[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 1.63 by root, Thu Aug 27 21:29:37 2009 UTC

…		…
8		8
9	$NODE # contains this node's noderef	9	$NODE # contains this node's noderef
10	NODE # returns this node's noderef	10	NODE # returns this node's noderef
11	NODE $port # returns the noderef of the port	11	NODE $port # returns the noderef of the port
12		12
		13	$SELF # receiving/own port id in rcv callbacks
		14
		15	# initialise the node so it can send/receive messages
		16	initialise_node;
		17
		18	# ports are message endpoints
		19
		20	# sending messages
13	snd $port, type => data...;	21	snd $port, type => data...;
		22	snd $port, @msg;
		23	snd @msg_with_first_element_being_a_port;
14		24
15	$SELF # receiving/own port id in rcv callbacks	25	# creating/using ports, the simple way
		26	my $simple_port = port { my @msg = @_; 0 };
16		27
17	rcv $port, smartmatch => $cb->($port, @msg);	28	# creating/using ports, tagged message matching
18		29	my $port = port;
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	30	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
21	rcv $port1, pong => sub { warn "pong received\n" };	31	rcv $port, pong => sub { warn "pong received\n"; 0 };
22	snd $port2, ping => $port1;
23		32
24	# more, smarter, matches (_any_ is exported by this module)	33	# create a port on another node
25	rcv $port, [child_died => $pid] => sub { ...	34	my $port = spawn $node, $initfunc, @initdata;
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	35
		36	# monitoring
		37	mon $port, $cb->(@msg) # callback is invoked on death
		38	mon $port, $otherport # kill otherport on abnormal death
		39	mon $port, $otherport, @msg # send message on death
		40
		41	=head1 CURRENT STATUS
		42
		43	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		44	AnyEvent::MP::Intro - outdated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.
27		49
28	=head1 DESCRIPTION	50	=head1 DESCRIPTION
29		51
30	This module (-family) implements a simple message passing framework.	52	This module (-family) implements a simple message passing framework.
31		53
…		…
35	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>
36	manual page.	58	manual page.
37		59
38	At the moment, this module family is severly broken and underdocumented,	60	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 -	61	so do not use. This was uploaded mainly to reserve the CPAN namespace -
40	stay tuned! The basic API should be finished, however.	62	stay tuned!
41		63
42	=head1 CONCEPTS	64	=head1 CONCEPTS
43		65
44	=over 4	66	=over 4
45		67
46	=item port	68	=item port
47		69
48	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).
49		71
50	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
51	messages. All C<rcv> handlers will receive messages they match, messages	73	some messages. Messages will not be queued.
52	will not be queued.
53		74
54	=item port id - C<noderef#portname>	75	=item port ID - C<noderef#portname>
55		76
56	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	77	A port ID is the concatenation of a noderef, a hash-mark (C<#>) as
57	separator, and a port name (a printable string of unspecified format). An	78	separator, and a port name (a printable string of unspecified format). An
58	exception is the the node port, whose ID is identical to its node	79	exception is the the node port, whose ID is identical to its node
59	reference.	80	reference.
60		81
61	=item node	82	=item node
62		83
63	A node is a single process containing at least one port - the node	84	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	85	which provides nodes to manage each other remotely, and to create new
65	create new ports, among other things.	86	ports.
66		87
67	Nodes are either private (single-process only), slaves (connected to a	88	Nodes are either private (single-process only), slaves (can only talk to
68	master node only) or public nodes (connectable from unrelated nodes).	89	public nodes, but do not need an open port) or public nodes (connectable
		90	from any other node).
69		91
70	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	92	=item node ID - C<[a-za-Z0-9_\-.:]+>
71		93
72	A node reference is a string that either simply identifies the node (for	94	A node ID 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	95	private and slave nodes), or contains a recipe on how to reach a given
74	node (for public nodes).	96	node (for public nodes).
75		97
76	This recipe is simply a comma-separated list of C<address:port> pairs (for	98	This recipe is simply a comma-separated list of C<address:port> pairs (for
77	TCP/IP, other protocols might look different).	99	TCP/IP, other protocols might look different).
…		…
90		112
91	=cut	113	=cut
92		114
93	package AnyEvent::MP;	115	package AnyEvent::MP;
94		116
95	use AnyEvent::MP::Base;	117	use AnyEvent::MP::Kernel;
96		118
97	use common::sense;	119	use common::sense;
98		120
99	use Carp ();	121	use Carp ();
100		122
101	use AE ();	123	use AE ();
102		124
103	use base "Exporter";	125	use base "Exporter";
104		126
105	our $VERSION = '0.1';	127	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		128
106	our @EXPORT = qw(	129	our @EXPORT = qw(
107	NODE $NODE *SELF node_of _any_	130	NODE $NODE *SELF node_of after
108	resolve_node initialise_node	131	resolve_node initialise_node
109	snd rcv mon kil reg psub	132	snd rcv mon mon_guard kil reg psub spawn
110	port	133	port
111	);	134	);
112		135
113	our $SELF;	136	our $SELF;
114		137
…		…
118	kil $SELF, die => $msg;	141	kil $SELF, die => $msg;
119	}	142	}
120		143
121	=item $thisnode = NODE / $NODE	144	=item $thisnode = NODE / $NODE
122		145
123	The C<NODE> function returns, and the C<$NODE> variable contains	146	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	147	node id 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	148	C<initialise_node>.
126	identifiers become invalid.
127		149
128	=item $noderef = node_of $port	150	=item $nodeid = node_of $port
129		151
130	Extracts and returns the noderef from a portid or a noderef.	152	Extracts and returns the noderef from a port ID or a node ID.
		153
		154	=item initialise_node $profile_name
		155
		156	Before a node can talk to other nodes on the network it has to initialise
		157	itself - the minimum a node needs to know is it's own name, and optionally
		158	it should know the noderefs of some other nodes in the network.
		159
		160	This function initialises a node - it must be called exactly once (or
		161	never) before calling other AnyEvent::MP functions.
		162
		163	All arguments (optionally except for the first) are noderefs, which can be
		164	either resolved or unresolved.
		165
		166	The first argument will be looked up in the configuration database first
		167	(if it is C<undef> then the current nodename will be used instead) to find
		168	the relevant configuration profile (see L<aemp>). If none is found then
		169	the default configuration is used. The configuration supplies additional
		170	seed/master nodes and can override the actual noderef.
		171
		172	There are two types of networked nodes, public nodes and slave nodes:
		173
		174	=over 4
		175
		176	=item public nodes
		177
		178	For public nodes, C<$noderef> (supplied either directly to
		179	C<initialise_node> or indirectly via a profile or the nodename) must be a
		180	noderef (possibly unresolved, in which case it will be resolved).
		181
		182	After resolving, the node will bind itself on all endpoints.
		183
		184	=item slave nodes
		185
		186	When the C<$noderef> (either as given or overriden by the config file)
		187	is the special string C<slave/>, then the node will become a slave
		188	node. Slave nodes cannot be contacted from outside, and cannot talk to
		189	each other (at least in this version of AnyEvent::MP).
		190
		191	Slave nodes work by creating connections to all public nodes, using the
		192	L<AnyEvent::MP::Global> service.
		193
		194	=back
		195
		196	After initialising itself, the node will connect to all additional
		197	C<$seednodes> that are specified diretcly or via a profile. Seednodes are
		198	optional and can be used to quickly bootstrap the node into an existing
		199	network.
		200
		201	All the seednodes will also be specially marked to automatically retry
		202	connecting to them indefinitely, so make sure that seednodes are really
		203	reliable and up (this might also change in the future).
		204
		205	Example: become a public node listening on the guessed noderef, or the one
		206	specified via C<aemp> for the current node. This should be the most common
		207	form of invocation for "daemon"-type nodes.
		208
		209	initialise_node;
		210
		211	Example: become a slave node to any of the the seednodes specified via
		212	C<aemp>. This form is often used for commandline clients.
		213
		214	initialise_node "slave/";
		215
		216	Example: become a public node, and try to contact some well-known master
		217	servers to become part of the network.
		218
		219	initialise_node undef, "master1", "master2";
		220
		221	Example: become a public node listening on port C<4041>.
		222
		223	initialise_node 4041;
		224
		225	Example: become a public node, only visible on localhost port 4044.
		226
		227	initialise_node "localhost:4044";
131		228
132	=item $cv = resolve_node $noderef	229	=item $cv = resolve_node $noderef
133		230
134	Takes an unresolved node reference that may contain hostnames and	231	Takes an unresolved node reference that may contain hostnames and
135	abbreviated IDs, resolves all of them and returns a resolved node	232	abbreviated IDs, resolves all of them and returns a resolved node
…		…
172	=item snd $port, type => @data	269	=item snd $port, type => @data
173		270
174	=item snd $port, @msg	271	=item snd $port, @msg
175		272
176	Send the given message to the given port ID, which can identify either	273	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	274	a local or a remote port, and must be a port ID.
178	stringifies a sa port ID (such as a port object :).
179		275
180	While the message can be about anything, it is highly recommended to use a	276	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	277	string as first element (a port ID, or some word that indicates a request
182	type etc.).	278	type etc.).
183		279
184	The message data effectively becomes read-only after a call to this	280	The message data effectively becomes read-only after a call to this
185	function: modifying any argument is not allowed and can cause many	281	function: modifying any argument is not allowed and can cause many
186	problems.	282	problems.
…		…
191	that Storable can serialise and deserialise is allowed, and for the local	287	that Storable can serialise and deserialise is allowed, and for the local
192	node, anything can be passed.	288	node, anything can be passed.
193		289
194	=item $local_port = port	290	=item $local_port = port
195		291
196	Create a new local port object that can be used either as a pattern	292	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"),	293	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		294
200	=item $port = port { my @msg = @_; $finished }	295	=item $local_port = port { my @msg = @_ }
201		296
202	Creates a "miniport", that is, a very lightweight port without any pattern	297	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.	298	creating a port and calling C<rcv $port, $callback> on it.
205		299
206	The block will be called for every message received on the port. When the	300	The block will be called for every message received on the port, with the
207	callback returns a true value its job is considered "done" and the port	301	global variable C<$SELF> set to the port ID. Runtime errors will cause the
208	will be destroyed. Otherwise it will stay alive.	302	port to be C<kil>ed. The message will be passed as-is, no extra argument
		303	(i.e. no port ID) will be passed to the callback.
209		304
210	The message will be passed as-is, no extra argument (i.e. no port id) will	305	If you want to stop/destroy the port, simply C<kil> it:
211	be passed to the callback.
212		306
213	If you need the local port id in the callback, this works nicely:	307	my $port = port {
214		308	my @msg = @_;
215	my $port; $port = port {	309	...
216	snd $otherport, reply => $port;	310	kil $SELF;
217	};	311	};
218		312
219	=cut	313	=cut
220		314
221	sub rcv($@);	315	sub rcv($@);
		316
		317	sub _kilme {
		318	die "received message on port without callback";
		319	}
222		320
223	sub port(;&) {	321	sub port(;&) {
224	my $id = "$UNIQ." . $ID++;	322	my $id = "$UNIQ." . $ID++;
225	my $port = "$NODE#$id";	323	my $port = "$NODE#$id";
226		324
227	if (@_) {	325	rcv $port, shift \|\| \&_kilme;
228	rcv $port, shift;
229	} else {
230	$PORT{$id} = sub { }; # nop
231	}
232		326
233	$port	327	$port
234	}	328	}
235		329
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)	330	=item rcv $local_port, $callback->(@msg)
254		331
255	Replaces the callback on the specified miniport (after converting it to	332	Replaces the default callback on the specified port. There is no way to
256	one if required).	333	remove the default callback: use C<sub { }> to disable it, or better
257		334	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...] => $callback->(@msg), ...
263
264	Register callbacks to be called on matching messages on the given full
265	port (after converting it to one if required).
266
267	The callback has to return a true value when its work is done, after
268	which is will be removed, or a false value in which case it will stay
269	registered.
270		335
271	The global C<$SELF> (exported by this module) contains C<$port> while	336	The global C<$SELF> (exported by this module) contains C<$port> while
272	executing the callback.	337	executing the callback. Runtime errors during callback execution will
		338	result in the port being C<kil>ed.
273		339
274	Runtime errors wdurign callback execution will result in the port being	340	The default callback received all messages not matched by a more specific
275	C<kil>ed.	341	C<tag> match.
276		342
277	If the match is an array reference, then it will be matched against the	343	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
278	first elements of the message, otherwise only the first element is being
279	matched.
280		344
281	Any element in the match that is specified as C<_any_> (a function	345	Register (or replace) callbacks to be called on messages starting with the
282	exported by this module) matches any single element of the message.	346	given tag on the given port (and return the port), or unregister it (when
		347	C<$callback> is C<$undef> or missing). There can only be one callback
		348	registered for each tag.
283		349
284	While not required, it is highly recommended that the first matching	350	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	351	element (the tag) has been removed. The callback will use the same
286	also the most efficient match (by far).	352	environment as the default callback (see above).
		353
		354	Example: create a port and bind receivers on it in one go.
		355
		356	my $port = rcv port,
		357	msg1 => sub { ... },
		358	msg2 => sub { ... },
		359	;
		360
		361	Example: create a port, bind receivers and send it in a message elsewhere
		362	in one go:
		363
		364	snd $otherport, reply =>
		365	rcv port,
		366	msg1 => sub { ... },
		367	...
		368	;
		369
		370	Example: temporarily register a rcv callback for a tag matching some port
		371	(e.g. for a rpc reply) and unregister it after a message was received.
		372
		373	rcv $port, $otherport => sub {
		374	my @reply = @_;
		375
		376	rcv $SELF, $otherport;
		377	};
287		378
288	=cut	379	=cut
289		380
290	sub rcv($@) {	381	sub rcv($@) {
291	my $port = shift;	382	my $port = shift;
292	my ($noderef, $portid) = split /#/, $port, 2;	383	my ($noderef, $portid) = split /#/, $port, 2;
293		384
294	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	385	$NODE{$noderef} == $NODE{""}
295	or Carp::croak "$port: rcv can only be called on local ports, caught";	386	or Carp::croak "$port: rcv can only be called on local ports, caught";
296		387
297	if (@_ == 1) {	388	while (@_) {
		389	if (ref $_[0]) {
		390	if (my $self = $PORT_DATA{$portid}) {
		391	"AnyEvent::MP::Port" eq ref $self
		392	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		393
		394	$self->[2] = shift;
		395	} else {
298	my $cb = shift;	396	my $cb = shift;
299	delete $PORT_DATA{$portid};
300	$PORT{$portid} = sub {	397	$PORT{$portid} = sub {
301	local $SELF = $port;	398	local $SELF = $port;
302	eval {	399	eval { &$cb }; _self_die if $@;
303	&$cb	400	};
304	and kil $port;
305	};	401	}
306	_self_die if $@;	402	} elsif (defined $_[0]) {
307	};
308	} else {
309	my $self = $PORT_DATA{$portid} \|\|= do {	403	my $self = $PORT_DATA{$portid} \|\|= do {
310	my $self = bless {	404	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
311	id => $port,
312	}, "AnyEvent::MP::Port";
313		405
314	$PORT{$portid} = sub {	406	$PORT{$portid} = sub {
315	local $SELF = $port;	407	local $SELF = $port;
316		408
317	eval {
318	for (@{ $self->{rc0}{$_[0]} }) {	409	if (my $cb = $self->[1]{$_[0]}) {
319	$_ && &{$_->[0]}	410	shift;
320	&& undef $_;	411	eval { &$cb }; _self_die if $@;
321	}	412	} else {
322
323	for (@{ $self->{rcv}{$_[0]} }) {
324	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
325	&& &{$_->[0]}	413	&{ $self->[0] };
326	&& undef $_;
327	}
328
329	for (@{ $self->{any} }) {
330	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
331	&& &{$_->[0]}
332	&& undef $_;
333	}	414	}
334	};	415	};
335	_self_die if $@;	416
		417	$self
336	};	418	};
337		419
338	$self
339	};
340
341	"AnyEvent::MP::Port" eq ref $self	420	"AnyEvent::MP::Port" eq ref $self
342	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	421	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
343		422
344	while (@_) {
345	my ($match, $cb) = splice @_, 0, 2;	423	my ($tag, $cb) = splice @_, 0, 2;
346		424
347	if (!ref $match) {	425	if (defined $cb) {
348	push @{ $self->{rc0}{$match} }, [$cb];	426	$self->[1]{$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 {	427	} else {
355	push @{ $self->{any} }, [$cb, $match];	428	delete $self->[1]{$tag};
356	}	429	}
357	}	430	}
358	}	431	}
359		432
360	$port	433	$port
…		…
398	}	471	}
399	}	472	}
400		473
401	=item $guard = mon $port, $cb->(@reason)	474	=item $guard = mon $port, $cb->(@reason)
402		475
403	=item $guard = mon $port, $otherport	476	=item $guard = mon $port, $rcvport
404		477
		478	=item $guard = mon $port
		479
405	=item $guard = mon $port, $otherport, @msg	480	=item $guard = mon $port, $rcvport, @msg
406		481
407	Monitor the given port and do something when the port is killed.	482	Monitor the given port and do something when the port is killed or
		483	messages to it were lost, and optionally return a guard that can be used
		484	to stop monitoring again.
408		485
		486	C<mon> effectively guarantees that, in the absence of hardware failures,
		487	that after starting the monitor, either all messages sent to the port
		488	will arrive, or the monitoring action will be invoked after possible
		489	message loss has been detected. No messages will be lost "in between"
		490	(after the first lost message no further messages will be received by the
		491	port). After the monitoring action was invoked, further messages might get
		492	delivered again.
		493
		494	Note that monitoring-actions are one-shot: once released, they are removed
		495	and will not trigger again.
		496
409	In the first form, the callback is simply called with any number	497	In the first form (callback), the callback is simply called with any
410	of C<@reason> elements (no @reason means that the port was deleted	498	number of C<@reason> elements (no @reason means that the port was deleted
411	"normally"). Note also that I<< the callback B<must> never die >>, so use	499	"normally"). Note also that I<< the callback B<must> never die >>, so use
412	C<eval> if unsure.	500	C<eval> if unsure.
413		501
414	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	502	In the second form (another port given), the other port (C<$rcvport>)
415	a @reason was specified, i.e. on "normal" kils nothing happens, while	503	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.	504	"normal" kils nothing happens, while under all other conditions, the other
		505	port is killed with the same reason.
417		506
		507	The third form (kill self) is the same as the second form, except that
		508	C<$rvport> defaults to C<$SELF>.
		509
418	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	510	In the last form (message), a message of the form C<@msg, @reason> will be
		511	C<snd>.
		512
		513	As a rule of thumb, monitoring requests should always monitor a port from
		514	a local port (or callback). The reason is that kill messages might get
		515	lost, just like any other message. Another less obvious reason is that
		516	even monitoring requests can get lost (for exmaple, when the connection
		517	to the other node goes down permanently). When monitoring a port locally
		518	these problems do not exist.
419		519
420	Example: call a given callback when C<$port> is killed.	520	Example: call a given callback when C<$port> is killed.
421		521
422	mon $port, sub { warn "port died because of <@_>\n" };	522	mon $port, sub { warn "port died because of <@_>\n" };
423		523
424	Example: kill ourselves when C<$port> is killed abnormally.	524	Example: kill ourselves when C<$port> is killed abnormally.
425		525
426	mon $port, $self;	526	mon $port;
427		527
428	Example: send us a restart message another C<$port> is killed.	528	Example: send us a restart message when another C<$port> is killed.
429		529
430	mon $port, $self => "restart";	530	mon $port, $self => "restart";
431		531
432	=cut	532	=cut
433		533
434	sub mon {	534	sub mon {
435	my ($noderef, $port) = split /#/, shift, 2;	535	my ($noderef, $port) = split /#/, shift, 2;
436		536
437	my $node = $NODE{$noderef} \|\| add_node $noderef;	537	my $node = $NODE{$noderef} \|\| add_node $noderef;
438		538
439	my $cb = shift;	539	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
440		540
441	unless (ref $cb) {	541	unless (ref $cb) {
442	if (@_) {	542	if (@_) {
443	# send a kill info message	543	# send a kill info message
444	my (@msg) = ($cb, @_);	544	my (@msg) = ($cb, @_);
…		…
475	=cut	575	=cut
476		576
477	sub mon_guard {	577	sub mon_guard {
478	my ($port, @refs) = @_;	578	my ($port, @refs) = @_;
479		579
		580	#TODO: mon-less form?
		581
480	mon $port, sub { 0 && @refs }	582	mon $port, sub { 0 && @refs }
481	}	583	}
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		584
493	=item kil $port[, @reason]	585	=item kil $port[, @reason]
494		586
495	Kill the specified port with the given C<@reason>.	587	Kill the specified port with the given C<@reason>.
496		588
…		…
504	will be reported as reason C<< die => $@ >>.	596	will be reported as reason C<< die => $@ >>.
505		597
506	Transport/communication errors are reported as C<< transport_error =>	598	Transport/communication errors are reported as C<< transport_error =>
507	$message >>.	599	$message >>.
508		600
		601	=cut
		602
		603	=item $port = spawn $node, $initfunc[, @initdata]
		604
		605	Creates a port on the node C<$node> (which can also be a port ID, in which
		606	case it's the node where that port resides).
		607
		608	The port ID of the newly created port is return immediately, and it is
		609	permissible to immediately start sending messages or monitor the port.
		610
		611	After the port has been created, the init function is
		612	called. This function must be a fully-qualified function name
		613	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		614	program, use C<::name>.
		615
		616	If the function doesn't exist, then the node tries to C<require>
		617	the package, then the package above the package and so on (e.g.
		618	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		619	exists or it runs out of package names.
		620
		621	The init function is then called with the newly-created port as context
		622	object (C<$SELF>) and the C<@initdata> values as arguments.
		623
		624	A common idiom is to pass your own port, monitor the spawned port, and
		625	in the init function, monitor the original port. This two-way monitoring
		626	ensures that both ports get cleaned up when there is a problem.
		627
		628	Example: spawn a chat server port on C<$othernode>.
		629
		630	# this node, executed from within a port context:
		631	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		632	mon $server;
		633
		634	# init function on C<$othernode>
		635	sub connect {
		636	my ($srcport) = @_;
		637
		638	mon $srcport;
		639
		640	rcv $SELF, sub {
		641	...
		642	};
		643	}
		644
		645	=cut
		646
		647	sub _spawn {
		648	my $port = shift;
		649	my $init = shift;
		650
		651	local $SELF = "$NODE#$port";
		652	eval {
		653	&{ load_func $init }
		654	};
		655	_self_die if $@;
		656	}
		657
		658	sub spawn(@) {
		659	my ($noderef, undef) = split /#/, shift, 2;
		660
		661	my $id = "$RUNIQ." . $ID++;
		662
		663	$_[0] =~ /::/
		664	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		665
		666	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
		667
		668	"$noderef#$id"
		669	}
		670
		671	=item after $timeout, @msg
		672
		673	=item after $timeout, $callback
		674
		675	Either sends the given message, or call the given callback, after the
		676	specified number of seconds.
		677
		678	This is simply a utility function that come sin handy at times.
		679
		680	=cut
		681
		682	sub after($@) {
		683	my ($timeout, @action) = @_;
		684
		685	my $t; $t = AE::timer $timeout, 0, sub {
		686	undef $t;
		687	ref $action[0]
		688	? $action[0]()
		689	: snd @action;
		690	};
		691	}
		692
509	=back	693	=back
510		694
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	695	=head1 AnyEvent::MP vs. Distributed Erlang
626		696
627	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node	697	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	698	== 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	699	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
630	sample:	700	sample:
631		701
632	http://www.erlang.se/doc/programming_rules.shtml	702	http://www.Erlang.se/doc/programming_rules.shtml
633	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	703	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	704	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	705	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
636		706
637	Despite the similarities, there are also some important differences:	707	Despite the similarities, there are also some important differences:
638		708
639	=over 4	709	=over 4
640		710
…		…
645	convenience functionality.	715	convenience functionality.
646		716
647	This means that AEMP requires a less tightly controlled environment at the	717	This means that AEMP requires a less tightly controlled environment at the
648	cost of longer node references and a slightly higher management overhead.	718	cost of longer node references and a slightly higher management overhead.
649		719
		720	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
		721	uses "local ports are like remote ports".
		722
		723	The failure modes for local ports are quite different (runtime errors
		724	only) then for remote ports - when a local port dies, you I<know> it dies,
		725	when a connection to another node dies, you know nothing about the other
		726	port.
		727
		728	Erlang pretends remote ports are as reliable as local ports, even when
		729	they are not.
		730
		731	AEMP encourages a "treat remote ports differently" philosophy, with local
		732	ports being the special case/exception, where transport errors cannot
		733	occur.
		734
650	=item * Erlang uses processes and a mailbox, AEMP does not queue.	735	=item * Erlang uses processes and a mailbox, AEMP does not queue.
651		736
652	Erlang uses processes that selctively receive messages, and therefore	737	Erlang uses processes that selectively receive messages, and therefore
653	needs a queue. AEMP is event based, queuing messages would serve no useful	738	needs a queue. AEMP is event based, queuing messages would serve no
654	purpose.	739	useful purpose. For the same reason the pattern-matching abilities of
		740	AnyEvent::MP are more limited, as there is little need to be able to
		741	filter messages without dequeing them.
655		742
656	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	743	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
657		744
658	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	745	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
659		746
660	Sending messages in erlang is synchronous and blocks the process. AEMP	747	Sending messages in Erlang is synchronous and blocks the process (and
661	sends are immediate, connection establishment is handled in the	748	so does not need a queue that can overflow). AEMP sends are immediate,
662	background.	749	connection establishment is handled in the background.
663		750
664	=item * Erlang can silently lose messages, AEMP cannot.	751	=item * Erlang suffers from silent message loss, AEMP does not.
665		752
666	Erlang makes few guarantees on messages delivery - messages can get lost	753	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,	754	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).	755	and c, and the other side only receives messages a and c).
669		756
670	AEMP guarantees correct ordering, and the guarantee that there are no	757	AEMP guarantees correct ordering, and the guarantee that there are no
671	holes in the message sequence.	758	holes in the message sequence.
672		759
673	=item * In erlang, processes can be declared dead and later be found to be	760	=item * In Erlang, processes can be declared dead and later be found to be
674	alive.	761	alive.
675		762
676	In erlang it can happen that a monitored process is declared dead and	763	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	764	linked processes get killed, but later it turns out that the process is
678	still alive - and can receive messages.	765	still alive - and can receive messages.
679		766
680	In AEMP, when port monitoring detects a port as dead, then that port will	767	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	768	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.	769	and then later sends messages to it, finding it is still alive.
683		770
684	=item * Erlang can send messages to the wrong port, AEMP does not.	771	=item * Erlang can send messages to the wrong port, AEMP does not.
685		772
686	In erlang it is quite possible that a node that restarts reuses a process	773	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	774	known to other nodes for a completely different process, causing messages
688	messages destined for that process to end up in an unrelated process.	775	destined for that process to end up in an unrelated process.
689		776
690	AEMP never reuses port IDs, so old messages or old port IDs floating	777	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.	778	around in the network will not be sent to an unrelated port.
692		779
693	=item * Erlang uses unprotected connections, AEMP uses secure	780	=item * Erlang uses unprotected connections, AEMP uses secure
…		…
697	securely authenticate nodes.	784	securely authenticate nodes.
698		785
699	=item * The AEMP protocol is optimised for both text-based and binary	786	=item * The AEMP protocol is optimised for both text-based and binary
700	communications.	787	communications.
701		788
702	The AEMP protocol, unlike the erlang protocol, supports both	789	The AEMP protocol, unlike the Erlang protocol, supports both
703	language-independent text-only protocols (good for debugging) and binary,	790	language-independent text-only protocols (good for debugging) and binary,
704	language-specific serialisers (e.g. Storable).	791	language-specific serialisers (e.g. Storable).
705		792
706	It has also been carefully designed to be implementable in other languages	793	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	794	with a minimum of work while gracefully degrading fucntionality to make the
708	protocol simple.	795	protocol simple.
709		796
		797	=item * AEMP has more flexible monitoring options than Erlang.
		798
		799	In Erlang, you can chose to receive I<all> exit signals as messages
		800	or I<none>, there is no in-between, so monitoring single processes is
		801	difficult to implement. Monitoring in AEMP is more flexible than in
		802	Erlang, as one can choose between automatic kill, exit message or callback
		803	on a per-process basis.
		804
		805	=item * Erlang tries to hide remote/local connections, AEMP does not.
		806
		807	Monitoring in Erlang is not an indicator of process death/crashes,
		808	as linking is (except linking is unreliable in Erlang).
		809
		810	In AEMP, you don't "look up" registered port names or send to named ports
		811	that might or might not be persistent. Instead, you normally spawn a port
		812	on the remote node. The init function monitors the you, and you monitor
		813	the remote port. Since both monitors are local to the node, they are much
		814	more reliable.
		815
		816	This also saves round-trips and avoids sending messages to the wrong port
		817	(hard to do in Erlang).
		818
		819	=back
		820
		821	=head1 RATIONALE
		822
		823	=over 4
		824
		825	=item Why strings for ports and noderefs, why not objects?
		826
		827	We considered "objects", but found that the actual number of methods
		828	thatc an be called are very low. Since port IDs and noderefs travel over
		829	the network frequently, the serialising/deserialising would add lots of
		830	overhead, as well as having to keep a proxy object.
		831
		832	Strings can easily be printed, easily serialised etc. and need no special
		833	procedures to be "valid".
		834
		835	And a a miniport consists of a single closure stored in a global hash - it
		836	can't become much cheaper.
		837
		838	=item Why favour JSON, why not real serialising format such as Storable?
		839
		840	In fact, any AnyEvent::MP node will happily accept Storable as framing
		841	format, but currently there is no way to make a node use Storable by
		842	default.
		843
		844	The default framing protocol is JSON because a) JSON::XS is many times
		845	faster for small messages and b) most importantly, after years of
		846	experience we found that object serialisation is causing more problems
		847	than it gains: Just like function calls, objects simply do not travel
		848	easily over the network, mostly because they will always be a copy, so you
		849	always have to re-think your design.
		850
		851	Keeping your messages simple, concentrating on data structures rather than
		852	objects, will keep your messages clean, tidy and efficient.
		853
710	=back	854	=back
711		855
712	=head1 SEE ALSO	856	=head1 SEE ALSO
713		857
714	L<AnyEvent>.	858	L<AnyEvent>.

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Revision 1.63 by root, Thu Aug 27 21:29:37 2009 UTC