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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.34 by root, Wed Aug 5 23:50:46 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		44	AnyEvent::MP::Intro - outdated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.
131		153
132	=item initialise_node $noderef, $seednode, $seednode...	154	=item initialise_node $profile_name
133
134	=item initialise_node "slave/", $master, $master...
135		155
136	Before a node can talk to other nodes on the network it has to initialise	156	Before a node can talk to other nodes on the network it has to initialise
137	itself - the minimum a node needs to know is it's own name, and optionally	157	itself - the minimum a node needs to know is it's own name, and optionally
138	it should know the noderefs of some other nodes in the network.	158	it should know the noderefs of some other nodes in the network.
139		159
140	This function initialises a node - it must be called exactly once (or	160	This function initialises a node - it must be called exactly once (or
141	never) before calling other AnyEvent::MP functions.	161	never) before calling other AnyEvent::MP functions.
142		162
143	All arguments are noderefs, which can be either resolved or unresolved.	163	All arguments (optionally except for the first) are noderefs, which can be
		164	either resolved or unresolved.
		165
		166	The first argument will be looked up in the configuration database first
		167	(if it is C<undef> then the current nodename will be used instead) to find
		168	the relevant configuration profile (see L<aemp>). If none is found then
		169	the default configuration is used. The configuration supplies additional
		170	seed/master nodes and can override the actual noderef.
144		171
145	There are two types of networked nodes, public nodes and slave nodes:	172	There are two types of networked nodes, public nodes and slave nodes:
146		173
147	=over 4	174	=over 4
148		175
149	=item public nodes	176	=item public nodes
150		177
151	For public nodes, C<$noderef> must either be a (possibly unresolved)	178	For public nodes, C<$noderef> (supplied either directly to
152	noderef, in which case it will be resolved, or C<undef> (or missing), in	179	C<initialise_node> or indirectly via a profile or the nodename) must be a
153	which case the noderef will be guessed.	180	noderef (possibly unresolved, in which case it will be resolved).
154		181
155	Afterwards, the node will bind itself on all endpoints and try to connect	182	After resolving, the node will bind itself on all endpoints.
156	to all additional C<$seednodes> that are specified. Seednodes are optional
157	and can be used to quickly bootstrap the node into an existing network.
158		183
159	=item slave nodes	184	=item slave nodes
160		185
161	When the C<$noderef> is the special string C<slave/>, then the node will	186	When the C<$noderef> (either as given or overriden by the config file)
		187	is the special string C<slave/>, then the node will become a slave
162	become a slave node. Slave nodes cannot be contacted from outside and will	188	node. Slave nodes cannot be contacted from outside, and cannot talk to
163	route most of their traffic to the master node that they attach to.	189	each other (at least in this version of AnyEvent::MP).
164		190
165	At least one additional noderef is required: The node will try to connect	191	Slave nodes work by creating connections to all public nodes, using the
166	to all of them and will become a slave attached to the first node it can	192	L<AnyEvent::MP::Global> service.
167	successfully connect to.
168		193
169	=back	194	=back
170		195
171	This function will block until all nodes have been resolved and, for slave	196	After initialising itself, the node will connect to all additional
172	nodes, until it has successfully established a connection to a master	197	C<$seednodes> that are specified diretcly or via a profile. Seednodes are
173	server.	198	optional and can be used to quickly bootstrap the node into an existing
		199	network.
174		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
175	Example: become a public node listening on the default node.	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.
176		208
177	initialise_node;	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/";
178		215
179	Example: become a public node, and try to contact some well-known master	216	Example: become a public node, and try to contact some well-known master
180	servers to become part of the network.	217	servers to become part of the network.
181		218
182	initialise_node undef, "master1", "master2";	219	initialise_node undef, "master1", "master2";
…		…
185		222
186	initialise_node 4041;	223	initialise_node 4041;
187		224
188	Example: become a public node, only visible on localhost port 4044.	225	Example: become a public node, only visible on localhost port 4044.
189		226
190	initialise_node "locahost:4044";	227	initialise_node "localhost:4044";
191
192	Example: become a slave node to any of the specified master servers.
193
194	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
195		228
196	=item $cv = resolve_node $noderef	229	=item $cv = resolve_node $noderef
197		230
198	Takes an unresolved node reference that may contain hostnames and	231	Takes an unresolved node reference that may contain hostnames and
199	abbreviated IDs, resolves all of them and returns a resolved node	232	abbreviated IDs, resolves all of them and returns a resolved node
…		…
236	=item snd $port, type => @data	269	=item snd $port, type => @data
237		270
238	=item snd $port, @msg	271	=item snd $port, @msg
239		272
240	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
241	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.
242	stringifies a sa port ID (such as a port object :).
243		275
244	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
245	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
246	type etc.).	278	type etc.).
247		279
248	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
249	function: modifying any argument is not allowed and can cause many	281	function: modifying any argument is not allowed and can cause many
250	problems.	282	problems.
…		…
255	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
256	node, anything can be passed.	288	node, anything can be passed.
257		289
258	=item $local_port = port	290	=item $local_port = port
259		291
260	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
261	matching port ("full port") or a single-callback port ("miniport"),	293	no callbacks set and will throw an error when it receives messages.
262	depending on how C<rcv> callbacks are bound to the object.
263		294
264	=item $port = port { my @msg = @_; $finished }	295	=item $local_port = port { my @msg = @_ }
265		296
266	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
267	matching behind it, and returns its ID. Semantically the same as creating
268	a port and calling C<rcv $port, $callback> on it.	298	creating a port and calling C<rcv $port, $callback> on it.
269		299
270	The block will be called for every message received on the port. When the	300	The block will be called for every message received on the port, with the
271	callback returns a true value its job is considered "done" and the port	301	global variable C<$SELF> set to the port ID. Runtime errors will cause the
272	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.
273		304
274	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:
275	be passed to the callback.
276		306
277	If you need the local port id in the callback, this works nicely:	307	my $port = port {
278		308	my @msg = @_;
279	my $port; $port = port {	309	...
280	snd $otherport, reply => $port;	310	kil $SELF;
281	};	311	};
282		312
283	=cut	313	=cut
284		314
285	sub rcv($@);	315	sub rcv($@);
		316
		317	sub _kilme {
		318	die "received message on port without callback";
		319	}
286		320
287	sub port(;&) {	321	sub port(;&) {
288	my $id = "$UNIQ." . $ID++;	322	my $id = "$UNIQ." . $ID++;
289	my $port = "$NODE#$id";	323	my $port = "$NODE#$id";
290		324
291	if (@_) {	325	rcv $port, shift \|\| \&_kilme;
292	rcv $port, shift;
293	} else {
294	$PORT{$id} = sub { }; # nop
295	}
296		326
297	$port	327	$port
298	}	328	}
299		329
300	=item reg $port, $name
301
302	Registers the given port under the name C<$name>. If the name already
303	exists it is replaced.
304
305	A port can only be registered under one well known name.
306
307	A port automatically becomes unregistered when it is killed.
308
309	=cut
310
311	sub reg(@) {
312	my ($port, $name) = @_;
313
314	$REG{$name} = $port;
315	}
316
317	=item rcv $port, $callback->(@msg)	330	=item rcv $local_port, $callback->(@msg)
318		331
319	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
320	one if required).	333	remove the default callback: use C<sub { }> to disable it, or better
321		334	C<kil> the port when it is no longer needed.
322	=item rcv $port, tagstring => $callback->(@msg), ...
323
324	=item rcv $port, $smartmatch => $callback->(@msg), ...
325
326	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
327
328	Register callbacks to be called on matching messages on the given full
329	port (after converting it to one if required).
330
331	The callback has to return a true value when its work is done, after
332	which is will be removed, or a false value in which case it will stay
333	registered.
334		335
335	The global C<$SELF> (exported by this module) contains C<$port> while	336	The global C<$SELF> (exported by this module) contains C<$port> while
336	executing the callback.	337	executing the callback. Runtime errors during callback execution will
		338	result in the port being C<kil>ed.
337		339
338	Runtime errors wdurign callback execution will result in the port being	340	The default callback received all messages not matched by a more specific
339	C<kil>ed.	341	C<tag> match.
340		342
341	If the match is an array reference, then it will be matched against the	343	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
342	first elements of the message, otherwise only the first element is being
343	matched.
344		344
345	Any element in the match that is specified as C<_any_> (a function	345	Register (or replace) callbacks to be called on messages starting with the
346	exported by this module) matches any single element of the message.	346	given tag on the given port (and return the port), or unregister it (when
		347	C<$callback> is C<$undef> or missing). There can only be one callback
		348	registered for each tag.
347		349
348	While not required, it is highly recommended that the first matching	350	The original message will be passed to the callback, after the first
349	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
350	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, $otherport;
		377	};
351		378
352	=cut	379	=cut
353		380
354	sub rcv($@) {	381	sub rcv($@) {
355	my $port = shift;	382	my $port = shift;
356	my ($noderef, $portid) = split /#/, $port, 2;	383	my ($noderef, $portid) = split /#/, $port, 2;
357		384
358	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	385	$NODE{$noderef} == $NODE{""}
359	or Carp::croak "$port: rcv can only be called on local ports, caught";	386	or Carp::croak "$port: rcv can only be called on local ports, caught";
360		387
361	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 {
362	my $cb = shift;	396	my $cb = shift;
363	delete $PORT_DATA{$portid};
364	$PORT{$portid} = sub {	397	$PORT{$portid} = sub {
365	local $SELF = $port;	398	local $SELF = $port;
366	eval {	399	eval { &$cb }; _self_die if $@;
367	&$cb	400	};
368	and kil $port;
369	};	401	}
370	_self_die if $@;	402	} elsif (defined $_[0]) {
371	};
372	} else {
373	my $self = $PORT_DATA{$portid} \|\|= do {	403	my $self = $PORT_DATA{$portid} \|\|= do {
374	my $self = bless {	404	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
375	id => $port,
376	}, "AnyEvent::MP::Port";
377		405
378	$PORT{$portid} = sub {	406	$PORT{$portid} = sub {
379	local $SELF = $port;	407	local $SELF = $port;
380		408
381	eval {
382	for (@{ $self->{rc0}{$_[0]} }) {	409	if (my $cb = $self->[1]{$_[0]}) {
383	$_ && &{$_->[0]}	410	shift;
384	&& undef $_;	411	eval { &$cb }; _self_die if $@;
385	}	412	} else {
386
387	for (@{ $self->{rcv}{$_[0]} }) {
388	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
389	&& &{$_->[0]}	413	&{ $self->[0] };
390	&& undef $_;
391	}
392
393	for (@{ $self->{any} }) {
394	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
395	&& &{$_->[0]}
396	&& undef $_;
397	}	414	}
398	};	415	};
399	_self_die if $@;	416
		417	$self
400	};	418	};
401		419
402	$self
403	};
404
405	"AnyEvent::MP::Port" eq ref $self	420	"AnyEvent::MP::Port" eq ref $self
406	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	421	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
407		422
408	while (@_) {
409	my ($match, $cb) = splice @_, 0, 2;	423	my ($tag, $cb) = splice @_, 0, 2;
410		424
411	if (!ref $match) {	425	if (defined $cb) {
412	push @{ $self->{rc0}{$match} }, [$cb];	426	$self->[1]{$tag} = $cb;
413	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
414	my ($type, @match) = @$match;
415	@match
416	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
417	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
418	} else {	427	} else {
419	push @{ $self->{any} }, [$cb, $match];	428	delete $self->[1]{$tag};
420	}	429	}
421	}	430	}
422	}	431	}
423		432
424	$port	433	$port
…		…
462	}	471	}
463	}	472	}
464		473
465	=item $guard = mon $port, $cb->(@reason)	474	=item $guard = mon $port, $cb->(@reason)
466		475
467	=item $guard = mon $port, $otherport	476	=item $guard = mon $port, $rcvport
468		477
		478	=item $guard = mon $port
		479
469	=item $guard = mon $port, $otherport, @msg	480	=item $guard = mon $port, $rcvport, @msg
470		481
471	Monitor the given port and do something when the port is killed.	482	Monitor the given port and do something when the port is killed or
		483	messages to it were lost, and optionally return a guard that can be used
		484	to stop monitoring again.
472		485
		486	C<mon> effectively guarantees that, in the absence of hardware failures,
		487	that after starting the monitor, either all messages sent to the port
		488	will arrive, or the monitoring action will be invoked after possible
		489	message loss has been detected. No messages will be lost "in between"
		490	(after the first lost message no further messages will be received by the
		491	port). After the monitoring action was invoked, further messages might get
		492	delivered again.
		493
		494	Note that monitoring-actions are one-shot: once released, they are removed
		495	and will not trigger again.
		496
473	In the first form, the callback is simply called with any number	497	In the first form (callback), the callback is simply called with any
474	of C<@reason> elements (no @reason means that the port was deleted	498	number of C<@reason> elements (no @reason means that the port was deleted
475	"normally"). Note also that I<< the callback B<must> never die >>, so use	499	"normally"). Note also that I<< the callback B<must> never die >>, so use
476	C<eval> if unsure.	500	C<eval> if unsure.
477		501
478	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	502	In the second form (another port given), the other port (C<$rcvport>)
479	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
480	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.
481		506
		507	The third form (kill self) is the same as the second form, except that
		508	C<$rvport> defaults to C<$SELF>.
		509
482	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.
483		519
484	Example: call a given callback when C<$port> is killed.	520	Example: call a given callback when C<$port> is killed.
485		521
486	mon $port, sub { warn "port died because of <@_>\n" };	522	mon $port, sub { warn "port died because of <@_>\n" };
487		523
488	Example: kill ourselves when C<$port> is killed abnormally.	524	Example: kill ourselves when C<$port> is killed abnormally.
489		525
490	mon $port, $self;	526	mon $port;
491		527
492	Example: send us a restart message another C<$port> is killed.	528	Example: send us a restart message when another C<$port> is killed.
493		529
494	mon $port, $self => "restart";	530	mon $port, $self => "restart";
495		531
496	=cut	532	=cut
497		533
498	sub mon {	534	sub mon {
499	my ($noderef, $port) = split /#/, shift, 2;	535	my ($noderef, $port) = split /#/, shift, 2;
500		536
501	my $node = $NODE{$noderef} \|\| add_node $noderef;	537	my $node = $NODE{$noderef} \|\| add_node $noderef;
502		538
503	my $cb = shift;	539	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
504		540
505	unless (ref $cb) {	541	unless (ref $cb) {
506	if (@_) {	542	if (@_) {
507	# send a kill info message	543	# send a kill info message
508	my (@msg) = ($cb, @_);	544	my (@msg) = ($cb, @_);
…		…
539	=cut	575	=cut
540		576
541	sub mon_guard {	577	sub mon_guard {
542	my ($port, @refs) = @_;	578	my ($port, @refs) = @_;
543		579
		580	#TODO: mon-less form?
		581
544	mon $port, sub { 0 && @refs }	582	mon $port, sub { 0 && @refs }
545	}	583	}
546
547	=item lnk $port1, $port2
548
549	Link two ports. This is simply a shorthand for:
550
551	mon $port1, $port2;
552	mon $port2, $port1;
553
554	It means that if either one is killed abnormally, the other one gets
555	killed as well.
556		584
557	=item kil $port[, @reason]	585	=item kil $port[, @reason]
558		586
559	Kill the specified port with the given C<@reason>.	587	Kill the specified port with the given C<@reason>.
560		588
…		…
568	will be reported as reason C<< die => $@ >>.	596	will be reported as reason C<< die => $@ >>.
569		597
570	Transport/communication errors are reported as C<< transport_error =>	598	Transport/communication errors are reported as C<< transport_error =>
571	$message >>.	599	$message >>.
572		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	? $action[0]()
		689	: snd @action;
		690	};
		691	}
		692
573	=back	693	=back
574		694
575	=head1 NODE MESSAGES
576
577	Nodes understand the following messages sent to them. Many of them take
578	arguments called C<@reply>, which will simply be used to compose a reply
579	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
580	the remaining arguments are simply the message data.
581
582	While other messages exist, they are not public and subject to change.
583
584	=over 4
585
586	=cut
587
588	=item lookup => $name, @reply
589
590	Replies with the port ID of the specified well-known port, or C<undef>.
591
592	=item devnull => ...
593
594	Generic data sink/CPU heat conversion.
595
596	=item relay => $port, @msg
597
598	Simply forwards the message to the given port.
599
600	=item eval => $string[ @reply]
601
602	Evaluates the given string. If C<@reply> is given, then a message of the
603	form C<@reply, $@, @evalres> is sent.
604
605	Example: crash another node.
606
607	snd $othernode, eval => "exit";
608
609	=item time => @reply
610
611	Replies the the current node time to C<@reply>.
612
613	Example: tell the current node to send the current time to C<$myport> in a
614	C<timereply> message.
615
616	snd $NODE, time => $myport, timereply => 1, 2;
617	# => snd $myport, timereply => 1, 2, <time>
618
619	=back
620
621	=head1 AnyEvent::MP vs. Distributed Erlang	695	=head1 AnyEvent::MP vs. Distributed Erlang
622		696
623	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
624	== 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
625	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
626	sample:	700	sample:
627		701
628	http://www.erlang.se/doc/programming_rules.shtml	702	http://www.Erlang.se/doc/programming_rules.shtml
629	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
630	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
631	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
632		706
633	Despite the similarities, there are also some important differences:	707	Despite the similarities, there are also some important differences:
634		708
635	=over 4	709	=over 4
636		710
…		…
641	convenience functionality.	715	convenience functionality.
642		716
643	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
644	cost of longer node references and a slightly higher management overhead.	718	cost of longer node references and a slightly higher management overhead.
645		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
646	=item * Erlang uses processes and a mailbox, AEMP does not queue.	735	=item * Erlang uses processes and a mailbox, AEMP does not queue.
647		736
648	Erlang uses processes that selctively receive messages, and therefore	737	Erlang uses processes that selectively receive messages, and therefore
649	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
650	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.
651		742
652	(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).
653		744
654	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	745	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
655		746
656	Sending messages in erlang is synchronous and blocks the process. AEMP	747	Sending messages in Erlang is synchronous and blocks the process (and
657	sends are immediate, connection establishment is handled in the	748	so does not need a queue that can overflow). AEMP sends are immediate,
658	background.	749	connection establishment is handled in the background.
659		750
660	=item * Erlang can silently lose messages, AEMP cannot.	751	=item * Erlang suffers from silent message loss, AEMP does not.
661		752
662	Erlang makes few guarantees on messages delivery - messages can get lost	753	Erlang makes few guarantees on messages delivery - messages can get lost
663	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,
664	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).
665		756
666	AEMP guarantees correct ordering, and the guarantee that there are no	757	AEMP guarantees correct ordering, and the guarantee that there are no
667	holes in the message sequence.	758	holes in the message sequence.
668		759
669	=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
670	alive.	761	alive.
671		762
672	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
673	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
674	still alive - and can receive messages.	765	still alive - and can receive messages.
675		766
676	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
677	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
678	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.
679		770
680	=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.
681		772
682	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
683	ID known to other nodes for a completely different process, causing	774	known to other nodes for a completely different process, causing messages
684	messages destined for that process to end up in an unrelated process.	775	destined for that process to end up in an unrelated process.
685		776
686	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
687	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.
688		779
689	=item * Erlang uses unprotected connections, AEMP uses secure	780	=item * Erlang uses unprotected connections, AEMP uses secure
…		…
693	securely authenticate nodes.	784	securely authenticate nodes.
694		785
695	=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
696	communications.	787	communications.
697		788
698	The AEMP protocol, unlike the erlang protocol, supports both	789	The AEMP protocol, unlike the Erlang protocol, supports both
699	language-independent text-only protocols (good for debugging) and binary,	790	language-independent text-only protocols (good for debugging) and binary,
700	language-specific serialisers (e.g. Storable).	791	language-specific serialisers (e.g. Storable).
701		792
702	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
703	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
704	protocol simple.	795	protocol simple.
705		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
706	=back	854	=back
707		855
708	=head1 SEE ALSO	856	=head1 SEE ALSO
709		857
710	L<AnyEvent>.	858	L<AnyEvent>.

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