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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.39 by root, Fri Aug 7 23:21:48 2009 UTC vs.
Revision 1.65 by root, Fri Aug 28 01:00:34 2009 UTC

…		…
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	13	$SELF # receiving/own port id in rcv callbacks
		14
		15	# initialise the node so it can send/receive messages
		16	initialise_node;
14		17
15	# ports are message endpoints	18	# ports are message endpoints
16		19
17	# sending messages	20	# sending messages
18	snd $port, type => data...;	21	snd $port, type => data...;
19	snd $port, @msg;	22	snd $port, @msg;
20	snd @msg_with_first_element_being_a_port;	23	snd @msg_with_first_element_being_a_port;
21		24
22	# miniports	25	# creating/using ports, the simple way
23	my $miniport = port { my @msg = @_; 0 };	26	my $simple_port = port { my @msg = @_; 0 };
24		27
25	# full ports	28	# creating/using ports, tagged message matching
26	my $port = port;	29	my $port = port;
27	rcv $port, smartmatch => $cb->(@msg);
28	rcv $port, ping => sub { snd $_[0], "pong"; 0 };	30	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
29	rcv $port, pong => sub { warn "pong received\n"; 0 };	31	rcv $port, pong => sub { warn "pong received\n"; 0 };
30		32
31	# remote ports	33	# create a port on another node
32	my $port = spawn $node, $initfunc, @initdata;	34	my $port = spawn $node, $initfunc, @initdata;
33
34	# more, smarter, matches (_any_ is exported by this module)
35	rcv $port, [child_died => $pid] => sub { ...
36	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
37		35
38	# monitoring	36	# monitoring
39	mon $port, $cb->(@msg) # callback is invoked on death	37	mon $port, $cb->(@msg) # callback is invoked on death
40	mon $port, $otherport # kill otherport on abnormal death	38	mon $port, $otherport # kill otherport on abnormal death
41	mon $port, $otherport, @msg # send message on death	39	mon $port, $otherport, @msg # send message on death
42		40
		41	=head1 CURRENT STATUS
		42
		43	AnyEvent::MP - stable API, should work
		44	AnyEvent::MP::Intro - outdated
		45	AnyEvent::MP::Kernel - WIP
		46	AnyEvent::MP::Transport - mostly stable
		47
		48	stay tuned.
		49
43	=head1 DESCRIPTION	50	=head1 DESCRIPTION
44		51
45	This module (-family) implements a simple message passing framework.	52	This module (-family) implements a simple message passing framework.
46		53
47	Despite its simplicity, you can securely message other processes running	54	Despite its simplicity, you can securely message other processes running
…		…
50	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	57	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
51	manual page.	58	manual page.
52		59
53	At the moment, this module family is severly broken and underdocumented,	60	At the moment, this module family is severly broken and underdocumented,
54	so do not use. This was uploaded mainly to reserve the CPAN namespace -	61	so do not use. This was uploaded mainly to reserve the CPAN namespace -
55	stay tuned! The basic API should be finished, however.	62	stay tuned!
56		63
57	=head1 CONCEPTS	64	=head1 CONCEPTS
58		65
59	=over 4	66	=over 4
60		67
61	=item port	68	=item port
62		69
63	A port is something you can send messages to (with the C<snd> function).	70	A port is something you can send messages to (with the C<snd> function).
64		71
65	Some ports allow you to register C<rcv> handlers that can match specific	72	Ports allow you to register C<rcv> handlers that can match all or just
66	messages. All C<rcv> handlers will receive messages they match, messages	73	some messages. Messages send to ports will not be queued, regardless of
67	will not be queued.	74	anything was listening for them or not.
68		75
69	=item port id - C<noderef#portname>	76	=item port ID - C<noderef#portname>
70		77
71	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	78	A port ID is the concatenation of a noderef, a hash-mark (C<#>) as
72	separator, and a port name (a printable string of unspecified format). An	79	separator, and a port name (a printable string of unspecified format). An
73	exception is the the node port, whose ID is identical to its node	80	exception is the the node port, whose ID is identical to its node
74	reference.	81	reference.
75		82
76	=item node	83	=item node
77		84
78	A node is a single process containing at least one port - the node	85	A node is a single process containing at least one port - the node port,
79	port. You can send messages to node ports to find existing ports or to	86	which provides nodes to manage each other remotely, and to create new
80	create new ports, among other things.	87	ports.
81		88
82	Nodes are either private (single-process only), slaves (connected to a	89	Nodes are either private (single-process only), slaves (can only talk to
83	master node only) or public nodes (connectable from unrelated nodes).	90	public nodes, but do not need an open port) or public nodes (connectable
		91	from any other node).
84		92
85	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	93	=item node ID - C<[a-za-Z0-9_\-.:]+>
86		94
87	A node reference is a string that either simply identifies the node (for	95	A node ID is a string that uniquely identifies the node within a
88	private and slave nodes), or contains a recipe on how to reach a given	96	network. Depending on the configuration used, node IDs can look like a
89	node (for public nodes).	97	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
		98	doesn't interpret node IDs in any way.
90		99
91	This recipe is simply a comma-separated list of C<address:port> pairs (for	100	=item binds - C<ip:port>
92	TCP/IP, other protocols might look different).
93		101
94	Node references come in two flavours: resolved (containing only numerical	102	Nodes can only talk to each other by creating some kind of connection to
95	addresses) or unresolved (where hostnames are used instead of addresses).	103	each other. To do this, nodes should listen on one or more local transport
		104	endpoints - binds. Currently, only standard C<ip:port> specifications can
		105	be used, which specify TCP ports to listen on.
96		106
97	Before using an unresolved node reference in a message you first have to	107	=item seeds - C<host:port>
98	resolve it.	108
		109	When a node starts, it knows nothing about the network. To teach the node
		110	about the network it first has to contact some other node within the
		111	network. This node is called a seed.
		112
		113	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes
		114	are expected to be long-running, and at least one of those should always
		115	be available. When nodes run out of connections (e.g. due to a network
		116	error), they try to re-establish connections to some seednodes again to
		117	join the network.
99		118
100	=back	119	=back
101		120
102	=head1 VARIABLES/FUNCTIONS	121	=head1 VARIABLES/FUNCTIONS
103		122
…		…
105		124
106	=cut	125	=cut
107		126
108	package AnyEvent::MP;	127	package AnyEvent::MP;
109		128
110	use AnyEvent::MP::Base;	129	use AnyEvent::MP::Kernel;
111		130
112	use common::sense;	131	use common::sense;
113		132
114	use Carp ();	133	use Carp ();
115		134
116	use AE ();	135	use AE ();
117		136
118	use base "Exporter";	137	use base "Exporter";
119		138
120	our $VERSION = '0.1';	139	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		140
121	our @EXPORT = qw(	141	our @EXPORT = qw(
122	NODE $NODE *SELF node_of _any_	142	NODE $NODE *SELF node_of after
123	resolve_node initialise_node	143	resolve_node initialise_node
124	snd rcv mon kil reg psub spawn	144	snd rcv mon mon_guard kil reg psub spawn
125	port	145	port
126	);	146	);
127		147
128	our $SELF;	148	our $SELF;
129		149
…		…
133	kil $SELF, die => $msg;	153	kil $SELF, die => $msg;
134	}	154	}
135		155
136	=item $thisnode = NODE / $NODE	156	=item $thisnode = NODE / $NODE
137		157
138	The C<NODE> function returns, and the C<$NODE> variable contains	158	The C<NODE> function returns, and the C<$NODE> variable contains the node
139	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
140	to C<become_public> or C<become_slave>, after which all local port	160	a call to C<initialise_node>.
141	identifiers become invalid.
142		161
143	=item $noderef = node_of $port	162	=item $nodeid = node_of $port
144		163
145	Extracts and returns the noderef from a portid or a noderef.	164	Extracts and returns the node ID part from a port ID or a node ID.
146		165
147	=item initialise_node $noderef, $seednode, $seednode...	166	=item initialise_node $profile_name
148		167
149	=item initialise_node "slave/", $master, $master...
150
151	Before a node can talk to other nodes on the network it has to initialise	168	Before a node can talk to other nodes on the network (i.e. enter
152	itself - the minimum a node needs to know is it's own name, and optionally	169	"distributed mode") it has to initialise itself - the minimum a node needs
153	it should know the noderefs of some other nodes in the network.	170	to know is its own name, and optionally it should know the addresses of
		171	some other nodes in the network to discover other nodes.
154		172
155	This function initialises a node - it must be called exactly once (or	173	This function initialises a node - it must be called exactly once (or
156	never) before calling other AnyEvent::MP functions.	174	never) before calling other AnyEvent::MP functions.
157		175
158	All arguments are noderefs, which can be either resolved or unresolved.	176	The first argument is a profile name. If it is C<undef> or missing, then
		177	the current nodename will be used instead (i.e. F<uname -n>).
159		178
160	There are two types of networked nodes, public nodes and slave nodes:	179	The function then looks up the profile in the aemp configuration (see the
		180	L<aemp> commandline utility).
161		181
162	=over 4	182	If the profile specifies a node ID, then this will become the node ID of
		183	this process. If not, then the profile name will be used as node ID. The
		184	special node ID of C<anon/> will be replaced by a random node ID.
163		185
164	=item public nodes	186	The next step is to look up the binds in the profile, followed by binding
		187	aemp protocol listeners on all binds specified (it is possible and valid
		188	to have no binds, meaning that the node cannot be contacted form the
		189	outside. This means the node cannot talk to other nodes that also have no
		190	binds, but it can still talk to all "normal" nodes).
165		191
166	For public nodes, C<$noderef> must either be a (possibly unresolved)	192	If the profile does not specify a binds list, then the node ID will be
167	noderef, in which case it will be resolved, or C<undef> (or missing), in	193	treated as if it were of the form C<host:port>, which will be resolved and
168	which case the noderef will be guessed.	194	used as binds list.
169		195
170	Afterwards, the node will bind itself on all endpoints and try to connect	196	Lastly, the seeds list from the profile is passed to the
171	to all additional C<$seednodes> that are specified. Seednodes are optional	197	L<AnyEvent::MP::Global> module, which will then use it to keep
172	and can be used to quickly bootstrap the node into an existing network.	198	connectivity with at least on of those seed nodes at any point in time.
173		199
174	=item slave nodes	200	Example: become a distributed node listening on the guessed noderef, or
175		201	the one specified via C<aemp> for the current node. This should be the
176	When the C<$noderef> is the special string C<slave/>, then the node will	202	most common form of invocation for "daemon"-type nodes.
177	become a slave node. Slave nodes cannot be contacted from outside and will
178	route most of their traffic to the master node that they attach to.
179
180	At least one additional noderef is required: The node will try to connect
181	to all of them and will become a slave attached to the first node it can
182	successfully connect to.
183
184	=back
185
186	This function will block until all nodes have been resolved and, for slave
187	nodes, until it has successfully established a connection to a master
188	server.
189
190	Example: become a public node listening on the default node.
191		203
192	initialise_node;	204	initialise_node;
193		205
194	Example: become a public node, and try to contact some well-known master	206	Example: become an anonymous node. This form is often used for commandline
195	servers to become part of the network.	207	clients.
196		208
197	initialise_node undef, "master1", "master2";
198
199	Example: become a public node listening on port C<4041>.
200
201	initialise_node 4041;	209	initialise_node "anon/";
202		210
203	Example: become a public node, only visible on localhost port 4044.	211	Example: become a distributed node. If there is no profile of the given
		212	name, or no binds list was specified, resolve C<localhost:4044> and bind
		213	on the resulting addresses.
204		214
205	initialise_node "locahost:4044";	215	initialise_node "localhost:4044";
206
207	Example: become a slave node to any of the specified master servers.
208
209	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
210
211	=item $cv = resolve_node $noderef
212
213	Takes an unresolved node reference that may contain hostnames and
214	abbreviated IDs, resolves all of them and returns a resolved node
215	reference.
216
217	In addition to C<address:port> pairs allowed in resolved noderefs, the
218	following forms are supported:
219
220	=over 4
221
222	=item the empty string
223
224	An empty-string component gets resolved as if the default port (4040) was
225	specified.
226
227	=item naked port numbers (e.g. C<1234>)
228
229	These are resolved by prepending the local nodename and a colon, to be
230	further resolved.
231
232	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
233
234	These are resolved by using AnyEvent::DNS to resolve them, optionally
235	looking up SRV records for the C<aemp=4040> port, if no port was
236	specified.
237
238	=back
239		216
240	=item $SELF	217	=item $SELF
241		218
242	Contains the current port id while executing C<rcv> callbacks or C<psub>	219	Contains the current port id while executing C<rcv> callbacks or C<psub>
243	blocks.	220	blocks.
…		…
251	=item snd $port, type => @data	228	=item snd $port, type => @data
252		229
253	=item snd $port, @msg	230	=item snd $port, @msg
254		231
255	Send the given message to the given port ID, which can identify either	232	Send the given message to the given port ID, which can identify either
256	a local or a remote port, and can be either a string or soemthignt hat	233	a local or a remote port, and must be a port ID.
257	stringifies a sa port ID (such as a port object :).
258		234
259	While the message can be about anything, it is highly recommended to use a	235	While the message can be about anything, it is highly recommended to use a
260	string as first element (a portid, or some word that indicates a request	236	string as first element (a port ID, or some word that indicates a request
261	type etc.).	237	type etc.).
262		238
263	The message data effectively becomes read-only after a call to this	239	The message data effectively becomes read-only after a call to this
264	function: modifying any argument is not allowed and can cause many	240	function: modifying any argument is not allowed and can cause many
265	problems.	241	problems.
…		…
270	that Storable can serialise and deserialise is allowed, and for the local	246	that Storable can serialise and deserialise is allowed, and for the local
271	node, anything can be passed.	247	node, anything can be passed.
272		248
273	=item $local_port = port	249	=item $local_port = port
274		250
275	Create a new local port object that can be used either as a pattern	251	Create a new local port object and returns its port ID. Initially it has
276	matching port ("full port") or a single-callback port ("miniport"),	252	no callbacks set and will throw an error when it receives messages.
277	depending on how C<rcv> callbacks are bound to the object.
278		253
279	=item $port = port { my @msg = @_; $finished }	254	=item $local_port = port { my @msg = @_ }
280		255
281	Creates a "miniport", that is, a very lightweight port without any pattern	256	Creates a new local port, and returns its ID. Semantically the same as
282	matching behind it, and returns its ID. Semantically the same as creating
283	a port and calling C<rcv $port, $callback> on it.	257	creating a port and calling C<rcv $port, $callback> on it.
284		258
285	The block will be called for every message received on the port. When the	259	The block will be called for every message received on the port, with the
286	callback returns a true value its job is considered "done" and the port	260	global variable C<$SELF> set to the port ID. Runtime errors will cause the
287	will be destroyed. Otherwise it will stay alive.	261	port to be C<kil>ed. The message will be passed as-is, no extra argument
		262	(i.e. no port ID) will be passed to the callback.
288		263
289	The message will be passed as-is, no extra argument (i.e. no port id) will	264	If you want to stop/destroy the port, simply C<kil> it:
290	be passed to the callback.
291		265
292	If you need the local port id in the callback, this works nicely:	266	my $port = port {
293		267	my @msg = @_;
294	my $port; $port = port {	268	...
295	snd $otherport, reply => $port;	269	kil $SELF;
296	};	270	};
297		271
298	=cut	272	=cut
299		273
300	sub rcv($@);	274	sub rcv($@);
		275
		276	sub _kilme {
		277	die "received message on port without callback";
		278	}
301		279
302	sub port(;&) {	280	sub port(;&) {
303	my $id = "$UNIQ." . $ID++;	281	my $id = "$UNIQ." . $ID++;
304	my $port = "$NODE#$id";	282	my $port = "$NODE#$id";
305		283
306	if (@_) {	284	rcv $port, shift \|\| \&_kilme;
307	rcv $port, shift;
308	} else {
309	$PORT{$id} = sub { }; # nop
310	}
311		285
312	$port	286	$port
313	}	287	}
314		288
315	=item reg $port, $name
316
317	=item reg $name
318
319	Registers the given port (or C<$SELF><<< if missing) under the name
320	C<$name>. If the name already exists it is replaced.
321
322	A port can only be registered under one well known name.
323
324	A port automatically becomes unregistered when it is killed.
325
326	=cut
327
328	sub reg(@) {
329	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
330
331	$REG{$_[0]} = $port;
332	}
333
334	=item rcv $port, $callback->(@msg)	289	=item rcv $local_port, $callback->(@msg)
335		290
336	Replaces the callback on the specified miniport (after converting it to	291	Replaces the default callback on the specified port. There is no way to
337	one if required).	292	remove the default callback: use C<sub { }> to disable it, or better
338		293	C<kil> the port when it is no longer needed.
339	=item rcv $port, tagstring => $callback->(@msg), ...
340
341	=item rcv $port, $smartmatch => $callback->(@msg), ...
342
343	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
344
345	Register callbacks to be called on matching messages on the given full
346	port (after converting it to one if required) and return the port.
347
348	The callback has to return a true value when its work is done, after
349	which is will be removed, or a false value in which case it will stay
350	registered.
351		294
352	The global C<$SELF> (exported by this module) contains C<$port> while	295	The global C<$SELF> (exported by this module) contains C<$port> while
353	executing the callback.	296	executing the callback. Runtime errors during callback execution will
		297	result in the port being C<kil>ed.
354		298
355	Runtime errors during callback execution will result in the port being	299	The default callback received all messages not matched by a more specific
356	C<kil>ed.	300	C<tag> match.
357		301
358	If the match is an array reference, then it will be matched against the	302	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
359	first elements of the message, otherwise only the first element is being
360	matched.
361		303
362	Any element in the match that is specified as C<_any_> (a function	304	Register (or replace) callbacks to be called on messages starting with the
363	exported by this module) matches any single element of the message.	305	given tag on the given port (and return the port), or unregister it (when
		306	C<$callback> is C<$undef> or missing). There can only be one callback
		307	registered for each tag.
364		308
365	While not required, it is highly recommended that the first matching	309	The original message will be passed to the callback, after the first
366	element is a string identifying the message. The one-string-only match is	310	element (the tag) has been removed. The callback will use the same
367	also the most efficient match (by far).	311	environment as the default callback (see above).
368		312
369	Example: create a port and bind receivers on it in one go.	313	Example: create a port and bind receivers on it in one go.
370		314
371	my $port = rcv port,	315	my $port = rcv port,
372	msg1 => sub { ...; 0 },	316	msg1 => sub { ... },
373	msg2 => sub { ...; 0 },	317	msg2 => sub { ... },
374	;	318	;
375		319
376	Example: create a port, bind receivers and send it in a message elsewhere	320	Example: create a port, bind receivers and send it in a message elsewhere
377	in one go:	321	in one go:
378		322
379	snd $otherport, reply =>	323	snd $otherport, reply =>
380	rcv port,	324	rcv port,
381	msg1 => sub { ...; 0 },	325	msg1 => sub { ... },
382	...	326	...
383	;	327	;
		328
		329	Example: temporarily register a rcv callback for a tag matching some port
		330	(e.g. for a rpc reply) and unregister it after a message was received.
		331
		332	rcv $port, $otherport => sub {
		333	my @reply = @_;
		334
		335	rcv $SELF, $otherport;
		336	};
384		337
385	=cut	338	=cut
386		339
387	sub rcv($@) {	340	sub rcv($@) {
388	my $port = shift;	341	my $port = shift;
389	my ($noderef, $portid) = split /#/, $port, 2;	342	my ($noderef, $portid) = split /#/, $port, 2;
390		343
391	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	344	$NODE{$noderef} == $NODE{""}
392	or Carp::croak "$port: rcv can only be called on local ports, caught";	345	or Carp::croak "$port: rcv can only be called on local ports, caught";
393		346
394	if (@_ == 1) {	347	while (@_) {
		348	if (ref $_[0]) {
		349	if (my $self = $PORT_DATA{$portid}) {
		350	"AnyEvent::MP::Port" eq ref $self
		351	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		352
		353	$self->[2] = shift;
		354	} else {
395	my $cb = shift;	355	my $cb = shift;
396	delete $PORT_DATA{$portid};
397	$PORT{$portid} = sub {	356	$PORT{$portid} = sub {
398	local $SELF = $port;	357	local $SELF = $port;
399	eval {	358	eval { &$cb }; _self_die if $@;
400	&$cb	359	};
401	and kil $port;
402	};	360	}
403	_self_die if $@;	361	} elsif (defined $_[0]) {
404	};
405	} else {
406	my $self = $PORT_DATA{$portid} \|\|= do {	362	my $self = $PORT_DATA{$portid} \|\|= do {
407	my $self = bless {	363	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
408	id => $port,
409	}, "AnyEvent::MP::Port";
410		364
411	$PORT{$portid} = sub {	365	$PORT{$portid} = sub {
412	local $SELF = $port;	366	local $SELF = $port;
413		367
414	eval {
415	for (@{ $self->{rc0}{$_[0]} }) {	368	if (my $cb = $self->[1]{$_[0]}) {
416	$_ && &{$_->[0]}	369	shift;
417	&& undef $_;	370	eval { &$cb }; _self_die if $@;
418	}	371	} else {
419
420	for (@{ $self->{rcv}{$_[0]} }) {
421	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
422	&& &{$_->[0]}	372	&{ $self->[0] };
423	&& undef $_;
424	}
425
426	for (@{ $self->{any} }) {
427	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
428	&& &{$_->[0]}
429	&& undef $_;
430	}	373	}
431	};	374	};
432	_self_die if $@;	375
		376	$self
433	};	377	};
434		378
435	$self
436	};
437
438	"AnyEvent::MP::Port" eq ref $self	379	"AnyEvent::MP::Port" eq ref $self
439	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	380	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
440		381
441	while (@_) {
442	my ($match, $cb) = splice @_, 0, 2;	382	my ($tag, $cb) = splice @_, 0, 2;
443		383
444	if (!ref $match) {	384	if (defined $cb) {
445	push @{ $self->{rc0}{$match} }, [$cb];	385	$self->[1]{$tag} = $cb;
446	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
447	my ($type, @match) = @$match;
448	@match
449	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
450	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
451	} else {	386	} else {
452	push @{ $self->{any} }, [$cb, $match];	387	delete $self->[1]{$tag};
453	}	388	}
454	}	389	}
455	}	390	}
456		391
457	$port	392	$port
…		…
501		436
502	=item $guard = mon $port	437	=item $guard = mon $port
503		438
504	=item $guard = mon $port, $rcvport, @msg	439	=item $guard = mon $port, $rcvport, @msg
505		440
506	Monitor the given port and do something when the port is killed, and	441	Monitor the given port and do something when the port is killed or
507	optionally return a guard that can be used to stop monitoring again.	442	messages to it were lost, and optionally return a guard that can be used
		443	to stop monitoring again.
		444
		445	C<mon> effectively guarantees that, in the absence of hardware failures,
		446	that after starting the monitor, either all messages sent to the port
		447	will arrive, or the monitoring action will be invoked after possible
		448	message loss has been detected. No messages will be lost "in between"
		449	(after the first lost message no further messages will be received by the
		450	port). After the monitoring action was invoked, further messages might get
		451	delivered again.
		452
		453	Note that monitoring-actions are one-shot: once released, they are removed
		454	and will not trigger again.
508		455
509	In the first form (callback), the callback is simply called with any	456	In the first form (callback), the callback is simply called with any
510	number of C<@reason> elements (no @reason means that the port was deleted	457	number of C<@reason> elements (no @reason means that the port was deleted
511	"normally"). Note also that I<< the callback B<must> never die >>, so use	458	"normally"). Note also that I<< the callback B<must> never die >>, so use
512	C<eval> if unsure.	459	C<eval> if unsure.
513		460
514	In the second form (another port given), the other port (C<$rcvport)	461	In the second form (another port given), the other port (C<$rcvport>)
515	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on	462	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
516	"normal" kils nothing happens, while under all other conditions, the other	463	"normal" kils nothing happens, while under all other conditions, the other
517	port is killed with the same reason.	464	port is killed with the same reason.
518		465
519	The third form (kill self) is the same as the second form, except that	466	The third form (kill self) is the same as the second form, except that
…		…
546	sub mon {	493	sub mon {
547	my ($noderef, $port) = split /#/, shift, 2;	494	my ($noderef, $port) = split /#/, shift, 2;
548		495
549	my $node = $NODE{$noderef} \|\| add_node $noderef;	496	my $node = $NODE{$noderef} \|\| add_node $noderef;
550		497
551	my $cb = @_ ? $_[0] : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	498	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
552		499
553	unless (ref $cb) {	500	unless (ref $cb) {
554	if (@_) {	501	if (@_) {
555	# send a kill info message	502	# send a kill info message
556	my (@msg) = @_;	503	my (@msg) = ($cb, @_);
557	$cb = sub { snd @msg, @_ };	504	$cb = sub { snd @msg, @_ };
558	} else {	505	} else {
559	# simply kill other port	506	# simply kill other port
560	my $port = $cb;	507	my $port = $cb;
561	$cb = sub { kil $port, @_ if @_ };	508	$cb = sub { kil $port, @_ if @_ };
…		…
620	The port ID of the newly created port is return immediately, and it is	567	The port ID of the newly created port is return immediately, and it is
621	permissible to immediately start sending messages or monitor the port.	568	permissible to immediately start sending messages or monitor the port.
622		569
623	After the port has been created, the init function is	570	After the port has been created, the init function is
624	called. This function must be a fully-qualified function name	571	called. This function must be a fully-qualified function name
625	(e.g. C<MyApp::Chat::Server::init>).	572	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		573	program, use C<::name>.
626		574
627	If the function doesn't exist, then the node tries to C<require>	575	If the function doesn't exist, then the node tries to C<require>
628	the package, then the package above the package and so on (e.g.	576	the package, then the package above the package and so on (e.g.
629	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	577	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
630	exists or it runs out of package names.	578	exists or it runs out of package names.
…		…
672	my $id = "$RUNIQ." . $ID++;	620	my $id = "$RUNIQ." . $ID++;
673		621
674	$_[0] =~ /::/	622	$_[0] =~ /::/
675	or Carp::croak "spawn init function must be a fully-qualified name, caught";	623	or Carp::croak "spawn init function must be a fully-qualified name, caught";
676		624
677	($NODE{$noderef} \|\| add_node $noderef)	625	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
678	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
679		626
680	"$noderef#$id"	627	"$noderef#$id"
681	}	628	}
682		629
683	=back	630	=item after $timeout, @msg
684		631
685	=head1 NODE MESSAGES	632	=item after $timeout, $callback
686		633
687	Nodes understand the following messages sent to them. Many of them take	634	Either sends the given message, or call the given callback, after the
688	arguments called C<@reply>, which will simply be used to compose a reply	635	specified number of seconds.
689	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
690	the remaining arguments are simply the message data.
691		636
692	While other messages exist, they are not public and subject to change.	637	This is simply a utility function that come sin handy at times.
693		638
694	=over 4
695
696	=cut	639	=cut
697		640
698	=item lookup => $name, @reply	641	sub after($@) {
		642	my ($timeout, @action) = @_;
699		643
700	Replies with the port ID of the specified well-known port, or C<undef>.	644	my $t; $t = AE::timer $timeout, 0, sub {
701		645	undef $t;
702	=item devnull => ...	646	ref $action[0]
703		647	? $action[0]()
704	Generic data sink/CPU heat conversion.	648	: snd @action;
705		649	};
706	=item relay => $port, @msg	650	}
707
708	Simply forwards the message to the given port.
709
710	=item eval => $string[ @reply]
711
712	Evaluates the given string. If C<@reply> is given, then a message of the
713	form C<@reply, $@, @evalres> is sent.
714
715	Example: crash another node.
716
717	snd $othernode, eval => "exit";
718
719	=item time => @reply
720
721	Replies the the current node time to C<@reply>.
722
723	Example: tell the current node to send the current time to C<$myport> in a
724	C<timereply> message.
725
726	snd $NODE, time => $myport, timereply => 1, 2;
727	# => snd $myport, timereply => 1, 2, <time>
728		651
729	=back	652	=back
730		653
731	=head1 AnyEvent::MP vs. Distributed Erlang	654	=head1 AnyEvent::MP vs. Distributed Erlang
732		655
…		…
742		665
743	Despite the similarities, there are also some important differences:	666	Despite the similarities, there are also some important differences:
744		667
745	=over 4	668	=over 4
746		669
747	=item * Node references contain the recipe on how to contact them.	670	=item * Node IDs are arbitrary strings in AEMP.
748		671
749	Erlang relies on special naming and DNS to work everywhere in the	672	Erlang relies on special naming and DNS to work everywhere in the same
750	same way. AEMP relies on each node knowing it's own address(es), with	673	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
751	convenience functionality.	674	configuraiton or DNS), but will otherwise discover other odes itself.
752		675
753	This means that AEMP requires a less tightly controlled environment at the	676	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
754	cost of longer node references and a slightly higher management overhead.	677	uses "local ports are like remote ports".
		678
		679	The failure modes for local ports are quite different (runtime errors
		680	only) then for remote ports - when a local port dies, you I<know> it dies,
		681	when a connection to another node dies, you know nothing about the other
		682	port.
		683
		684	Erlang pretends remote ports are as reliable as local ports, even when
		685	they are not.
		686
		687	AEMP encourages a "treat remote ports differently" philosophy, with local
		688	ports being the special case/exception, where transport errors cannot
		689	occur.
755		690
756	=item * Erlang uses processes and a mailbox, AEMP does not queue.	691	=item * Erlang uses processes and a mailbox, AEMP does not queue.
757		692
758	Erlang uses processes that selctively receive messages, and therefore	693	Erlang uses processes that selectively receive messages, and therefore
759	needs a queue. AEMP is event based, queuing messages would serve no useful	694	needs a queue. AEMP is event based, queuing messages would serve no
760	purpose.	695	useful purpose. For the same reason the pattern-matching abilities of
		696	AnyEvent::MP are more limited, as there is little need to be able to
		697	filter messages without dequeing them.
761		698
762	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	699	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
763		700
764	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	701	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
765		702
766	Sending messages in Erlang is synchronous and blocks the process. AEMP	703	Sending messages in Erlang is synchronous and blocks the process (and
767	sends are immediate, connection establishment is handled in the	704	so does not need a queue that can overflow). AEMP sends are immediate,
768	background.	705	connection establishment is handled in the background.
769		706
770	=item * Erlang can silently lose messages, AEMP cannot.	707	=item * Erlang suffers from silent message loss, AEMP does not.
771		708
772	Erlang makes few guarantees on messages delivery - messages can get lost	709	Erlang makes few guarantees on messages delivery - messages can get lost
773	without any of the processes realising it (i.e. you send messages a, b,	710	without any of the processes realising it (i.e. you send messages a, b,
774	and c, and the other side only receives messages a and c).	711	and c, and the other side only receives messages a and c).
775		712
…		…
787	eventually be killed - it cannot happen that a node detects a port as dead	724	eventually be killed - it cannot happen that a node detects a port as dead
788	and then later sends messages to it, finding it is still alive.	725	and then later sends messages to it, finding it is still alive.
789		726
790	=item * Erlang can send messages to the wrong port, AEMP does not.	727	=item * Erlang can send messages to the wrong port, AEMP does not.
791		728
792	In Erlang it is quite possible that a node that restarts reuses a process	729	In Erlang it is quite likely that a node that restarts reuses a process ID
793	ID known to other nodes for a completely different process, causing	730	known to other nodes for a completely different process, causing messages
794	messages destined for that process to end up in an unrelated process.	731	destined for that process to end up in an unrelated process.
795		732
796	AEMP never reuses port IDs, so old messages or old port IDs floating	733	AEMP never reuses port IDs, so old messages or old port IDs floating
797	around in the network will not be sent to an unrelated port.	734	around in the network will not be sent to an unrelated port.
798		735
799	=item * Erlang uses unprotected connections, AEMP uses secure	736	=item * Erlang uses unprotected connections, AEMP uses secure
…		…
835	This also saves round-trips and avoids sending messages to the wrong port	772	This also saves round-trips and avoids sending messages to the wrong port
836	(hard to do in Erlang).	773	(hard to do in Erlang).
837		774
838	=back	775	=back
839		776
		777	=head1 RATIONALE
		778
		779	=over 4
		780
		781	=item Why strings for ports and noderefs, why not objects?
		782
		783	We considered "objects", but found that the actual number of methods
		784	thatc an be called are very low. Since port IDs and noderefs travel over
		785	the network frequently, the serialising/deserialising would add lots of
		786	overhead, as well as having to keep a proxy object.
		787
		788	Strings can easily be printed, easily serialised etc. and need no special
		789	procedures to be "valid".
		790
		791	And a a miniport consists of a single closure stored in a global hash - it
		792	can't become much cheaper.
		793
		794	=item Why favour JSON, why not real serialising format such as Storable?
		795
		796	In fact, any AnyEvent::MP node will happily accept Storable as framing
		797	format, but currently there is no way to make a node use Storable by
		798	default.
		799
		800	The default framing protocol is JSON because a) JSON::XS is many times
		801	faster for small messages and b) most importantly, after years of
		802	experience we found that object serialisation is causing more problems
		803	than it gains: Just like function calls, objects simply do not travel
		804	easily over the network, mostly because they will always be a copy, so you
		805	always have to re-think your design.
		806
		807	Keeping your messages simple, concentrating on data structures rather than
		808	objects, will keep your messages clean, tidy and efficient.
		809
		810	=back
		811
840	=head1 SEE ALSO	812	=head1 SEE ALSO
841		813
842	L<AnyEvent>.	814	L<AnyEvent>.
843		815
844	=head1 AUTHOR	816	=head1 AUTHOR

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.39 by root, Fri Aug 7 23:21:48 2009 UTC vs. Revision 1.65 by root, Fri Aug 28 01:00:34 2009 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.39 by root, Fri Aug 7 23:21:48 2009 UTC vs.
Revision 1.65 by root, Fri Aug 28 01:00:34 2009 UTC