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

Comparing cvsroot/AnyEvent-MP/MP.pm (file contents):
Revision 1.33 by root, Wed Aug 5 22:40:51 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 $cv = resolve_node $noderef	166	=item configure key => value...
133		167
134	Takes an unresolved node reference that may contain hostnames and	168	Before a node can talk to other nodes on the network (i.e. enter
135	abbreviated IDs, resolves all of them and returns a resolved node	169	"distributed mode") it has to configure itself - the minimum a node needs
136	reference.	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.
137		172
138	In addition to C<address:port> pairs allowed in resolved noderefs, the	173	This function configures a node - it must be called exactly once (or
139	following forms are supported:	174	never) before calling other AnyEvent::MP functions.
140		175
141	=over 4	176	=over 4
142		177
143	=item the empty string	178	=item step 1, gathering configuration from profiles
144		179
145	An empty-string component gets resolved as if the default port (4040) was	180	The function first looks up a profile in the aemp configuration (see the
146	specified.	181	L<aemp> commandline utility). The profile name can be specified via the
		182	named C<profile> parameter. If it is missing, then the nodename (F<uname
		183	-n>) will be used as profile name.
147		184
148	=item naked port numbers (e.g. C<1234>)	185	The profile data is then gathered as follows:
149		186
150	These are resolved by prepending the local nodename and a colon, to be	187	First, all remaining key => value pairs (all of which are conviniently
151	further resolved.	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).
152		192
153	=item hostnames (e.g. C<localhost:1234>, C<localhost>)	193	That means that the values specified in the profile have highest priority
		194	and the values specified directly via C<configure> have lowest priority,
		195	and can only be used to specify defaults.
154		196
155	These are resolved by using AnyEvent::DNS to resolve them, optionally	197	If the profile specifies a node ID, then this will become the node ID of
156	looking up SRV records for the C<aemp=4040> port, if no port was	198	this process. If not, then the profile name will be used as node ID. The
157	specified.	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.
158		218
159	=back	219	=back
		220
		221	Example: become a distributed node using the locla node name as profile.
		222	This should be the most common form of invocation for "daemon"-type nodes.
		223
		224	configure
		225
		226	Example: become an anonymous node. This form is often used for commandline
		227	clients.
		228
		229	configure nodeid => "anon/";
		230
		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).
		234
		235	# use the aemp commandline utility
		236	# aemp profile seed setnodeid anon/ setbinds '*:4040'
		237
		238	# then use it
		239	configure profile => "seed";
		240
		241	# or simply use aemp from the shell again:
		242	# aemp run profile seed
		243
		244	# or provide a nicer-to-remember nodeid
		245	# aemp run profile seed nodeid "$(hostname)"
160		246
161	=item $SELF	247	=item $SELF
162		248
163	Contains the current port id while executing C<rcv> callbacks or C<psub>	249	Contains the current port id while executing C<rcv> callbacks or C<psub>
164	blocks.	250	blocks.
165		251
166	=item SELF, %SELF, @SELF...	252	=item *SELF, SELF, %SELF, @SELF...
167		253
168	Due to some quirks in how perl exports variables, it is impossible to	254	Due to some quirks in how perl exports variables, it is impossible to
169	just export C<$SELF>, all the symbols called C<SELF> are exported by this	255	just export C<$SELF>, all the symbols named C<SELF> are exported by this
170	module, but only C<$SELF> is currently used.	256	module, but only C<$SELF> is currently used.
171		257
172	=item snd $port, type => @data	258	=item snd $port, type => @data
173		259
174	=item snd $port, @msg	260	=item snd $port, @msg
175		261
176	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
177	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.
178	stringifies a sa port ID (such as a port object :).
179		264
180	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
181	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
182	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.
183		269
184	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
185	function: modifying any argument is not allowed and can cause many	271	function: modifying any argument (or values referenced by them) is
186	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.
187		276
188	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
189	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
190	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
191	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
192	node, anything can be passed.	281	node, anything can be passed. Best rely only on the common denominator of
		282	these.
193		283
194	=item $local_port = port	284	=item $local_port = port
195		285
196	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
197	matching port ("full port") or a single-callback port ("miniport"),	287	no callbacks set and will throw an error when it receives messages.
198	depending on how C<rcv> callbacks are bound to the object.
199		288
200	=item $port = port { my @msg = @_; $finished }	289	=item $local_port = port { my @msg = @_ }
201		290
202	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
203	matching behind it, and returns its ID. Semantically the same as creating
204	a port and calling C<rcv $port, $callback> on it.	292	creating a port and calling C<rcv $port, $callback> on it.
205		293
206	The block will be called for every message received on the port. When the	294	The block will be called for every message received on the port, with the
207	callback returns a true value its job is considered "done" and the port	295	global variable C<$SELF> set to the port ID. Runtime errors will cause the
208	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.
209		298
210	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:
211	be passed to the callback.
212		300
213	If you need the local port id in the callback, this works nicely:	301	my $port = port {
214		302	my @msg = @_;
215	my $port; $port = port {	303	...
216	snd $otherport, reply => $port;	304	kil $SELF;
217	};	305	};
218		306
219	=cut	307	=cut
220		308
221	sub rcv($@);	309	sub rcv($@);
		310
		311	sub _kilme {
		312	die "received message on port without callback";
		313	}
222		314
223	sub port(;&) {	315	sub port(;&) {
224	my $id = "$UNIQ." . $ID++;	316	my $id = "$UNIQ." . $ID++;
225	my $port = "$NODE#$id";	317	my $port = "$NODE#$id";
226		318
227	if (@_) {	319	rcv $port, shift \|\| \&_kilme;
228	rcv $port, shift;
229	} else {
230	$PORT{$id} = sub { }; # nop
231	}
232		320
233	$port	321	$port
234	}	322	}
235		323
236	=item reg $port, $name
237
238	Registers the given port under the name C<$name>. If the name already
239	exists it is replaced.
240
241	A port can only be registered under one well known name.
242
243	A port automatically becomes unregistered when it is killed.
244
245	=cut
246
247	sub reg(@) {
248	my ($port, $name) = @_;
249
250	$REG{$name} = $port;
251	}
252
253	=item rcv $port, $callback->(@msg)	324	=item rcv $local_port, $callback->(@msg)
254		325
255	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
256	one if required).	327	remove the default callback: use C<sub { }> to disable it, or better
257		328	C<kil> the port when it is no longer needed.
258	=item rcv $port, tagstring => $callback->(@msg), ...
259
260	=item rcv $port, $smartmatch => $callback->(@msg), ...
261
262	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
263
264	Register callbacks to be called on matching messages on the given full
265	port (after converting it to one if required).
266
267	The callback has to return a true value when its work is done, after
268	which is will be removed, or a false value in which case it will stay
269	registered.
270		329
271	The global C<$SELF> (exported by this module) contains C<$port> while	330	The global C<$SELF> (exported by this module) contains C<$port> while
272	executing the callback.	331	executing the callback. Runtime errors during callback execution will
		332	result in the port being C<kil>ed.
273		333
274	Runtime errors wdurign callback execution will result in the port being	334	The default callback received all messages not matched by a more specific
275	C<kil>ed.	335	C<tag> match.
276		336
277	If the match is an array reference, then it will be matched against the	337	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
278	first elements of the message, otherwise only the first element is being
279	matched.
280		338
281	Any element in the match that is specified as C<_any_> (a function	339	Register (or replace) callbacks to be called on messages starting with the
282	exported by this module) matches any single element of the message.	340	given tag on the given port (and return the port), or unregister it (when
		341	C<$callback> is C<$undef> or missing). There can only be one callback
		342	registered for each tag.
283		343
284	While not required, it is highly recommended that the first matching	344	The original message will be passed to the callback, after the first
285	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
286	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, $otherport;
		371	};
287		372
288	=cut	373	=cut
289		374
290	sub rcv($@) {	375	sub rcv($@) {
291	my $port = shift;	376	my $port = shift;
292	my ($noderef, $portid) = split /#/, $port, 2;	377	my ($noderef, $portid) = split /#/, $port, 2;
293		378
294	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	379	$NODE{$noderef} == $NODE{""}
295	or Carp::croak "$port: rcv can only be called on local ports, caught";	380	or Carp::croak "$port: rcv can only be called on local ports, caught";
296		381
297	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 {
298	my $cb = shift;	390	my $cb = shift;
299	delete $PORT_DATA{$portid};
300	$PORT{$portid} = sub {	391	$PORT{$portid} = sub {
301	local $SELF = $port;	392	local $SELF = $port;
302	eval {	393	eval { &$cb }; _self_die if $@;
303	&$cb	394	};
304	and kil $port;
305	};	395	}
306	_self_die if $@;	396	} elsif (defined $_[0]) {
307	};
308	} else {
309	my $self = $PORT_DATA{$portid} \|\|= do {	397	my $self = $PORT_DATA{$portid} \|\|= do {
310	my $self = bless {	398	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
311	id => $port,
312	}, "AnyEvent::MP::Port";
313		399
314	$PORT{$portid} = sub {	400	$PORT{$portid} = sub {
315	local $SELF = $port;	401	local $SELF = $port;
316		402
317	eval {
318	for (@{ $self->{rc0}{$_[0]} }) {	403	if (my $cb = $self->[1]{$_[0]}) {
319	$_ && &{$_->[0]}	404	shift;
320	&& undef $_;	405	eval { &$cb }; _self_die if $@;
321	}	406	} else {
322
323	for (@{ $self->{rcv}{$_[0]} }) {
324	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
325	&& &{$_->[0]}	407	&{ $self->[0] };
326	&& undef $_;
327	}
328
329	for (@{ $self->{any} }) {
330	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
331	&& &{$_->[0]}
332	&& undef $_;
333	}	408	}
334	};	409	};
335	_self_die if $@;	410
		411	$self
336	};	412	};
337		413
338	$self
339	};
340
341	"AnyEvent::MP::Port" eq ref $self	414	"AnyEvent::MP::Port" eq ref $self
342	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	415	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
343		416
344	while (@_) {
345	my ($match, $cb) = splice @_, 0, 2;	417	my ($tag, $cb) = splice @_, 0, 2;
346		418
347	if (!ref $match) {	419	if (defined $cb) {
348	push @{ $self->{rc0}{$match} }, [$cb];	420	$self->[1]{$tag} = $cb;
349	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
350	my ($type, @match) = @$match;
351	@match
352	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
353	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
354	} else {	421	} else {
355	push @{ $self->{any} }, [$cb, $match];	422	delete $self->[1]{$tag};
356	}	423	}
357	}	424	}
358	}	425	}
359		426
360	$port	427	$port
…		…
396	$res	463	$res
397	}	464	}
398	}	465	}
399	}	466	}
400		467
401	=item $guard = mon $port, $cb->(@reason)	468	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
402		469
403	=item $guard = mon $port, $otherport	470	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
404		471
405	=item $guard = mon $port, $otherport, @msg	472	=item $guard = mon $port # kill $SELF when $port dies
406		473
		474	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
		475
407	Monitor the given port and do something when the port is killed.	476	Monitor the given port and do something when the port is killed or
		477	messages to it were lost, and optionally return a guard that can be used
		478	to stop monitoring again.
408		479
		480	C<mon> effectively guarantees that, in the absence of hardware failures,
		481	after starting the monitor, either all messages sent to the port will
		482	arrive, or the monitoring action will be invoked after possible message
		483	loss has been detected. No messages will be lost "in between" (after
		484	the first lost message no further messages will be received by the
		485	port). After the monitoring action was invoked, further messages might get
		486	delivered again.
		487
		488	Note that monitoring-actions are one-shot: once messages are lost (and a
		489	monitoring alert was raised), they are removed and will not trigger again.
		490
409	In the first form, the callback is simply called with any number	491	In the first form (callback), the callback is simply called with any
410	of C<@reason> elements (no @reason means that the port was deleted	492	number of C<@reason> elements (no @reason means that the port was deleted
411	"normally"). Note also that I<< the callback B<must> never die >>, so use	493	"normally"). Note also that I<< the callback B<must> never die >>, so use
412	C<eval> if unsure.	494	C<eval> if unsure.
413		495
414	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	496	In the second form (another port given), the other port (C<$rcvport>)
415	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
416	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.
417		500
		501	The third form (kill self) is the same as the second form, except that
		502	C<$rvport> defaults to C<$SELF>.
		503
418	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.
419		513
420	Example: call a given callback when C<$port> is killed.	514	Example: call a given callback when C<$port> is killed.
421		515
422	mon $port, sub { warn "port died because of <@_>\n" };	516	mon $port, sub { warn "port died because of <@_>\n" };
423		517
424	Example: kill ourselves when C<$port> is killed abnormally.	518	Example: kill ourselves when C<$port> is killed abnormally.
425		519
426	mon $port, $self;	520	mon $port;
427		521
428	Example: send us a restart message another C<$port> is killed.	522	Example: send us a restart message when another C<$port> is killed.
429		523
430	mon $port, $self => "restart";	524	mon $port, $self => "restart";
431		525
432	=cut	526	=cut
433		527
434	sub mon {	528	sub mon {
435	my ($noderef, $port) = split /#/, shift, 2;	529	my ($noderef, $port) = split /#/, shift, 2;
436		530
437	my $node = $NODE{$noderef} \|\| add_node $noderef;	531	my $node = $NODE{$noderef} \|\| add_node $noderef;
438		532
439	my $cb = shift;	533	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
440		534
441	unless (ref $cb) {	535	unless (ref $cb) {
442	if (@_) {	536	if (@_) {
443	# send a kill info message	537	# send a kill info message
444	my (@msg) = ($cb, @_);	538	my (@msg) = ($cb, @_);
…		…
462	is killed, the references will be freed.	556	is killed, the references will be freed.
463		557
464	Optionally returns a guard that will stop the monitoring.	558	Optionally returns a guard that will stop the monitoring.
465		559
466	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
467	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>):
468		562
469	$port->rcv (start => sub {	563	$port->rcv (start => sub {
470	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	564	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
471	undef $timer if 0.9 < rand;	565	undef $timer if 0.9 < rand;
472	});	566	});
473	});	567	});
474		568
475	=cut	569	=cut
476		570
477	sub mon_guard {	571	sub mon_guard {
478	my ($port, @refs) = @_;	572	my ($port, @refs) = @_;
479		573
		574	#TODO: mon-less form?
		575
480	mon $port, sub { 0 && @refs }	576	mon $port, sub { 0 && @refs }
481	}	577	}
482		578
483	=item lnk $port1, $port2
484
485	Link two ports. This is simply a shorthand for:
486
487	mon $port1, $port2;
488	mon $port2, $port1;
489
490	It means that if either one is killed abnormally, the other one gets
491	killed as well.
492
493	=item kil $port[, @reason]	579	=item kil $port[, @reason]
494		580
495	Kill the specified port with the given C<@reason>.	581	Kill the specified port with the given C<@reason>.
496		582
497	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
498	ports will not be kileld, or even notified).	584	monitoring other ports will not necessarily die because a port dies
		585	"normally").
499		586
500	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
501	C<mon>, see below).	588	C<mon>, see above).
502		589
503	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
504	will be reported as reason C<< die => $@ >>.	591	will be reported as reason C<< die => $@ >>.
505		592
506	Transport/communication errors are reported as C<< transport_error =>	593	Transport/communication errors are reported as C<< transport_error =>
507	$message >>.	594	$message >>.
508		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
509	=back	691	=back
510		692
511	=head1 FUNCTIONS FOR NODES	693	=head1 AnyEvent::MP vs. Distributed Erlang
		694
		695	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
		696	== aemp node, Erlang process == aemp port), so many of the documents and
		697	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		698	sample:
		699
		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:
512		706
513	=over 4	707	=over 4
514		708
515	=item initialise_node $noderef, $seednode, $seednode...	709	=item * Node IDs are arbitrary strings in AEMP.
516		710
517	=item initialise_node "slave/", $master, $master...
518
519	Initialises a node - must be called exactly once before calling other
520	AnyEvent::MP functions when talking to other nodes is required.
521
522	All arguments are noderefs, which can be either resolved or unresolved.
523
524	There are two types of networked nodes, public nodes and slave nodes:
525
526	=over 4
527
528	=item public nodes
529
530	For public nodes, C<$noderef> must either be a (possibly unresolved)
531	noderef, in which case it will be resolved, or C<undef> (or missing), in
532	which case the noderef will be guessed.
533
534	Afterwards, the node will bind itself on all endpoints and try to connect
535	to all additional C<$seednodes> that are specified. Seednodes are optional
536	and can be used to quickly bootstrap the node into an existing network.
537
538	=item slave nodes
539
540	When the C<$noderef> is the special string C<slave/>, then the node will
541	become a slave node. Slave nodes cannot be contacted from outside and will
542	route most of their traffic to the master node that they attach to.
543
544	At least one additional noderef is required: The node will try to connect
545	to all of them and will become a slave attached to the first node it can
546	successfully connect to.
547
548	=back
549
550	This function will block until all nodes have been resolved and, for slave
551	nodes, until it has successfully established a connection to a master
552	server.
553
554	Example: become a public node listening on the default node.
555
556	initialise_node;
557
558	Example: become a public node, and try to contact some well-known master
559	servers to become part of the network.
560
561	initialise_node undef, "master1", "master2";
562
563	Example: become a public node listening on port C<4041>.
564
565	initialise_node 4041;
566
567	Example: become a public node, only visible on localhost port 4044.
568
569	initialise_node "locahost:4044";
570
571	Example: become a slave node to any of the specified master servers.
572
573	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
574
575	=cut
576
577	=back
578
579	=head1 NODE MESSAGES
580
581	Nodes understand the following messages sent to them. Many of them take
582	arguments called C<@reply>, which will simply be used to compose a reply
583	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
584	the remaining arguments are simply the message data.
585
586	While other messages exist, they are not public and subject to change.
587
588	=over 4
589
590	=cut
591
592	=item lookup => $name, @reply
593
594	Replies with the port ID of the specified well-known port, or C<undef>.
595
596	=item devnull => ...
597
598	Generic data sink/CPU heat conversion.
599
600	=item relay => $port, @msg
601
602	Simply forwards the message to the given port.
603
604	=item eval => $string[ @reply]
605
606	Evaluates the given string. If C<@reply> is given, then a message of the
607	form C<@reply, $@, @evalres> is sent.
608
609	Example: crash another node.
610
611	snd $othernode, eval => "exit";
612
613	=item time => @reply
614
615	Replies the the current node time to C<@reply>.
616
617	Example: tell the current node to send the current time to C<$myport> in a
618	C<timereply> message.
619
620	snd $NODE, time => $myport, timereply => 1, 2;
621	# => snd $myport, timereply => 1, 2, <time>
622
623	=back
624
625	=head1 AnyEvent::MP vs. Distributed Erlang
626
627	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node
628	== aemp node, erlang process == aemp port), so many of the documents and
629	programming techniques employed by erlang apply to AnyEvent::MP. Here is a
630	sample:
631
632	http://www.erlang.se/doc/programming_rules.shtml
633	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
634	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6
635	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
636
637	Despite the similarities, there are also some important differences:
638
639	=over 4
640
641	=item * Node references contain the recipe on how to contact them.
642
643	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
644	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
645	convenience functionality.	713	configuraiton or DNS), but will otherwise discover other odes itself.
646		714
647	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
648	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.
649		729
650	=item * Erlang uses processes and a mailbox, AEMP does not queue.	730	=item * Erlang uses processes and a mailbox, AEMP does not queue.
651		731
652	Erlang uses processes that selctively receive messages, and therefore	732	Erlang uses processes that selectively receive messages, and therefore
653	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
654	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.
655		737
656	(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).
657		739
658	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	740	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
659		741
660	Sending messages in erlang is synchronous and blocks the process. AEMP	742	Sending messages in Erlang is synchronous and blocks the process (and
661	sends are immediate, connection establishment is handled in the	743	so does not need a queue that can overflow). AEMP sends are immediate,
662	background.	744	connection establishment is handled in the background.
663		745
664	=item * Erlang can silently lose messages, AEMP cannot.	746	=item * Erlang suffers from silent message loss, AEMP does not.
665		747
666	Erlang makes few guarantees on messages delivery - messages can get lost	748	Erlang makes few guarantees on messages delivery - messages can get lost
667	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,
668	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).
669		751
670	AEMP guarantees correct ordering, and the guarantee that there are no	752	AEMP guarantees correct ordering, and the guarantee that after one message
671	holes in the message sequence.	753	is lost, all following ones sent to the same port are lost as well, until
672		754	monitoring raises an error, so there are no silent "holes" in the message
673	=item * In erlang, processes can be declared dead and later be found to be	755	sequence.
674	alive.
675
676	In erlang it can happen that a monitored process is declared dead and
677	linked processes get killed, but later it turns out that the process is
678	still alive - and can receive messages.
679
680	In AEMP, when port monitoring detects a port as dead, then that port will
681	eventually be killed - it cannot happen that a node detects a port as dead
682	and then later sends messages to it, finding it is still alive.
683		756
684	=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.
685		758
686	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
687	ID known to other nodes for a completely different process, causing	760	known to other nodes for a completely different process, causing messages
688	messages destined for that process to end up in an unrelated process.	761	destined for that process to end up in an unrelated process.
689		762
690	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
691	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.
692		765
693	=item * Erlang uses unprotected connections, AEMP uses secure	766	=item * Erlang uses unprotected connections, AEMP uses secure
694	authentication and can use TLS.	767	authentication and can use TLS.
695		768
696	AEMP can use a proven protocol - SSL/TLS - to protect connections and	769	AEMP can use a proven protocol - TLS - to protect connections and
697	securely authenticate nodes.	770	securely authenticate nodes.
698		771
699	=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
700	communications.	773	communications.
701		774
702	The AEMP protocol, unlike the erlang protocol, supports both	775	The AEMP protocol, unlike the Erlang protocol, supports both programming
703	language-independent text-only protocols (good for debugging) and binary,	776	language independent text-only protocols (good for debugging) and binary,
704	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.
705		779
706	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
707	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
708	protocol simple.	782	protocol simple.
709		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
710	=back	806	=back
711		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
712	=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.
713		851
714	L<AnyEvent>.	852	L<AnyEvent>.
715		853
716	=head1 AUTHOR	854	=head1 AUTHOR
717		855

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Comparing cvsroot/AnyEvent-MP/MP.pm (file contents): Revision 1.33 by root, Wed Aug 5 22:40:51 2009 UTC vs. Revision 1.73 by root, Mon Aug 31 11:08:25 2009 UTC

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Comparing cvsroot/AnyEvent-MP/MP.pm (file contents):
Revision 1.33 by root, Wed Aug 5 22:40:51 2009 UTC vs.
Revision 1.73 by root, Mon Aug 31 11:08:25 2009 UTC