[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 1.71 by root, Sun Aug 30 19:52:56 2009 UTC

…		…
8		8
9	$NODE # contains this node's noderef	9	$NODE # contains this node's noderef
10	NODE # returns this node's noderef	10	NODE # returns this node's noderef
11	NODE $port # returns the noderef of the port	11	NODE $port # returns the noderef of the port
12		12
		13	$SELF # receiving/own port id in rcv callbacks
		14
		15	# initialise the node so it can send/receive messages
		16	initialise_node;
		17
		18	# ports are message endpoints
		19
		20	# sending messages
13	snd $port, type => data...;	21	snd $port, type => data...;
		22	snd $port, @msg;
		23	snd @msg_with_first_element_being_a_port;
14		24
15	$SELF # receiving/own port id in rcv callbacks	25	# creating/using ports, the simple way
		26	my $simple_port = port { my @msg = @_; 0 };
16		27
17	rcv $port, smartmatch => $cb->($port, @msg);	28	# creating/using ports, tagged message matching
18		29	my $port = port;
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	30	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
21	rcv $port1, pong => sub { warn "pong received\n" };	31	rcv $port, pong => sub { warn "pong received\n"; 0 };
22	snd $port2, ping => $port1;
23		32
24	# more, smarter, matches (_any_ is exported by this module)	33	# create a port on another node
25	rcv $port, [child_died => $pid] => sub { ...	34	my $port = spawn $node, $initfunc, @initdata;
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	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	initialise_node
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<initialise_node>.
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 initialise_node $profile_name, 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 initialise 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 initialises 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	The first argument is a profile name. If it is C<undef> or missing, then
		177	the current nodename will be used instead (i.e. F<uname -n>).
142		178
143	=item the empty string	179	The function first looks up the profile in the aemp configuration (see the
		180	L<aemp> commandline utility). the profile is calculated as follows:
144		181
145	An empty-string component gets resolved as if the default port (4040) was	182	First, all remaining key => value pairs (all of which are conviniently
146	specified.	183	undocumented at the moment) will be used. Then they will be overwritten by
		184	any values specified in the global default configuration (see the F<aemp>
		185	utility), then the chain of profiles selected, if any. That means that
		186	the values specified in the profile have highest priority and the values
		187	specified via C<initialise_node> have lowest priority.
147		188
148	=item naked port numbers (e.g. C<1234>)	189	If the profile specifies a node ID, then this will become the node ID of
		190	this process. If not, then the profile name will be used as node ID. The
		191	special node ID of C<anon/> will be replaced by a random node ID.
149		192
150	These are resolved by prepending the local nodename and a colon, to be	193	The next step is to look up the binds in the profile, followed by binding
151	further resolved.	194	aemp protocol listeners on all binds specified (it is possible and valid
		195	to have no binds, meaning that the node cannot be contacted form the
		196	outside. This means the node cannot talk to other nodes that also have no
		197	binds, but it can still talk to all "normal" nodes).
152		198
153	=item hostnames (e.g. C<localhost:1234>, C<localhost>)	199	If the profile does not specify a binds list, then a default of C<*> is
		200	used.
154		201
155	These are resolved by using AnyEvent::DNS to resolve them, optionally	202	Lastly, the seeds list from the profile is passed to the
156	looking up SRV records for the C<aemp=4040> port, if no port was	203	L<AnyEvent::MP::Global> module, which will then use it to keep
157	specified.	204	connectivity with at least on of those seed nodes at any point in time.
158		205
159	=back	206	Example: become a distributed node listening on the guessed noderef, or
		207	the one specified via C<aemp> for the current node. This should be the
		208	most common form of invocation for "daemon"-type nodes.
		209
		210	initialise_node;
		211
		212	Example: become an anonymous node. This form is often used for commandline
		213	clients.
		214
		215	initialise_node "anon/";
		216
		217	Example: become a distributed node. If there is no profile of the given
		218	name, or no binds list was specified, resolve C<localhost:4044> and bind
		219	on the resulting addresses.
		220
		221	initialise_node "localhost:4044";
160		222
161	=item $SELF	223	=item $SELF
162		224
163	Contains the current port id while executing C<rcv> callbacks or C<psub>	225	Contains the current port id while executing C<rcv> callbacks or C<psub>
164	blocks.	226	blocks.
165		227
166	=item SELF, %SELF, @SELF...	228	=item *SELF, SELF, %SELF, @SELF...
167		229
168	Due to some quirks in how perl exports variables, it is impossible to	230	Due to some quirks in how perl exports variables, it is impossible to
169	just export C<$SELF>, all the symbols called C<SELF> are exported by this	231	just export C<$SELF>, all the symbols named C<SELF> are exported by this
170	module, but only C<$SELF> is currently used.	232	module, but only C<$SELF> is currently used.
171		233
172	=item snd $port, type => @data	234	=item snd $port, type => @data
173		235
174	=item snd $port, @msg	236	=item snd $port, @msg
175		237
176	Send the given message to the given port ID, which can identify either	238	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	239	local or a remote port, and must be a port ID.
178	stringifies a sa port ID (such as a port object :).
179		240
180	While the message can be about anything, it is highly recommended to use a	241	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	242	use a string as first element (a port ID, or some word that indicates a
182	type etc.).	243	request type etc.) and to consist if only simple perl values (scalars,
		244	arrays, hashes) - if you think you need to pass an object, think again.
183		245
184	The message data effectively becomes read-only after a call to this	246	The message data logically becomes read-only after a call to this
185	function: modifying any argument is not allowed and can cause many	247	function: modifying any argument (or values referenced by them) is
186	problems.	248	forbidden, as there can be considerable time between the call to C<snd>
		249	and the time the message is actually being serialised - in fact, it might
		250	never be copied as within the same process it is simply handed to the
		251	receiving port.
187		252
188	The type of data you can transfer depends on the transport protocol: when	253	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	254	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	255	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	256	that Storable can serialise and deserialise is allowed, and for the local
192	node, anything can be passed.	257	node, anything can be passed. Best rely only on the common denominator of
		258	these.
193		259
194	=item $local_port = port	260	=item $local_port = port
195		261
196	Create a new local port object that can be used either as a pattern	262	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"),	263	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		264
200	=item $port = port { my @msg = @_; $finished }	265	=item $local_port = port { my @msg = @_ }
201		266
202	Creates a "miniport", that is, a very lightweight port without any pattern	267	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.	268	creating a port and calling C<rcv $port, $callback> on it.
205		269
206	The block will be called for every message received on the port. When the	270	The block will be called for every message received on the port, with the
207	callback returns a true value its job is considered "done" and the port	271	global variable C<$SELF> set to the port ID. Runtime errors will cause the
208	will be destroyed. Otherwise it will stay alive.	272	port to be C<kil>ed. The message will be passed as-is, no extra argument
		273	(i.e. no port ID) will be passed to the callback.
209		274
210	The message will be passed as-is, no extra argument (i.e. no port id) will	275	If you want to stop/destroy the port, simply C<kil> it:
211	be passed to the callback.
212		276
213	If you need the local port id in the callback, this works nicely:	277	my $port = port {
214		278	my @msg = @_;
215	my $port; $port = port {	279	...
216	snd $otherport, reply => $port;	280	kil $SELF;
217	};	281	};
218		282
219	=cut	283	=cut
220		284
221	sub rcv($@);	285	sub rcv($@);
		286
		287	sub _kilme {
		288	die "received message on port without callback";
		289	}
222		290
223	sub port(;&) {	291	sub port(;&) {
224	my $id = "$UNIQ." . $ID++;	292	my $id = "$UNIQ." . $ID++;
225	my $port = "$NODE#$id";	293	my $port = "$NODE#$id";
226		294
227	if (@_) {	295	rcv $port, shift \|\| \&_kilme;
228	rcv $port, shift;
229	} else {
230	$PORT{$id} = sub { }; # nop
231	}
232		296
233	$port	297	$port
234	}	298	}
235		299
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)	300	=item rcv $local_port, $callback->(@msg)
254		301
255	Replaces the callback on the specified miniport (after converting it to	302	Replaces the default callback on the specified port. There is no way to
256	one if required).	303	remove the default callback: use C<sub { }> to disable it, or better
257		304	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...] => $callback->(@msg), ...
263
264	Register callbacks to be called on matching messages on the given full
265	port (after converting it to one if required).
266
267	The callback has to return a true value when its work is done, after
268	which is will be removed, or a false value in which case it will stay
269	registered.
270		305
271	The global C<$SELF> (exported by this module) contains C<$port> while	306	The global C<$SELF> (exported by this module) contains C<$port> while
272	executing the callback.	307	executing the callback. Runtime errors during callback execution will
		308	result in the port being C<kil>ed.
273		309
274	Runtime errors wdurign callback execution will result in the port being	310	The default callback received all messages not matched by a more specific
275	C<kil>ed.	311	C<tag> match.
276		312
277	If the match is an array reference, then it will be matched against the	313	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
278	first elements of the message, otherwise only the first element is being
279	matched.
280		314
281	Any element in the match that is specified as C<_any_> (a function	315	Register (or replace) callbacks to be called on messages starting with the
282	exported by this module) matches any single element of the message.	316	given tag on the given port (and return the port), or unregister it (when
		317	C<$callback> is C<$undef> or missing). There can only be one callback
		318	registered for each tag.
283		319
284	While not required, it is highly recommended that the first matching	320	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	321	element (the tag) has been removed. The callback will use the same
286	also the most efficient match (by far).	322	environment as the default callback (see above).
		323
		324	Example: create a port and bind receivers on it in one go.
		325
		326	my $port = rcv port,
		327	msg1 => sub { ... },
		328	msg2 => sub { ... },
		329	;
		330
		331	Example: create a port, bind receivers and send it in a message elsewhere
		332	in one go:
		333
		334	snd $otherport, reply =>
		335	rcv port,
		336	msg1 => sub { ... },
		337	...
		338	;
		339
		340	Example: temporarily register a rcv callback for a tag matching some port
		341	(e.g. for a rpc reply) and unregister it after a message was received.
		342
		343	rcv $port, $otherport => sub {
		344	my @reply = @_;
		345
		346	rcv $SELF, $otherport;
		347	};
287		348
288	=cut	349	=cut
289		350
290	sub rcv($@) {	351	sub rcv($@) {
291	my $port = shift;	352	my $port = shift;
292	my ($noderef, $portid) = split /#/, $port, 2;	353	my ($noderef, $portid) = split /#/, $port, 2;
293		354
294	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	355	$NODE{$noderef} == $NODE{""}
295	or Carp::croak "$port: rcv can only be called on local ports, caught";	356	or Carp::croak "$port: rcv can only be called on local ports, caught";
296		357
297	if (@_ == 1) {	358	while (@_) {
		359	if (ref $_[0]) {
		360	if (my $self = $PORT_DATA{$portid}) {
		361	"AnyEvent::MP::Port" eq ref $self
		362	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		363
		364	$self->[2] = shift;
		365	} else {
298	my $cb = shift;	366	my $cb = shift;
299	delete $PORT_DATA{$portid};
300	$PORT{$portid} = sub {	367	$PORT{$portid} = sub {
301	local $SELF = $port;	368	local $SELF = $port;
302	eval {	369	eval { &$cb }; _self_die if $@;
303	&$cb	370	};
304	and kil $port;
305	};	371	}
306	_self_die if $@;	372	} elsif (defined $_[0]) {
307	};
308	} else {
309	my $self = $PORT_DATA{$portid} \|\|= do {	373	my $self = $PORT_DATA{$portid} \|\|= do {
310	my $self = bless {	374	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
311	id => $port,
312	}, "AnyEvent::MP::Port";
313		375
314	$PORT{$portid} = sub {	376	$PORT{$portid} = sub {
315	local $SELF = $port;	377	local $SELF = $port;
316		378
317	eval {
318	for (@{ $self->{rc0}{$_[0]} }) {	379	if (my $cb = $self->[1]{$_[0]}) {
319	$_ && &{$_->[0]}	380	shift;
320	&& undef $_;	381	eval { &$cb }; _self_die if $@;
321	}	382	} else {
322
323	for (@{ $self->{rcv}{$_[0]} }) {
324	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
325	&& &{$_->[0]}	383	&{ $self->[0] };
326	&& undef $_;
327	}
328
329	for (@{ $self->{any} }) {
330	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
331	&& &{$_->[0]}
332	&& undef $_;
333	}	384	}
334	};	385	};
335	_self_die if $@;	386
		387	$self
336	};	388	};
337		389
338	$self
339	};
340
341	"AnyEvent::MP::Port" eq ref $self	390	"AnyEvent::MP::Port" eq ref $self
342	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	391	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
343		392
344	while (@_) {
345	my ($match, $cb) = splice @_, 0, 2;	393	my ($tag, $cb) = splice @_, 0, 2;
346		394
347	if (!ref $match) {	395	if (defined $cb) {
348	push @{ $self->{rc0}{$match} }, [$cb];	396	$self->[1]{$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 {	397	} else {
355	push @{ $self->{any} }, [$cb, $match];	398	delete $self->[1]{$tag};
356	}	399	}
357	}	400	}
358	}	401	}
359		402
360	$port	403	$port
…		…
396	$res	439	$res
397	}	440	}
398	}	441	}
399	}	442	}
400		443
401	=item $guard = mon $port, $cb->(@reason)	444	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
402		445
403	=item $guard = mon $port, $otherport	446	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
404		447
405	=item $guard = mon $port, $otherport, @msg	448	=item $guard = mon $port # kill $SELF when $port dies
406		449
		450	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
		451
407	Monitor the given port and do something when the port is killed.	452	Monitor the given port and do something when the port is killed or
		453	messages to it were lost, and optionally return a guard that can be used
		454	to stop monitoring again.
408		455
		456	C<mon> effectively guarantees that, in the absence of hardware failures,
		457	after starting the monitor, either all messages sent to the port will
		458	arrive, or the monitoring action will be invoked after possible message
		459	loss has been detected. No messages will be lost "in between" (after
		460	the first lost message no further messages will be received by the
		461	port). After the monitoring action was invoked, further messages might get
		462	delivered again.
		463
		464	Note that monitoring-actions are one-shot: once messages are lost (and a
		465	monitoring alert was raised), they are removed and will not trigger again.
		466
409	In the first form, the callback is simply called with any number	467	In the first form (callback), the callback is simply called with any
410	of C<@reason> elements (no @reason means that the port was deleted	468	number of C<@reason> elements (no @reason means that the port was deleted
411	"normally"). Note also that I<< the callback B<must> never die >>, so use	469	"normally"). Note also that I<< the callback B<must> never die >>, so use
412	C<eval> if unsure.	470	C<eval> if unsure.
413		471
414	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	472	In the second form (another port given), the other port (C<$rcvport>)
415	a @reason was specified, i.e. on "normal" kils nothing happens, while	473	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.	474	"normal" kils nothing happens, while under all other conditions, the other
		475	port is killed with the same reason.
417		476
		477	The third form (kill self) is the same as the second form, except that
		478	C<$rvport> defaults to C<$SELF>.
		479
418	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	480	In the last form (message), a message of the form C<@msg, @reason> will be
		481	C<snd>.
		482
		483	As a rule of thumb, monitoring requests should always monitor a port from
		484	a local port (or callback). The reason is that kill messages might get
		485	lost, just like any other message. Another less obvious reason is that
		486	even monitoring requests can get lost (for exmaple, when the connection
		487	to the other node goes down permanently). When monitoring a port locally
		488	these problems do not exist.
419		489
420	Example: call a given callback when C<$port> is killed.	490	Example: call a given callback when C<$port> is killed.
421		491
422	mon $port, sub { warn "port died because of <@_>\n" };	492	mon $port, sub { warn "port died because of <@_>\n" };
423		493
424	Example: kill ourselves when C<$port> is killed abnormally.	494	Example: kill ourselves when C<$port> is killed abnormally.
425		495
426	mon $port, $self;	496	mon $port;
427		497
428	Example: send us a restart message another C<$port> is killed.	498	Example: send us a restart message when another C<$port> is killed.
429		499
430	mon $port, $self => "restart";	500	mon $port, $self => "restart";
431		501
432	=cut	502	=cut
433		503
434	sub mon {	504	sub mon {
435	my ($noderef, $port) = split /#/, shift, 2;	505	my ($noderef, $port) = split /#/, shift, 2;
436		506
437	my $node = $NODE{$noderef} \|\| add_node $noderef;	507	my $node = $NODE{$noderef} \|\| add_node $noderef;
438		508
439	my $cb = shift;	509	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
440		510
441	unless (ref $cb) {	511	unless (ref $cb) {
442	if (@_) {	512	if (@_) {
443	# send a kill info message	513	# send a kill info message
444	my (@msg) = ($cb, @_);	514	my (@msg) = ($cb, @_);
…		…
462	is killed, the references will be freed.	532	is killed, the references will be freed.
463		533
464	Optionally returns a guard that will stop the monitoring.	534	Optionally returns a guard that will stop the monitoring.
465		535
466	This function is useful when you create e.g. timers or other watchers and	536	This function is useful when you create e.g. timers or other watchers and
467	want to free them when the port gets killed:	537	want to free them when the port gets killed (note the use of C<psub>):
468		538
469	$port->rcv (start => sub {	539	$port->rcv (start => sub {
470	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	540	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
471	undef $timer if 0.9 < rand;	541	undef $timer if 0.9 < rand;
472	});	542	});
473	});	543	});
474		544
475	=cut	545	=cut
476		546
477	sub mon_guard {	547	sub mon_guard {
478	my ($port, @refs) = @_;	548	my ($port, @refs) = @_;
479		549
		550	#TODO: mon-less form?
		551
480	mon $port, sub { 0 && @refs }	552	mon $port, sub { 0 && @refs }
481	}	553	}
482		554
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]	555	=item kil $port[, @reason]
494		556
495	Kill the specified port with the given C<@reason>.	557	Kill the specified port with the given C<@reason>.
496		558
497	If no C<@reason> is specified, then the port is killed "normally" (linked	559	If no C<@reason> is specified, then the port is killed "normally" (ports
498	ports will not be kileld, or even notified).	560	monitoring other ports will not necessarily die because a port dies
		561	"normally").
499		562
500	Otherwise, linked ports get killed with the same reason (second form of	563	Otherwise, linked ports get killed with the same reason (second form of
501	C<mon>, see below).	564	C<mon>, see above).
502		565
503	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	566	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
504	will be reported as reason C<< die => $@ >>.	567	will be reported as reason C<< die => $@ >>.
505		568
506	Transport/communication errors are reported as C<< transport_error =>	569	Transport/communication errors are reported as C<< transport_error =>
507	$message >>.	570	$message >>.
508		571
		572	=cut
		573
		574	=item $port = spawn $node, $initfunc[, @initdata]
		575
		576	Creates a port on the node C<$node> (which can also be a port ID, in which
		577	case it's the node where that port resides).
		578
		579	The port ID of the newly created port is returned immediately, and it is
		580	possible to immediately start sending messages or to monitor the port.
		581
		582	After the port has been created, the init function is called on the remote
		583	node, in the same context as a C<rcv> callback. This function must be a
		584	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
		585	specify a function in the main program, use C<::name>.
		586
		587	If the function doesn't exist, then the node tries to C<require>
		588	the package, then the package above the package and so on (e.g.
		589	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		590	exists or it runs out of package names.
		591
		592	The init function is then called with the newly-created port as context
		593	object (C<$SELF>) and the C<@initdata> values as arguments.
		594
		595	A common idiom is to pass a local port, immediately monitor the spawned
		596	port, and in the remote init function, immediately monitor the passed
		597	local port. This two-way monitoring ensures that both ports get cleaned up
		598	when there is a problem.
		599
		600	Example: spawn a chat server port on C<$othernode>.
		601
		602	# this node, executed from within a port context:
		603	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		604	mon $server;
		605
		606	# init function on C<$othernode>
		607	sub connect {
		608	my ($srcport) = @_;
		609
		610	mon $srcport;
		611
		612	rcv $SELF, sub {
		613	...
		614	};
		615	}
		616
		617	=cut
		618
		619	sub _spawn {
		620	my $port = shift;
		621	my $init = shift;
		622
		623	local $SELF = "$NODE#$port";
		624	eval {
		625	&{ load_func $init }
		626	};
		627	_self_die if $@;
		628	}
		629
		630	sub spawn(@) {
		631	my ($noderef, undef) = split /#/, shift, 2;
		632
		633	my $id = "$RUNIQ." . $ID++;
		634
		635	$_[0] =~ /::/
		636	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		637
		638	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
		639
		640	"$noderef#$id"
		641	}
		642
		643	=item after $timeout, @msg
		644
		645	=item after $timeout, $callback
		646
		647	Either sends the given message, or call the given callback, after the
		648	specified number of seconds.
		649
		650	This is simply a utility function that comes in handy at times - the
		651	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		652	so it may go away in the future.
		653
		654	=cut
		655
		656	sub after($@) {
		657	my ($timeout, @action) = @_;
		658
		659	my $t; $t = AE::timer $timeout, 0, sub {
		660	undef $t;
		661	ref $action[0]
		662	? $action[0]()
		663	: snd @action;
		664	};
		665	}
		666
509	=back	667	=back
510		668
511	=head1 FUNCTIONS FOR NODES	669	=head1 AnyEvent::MP vs. Distributed Erlang
		670
		671	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
		672	== aemp node, Erlang process == aemp port), so many of the documents and
		673	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		674	sample:
		675
		676	http://www.Erlang.se/doc/programming_rules.shtml
		677	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		678	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		679	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		680
		681	Despite the similarities, there are also some important differences:
512		682
513	=over 4	683	=over 4
514		684
515	=item initialise_node $noderef, $seednode, $seednode...	685	=item * Node IDs are arbitrary strings in AEMP.
516		686
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	687	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	688	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
645	convenience functionality.	689	configuraiton or DNS), but will otherwise discover other odes itself.
646		690
647	This means that AEMP requires a less tightly controlled environment at the	691	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
648	cost of longer node references and a slightly higher management overhead.	692	uses "local ports are like remote ports".
		693
		694	The failure modes for local ports are quite different (runtime errors
		695	only) then for remote ports - when a local port dies, you I<know> it dies,
		696	when a connection to another node dies, you know nothing about the other
		697	port.
		698
		699	Erlang pretends remote ports are as reliable as local ports, even when
		700	they are not.
		701
		702	AEMP encourages a "treat remote ports differently" philosophy, with local
		703	ports being the special case/exception, where transport errors cannot
		704	occur.
649		705
650	=item * Erlang uses processes and a mailbox, AEMP does not queue.	706	=item * Erlang uses processes and a mailbox, AEMP does not queue.
651		707
652	Erlang uses processes that selctively receive messages, and therefore	708	Erlang uses processes that selectively receive messages, and therefore
653	needs a queue. AEMP is event based, queuing messages would serve no useful	709	needs a queue. AEMP is event based, queuing messages would serve no
654	purpose.	710	useful purpose. For the same reason the pattern-matching abilities of
		711	AnyEvent::MP are more limited, as there is little need to be able to
		712	filter messages without dequeing them.
655		713
656	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	714	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
657		715
658	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	716	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
659		717
660	Sending messages in erlang is synchronous and blocks the process. AEMP	718	Sending messages in Erlang is synchronous and blocks the process (and
661	sends are immediate, connection establishment is handled in the	719	so does not need a queue that can overflow). AEMP sends are immediate,
662	background.	720	connection establishment is handled in the background.
663		721
664	=item * Erlang can silently lose messages, AEMP cannot.	722	=item * Erlang suffers from silent message loss, AEMP does not.
665		723
666	Erlang makes few guarantees on messages delivery - messages can get lost	724	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,	725	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).	726	and c, and the other side only receives messages a and c).
669		727
670	AEMP guarantees correct ordering, and the guarantee that there are no	728	AEMP guarantees correct ordering, and the guarantee that after one message
671	holes in the message sequence.	729	is lost, all following ones sent to the same port are lost as well, until
672		730	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	731	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		732
684	=item * Erlang can send messages to the wrong port, AEMP does not.	733	=item * Erlang can send messages to the wrong port, AEMP does not.
685		734
686	In erlang it is quite possible that a node that restarts reuses a process	735	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	736	known to other nodes for a completely different process, causing messages
688	messages destined for that process to end up in an unrelated process.	737	destined for that process to end up in an unrelated process.
689		738
690	AEMP never reuses port IDs, so old messages or old port IDs floating	739	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.	740	around in the network will not be sent to an unrelated port.
692		741
693	=item * Erlang uses unprotected connections, AEMP uses secure	742	=item * Erlang uses unprotected connections, AEMP uses secure
694	authentication and can use TLS.	743	authentication and can use TLS.
695		744
696	AEMP can use a proven protocol - SSL/TLS - to protect connections and	745	AEMP can use a proven protocol - TLS - to protect connections and
697	securely authenticate nodes.	746	securely authenticate nodes.
698		747
699	=item * The AEMP protocol is optimised for both text-based and binary	748	=item * The AEMP protocol is optimised for both text-based and binary
700	communications.	749	communications.
701		750
702	The AEMP protocol, unlike the erlang protocol, supports both	751	The AEMP protocol, unlike the Erlang protocol, supports both programming
703	language-independent text-only protocols (good for debugging) and binary,	752	language independent text-only protocols (good for debugging) and binary,
704	language-specific serialisers (e.g. Storable).	753	language-specific serialisers (e.g. Storable). By default, unless TLS is
		754	used, the protocol is actually completely text-based.
705		755
706	It has also been carefully designed to be implementable in other languages	756	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	757	with a minimum of work while gracefully degrading functionality to make the
708	protocol simple.	758	protocol simple.
709		759
		760	=item * AEMP has more flexible monitoring options than Erlang.
		761
		762	In Erlang, you can chose to receive I<all> exit signals as messages
		763	or I<none>, there is no in-between, so monitoring single processes is
		764	difficult to implement. Monitoring in AEMP is more flexible than in
		765	Erlang, as one can choose between automatic kill, exit message or callback
		766	on a per-process basis.
		767
		768	=item * Erlang tries to hide remote/local connections, AEMP does not.
		769
		770	Monitoring in Erlang is not an indicator of process death/crashes, in the
		771	same way as linking is (except linking is unreliable in Erlang).
		772
		773	In AEMP, you don't "look up" registered port names or send to named ports
		774	that might or might not be persistent. Instead, you normally spawn a port
		775	on the remote node. The init function monitors you, and you monitor the
		776	remote port. Since both monitors are local to the node, they are much more
		777	reliable (no need for C<spawn_link>).
		778
		779	This also saves round-trips and avoids sending messages to the wrong port
		780	(hard to do in Erlang).
		781
710	=back	782	=back
711		783
		784	=head1 RATIONALE
		785
		786	=over 4
		787
		788	=item Why strings for port and node IDs, why not objects?
		789
		790	We considered "objects", but found that the actual number of methods
		791	that can be called are quite low. Since port and node IDs travel over
		792	the network frequently, the serialising/deserialising would add lots of
		793	overhead, as well as having to keep a proxy object everywhere.
		794
		795	Strings can easily be printed, easily serialised etc. and need no special
		796	procedures to be "valid".
		797
		798	And as a result, a miniport consists of a single closure stored in a
		799	global hash - it can't become much cheaper.
		800
		801	=item Why favour JSON, why not a real serialising format such as Storable?
		802
		803	In fact, any AnyEvent::MP node will happily accept Storable as framing
		804	format, but currently there is no way to make a node use Storable by
		805	default (although all nodes will accept it).
		806
		807	The default framing protocol is JSON because a) JSON::XS is many times
		808	faster for small messages and b) most importantly, after years of
		809	experience we found that object serialisation is causing more problems
		810	than it solves: Just like function calls, objects simply do not travel
		811	easily over the network, mostly because they will always be a copy, so you
		812	always have to re-think your design.
		813
		814	Keeping your messages simple, concentrating on data structures rather than
		815	objects, will keep your messages clean, tidy and efficient.
		816
		817	=back
		818
712	=head1 SEE ALSO	819	=head1 SEE ALSO
		820
		821	L<AnyEvent::MP::Intro> - a gentle introduction.
		822
		823	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		824
		825	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		826	your applications.
713		827
714	L<AnyEvent>.	828	L<AnyEvent>.
715		829
716	=head1 AUTHOR	830	=head1 AUTHOR
717		831

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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 1.71 by root, Sun Aug 30 19:52:56 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 1.71 by root, Sun Aug 30 19:52:56 2009 UTC