[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 1.62 by root, Thu Aug 27 07:12:48 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; # -OR-
		17	initialise_node "localhost:4040"; # -OR-
		18	initialise_node "slave/", "localhost:4040"
		19
		20	# ports are message endpoints
		21
		22	# sending messages
13	snd $port, type => data...;	23	snd $port, type => data...;
		24	snd $port, @msg;
		25	snd @msg_with_first_element_being_a_port;
14		26
15	$SELF # receiving/own port id in rcv callbacks	27	# creating/using ports, the simple way
		28	my $simple_port = port { my @msg = @_; 0 };
16		29
17	rcv $port, smartmatch => $cb->($port, @msg);	30	# creating/using ports, tagged message matching
18		31	my $port = port;
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	32	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
21	rcv $port1, pong => sub { warn "pong received\n" };	33	rcv $port, pong => sub { warn "pong received\n"; 0 };
22	snd $port2, ping => $port1;
23		34
24	# more, smarter, matches (_any_ is exported by this module)	35	# create a port on another node
25	rcv $port, [child_died => $pid] => sub { ...	36	my $port = spawn $node, $initfunc, @initdata;
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	37
		38	# monitoring
		39	mon $port, $cb->(@msg) # callback is invoked on death
		40	mon $port, $otherport # kill otherport on abnormal death
		41	mon $port, $otherport, @msg # send message on death
		42
		43	=head1 CURRENT STATUS
		44
		45	AnyEvent::MP - stable API, should work
		46	AnyEvent::MP::Intro - outdated
		47	AnyEvent::MP::Kernel - WIP
		48	AnyEvent::MP::Transport - mostly stable
		49
		50	stay tuned.
27		51
28	=head1 DESCRIPTION	52	=head1 DESCRIPTION
29		53
30	This module (-family) implements a simple message passing framework.	54	This module (-family) implements a simple message passing framework.
31		55
…		…
35	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	59	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
36	manual page.	60	manual page.
37		61
38	At the moment, this module family is severly broken and underdocumented,	62	At the moment, this module family is severly broken and underdocumented,
39	so do not use. This was uploaded mainly to reserve the CPAN namespace -	63	so do not use. This was uploaded mainly to reserve the CPAN namespace -
40	stay tuned! The basic API should be finished, however.	64	stay tuned!
41		65
42	=head1 CONCEPTS	66	=head1 CONCEPTS
43		67
44	=over 4	68	=over 4
45		69
46	=item port	70	=item port
47		71
48	A port is something you can send messages to (with the C<snd> function).	72	A port is something you can send messages to (with the C<snd> function).
49		73
50	Some ports allow you to register C<rcv> handlers that can match specific	74	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	75	some messages. Messages will not be queued.
52	will not be queued.
53		76
54	=item port id - C<noderef#portname>	77	=item port id - C<noderef#portname>
55		78
56	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	79	A port ID is the concatenation of a noderef, a hash-mark (C<#>) as
57	separator, and a port name (a printable string of unspecified format). An	80	separator, and a port name (a printable string of unspecified format). An
58	exception is the the node port, whose ID is identical to its node	81	exception is the the node port, whose ID is identical to its node
59	reference.	82	reference.
60		83
61	=item node	84	=item node
62		85
63	A node is a single process containing at least one port - the node	86	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	87	which provides nodes to manage each other remotely, and to create new
65	create new ports, among other things.	88	ports.
66		89
67	Nodes are either private (single-process only), slaves (connected to a	90	Nodes are either private (single-process only), slaves (can only talk to
68	master node only) or public nodes (connectable from unrelated nodes).	91	public nodes, but do not need an open port) or public nodes (connectable
		92	from any other node).
69		93
70	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	94	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>
71		95
72	A node reference is a string that either simply identifies the node (for	96	A node reference is a string that either simply identifies the node (for
73	private and slave nodes), or contains a recipe on how to reach a given	97	private and slave nodes), or contains a recipe on how to reach a given
…		…
90		114
91	=cut	115	=cut
92		116
93	package AnyEvent::MP;	117	package AnyEvent::MP;
94		118
95	use AnyEvent::MP::Base;	119	use AnyEvent::MP::Kernel;
96		120
97	use common::sense;	121	use common::sense;
98		122
99	use Carp ();	123	use Carp ();
100		124
101	use AE ();	125	use AE ();
102		126
103	use base "Exporter";	127	use base "Exporter";
104		128
105	our $VERSION = '0.1';	129	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		130
106	our @EXPORT = qw(	131	our @EXPORT = qw(
107	NODE $NODE *SELF node_of _any_	132	NODE $NODE *SELF node_of after
108	resolve_node initialise_node	133	resolve_node initialise_node
109	snd rcv mon kil reg psub	134	snd rcv mon mon_guard kil reg psub spawn
110	port	135	port
111	);	136	);
112		137
113	our $SELF;	138	our $SELF;
114		139
…		…
118	kil $SELF, die => $msg;	143	kil $SELF, die => $msg;
119	}	144	}
120		145
121	=item $thisnode = NODE / $NODE	146	=item $thisnode = NODE / $NODE
122		147
123	The C<NODE> function returns, and the C<$NODE> variable contains	148	The C<NODE> function returns, and the C<$NODE> variable contains the
124	the noderef of the local node. The value is initialised by a call	149	noderef of the local node. The value is initialised by a call to
125	to C<become_public> or C<become_slave>, after which all local port	150	C<initialise_node>.
126	identifiers become invalid.
127		151
128	=item $noderef = node_of $port	152	=item $noderef = node_of $port
129		153
130	Extracts and returns the noderef from a portid or a noderef.	154	Extracts and returns the noderef from a port ID or a noderef.
		155
		156	=item initialise_node $noderef, $seednode, $seednode...
		157
		158	=item initialise_node "slave/", $master, $master...
		159
		160	Before a node can talk to other nodes on the network it has to initialise
		161	itself - the minimum a node needs to know is it's own name, and optionally
		162	it should know the noderefs of some other nodes in the network.
		163
		164	This function initialises a node - it must be called exactly once (or
		165	never) before calling other AnyEvent::MP functions.
		166
		167	All arguments (optionally except for the first) are noderefs, which can be
		168	either resolved or unresolved.
		169
		170	The first argument will be looked up in the configuration database first
		171	(if it is C<undef> then the current nodename will be used instead) to find
		172	the relevant configuration profile (see L<aemp>). If none is found then
		173	the default configuration is used. The configuration supplies additional
		174	seed/master nodes and can override the actual noderef.
		175
		176	There are two types of networked nodes, public nodes and slave nodes:
		177
		178	=over 4
		179
		180	=item public nodes
		181
		182	For public nodes, C<$noderef> (supplied either directly to
		183	C<initialise_node> or indirectly via a profile or the nodename) must be a
		184	noderef (possibly unresolved, in which case it will be resolved).
		185
		186	After resolving, the node will bind itself on all endpoints.
		187
		188	=item slave nodes
		189
		190	When the C<$noderef> (either as given or overriden by the config file)
		191	is the special string C<slave/>, then the node will become a slave
		192	node. Slave nodes cannot be contacted from outside, and cannot talk to
		193	each other (at least in this version of AnyEvent::MP).
		194
		195	Slave nodes work by creating connections to all public nodes, using the
		196	L<AnyEvent::MP::Global> service.
		197
		198	=back
		199
		200	After initialising itself, the node will connect to all additional
		201	C<$seednodes> that are specified diretcly or via a profile. Seednodes are
		202	optional and can be used to quickly bootstrap the node into an existing
		203	network.
		204
		205	All the seednodes will also be specially marked to automatically retry
		206	connecting to them indefinitely, so make sure that seednodes are really
		207	reliable and up (this might also change in the future).
		208
		209	Example: become a public node listening on the guessed noderef, or the one
		210	specified via C<aemp> for the current node. This should be the most common
		211	form of invocation for "daemon"-type nodes.
		212
		213	initialise_node;
		214
		215	Example: become a slave node to any of the the seednodes specified via
		216	C<aemp>. This form is often used for commandline clients.
		217
		218	initialise_node "slave/";
		219
		220	Example: become a public node, and try to contact some well-known master
		221	servers to become part of the network.
		222
		223	initialise_node undef, "master1", "master2";
		224
		225	Example: become a public node listening on port C<4041>.
		226
		227	initialise_node 4041;
		228
		229	Example: become a public node, only visible on localhost port 4044.
		230
		231	initialise_node "localhost:4044";
131		232
132	=item $cv = resolve_node $noderef	233	=item $cv = resolve_node $noderef
133		234
134	Takes an unresolved node reference that may contain hostnames and	235	Takes an unresolved node reference that may contain hostnames and
135	abbreviated IDs, resolves all of them and returns a resolved node	236	abbreviated IDs, resolves all of them and returns a resolved node
…		…
172	=item snd $port, type => @data	273	=item snd $port, type => @data
173		274
174	=item snd $port, @msg	275	=item snd $port, @msg
175		276
176	Send the given message to the given port ID, which can identify either	277	Send the given message to the given port ID, which can identify either
177	a local or a remote port, and can be either a string or soemthignt hat	278	a local or a remote port, and must be a port ID.
178	stringifies a sa port ID (such as a port object :).
179		279
180	While the message can be about anything, it is highly recommended to use a	280	While the message can be about anything, it is highly recommended to use a
181	string as first element (a portid, or some word that indicates a request	281	string as first element (a port ID, or some word that indicates a request
182	type etc.).	282	type etc.).
183		283
184	The message data effectively becomes read-only after a call to this	284	The message data effectively becomes read-only after a call to this
185	function: modifying any argument is not allowed and can cause many	285	function: modifying any argument is not allowed and can cause many
186	problems.	286	problems.
…		…
191	that Storable can serialise and deserialise is allowed, and for the local	291	that Storable can serialise and deserialise is allowed, and for the local
192	node, anything can be passed.	292	node, anything can be passed.
193		293
194	=item $local_port = port	294	=item $local_port = port
195		295
196	Create a new local port object that can be used either as a pattern	296	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"),	297	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		298
200	=item $port = port { my @msg = @_; $finished }	299	=item $local_port = port { my @msg = @_ }
201		300
202	Creates a "miniport", that is, a very lightweight port without any pattern	301	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.	302	creating a port and calling C<rcv $port, $callback> on it.
205		303
206	The block will be called for every message received on the port. When the	304	The block will be called for every message received on the port, with the
207	callback returns a true value its job is considered "done" and the port	305	global variable C<$SELF> set to the port ID. Runtime errors will cause the
208	will be destroyed. Otherwise it will stay alive.	306	port to be C<kil>ed. The message will be passed as-is, no extra argument
		307	(i.e. no port ID) will be passed to the callback.
209		308
210	The message will be passed as-is, no extra argument (i.e. no port id) will	309	If you want to stop/destroy the port, simply C<kil> it:
211	be passed to the callback.
212		310
213	If you need the local port id in the callback, this works nicely:	311	my $port = port {
214		312	my @msg = @_;
215	my $port; $port = port {	313	...
216	snd $otherport, reply => $port;	314	kil $SELF;
217	};	315	};
218		316
219	=cut	317	=cut
220		318
221	sub rcv($@);	319	sub rcv($@);
		320
		321	sub _kilme {
		322	die "received message on port without callback";
		323	}
222		324
223	sub port(;&) {	325	sub port(;&) {
224	my $id = "$UNIQ." . $ID++;	326	my $id = "$UNIQ." . $ID++;
225	my $port = "$NODE#$id";	327	my $port = "$NODE#$id";
226		328
227	if (@_) {	329	rcv $port, shift \|\| \&_kilme;
228	rcv $port, shift;
229	} else {
230	$PORT{$id} = sub { }; # nop
231	}
232		330
233	$port	331	$port
234	}	332	}
235		333
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)	334	=item rcv $local_port, $callback->(@msg)
254		335
255	Replaces the callback on the specified miniport (after converting it to	336	Replaces the default callback on the specified port. There is no way to
256	one if required).	337	remove the default callback: use C<sub { }> to disable it, or better
257		338	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...] => $callback->(@msg), ...
263
264	Register callbacks to be called on matching messages on the given full
265	port (after converting it to one if required).
266
267	The callback has to return a true value when its work is done, after
268	which is will be removed, or a false value in which case it will stay
269	registered.
270		339
271	The global C<$SELF> (exported by this module) contains C<$port> while	340	The global C<$SELF> (exported by this module) contains C<$port> while
272	executing the callback.	341	executing the callback. Runtime errors during callback execution will
		342	result in the port being C<kil>ed.
273		343
274	Runtime errors wdurign callback execution will result in the port being	344	The default callback received all messages not matched by a more specific
275	C<kil>ed.	345	C<tag> match.
276		346
277	If the match is an array reference, then it will be matched against the	347	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
278	first elements of the message, otherwise only the first element is being
279	matched.
280		348
281	Any element in the match that is specified as C<_any_> (a function	349	Register (or replace) callbacks to be called on messages starting with the
282	exported by this module) matches any single element of the message.	350	given tag on the given port (and return the port), or unregister it (when
		351	C<$callback> is C<$undef> or missing). There can only be one callback
		352	registered for each tag.
283		353
284	While not required, it is highly recommended that the first matching	354	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	355	element (the tag) has been removed. The callback will use the same
286	also the most efficient match (by far).	356	environment as the default callback (see above).
		357
		358	Example: create a port and bind receivers on it in one go.
		359
		360	my $port = rcv port,
		361	msg1 => sub { ... },
		362	msg2 => sub { ... },
		363	;
		364
		365	Example: create a port, bind receivers and send it in a message elsewhere
		366	in one go:
		367
		368	snd $otherport, reply =>
		369	rcv port,
		370	msg1 => sub { ... },
		371	...
		372	;
		373
		374	Example: temporarily register a rcv callback for a tag matching some port
		375	(e.g. for a rpc reply) and unregister it after a message was received.
		376
		377	rcv $port, $otherport => sub {
		378	my @reply = @_;
		379
		380	rcv $SELF, $otherport;
		381	};
287		382
288	=cut	383	=cut
289		384
290	sub rcv($@) {	385	sub rcv($@) {
291	my $port = shift;	386	my $port = shift;
292	my ($noderef, $portid) = split /#/, $port, 2;	387	my ($noderef, $portid) = split /#/, $port, 2;
293		388
294	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	389	$NODE{$noderef} == $NODE{""}
295	or Carp::croak "$port: rcv can only be called on local ports, caught";	390	or Carp::croak "$port: rcv can only be called on local ports, caught";
296		391
297	if (@_ == 1) {	392	while (@_) {
		393	if (ref $_[0]) {
		394	if (my $self = $PORT_DATA{$portid}) {
		395	"AnyEvent::MP::Port" eq ref $self
		396	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		397
		398	$self->[2] = shift;
		399	} else {
298	my $cb = shift;	400	my $cb = shift;
299	delete $PORT_DATA{$portid};
300	$PORT{$portid} = sub {	401	$PORT{$portid} = sub {
301	local $SELF = $port;	402	local $SELF = $port;
302	eval {	403	eval { &$cb }; _self_die if $@;
303	&$cb	404	};
304	and kil $port;
305	};	405	}
306	_self_die if $@;	406	} elsif (defined $_[0]) {
307	};
308	} else {
309	my $self = $PORT_DATA{$portid} \|\|= do {	407	my $self = $PORT_DATA{$portid} \|\|= do {
310	my $self = bless {	408	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
311	id => $port,
312	}, "AnyEvent::MP::Port";
313		409
314	$PORT{$portid} = sub {	410	$PORT{$portid} = sub {
315	local $SELF = $port;	411	local $SELF = $port;
316		412
317	eval {
318	for (@{ $self->{rc0}{$_[0]} }) {	413	if (my $cb = $self->[1]{$_[0]}) {
319	$_ && &{$_->[0]}	414	shift;
320	&& undef $_;	415	eval { &$cb }; _self_die if $@;
321	}	416	} else {
322
323	for (@{ $self->{rcv}{$_[0]} }) {
324	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
325	&& &{$_->[0]}	417	&{ $self->[0] };
326	&& undef $_;
327	}
328
329	for (@{ $self->{any} }) {
330	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
331	&& &{$_->[0]}
332	&& undef $_;
333	}	418	}
334	};	419	};
335	_self_die if $@;	420
		421	$self
336	};	422	};
337		423
338	$self
339	};
340
341	"AnyEvent::MP::Port" eq ref $self	424	"AnyEvent::MP::Port" eq ref $self
342	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	425	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
343		426
344	while (@_) {
345	my ($match, $cb) = splice @_, 0, 2;	427	my ($tag, $cb) = splice @_, 0, 2;
346		428
347	if (!ref $match) {	429	if (defined $cb) {
348	push @{ $self->{rc0}{$match} }, [$cb];	430	$self->[1]{$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 {	431	} else {
355	push @{ $self->{any} }, [$cb, $match];	432	delete $self->[1]{$tag};
356	}	433	}
357	}	434	}
358	}	435	}
359		436
360	$port	437	$port
…		…
398	}	475	}
399	}	476	}
400		477
401	=item $guard = mon $port, $cb->(@reason)	478	=item $guard = mon $port, $cb->(@reason)
402		479
403	=item $guard = mon $port, $otherport	480	=item $guard = mon $port, $rcvport
404		481
		482	=item $guard = mon $port
		483
405	=item $guard = mon $port, $otherport, @msg	484	=item $guard = mon $port, $rcvport, @msg
406		485
407	Monitor the given port and do something when the port is killed.	486	Monitor the given port and do something when the port is killed or
		487	messages to it were lost, and optionally return a guard that can be used
		488	to stop monitoring again.
408		489
		490	C<mon> effectively guarantees that, in the absence of hardware failures,
		491	that after starting the monitor, either all messages sent to the port
		492	will arrive, or the monitoring action will be invoked after possible
		493	message loss has been detected. No messages will be lost "in between"
		494	(after the first lost message no further messages will be received by the
		495	port). After the monitoring action was invoked, further messages might get
		496	delivered again.
		497
		498	Note that monitoring-actions are one-shot: once released, they are removed
		499	and will not trigger again.
		500
409	In the first form, the callback is simply called with any number	501	In the first form (callback), the callback is simply called with any
410	of C<@reason> elements (no @reason means that the port was deleted	502	number of C<@reason> elements (no @reason means that the port was deleted
411	"normally"). Note also that I<< the callback B<must> never die >>, so use	503	"normally"). Note also that I<< the callback B<must> never die >>, so use
412	C<eval> if unsure.	504	C<eval> if unsure.
413		505
414	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	506	In the second form (another port given), the other port (C<$rcvport>)
415	a @reason was specified, i.e. on "normal" kils nothing happens, while	507	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.	508	"normal" kils nothing happens, while under all other conditions, the other
		509	port is killed with the same reason.
417		510
		511	The third form (kill self) is the same as the second form, except that
		512	C<$rvport> defaults to C<$SELF>.
		513
418	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	514	In the last form (message), a message of the form C<@msg, @reason> will be
		515	C<snd>.
		516
		517	As a rule of thumb, monitoring requests should always monitor a port from
		518	a local port (or callback). The reason is that kill messages might get
		519	lost, just like any other message. Another less obvious reason is that
		520	even monitoring requests can get lost (for exmaple, when the connection
		521	to the other node goes down permanently). When monitoring a port locally
		522	these problems do not exist.
419		523
420	Example: call a given callback when C<$port> is killed.	524	Example: call a given callback when C<$port> is killed.
421		525
422	mon $port, sub { warn "port died because of <@_>\n" };	526	mon $port, sub { warn "port died because of <@_>\n" };
423		527
424	Example: kill ourselves when C<$port> is killed abnormally.	528	Example: kill ourselves when C<$port> is killed abnormally.
425		529
426	mon $port, $self;	530	mon $port;
427		531
428	Example: send us a restart message another C<$port> is killed.	532	Example: send us a restart message when another C<$port> is killed.
429		533
430	mon $port, $self => "restart";	534	mon $port, $self => "restart";
431		535
432	=cut	536	=cut
433		537
434	sub mon {	538	sub mon {
435	my ($noderef, $port) = split /#/, shift, 2;	539	my ($noderef, $port) = split /#/, shift, 2;
436		540
437	my $node = $NODE{$noderef} \|\| add_node $noderef;	541	my $node = $NODE{$noderef} \|\| add_node $noderef;
438		542
439	my $cb = shift;	543	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
440		544
441	unless (ref $cb) {	545	unless (ref $cb) {
442	if (@_) {	546	if (@_) {
443	# send a kill info message	547	# send a kill info message
444	my (@msg) = ($cb, @_);	548	my (@msg) = ($cb, @_);
…		…
475	=cut	579	=cut
476		580
477	sub mon_guard {	581	sub mon_guard {
478	my ($port, @refs) = @_;	582	my ($port, @refs) = @_;
479		583
		584	#TODO: mon-less form?
		585
480	mon $port, sub { 0 && @refs }	586	mon $port, sub { 0 && @refs }
481	}	587	}
482
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		588
493	=item kil $port[, @reason]	589	=item kil $port[, @reason]
494		590
495	Kill the specified port with the given C<@reason>.	591	Kill the specified port with the given C<@reason>.
496		592
…		…
504	will be reported as reason C<< die => $@ >>.	600	will be reported as reason C<< die => $@ >>.
505		601
506	Transport/communication errors are reported as C<< transport_error =>	602	Transport/communication errors are reported as C<< transport_error =>
507	$message >>.	603	$message >>.
508		604
		605	=cut
		606
		607	=item $port = spawn $node, $initfunc[, @initdata]
		608
		609	Creates a port on the node C<$node> (which can also be a port ID, in which
		610	case it's the node where that port resides).
		611
		612	The port ID of the newly created port is return immediately, and it is
		613	permissible to immediately start sending messages or monitor the port.
		614
		615	After the port has been created, the init function is
		616	called. This function must be a fully-qualified function name
		617	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		618	program, use C<::name>.
		619
		620	If the function doesn't exist, then the node tries to C<require>
		621	the package, then the package above the package and so on (e.g.
		622	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		623	exists or it runs out of package names.
		624
		625	The init function is then called with the newly-created port as context
		626	object (C<$SELF>) and the C<@initdata> values as arguments.
		627
		628	A common idiom is to pass your own port, monitor the spawned port, and
		629	in the init function, monitor the original port. This two-way monitoring
		630	ensures that both ports get cleaned up when there is a problem.
		631
		632	Example: spawn a chat server port on C<$othernode>.
		633
		634	# this node, executed from within a port context:
		635	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		636	mon $server;
		637
		638	# init function on C<$othernode>
		639	sub connect {
		640	my ($srcport) = @_;
		641
		642	mon $srcport;
		643
		644	rcv $SELF, sub {
		645	...
		646	};
		647	}
		648
		649	=cut
		650
		651	sub _spawn {
		652	my $port = shift;
		653	my $init = shift;
		654
		655	local $SELF = "$NODE#$port";
		656	eval {
		657	&{ load_func $init }
		658	};
		659	_self_die if $@;
		660	}
		661
		662	sub spawn(@) {
		663	my ($noderef, undef) = split /#/, shift, 2;
		664
		665	my $id = "$RUNIQ." . $ID++;
		666
		667	$_[0] =~ /::/
		668	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		669
		670	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
		671
		672	"$noderef#$id"
		673	}
		674
		675	=item after $timeout, @msg
		676
		677	=item after $timeout, $callback
		678
		679	Either sends the given message, or call the given callback, after the
		680	specified number of seconds.
		681
		682	This is simply a utility function that come sin handy at times.
		683
		684	=cut
		685
		686	sub after($@) {
		687	my ($timeout, @action) = @_;
		688
		689	my $t; $t = AE::timer $timeout, 0, sub {
		690	undef $t;
		691	ref $action[0]
		692	? $action[0]()
		693	: snd @action;
		694	};
		695	}
		696
509	=back	697	=back
510		698
511	=head1 FUNCTIONS FOR NODES
512
513	=over 4
514
515	=item initialise_node $noderef, $seednode, $seednode...
516
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	699	=head1 AnyEvent::MP vs. Distributed Erlang
626		700
627	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node	701	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	702	== 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	703	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
630	sample:	704	sample:
631		705
632	http://www.erlang.se/doc/programming_rules.shtml	706	http://www.Erlang.se/doc/programming_rules.shtml
633	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	707	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	708	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	709	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
636		710
637	Despite the similarities, there are also some important differences:	711	Despite the similarities, there are also some important differences:
638		712
639	=over 4	713	=over 4
640		714
…		…
645	convenience functionality.	719	convenience functionality.
646		720
647	This means that AEMP requires a less tightly controlled environment at the	721	This means that AEMP requires a less tightly controlled environment at the
648	cost of longer node references and a slightly higher management overhead.	722	cost of longer node references and a slightly higher management overhead.
649		723
		724	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
		725	uses "local ports are like remote ports".
		726
		727	The failure modes for local ports are quite different (runtime errors
		728	only) then for remote ports - when a local port dies, you I<know> it dies,
		729	when a connection to another node dies, you know nothing about the other
		730	port.
		731
		732	Erlang pretends remote ports are as reliable as local ports, even when
		733	they are not.
		734
		735	AEMP encourages a "treat remote ports differently" philosophy, with local
		736	ports being the special case/exception, where transport errors cannot
		737	occur.
		738
650	=item * Erlang uses processes and a mailbox, AEMP does not queue.	739	=item * Erlang uses processes and a mailbox, AEMP does not queue.
651		740
652	Erlang uses processes that selctively receive messages, and therefore	741	Erlang uses processes that selectively receive messages, and therefore
653	needs a queue. AEMP is event based, queuing messages would serve no useful	742	needs a queue. AEMP is event based, queuing messages would serve no
654	purpose.	743	useful purpose. For the same reason the pattern-matching abilities of
		744	AnyEvent::MP are more limited, as there is little need to be able to
		745	filter messages without dequeing them.
655		746
656	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	747	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
657		748
658	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	749	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
659		750
660	Sending messages in erlang is synchronous and blocks the process. AEMP	751	Sending messages in Erlang is synchronous and blocks the process (and
661	sends are immediate, connection establishment is handled in the	752	so does not need a queue that can overflow). AEMP sends are immediate,
662	background.	753	connection establishment is handled in the background.
663		754
664	=item * Erlang can silently lose messages, AEMP cannot.	755	=item * Erlang suffers from silent message loss, AEMP does not.
665		756
666	Erlang makes few guarantees on messages delivery - messages can get lost	757	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,	758	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).	759	and c, and the other side only receives messages a and c).
669		760
670	AEMP guarantees correct ordering, and the guarantee that there are no	761	AEMP guarantees correct ordering, and the guarantee that there are no
671	holes in the message sequence.	762	holes in the message sequence.
672		763
673	=item * In erlang, processes can be declared dead and later be found to be	764	=item * In Erlang, processes can be declared dead and later be found to be
674	alive.	765	alive.
675		766
676	In erlang it can happen that a monitored process is declared dead and	767	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	768	linked processes get killed, but later it turns out that the process is
678	still alive - and can receive messages.	769	still alive - and can receive messages.
679		770
680	In AEMP, when port monitoring detects a port as dead, then that port will	771	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	772	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.	773	and then later sends messages to it, finding it is still alive.
683		774
684	=item * Erlang can send messages to the wrong port, AEMP does not.	775	=item * Erlang can send messages to the wrong port, AEMP does not.
685		776
686	In erlang it is quite possible that a node that restarts reuses a process	777	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	778	known to other nodes for a completely different process, causing messages
688	messages destined for that process to end up in an unrelated process.	779	destined for that process to end up in an unrelated process.
689		780
690	AEMP never reuses port IDs, so old messages or old port IDs floating	781	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.	782	around in the network will not be sent to an unrelated port.
692		783
693	=item * Erlang uses unprotected connections, AEMP uses secure	784	=item * Erlang uses unprotected connections, AEMP uses secure
…		…
697	securely authenticate nodes.	788	securely authenticate nodes.
698		789
699	=item * The AEMP protocol is optimised for both text-based and binary	790	=item * The AEMP protocol is optimised for both text-based and binary
700	communications.	791	communications.
701		792
702	The AEMP protocol, unlike the erlang protocol, supports both	793	The AEMP protocol, unlike the Erlang protocol, supports both
703	language-independent text-only protocols (good for debugging) and binary,	794	language-independent text-only protocols (good for debugging) and binary,
704	language-specific serialisers (e.g. Storable).	795	language-specific serialisers (e.g. Storable).
705		796
706	It has also been carefully designed to be implementable in other languages	797	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	798	with a minimum of work while gracefully degrading fucntionality to make the
708	protocol simple.	799	protocol simple.
709		800
		801	=item * AEMP has more flexible monitoring options than Erlang.
		802
		803	In Erlang, you can chose to receive I<all> exit signals as messages
		804	or I<none>, there is no in-between, so monitoring single processes is
		805	difficult to implement. Monitoring in AEMP is more flexible than in
		806	Erlang, as one can choose between automatic kill, exit message or callback
		807	on a per-process basis.
		808
		809	=item * Erlang tries to hide remote/local connections, AEMP does not.
		810
		811	Monitoring in Erlang is not an indicator of process death/crashes,
		812	as linking is (except linking is unreliable in Erlang).
		813
		814	In AEMP, you don't "look up" registered port names or send to named ports
		815	that might or might not be persistent. Instead, you normally spawn a port
		816	on the remote node. The init function monitors the you, and you monitor
		817	the remote port. Since both monitors are local to the node, they are much
		818	more reliable.
		819
		820	This also saves round-trips and avoids sending messages to the wrong port
		821	(hard to do in Erlang).
		822
		823	=back
		824
		825	=head1 RATIONALE
		826
		827	=over 4
		828
		829	=item Why strings for ports and noderefs, why not objects?
		830
		831	We considered "objects", but found that the actual number of methods
		832	thatc an be called are very low. Since port IDs and noderefs travel over
		833	the network frequently, the serialising/deserialising would add lots of
		834	overhead, as well as having to keep a proxy object.
		835
		836	Strings can easily be printed, easily serialised etc. and need no special
		837	procedures to be "valid".
		838
		839	And a a miniport consists of a single closure stored in a global hash - it
		840	can't become much cheaper.
		841
		842	=item Why favour JSON, why not real serialising format such as Storable?
		843
		844	In fact, any AnyEvent::MP node will happily accept Storable as framing
		845	format, but currently there is no way to make a node use Storable by
		846	default.
		847
		848	The default framing protocol is JSON because a) JSON::XS is many times
		849	faster for small messages and b) most importantly, after years of
		850	experience we found that object serialisation is causing more problems
		851	than it gains: Just like function calls, objects simply do not travel
		852	easily over the network, mostly because they will always be a copy, so you
		853	always have to re-think your design.
		854
		855	Keeping your messages simple, concentrating on data structures rather than
		856	objects, will keep your messages clean, tidy and efficient.
		857
710	=back	858	=back
711		859
712	=head1 SEE ALSO	860	=head1 SEE ALSO
713		861
714	L<AnyEvent>.	862	L<AnyEvent>.

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Revision 1.62 by root, Thu Aug 27 07:12:48 2009 UTC