) contains C<$port> while
336	executing the callback.	331	executing the callback. Runtime errors during callback execution will
		332	result in the port being C<kil>ed.
337		333
338	Runtime errors wdurign callback execution will result in the port being	334	The default callback received all messages not matched by a more specific
339	C<kil>ed.	335	C<tag> match.
340		336
341	If the match is an array reference, then it will be matched against the	337	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
342	first elements of the message, otherwise only the first element is being
343	matched.
344		338
345	Any element in the match that is specified as C<_any_> (a function	339	Register (or replace) callbacks to be called on messages starting with the
346	exported by this module) matches any single element of the message.	340	given tag on the given port (and return the port), or unregister it (when
		341	C<$callback> is C<$undef> or missing). There can only be one callback
		342	registered for each tag.
347		343
348	While not required, it is highly recommended that the first matching	344	The original message will be passed to the callback, after the first
349	element is a string identifying the message. The one-string-only match is	345	element (the tag) has been removed. The callback will use the same
350	also the most efficient match (by far).	346	environment as the default callback (see above).
		347
		348	Example: create a port and bind receivers on it in one go.
		349
		350	my $port = rcv port,
		351	msg1 => sub { ... },
		352	msg2 => sub { ... },
		353	;
		354
		355	Example: create a port, bind receivers and send it in a message elsewhere
		356	in one go:
		357
		358	snd $otherport, reply =>
		359	rcv port,
		360	msg1 => sub { ... },
		361	...
		362	;
		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, $otherport;
		371	};
351		372
352	=cut	373	=cut
353		374
354	sub rcv($@) {	375	sub rcv($@) {
355	my $port = shift;	376	my $port = shift;
356	my ($noderef, $portid) = split /#/, $port, 2;	377	my ($noderef, $portid) = split /#/, $port, 2;
357		378
358	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	379	$NODE{$noderef} == $NODE{""}
359	or Carp::croak "$port: rcv can only be called on local ports, caught";	380	or Carp::croak "$port: rcv can only be called on local ports, caught";
360		381
361	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 {
362	my $cb = shift;	390	my $cb = shift;
363	delete $PORT_DATA{$portid};
364	$PORT{$portid} = sub {	391	$PORT{$portid} = sub {
365	local $SELF = $port;	392	local $SELF = $port;
366	eval {	393	eval { &$cb }; _self_die if $@;
367	&$cb	394	};
368	and kil $port;
369	};	395	}
370	_self_die if $@;	396	} elsif (defined $_[0]) {
371	};
372	} else {
373	my $self = $PORT_DATA{$portid} \|\|= do {	397	my $self = $PORT_DATA{$portid} \|\|= do {
374	my $self = bless {	398	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
375	id => $port,
376	}, "AnyEvent::MP::Port";
377		399
378	$PORT{$portid} = sub {	400	$PORT{$portid} = sub {
379	local $SELF = $port;	401	local $SELF = $port;
380		402
381	eval {
382	for (@{ $self->{rc0}{$_[0]} }) {	403	if (my $cb = $self->[1]{$_[0]}) {
383	$_ && &{$_->[0]}	404	shift;
384	&& undef $_;	405	eval { &$cb }; _self_die if $@;
385	}	406	} else {
386
387	for (@{ $self->{rcv}{$_[0]} }) {
388	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
389	&& &{$_->[0]}	407	&{ $self->[0] };
390	&& undef $_;
391	}
392
393	for (@{ $self->{any} }) {
394	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
395	&& &{$_->[0]}
396	&& undef $_;
397	}	408	}
398	};	409	};
399	_self_die if $@;	410
		411	$self
400	};	412	};
401		413
402	$self
403	};
404
405	"AnyEvent::MP::Port" eq ref $self	414	"AnyEvent::MP::Port" eq ref $self
406	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	415	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
407		416
408	while (@_) {
409	my ($match, $cb) = splice @_, 0, 2;	417	my ($tag, $cb) = splice @_, 0, 2;
410		418
411	if (!ref $match) {	419	if (defined $cb) {
412	push @{ $self->{rc0}{$match} }, [$cb];	420	$self->[1]{$tag} = $cb;
413	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
414	my ($type, @match) = @$match;
415	@match
416	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
417	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
418	} else {	421	} else {
419	push @{ $self->{any} }, [$cb, $match];	422	delete $self->[1]{$tag};
420	}	423	}
421	}	424	}
422	}	425	}
423		426
424	$port	427	$port
…		…
460	$res	463	$res
461	}	464	}
462	}	465	}
463	}	466	}
464		467
465	=item $guard = mon $port, $cb->(@reason)	468	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
466		469
467	=item $guard = mon $port, $otherport	470	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
468		471
469	=item $guard = mon $port, $otherport, @msg	472	=item $guard = mon $port # kill $SELF when $port dies
470		473
		474	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
		475
471	Monitor the given port and do something when the port is killed.	476	Monitor the given port and do something when the port is killed or
		477	messages to it were lost, and optionally return a guard that can be used
		478	to stop monitoring again.
472		479
		480	C<mon> effectively guarantees that, in the absence of hardware failures,
		481	after starting the monitor, either all messages sent to the port will
		482	arrive, or the monitoring action will be invoked after possible message
		483	loss has been detected. No messages will be lost "in between" (after
		484	the first lost message no further messages will be received by the
		485	port). After the monitoring action was invoked, further messages might get
		486	delivered again.
		487
		488	Note that monitoring-actions are one-shot: once messages are lost (and a
		489	monitoring alert was raised), they are removed and will not trigger again.
		490
473	In the first form, the callback is simply called with any number	491	In the first form (callback), the callback is simply called with any
474	of C<@reason> elements (no @reason means that the port was deleted	492	number of C<@reason> elements (no @reason means that the port was deleted
475	"normally"). Note also that I<< the callback B<must> never die >>, so use	493	"normally"). Note also that I<< the callback B<must> never die >>, so use
476	C<eval> if unsure.	494	C<eval> if unsure.
477		495
478	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	496	In the second form (another port given), the other port (C<$rcvport>)
479	a @reason was specified, i.e. on "normal" kils nothing happens, while	497	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
480	under all other conditions, the other port is killed with the same reason.	498	"normal" kils nothing happens, while under all other conditions, the other
		499	port is killed with the same reason.
481		500
		501	The third form (kill self) is the same as the second form, except that
		502	C<$rvport> defaults to C<$SELF>.
		503
482	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	504	In the last form (message), a message of the form C<@msg, @reason> will be
		505	C<snd>.
		506
		507	As a rule of thumb, monitoring requests should always monitor a port from
		508	a local port (or callback). The reason is that kill messages might get
		509	lost, just like any other message. Another less obvious reason is that
		510	even monitoring requests can get lost (for exmaple, when the connection
		511	to the other node goes down permanently). When monitoring a port locally
		512	these problems do not exist.
483		513
484	Example: call a given callback when C<$port> is killed.	514	Example: call a given callback when C<$port> is killed.
485		515
486	mon $port, sub { warn "port died because of <@_>\n" };	516	mon $port, sub { warn "port died because of <@_>\n" };
487		517
488	Example: kill ourselves when C<$port> is killed abnormally.	518	Example: kill ourselves when C<$port> is killed abnormally.
489		519
490	mon $port, $self;	520	mon $port;
491		521
492	Example: send us a restart message another C<$port> is killed.	522	Example: send us a restart message when another C<$port> is killed.
493		523
494	mon $port, $self => "restart";	524	mon $port, $self => "restart";
495		525
496	=cut	526	=cut
497		527
498	sub mon {	528	sub mon {
499	my ($noderef, $port) = split /#/, shift, 2;	529	my ($noderef, $port) = split /#/, shift, 2;
500		530
501	my $node = $NODE{$noderef} \|\| add_node $noderef;	531	my $node = $NODE{$noderef} \|\| add_node $noderef;
502		532
503	my $cb = shift;	533	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
504		534
505	unless (ref $cb) {	535	unless (ref $cb) {
506	if (@_) {	536	if (@_) {
507	# send a kill info message	537	# send a kill info message
508	my (@msg) = ($cb, @_);	538	my (@msg) = ($cb, @_);
…		…
526	is killed, the references will be freed.	556	is killed, the references will be freed.
527		557
528	Optionally returns a guard that will stop the monitoring.	558	Optionally returns a guard that will stop the monitoring.
529		559
530	This function is useful when you create e.g. timers or other watchers and	560	This function is useful when you create e.g. timers or other watchers and
531	want to free them when the port gets killed:	561	want to free them when the port gets killed (note the use of C<psub>):
532		562
533	$port->rcv (start => sub {	563	$port->rcv (start => sub {
534	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	564	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
535	undef $timer if 0.9 < rand;	565	undef $timer if 0.9 < rand;
536	});	566	});
537	});	567	});
538		568
539	=cut	569	=cut
540		570
541	sub mon_guard {	571	sub mon_guard {
542	my ($port, @refs) = @_;	572	my ($port, @refs) = @_;
543		573
		574	#TODO: mon-less form?
		575
544	mon $port, sub { 0 && @refs }	576	mon $port, sub { 0 && @refs }
545	}	577	}
546		578
547	=item lnk $port1, $port2
548
549	Link two ports. This is simply a shorthand for:
550
551	mon $port1, $port2;
552	mon $port2, $port1;
553
554	It means that if either one is killed abnormally, the other one gets
555	killed as well.
556
557	=item kil $port[, @reason]	579	=item kil $port[, @reason]
558		580
559	Kill the specified port with the given C<@reason>.	581	Kill the specified port with the given C<@reason>.
560		582
561	If no C<@reason> is specified, then the port is killed "normally" (linked	583	If no C<@reason> is specified, then the port is killed "normally" (ports
562	ports will not be kileld, or even notified).	584	monitoring other ports will not necessarily die because a port dies
		585	"normally").
563		586
564	Otherwise, linked ports get killed with the same reason (second form of	587	Otherwise, linked ports get killed with the same reason (second form of
565	C<mon>, see below).	588	C<mon>, see above).
566		589
567	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	590	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
568	will be reported as reason C<< die => $@ >>.	591	will be reported as reason C<< die => $@ >>.
569		592
570	Transport/communication errors are reported as C<< transport_error =>	593	Transport/communication errors are reported as C<< transport_error =>
571	$message >>.	594	$message >>.
572		595
		596	=cut
		597
		598	=item $port = spawn $node, $initfunc[, @initdata]
		599
		600	Creates a port on the node C<$node> (which can also be a port ID, in which
		601	case it's the node where that port resides).
		602
		603	The port ID of the newly created port is returned immediately, and it is
		604	possible to immediately start sending messages or to monitor the port.
		605
		606	After the port has been created, the init function is called on the remote
		607	node, in the same context as a C<rcv> callback. This function must be a
		608	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
		609	specify a function in the main program, use C<::name>.
		610
		611	If the function doesn't exist, then the node tries to C<require>
		612	the package, then the package above the package and so on (e.g.
		613	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		614	exists or it runs out of package names.
		615
		616	The init function is then called with the newly-created port as context
		617	object (C<$SELF>) and the C<@initdata> values as arguments.
		618
		619	A common idiom is to pass a local port, immediately monitor the spawned
		620	port, and in the remote init function, immediately monitor the passed
		621	local port. This two-way monitoring ensures that both ports get cleaned up
		622	when there is a problem.
		623
		624	Example: spawn a chat server port on C<$othernode>.
		625
		626	# this node, executed from within a port context:
		627	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		628	mon $server;
		629
		630	# init function on C<$othernode>
		631	sub connect {
		632	my ($srcport) = @_;
		633
		634	mon $srcport;
		635
		636	rcv $SELF, sub {
		637	...
		638	};
		639	}
		640
		641	=cut
		642
		643	sub _spawn {
		644	my $port = shift;
		645	my $init = shift;
		646
		647	local $SELF = "$NODE#$port";
		648	eval {
		649	&{ load_func $init }
		650	};
		651	_self_die if $@;
		652	}
		653
		654	sub spawn(@) {
		655	my ($noderef, undef) = split /#/, shift, 2;
		656
		657	my $id = "$RUNIQ." . $ID++;
		658
		659	$_[0] =~ /::/
		660	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		661
		662	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
		663
		664	"$noderef#$id"
		665	}
		666
		667	=item after $timeout, @msg
		668
		669	=item after $timeout, $callback
		670
		671	Either sends the given message, or call the given callback, after the
		672	specified number of seconds.
		673
		674	This is simply a utility function that comes in handy at times - the
		675	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		676	so it may go away in the future.
		677
		678	=cut
		679
		680	sub after($@) {
		681	my ($timeout, @action) = @_;
		682
		683	my $t; $t = AE::timer $timeout, 0, sub {
		684	undef $t;
		685	ref $action[0]
		686	? $action[0]()
		687	: snd @action;
		688	};
		689	}
		690
573	=back	691	=back
574		692
575	=head1 NODE MESSAGES	693	=head1 AnyEvent::MP vs. Distributed Erlang
576		694
577	Nodes understand the following messages sent to them. Many of them take	695	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
578	arguments called C<@reply>, which will simply be used to compose a reply	696	== aemp node, Erlang process == aemp port), so many of the documents and
579	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and	697	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
580	the remaining arguments are simply the message data.	698	sample:
581		699
582	While other messages exist, they are not public and subject to change.	700	http://www.Erlang.se/doc/programming_rules.shtml
		701	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		702	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		703	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		704
		705	Despite the similarities, there are also some important differences:
583		706
584	=over 4	707	=over 4
585		708
586	=cut	709	=item * Node IDs are arbitrary strings in AEMP.
587		710
588	=item lookup => $name, @reply
589
590	Replies with the port ID of the specified well-known port, or C<undef>.
591
592	=item devnull => ...
593
594	Generic data sink/CPU heat conversion.
595
596	=item relay => $port, @msg
597
598	Simply forwards the message to the given port.
599
600	=item eval => $string[ @reply]
601
602	Evaluates the given string. If C<@reply> is given, then a message of the
603	form C<@reply, $@, @evalres> is sent.
604
605	Example: crash another node.
606
607	snd $othernode, eval => "exit";
608
609	=item time => @reply
610
611	Replies the the current node time to C<@reply>.
612
613	Example: tell the current node to send the current time to C<$myport> in a
614	C<timereply> message.
615
616	snd $NODE, time => $myport, timereply => 1, 2;
617	# => snd $myport, timereply => 1, 2, <time>
618
619	=back
620
621	=head1 AnyEvent::MP vs. Distributed Erlang
622
623	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node
624	== aemp node, erlang process == aemp port), so many of the documents and
625	programming techniques employed by erlang apply to AnyEvent::MP. Here is a
626	sample:
627
628	http://www.erlang.se/doc/programming_rules.shtml
629	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
630	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6
631	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
632
633	Despite the similarities, there are also some important differences:
634
635	=over 4
636
637	=item * Node references contain the recipe on how to contact them.
638
639	Erlang relies on special naming and DNS to work everywhere in the	711	Erlang relies on special naming and DNS to work everywhere in the same
640	same way. AEMP relies on each node knowing it's own address(es), with	712	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
641	convenience functionality.	713	configuraiton or DNS), but will otherwise discover other odes itself.
642		714
643	This means that AEMP requires a less tightly controlled environment at the	715	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
644	cost of longer node references and a slightly higher management overhead.	716	uses "local ports are like remote ports".
		717
		718	The failure modes for local ports are quite different (runtime errors
		719	only) then for remote ports - when a local port dies, you I<know> it dies,
		720	when a connection to another node dies, you know nothing about the other
		721	port.
		722
		723	Erlang pretends remote ports are as reliable as local ports, even when
		724	they are not.
		725
		726	AEMP encourages a "treat remote ports differently" philosophy, with local
		727	ports being the special case/exception, where transport errors cannot
		728	occur.
645		729
646	=item * Erlang uses processes and a mailbox, AEMP does not queue.	730	=item * Erlang uses processes and a mailbox, AEMP does not queue.
647		731
648	Erlang uses processes that selctively receive messages, and therefore	732	Erlang uses processes that selectively receive messages, and therefore
649	needs a queue. AEMP is event based, queuing messages would serve no useful	733	needs a queue. AEMP is event based, queuing messages would serve no
650	purpose.	734	useful purpose. For the same reason the pattern-matching abilities of
		735	AnyEvent::MP are more limited, as there is little need to be able to
		736	filter messages without dequeing them.
651		737
652	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	738	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
653		739
654	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	740	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
655		741
656	Sending messages in erlang is synchronous and blocks the process. AEMP	742	Sending messages in Erlang is synchronous and blocks the process (and
657	sends are immediate, connection establishment is handled in the	743	so does not need a queue that can overflow). AEMP sends are immediate,
658	background.	744	connection establishment is handled in the background.
659		745
660	=item * Erlang can silently lose messages, AEMP cannot.	746	=item * Erlang suffers from silent message loss, AEMP does not.
661		747
662	Erlang makes few guarantees on messages delivery - messages can get lost	748	Erlang makes few guarantees on messages delivery - messages can get lost
663	without any of the processes realising it (i.e. you send messages a, b,	749	without any of the processes realising it (i.e. you send messages a, b,
664	and c, and the other side only receives messages a and c).	750	and c, and the other side only receives messages a and c).
665		751
666	AEMP guarantees correct ordering, and the guarantee that there are no	752	AEMP guarantees correct ordering, and the guarantee that after one message
667	holes in the message sequence.	753	is lost, all following ones sent to the same port are lost as well, until
668		754	monitoring raises an error, so there are no silent "holes" in the message
669	=item * In erlang, processes can be declared dead and later be found to be	755	sequence.
670	alive.
671
672	In erlang it can happen that a monitored process is declared dead and
673	linked processes get killed, but later it turns out that the process is
674	still alive - and can receive messages.
675
676	In AEMP, when port monitoring detects a port as dead, then that port will
677	eventually be killed - it cannot happen that a node detects a port as dead
678	and then later sends messages to it, finding it is still alive.
679		756
680	=item * Erlang can send messages to the wrong port, AEMP does not.	757	=item * Erlang can send messages to the wrong port, AEMP does not.
681		758
682	In erlang it is quite possible that a node that restarts reuses a process	759	In Erlang it is quite likely that a node that restarts reuses a process ID
683	ID known to other nodes for a completely different process, causing	760	known to other nodes for a completely different process, causing messages
684	messages destined for that process to end up in an unrelated process.	761	destined for that process to end up in an unrelated process.
685		762
686	AEMP never reuses port IDs, so old messages or old port IDs floating	763	AEMP never reuses port IDs, so old messages or old port IDs floating
687	around in the network will not be sent to an unrelated port.	764	around in the network will not be sent to an unrelated port.
688		765
689	=item * Erlang uses unprotected connections, AEMP uses secure	766	=item * Erlang uses unprotected connections, AEMP uses secure
690	authentication and can use TLS.	767	authentication and can use TLS.
691		768
692	AEMP can use a proven protocol - SSL/TLS - to protect connections and	769	AEMP can use a proven protocol - TLS - to protect connections and
693	securely authenticate nodes.	770	securely authenticate nodes.
694		771
695	=item * The AEMP protocol is optimised for both text-based and binary	772	=item * The AEMP protocol is optimised for both text-based and binary
696	communications.	773	communications.
697		774
698	The AEMP protocol, unlike the erlang protocol, supports both	775	The AEMP protocol, unlike the Erlang protocol, supports both programming
699	language-independent text-only protocols (good for debugging) and binary,	776	language independent text-only protocols (good for debugging) and binary,
700	language-specific serialisers (e.g. Storable).	777	language-specific serialisers (e.g. Storable). By default, unless TLS is
		778	used, the protocol is actually completely text-based.
701		779
702	It has also been carefully designed to be implementable in other languages	780	It has also been carefully designed to be implementable in other languages
703	with a minimum of work while gracefully degrading fucntionality to make the	781	with a minimum of work while gracefully degrading functionality to make the
704	protocol simple.	782	protocol simple.
705		783
		784	=item * AEMP has more flexible monitoring options than Erlang.
		785
		786	In Erlang, you can chose to receive I<all> exit signals as messages
		787	or I<none>, there is no in-between, so monitoring single processes is
		788	difficult to implement. Monitoring in AEMP is more flexible than in
		789	Erlang, as one can choose between automatic kill, exit message or callback
		790	on a per-process basis.
		791
		792	=item * Erlang tries to hide remote/local connections, AEMP does not.
		793
		794	Monitoring in Erlang is not an indicator of process death/crashes, in the
		795	same way as linking is (except linking is unreliable in Erlang).
		796
		797	In AEMP, you don't "look up" registered port names or send to named ports
		798	that might or might not be persistent. Instead, you normally spawn a port
		799	on the remote node. The init function monitors you, and you monitor the
		800	remote port. Since both monitors are local to the node, they are much more
		801	reliable (no need for C<spawn_link>).
		802
		803	This also saves round-trips and avoids sending messages to the wrong port
		804	(hard to do in Erlang).
		805
706	=back	806	=back
707		807
		808	=head1 RATIONALE
		809
		810	=over 4
		811
		812	=item Why strings for port and node IDs, why not objects?
		813
		814	We considered "objects", but found that the actual number of methods
		815	that can be called are quite low. Since port and node IDs travel over
		816	the network frequently, the serialising/deserialising would add lots of
		817	overhead, as well as having to keep a proxy object everywhere.
		818
		819	Strings can easily be printed, easily serialised etc. and need no special
		820	procedures to be "valid".
		821
		822	And as a result, a miniport consists of a single closure stored in a
		823	global hash - it can't become much cheaper.
		824
		825	=item Why favour JSON, why not a real serialising format such as Storable?
		826
		827	In fact, any AnyEvent::MP node will happily accept Storable as framing
		828	format, but currently there is no way to make a node use Storable by
		829	default (although all nodes will accept it).
		830
		831	The default framing protocol is JSON because a) JSON::XS is many times
		832	faster for small messages and b) most importantly, after years of
		833	experience we found that object serialisation is causing more problems
		834	than it solves: Just like function calls, objects simply do not travel
		835	easily over the network, mostly because they will always be a copy, so you
		836	always have to re-think your design.
		837
		838	Keeping your messages simple, concentrating on data structures rather than
		839	objects, will keep your messages clean, tidy and efficient.
		840
		841	=back
		842
708	=head1 SEE ALSO	843	=head1 SEE ALSO
		844
		845	L<AnyEvent::MP::Intro> - a gentle introduction.
		846
		847	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		848
		849	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		850	your applications.
709		851
710	L<AnyEvent>.	852	L<AnyEvent>.
711		853
712	=head1 AUTHOR	854	=head1 AUTHOR
713		855

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.34 by root, Wed Aug 5 23:50:46 2009 UTC vs. Revision 1.73 by root, Mon Aug 31 11:08:25 2009 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.34 by root, Wed Aug 5 23:50:46 2009 UTC vs.
Revision 1.73 by root, Mon Aug 31 11:08:25 2009 UTC