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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.37 by root, Fri Aug 7 16:47:23 2009 UTC vs.
Revision 1.65 by root, Fri Aug 28 01:00:34 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
27		35
28	# monitoring	36	# monitoring
29	mon $port, $cb->(@msg) # callback is invoked on death	37	mon $port, $cb->(@msg) # callback is invoked on death
30	mon $port, $otherport # kill otherport on abnormal death	38	mon $port, $otherport # kill otherport on abnormal death
31	mon $port, $otherport, @msg # send message on death	39	mon $port, $otherport, @msg # send message on death
32		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		44	AnyEvent::MP::Intro - outdated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
33	=head1 DESCRIPTION	50	=head1 DESCRIPTION
34		51
35	This module (-family) implements a simple message passing framework.	52	This module (-family) implements a simple message passing framework.
36		53
37	Despite its simplicity, you can securely message other processes running	54	Despite its simplicity, you can securely message other processes running
…		…
40	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>
41	manual page.	58	manual page.
42		59
43	At the moment, this module family is severly broken and underdocumented,	60	At the moment, this module family is severly broken and underdocumented,
44	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 -
45	stay tuned! The basic API should be finished, however.	62	stay tuned!
46		63
47	=head1 CONCEPTS	64	=head1 CONCEPTS
48		65
49	=over 4	66	=over 4
50		67
51	=item port	68	=item port
52		69
53	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).
54		71
55	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
56	messages. All C<rcv> handlers will receive messages they match, messages	73	some messages. Messages send to ports will not be queued, regardless of
57	will not be queued.	74	anything was listening for them or not.
58		75
59	=item port id - C<noderef#portname>	76	=item port ID - C<noderef#portname>
60		77
61	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
62	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
63	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
64	reference.	81	reference.
65		82
66	=item node	83	=item node
67		84
68	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,
69	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
70	create new ports, among other things.	87	ports.
71		88
72	Nodes are either private (single-process only), slaves (connected to a	89	Nodes are either private (single-process only), slaves (can only talk to
73	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).
74		92
75	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	93	=item node ID - C<[a-za-Z0-9_\-.:]+>
76		94
77	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
78	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
79	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.
80		99
81	This recipe is simply a comma-separated list of C<address:port> pairs (for	100	=item binds - C<ip:port>
82	TCP/IP, other protocols might look different).
83		101
84	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
85	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.
86		106
87	Before using an unresolved node reference in a message you first have to	107	=item seeds - C<host:port>
88	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.
89		118
90	=back	119	=back
91		120
92	=head1 VARIABLES/FUNCTIONS	121	=head1 VARIABLES/FUNCTIONS
93		122
…		…
95		124
96	=cut	125	=cut
97		126
98	package AnyEvent::MP;	127	package AnyEvent::MP;
99		128
100	use AnyEvent::MP::Base;	129	use AnyEvent::MP::Kernel;
101		130
102	use common::sense;	131	use common::sense;
103		132
104	use Carp ();	133	use Carp ();
105		134
106	use AE ();	135	use AE ();
107		136
108	use base "Exporter";	137	use base "Exporter";
109		138
110	our $VERSION = '0.1';	139	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		140
111	our @EXPORT = qw(	141	our @EXPORT = qw(
112	NODE $NODE *SELF node_of _any_	142	NODE $NODE *SELF node_of after
113	resolve_node initialise_node	143	resolve_node initialise_node
114	snd rcv mon kil reg psub	144	snd rcv mon mon_guard kil reg psub spawn
115	port	145	port
116	);	146	);
117		147
118	our $SELF;	148	our $SELF;
119		149
…		…
123	kil $SELF, die => $msg;	153	kil $SELF, die => $msg;
124	}	154	}
125		155
126	=item $thisnode = NODE / $NODE	156	=item $thisnode = NODE / $NODE
127		157
128	The C<NODE> function returns, and the C<$NODE> variable contains	158	The C<NODE> function returns, and the C<$NODE> variable contains the node
129	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
130	to C<become_public> or C<become_slave>, after which all local port	160	a call to C<initialise_node>.
131	identifiers become invalid.
132		161
133	=item $noderef = node_of $port	162	=item $nodeid = node_of $port
134		163
135	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.
136		165
137	=item initialise_node $noderef, $seednode, $seednode...	166	=item initialise_node $profile_name
138		167
139	=item initialise_node "slave/", $master, $master...
140
141	Before a node can talk to other nodes on the network it has to initialise	168	Before a node can talk to other nodes on the network (i.e. enter
142	itself - the minimum a node needs to know is it's own name, and optionally	169	"distributed mode") it has to initialise itself - the minimum a node needs
143	it should know the noderefs of some other nodes in the network.	170	to know is its own name, and optionally it should know the addresses of
		171	some other nodes in the network to discover other nodes.
144		172
145	This function initialises a node - it must be called exactly once (or	173	This function initialises a node - it must be called exactly once (or
146	never) before calling other AnyEvent::MP functions.	174	never) before calling other AnyEvent::MP functions.
147		175
148	All arguments are noderefs, which can be either resolved or unresolved.	176	The first argument is a profile name. If it is C<undef> or missing, then
		177	the current nodename will be used instead (i.e. F<uname -n>).
149		178
150	There are two types of networked nodes, public nodes and slave nodes:	179	The function then looks up the profile in the aemp configuration (see the
		180	L<aemp> commandline utility).
151		181
152	=over 4	182	If the profile specifies a node ID, then this will become the node ID of
		183	this process. If not, then the profile name will be used as node ID. The
		184	special node ID of C<anon/> will be replaced by a random node ID.
153		185
154	=item public nodes	186	The next step is to look up the binds in the profile, followed by binding
		187	aemp protocol listeners on all binds specified (it is possible and valid
		188	to have no binds, meaning that the node cannot be contacted form the
		189	outside. This means the node cannot talk to other nodes that also have no
		190	binds, but it can still talk to all "normal" nodes).
155		191
156	For public nodes, C<$noderef> must either be a (possibly unresolved)	192	If the profile does not specify a binds list, then the node ID will be
157	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
158	which case the noderef will be guessed.	194	used as binds list.
159		195
160	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
161	to all additional C<$seednodes> that are specified. Seednodes are optional	197	L<AnyEvent::MP::Global> module, which will then use it to keep
162	and can be used to quickly bootstrap the node into an existing network.	198	connectivity with at least on of those seed nodes at any point in time.
163		199
164	=item slave nodes	200	Example: become a distributed node listening on the guessed noderef, or
165		201	the one specified via C<aemp> for the current node. This should be the
166	When the C<$noderef> is the special string C<slave/>, then the node will	202	most common form of invocation for "daemon"-type nodes.
167	become a slave node. Slave nodes cannot be contacted from outside and will
168	route most of their traffic to the master node that they attach to.
169
170	At least one additional noderef is required: The node will try to connect
171	to all of them and will become a slave attached to the first node it can
172	successfully connect to.
173
174	=back
175
176	This function will block until all nodes have been resolved and, for slave
177	nodes, until it has successfully established a connection to a master
178	server.
179
180	Example: become a public node listening on the default node.
181		203
182	initialise_node;	204	initialise_node;
183		205
184	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
185	servers to become part of the network.	207	clients.
186		208
187	initialise_node undef, "master1", "master2";
188
189	Example: become a public node listening on port C<4041>.
190
191	initialise_node 4041;	209	initialise_node "anon/";
192		210
193	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.
194		214
195	initialise_node "locahost:4044";	215	initialise_node "localhost:4044";
196
197	Example: become a slave node to any of the specified master servers.
198
199	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
200
201	=item $cv = resolve_node $noderef
202
203	Takes an unresolved node reference that may contain hostnames and
204	abbreviated IDs, resolves all of them and returns a resolved node
205	reference.
206
207	In addition to C<address:port> pairs allowed in resolved noderefs, the
208	following forms are supported:
209
210	=over 4
211
212	=item the empty string
213
214	An empty-string component gets resolved as if the default port (4040) was
215	specified.
216
217	=item naked port numbers (e.g. C<1234>)
218
219	These are resolved by prepending the local nodename and a colon, to be
220	further resolved.
221
222	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
223
224	These are resolved by using AnyEvent::DNS to resolve them, optionally
225	looking up SRV records for the C<aemp=4040> port, if no port was
226	specified.
227
228	=back
229		216
230	=item $SELF	217	=item $SELF
231		218
232	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>
233	blocks.	220	blocks.
…		…
241	=item snd $port, type => @data	228	=item snd $port, type => @data
242		229
243	=item snd $port, @msg	230	=item snd $port, @msg
244		231
245	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
246	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.
247	stringifies a sa port ID (such as a port object :).
248		234
249	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
250	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
251	type etc.).	237	type etc.).
252		238
253	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
254	function: modifying any argument is not allowed and can cause many	240	function: modifying any argument is not allowed and can cause many
255	problems.	241	problems.
…		…
260	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
261	node, anything can be passed.	247	node, anything can be passed.
262		248
263	=item $local_port = port	249	=item $local_port = port
264		250
265	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
266	matching port ("full port") or a single-callback port ("miniport"),	252	no callbacks set and will throw an error when it receives messages.
267	depending on how C<rcv> callbacks are bound to the object.
268		253
269	=item $port = port { my @msg = @_; $finished }	254	=item $local_port = port { my @msg = @_ }
270		255
271	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
272	matching behind it, and returns its ID. Semantically the same as creating
273	a port and calling C<rcv $port, $callback> on it.	257	creating a port and calling C<rcv $port, $callback> on it.
274		258
275	The block will be called for every message received on the port. When the	259	The block will be called for every message received on the port, with the
276	callback returns a true value its job is considered "done" and the port	260	global variable C<$SELF> set to the port ID. Runtime errors will cause the
277	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.
278		263
279	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:
280	be passed to the callback.
281		265
282	If you need the local port id in the callback, this works nicely:	266	my $port = port {
283		267	my @msg = @_;
284	my $port; $port = port {	268	...
285	snd $otherport, reply => $port;	269	kil $SELF;
286	};	270	};
287		271
288	=cut	272	=cut
289		273
290	sub rcv($@);	274	sub rcv($@);
		275
		276	sub _kilme {
		277	die "received message on port without callback";
		278	}
291		279
292	sub port(;&) {	280	sub port(;&) {
293	my $id = "$UNIQ." . $ID++;	281	my $id = "$UNIQ." . $ID++;
294	my $port = "$NODE#$id";	282	my $port = "$NODE#$id";
295		283
296	if (@_) {	284	rcv $port, shift \|\| \&_kilme;
297	rcv $port, shift;
298	} else {
299	$PORT{$id} = sub { }; # nop
300	}
301		285
302	$port	286	$port
303	}	287	}
304		288
305	=item reg $port, $name
306
307	=item reg $name
308
309	Registers the given port (or C<$SELF><<< if missing) under the name
310	C<$name>. If the name already exists it is replaced.
311
312	A port can only be registered under one well known name.
313
314	A port automatically becomes unregistered when it is killed.
315
316	=cut
317
318	sub reg(@) {
319	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
320
321	$REG{$_[0]} = $port;
322	}
323
324	=item rcv $port, $callback->(@msg)	289	=item rcv $local_port, $callback->(@msg)
325		290
326	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
327	one if required).	292	remove the default callback: use C<sub { }> to disable it, or better
328		293	C<kil> the port when it is no longer needed.
329	=item rcv $port, tagstring => $callback->(@msg), ...
330
331	=item rcv $port, $smartmatch => $callback->(@msg), ...
332
333	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
334
335	Register callbacks to be called on matching messages on the given full
336	port (after converting it to one if required) and return the port.
337
338	The callback has to return a true value when its work is done, after
339	which is will be removed, or a false value in which case it will stay
340	registered.
341		294
342	The global C<$SELF> (exported by this module) contains C<$port> while	295	The global C<$SELF> (exported by this module) contains C<$port> while
343	executing the callback.	296	executing the callback. Runtime errors during callback execution will
		297	result in the port being C<kil>ed.
344		298
345	Runtime errors wdurign callback execution will result in the port being	299	The default callback received all messages not matched by a more specific
346	C<kil>ed.	300	C<tag> match.
347		301
348	If the match is an array reference, then it will be matched against the	302	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
349	first elements of the message, otherwise only the first element is being
350	matched.
351		303
352	Any element in the match that is specified as C<_any_> (a function	304	Register (or replace) callbacks to be called on messages starting with the
353	exported by this module) matches any single element of the message.	305	given tag on the given port (and return the port), or unregister it (when
		306	C<$callback> is C<$undef> or missing). There can only be one callback
		307	registered for each tag.
354		308
355	While not required, it is highly recommended that the first matching	309	The original message will be passed to the callback, after the first
356	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
357	also the most efficient match (by far).	311	environment as the default callback (see above).
358		312
359	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.
360		314
361	my $port = rcv port,	315	my $port = rcv port,
362	msg1 => sub { ...; 0 },	316	msg1 => sub { ... },
363	msg2 => sub { ...; 0 },	317	msg2 => sub { ... },
364	;	318	;
365		319
366	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
367	in one go:	321	in one go:
368		322
369	snd $otherport, reply =>	323	snd $otherport, reply =>
370	rcv port,	324	rcv port,
371	msg1 => sub { ...; 0 },	325	msg1 => sub { ... },
372	...	326	...
373	;	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, $otherport;
		336	};
374		337
375	=cut	338	=cut
376		339
377	sub rcv($@) {	340	sub rcv($@) {
378	my $port = shift;	341	my $port = shift;
379	my ($noderef, $portid) = split /#/, $port, 2;	342	my ($noderef, $portid) = split /#/, $port, 2;
380		343
381	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	344	$NODE{$noderef} == $NODE{""}
382	or Carp::croak "$port: rcv can only be called on local ports, caught";	345	or Carp::croak "$port: rcv can only be called on local ports, caught";
383		346
384	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 {
385	my $cb = shift;	355	my $cb = shift;
386	delete $PORT_DATA{$portid};
387	$PORT{$portid} = sub {	356	$PORT{$portid} = sub {
388	local $SELF = $port;	357	local $SELF = $port;
389	eval {	358	eval { &$cb }; _self_die if $@;
390	&$cb	359	};
391	and kil $port;
392	};	360	}
393	_self_die if $@;	361	} elsif (defined $_[0]) {
394	};
395	} else {
396	my $self = $PORT_DATA{$portid} \|\|= do {	362	my $self = $PORT_DATA{$portid} \|\|= do {
397	my $self = bless {	363	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
398	id => $port,
399	}, "AnyEvent::MP::Port";
400		364
401	$PORT{$portid} = sub {	365	$PORT{$portid} = sub {
402	local $SELF = $port;	366	local $SELF = $port;
403		367
404	eval {
405	for (@{ $self->{rc0}{$_[0]} }) {	368	if (my $cb = $self->[1]{$_[0]}) {
406	$_ && &{$_->[0]}	369	shift;
407	&& undef $_;	370	eval { &$cb }; _self_die if $@;
408	}	371	} else {
409
410	for (@{ $self->{rcv}{$_[0]} }) {
411	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
412	&& &{$_->[0]}	372	&{ $self->[0] };
413	&& undef $_;
414	}
415
416	for (@{ $self->{any} }) {
417	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
418	&& &{$_->[0]}
419	&& undef $_;
420	}	373	}
421	};	374	};
422	_self_die if $@;	375
		376	$self
423	};	377	};
424		378
425	$self
426	};
427
428	"AnyEvent::MP::Port" eq ref $self	379	"AnyEvent::MP::Port" eq ref $self
429	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	380	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
430		381
431	while (@_) {
432	my ($match, $cb) = splice @_, 0, 2;	382	my ($tag, $cb) = splice @_, 0, 2;
433		383
434	if (!ref $match) {	384	if (defined $cb) {
435	push @{ $self->{rc0}{$match} }, [$cb];	385	$self->[1]{$tag} = $cb;
436	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
437	my ($type, @match) = @$match;
438	@match
439	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
440	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
441	} else {	386	} else {
442	push @{ $self->{any} }, [$cb, $match];	387	delete $self->[1]{$tag};
443	}	388	}
444	}	389	}
445	}	390	}
446		391
447	$port	392	$port
…		…
491		436
492	=item $guard = mon $port	437	=item $guard = mon $port
493		438
494	=item $guard = mon $port, $rcvport, @msg	439	=item $guard = mon $port, $rcvport, @msg
495		440
496	Monitor the given port and do something when the port is killed, and	441	Monitor the given port and do something when the port is killed or
497	optionally return a guard that can be used to stop monitoring again.	442	messages to it were lost, and optionally return a guard that can be used
		443	to stop monitoring again.
		444
		445	C<mon> effectively guarantees that, in the absence of hardware failures,
		446	that after starting the monitor, either all messages sent to the port
		447	will arrive, or the monitoring action will be invoked after possible
		448	message loss has been detected. No messages will be lost "in between"
		449	(after the first lost message no further messages will be received by the
		450	port). After the monitoring action was invoked, further messages might get
		451	delivered again.
		452
		453	Note that monitoring-actions are one-shot: once released, they are removed
		454	and will not trigger again.
498		455
499	In the first form (callback), the callback is simply called with any	456	In the first form (callback), the callback is simply called with any
500	number of C<@reason> elements (no @reason means that the port was deleted	457	number of C<@reason> elements (no @reason means that the port was deleted
501	"normally"). Note also that I<< the callback B<must> never die >>, so use	458	"normally"). Note also that I<< the callback B<must> never die >>, so use
502	C<eval> if unsure.	459	C<eval> if unsure.
503		460
504	In the second form (another port given), the other port (C<$rcvport)	461	In the second form (another port given), the other port (C<$rcvport>)
505	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on	462	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
506	"normal" kils nothing happens, while under all other conditions, the other	463	"normal" kils nothing happens, while under all other conditions, the other
507	port is killed with the same reason.	464	port is killed with the same reason.
508		465
509	The third form (kill self) is the same as the second form, except that	466	The third form (kill self) is the same as the second form, except that
…		…
536	sub mon {	493	sub mon {
537	my ($noderef, $port) = split /#/, shift, 2;	494	my ($noderef, $port) = split /#/, shift, 2;
538		495
539	my $node = $NODE{$noderef} \|\| add_node $noderef;	496	my $node = $NODE{$noderef} \|\| add_node $noderef;
540		497
541	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,';
542		499
543	unless (ref $cb) {	500	unless (ref $cb) {
544	if (@_) {	501	if (@_) {
545	# send a kill info message	502	# send a kill info message
546	my (@msg) = @_;	503	my (@msg) = ($cb, @_);
547	$cb = sub { snd @msg, @_ };	504	$cb = sub { snd @msg, @_ };
548	} else {	505	} else {
549	# simply kill other port	506	# simply kill other port
550	my $port = $cb;	507	my $port = $cb;
551	$cb = sub { kil $port, @_ if @_ };	508	$cb = sub { kil $port, @_ if @_ };
…		…
598	will be reported as reason C<< die => $@ >>.	555	will be reported as reason C<< die => $@ >>.
599		556
600	Transport/communication errors are reported as C<< transport_error =>	557	Transport/communication errors are reported as C<< transport_error =>
601	$message >>.	558	$message >>.
602		559
603	=back
604
605	=head1 NODE MESSAGES
606
607	Nodes understand the following messages sent to them. Many of them take
608	arguments called C<@reply>, which will simply be used to compose a reply
609	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
610	the remaining arguments are simply the message data.
611
612	While other messages exist, they are not public and subject to change.
613
614	=over 4
615
616	=cut	560	=cut
617		561
618	=item lookup => $name, @reply	562	=item $port = spawn $node, $initfunc[, @initdata]
619		563
620	Replies with the port ID of the specified well-known port, or C<undef>.	564	Creates a port on the node C<$node> (which can also be a port ID, in which
		565	case it's the node where that port resides).
621		566
622	=item devnull => ...	567	The port ID of the newly created port is return immediately, and it is
		568	permissible to immediately start sending messages or monitor the port.
623		569
624	Generic data sink/CPU heat conversion.	570	After the port has been created, the init function is
		571	called. This function must be a fully-qualified function name
		572	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		573	program, use C<::name>.
625		574
626	=item relay => $port, @msg	575	If the function doesn't exist, then the node tries to C<require>
		576	the package, then the package above the package and so on (e.g.
		577	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		578	exists or it runs out of package names.
627		579
628	Simply forwards the message to the given port.	580	The init function is then called with the newly-created port as context
		581	object (C<$SELF>) and the C<@initdata> values as arguments.
629		582
630	=item eval => $string[ @reply]	583	A common idiom is to pass your own port, monitor the spawned port, and
		584	in the init function, monitor the original port. This two-way monitoring
		585	ensures that both ports get cleaned up when there is a problem.
631		586
632	Evaluates the given string. If C<@reply> is given, then a message of the	587	Example: spawn a chat server port on C<$othernode>.
633	form C<@reply, $@, @evalres> is sent.
634		588
635	Example: crash another node.	589	# this node, executed from within a port context:
		590	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		591	mon $server;
636		592
637	snd $othernode, eval => "exit";	593	# init function on C<$othernode>
		594	sub connect {
		595	my ($srcport) = @_;
638		596
639	=item time => @reply	597	mon $srcport;
640		598
641	Replies the the current node time to C<@reply>.	599	rcv $SELF, sub {
		600	...
		601	};
		602	}
642		603
643	Example: tell the current node to send the current time to C<$myport> in a	604	=cut
644	C<timereply> message.
645		605
646	snd $NODE, time => $myport, timereply => 1, 2;	606	sub _spawn {
647	# => snd $myport, timereply => 1, 2, <time>	607	my $port = shift;
		608	my $init = shift;
		609
		610	local $SELF = "$NODE#$port";
		611	eval {
		612	&{ load_func $init }
		613	};
		614	_self_die if $@;
		615	}
		616
		617	sub spawn(@) {
		618	my ($noderef, undef) = split /#/, shift, 2;
		619
		620	my $id = "$RUNIQ." . $ID++;
		621
		622	$_[0] =~ /::/
		623	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		624
		625	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
		626
		627	"$noderef#$id"
		628	}
		629
		630	=item after $timeout, @msg
		631
		632	=item after $timeout, $callback
		633
		634	Either sends the given message, or call the given callback, after the
		635	specified number of seconds.
		636
		637	This is simply a utility function that come sin handy at times.
		638
		639	=cut
		640
		641	sub after($@) {
		642	my ($timeout, @action) = @_;
		643
		644	my $t; $t = AE::timer $timeout, 0, sub {
		645	undef $t;
		646	ref $action[0]
		647	? $action[0]()
		648	: snd @action;
		649	};
		650	}
648		651
649	=back	652	=back
650		653
651	=head1 AnyEvent::MP vs. Distributed Erlang	654	=head1 AnyEvent::MP vs. Distributed Erlang
652		655
…		…
662		665
663	Despite the similarities, there are also some important differences:	666	Despite the similarities, there are also some important differences:
664		667
665	=over 4	668	=over 4
666		669
667	=item * Node references contain the recipe on how to contact them.	670	=item * Node IDs are arbitrary strings in AEMP.
668		671
669	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
670	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
671	convenience functionality.	674	configuraiton or DNS), but will otherwise discover other odes itself.
672		675
673	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
674	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.
675		690
676	=item * Erlang uses processes and a mailbox, AEMP does not queue.	691	=item * Erlang uses processes and a mailbox, AEMP does not queue.
677		692
678	Erlang uses processes that selctively receive messages, and therefore	693	Erlang uses processes that selectively receive messages, and therefore
679	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
680	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.
681		698
682	(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).
683		700
684	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	701	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
685		702
686	Sending messages in Erlang is synchronous and blocks the process. AEMP	703	Sending messages in Erlang is synchronous and blocks the process (and
687	sends are immediate, connection establishment is handled in the	704	so does not need a queue that can overflow). AEMP sends are immediate,
688	background.	705	connection establishment is handled in the background.
689		706
690	=item * Erlang can silently lose messages, AEMP cannot.	707	=item * Erlang suffers from silent message loss, AEMP does not.
691		708
692	Erlang makes few guarantees on messages delivery - messages can get lost	709	Erlang makes few guarantees on messages delivery - messages can get lost
693	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,
694	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).
695		712
…		…
707	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
708	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.
709		726
710	=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.
711		728
712	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
713	ID known to other nodes for a completely different process, causing	730	known to other nodes for a completely different process, causing messages
714	messages destined for that process to end up in an unrelated process.	731	destined for that process to end up in an unrelated process.
715		732
716	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
717	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.
718		735
719	=item * Erlang uses unprotected connections, AEMP uses secure	736	=item * Erlang uses unprotected connections, AEMP uses secure
…		…
755	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
756	(hard to do in Erlang).	773	(hard to do in Erlang).
757		774
758	=back	775	=back
759		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
760	=head1 SEE ALSO	812	=head1 SEE ALSO
761		813
762	L<AnyEvent>.	814	L<AnyEvent>.
763		815
764	=head1 AUTHOR	816	=head1 AUTHOR

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.37 by root, Fri Aug 7 16:47:23 2009 UTC vs.
Revision 1.65 by root, Fri Aug 28 01:00:34 2009 UTC