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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.32 by root, Wed Aug 5 19:58:46 2009 UTC vs.
Revision 1.61 by root, Mon Aug 24 08:06:49 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		46	AnyEvent::MP::Intro - outdated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 (connected to a
68	master node only) or public nodes (connectable from unrelated nodes).	91	master node only) or public nodes (connectable from unrelated nodes).
69		92
70	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	93	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>
…		…
90		113
91	=cut	114	=cut
92		115
93	package AnyEvent::MP;	116	package AnyEvent::MP;
94		117
95	use AnyEvent::MP::Base;	118	use AnyEvent::MP::Kernel;
96		119
97	use common::sense;	120	use common::sense;
98		121
99	use Carp ();	122	use Carp ();
100		123
101	use AE ();	124	use AE ();
102		125
103	use base "Exporter";	126	use base "Exporter";
104		127
105	our $VERSION = '0.1';	128	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		129
106	our @EXPORT = qw(	130	our @EXPORT = qw(
107	NODE $NODE *SELF node_of _any_	131	NODE $NODE *SELF node_of after
108	resolve_node initialise_node	132	resolve_node initialise_node
109	snd rcv mon kil reg psub	133	snd rcv mon mon_guard kil reg psub spawn
110	port	134	port
111	);	135	);
112		136
113	our $SELF;	137	our $SELF;
114		138
…		…
118	kil $SELF, die => $msg;	142	kil $SELF, die => $msg;
119	}	143	}
120		144
121	=item $thisnode = NODE / $NODE	145	=item $thisnode = NODE / $NODE
122		146
123	The C<NODE> function returns, and the C<$NODE> variable contains	147	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	148	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	149	C<initialise_node>.
126	identifiers become invalid.
127		150
128	=item $noderef = node_of $portid	151	=item $noderef = node_of $port
129		152
130	Extracts and returns the noderef from a portid or a noderef.	153	Extracts and returns the noderef from a port ID or a noderef.
		154
		155	=item initialise_node $noderef, $seednode, $seednode...
		156
		157	=item initialise_node "slave/", $master, $master...
		158
		159	Before a node can talk to other nodes on the network it has to initialise
		160	itself - the minimum a node needs to know is it's own name, and optionally
		161	it should know the noderefs of some other nodes in the network.
		162
		163	This function initialises a node - it must be called exactly once (or
		164	never) before calling other AnyEvent::MP functions.
		165
		166	All arguments (optionally except for the first) are noderefs, which can be
		167	either resolved or unresolved.
		168
		169	The first argument will be looked up in the configuration database first
		170	(if it is C<undef> then the current nodename will be used instead) to find
		171	the relevant configuration profile (see L<aemp>). If none is found then
		172	the default configuration is used. The configuration supplies additional
		173	seed/master nodes and can override the actual noderef.
		174
		175	There are two types of networked nodes, public nodes and slave nodes:
		176
		177	=over 4
		178
		179	=item public nodes
		180
		181	For public nodes, C<$noderef> (supplied either directly to
		182	C<initialise_node> or indirectly via a profile or the nodename) must be a
		183	noderef (possibly unresolved, in which case it will be resolved).
		184
		185	After resolving, the node will bind itself on all endpoints and try to
		186	connect to all additional C<$seednodes> that are specified. Seednodes are
		187	optional and can be used to quickly bootstrap the node into an existing
		188	network.
		189
		190	=item slave nodes
		191
		192	When the C<$noderef> (either as given or overriden by the config file)
		193	is the special string C<slave/>, then the node will become a slave
		194	node. Slave nodes cannot be contacted from outside and will route most of
		195	their traffic to the master node that they attach to.
		196
		197	At least one additional noderef is required (either by specifying it
		198	directly or because it is part of the configuration profile): The node
		199	will try to connect to all of them and will become a slave attached to the
		200	first node it can successfully connect to.
		201
		202	Note that slave nodes cannot change their name, and consequently, their
		203	master, so if the master goes down, the slave node will not function well
		204	anymore until it can re-establish conenciton to its master. This makes
		205	slave nodes unsuitable for long-term nodes or fault-tolerant networks.
		206
		207	=back
		208
		209	This function will block until all nodes have been resolved and, for slave
		210	nodes, until it has successfully established a connection to a master
		211	server.
		212
		213	All the seednodes will also be specially marked to automatically retry
		214	connecting to them infinitely.
		215
		216	Example: become a public node listening on the guessed noderef, or the one
		217	specified via C<aemp> for the current node. This should be the most common
		218	form of invocation for "daemon"-type nodes.
		219
		220	initialise_node;
		221
		222	Example: become a slave node to any of the the seednodes specified via
		223	C<aemp>. This form is often used for commandline clients.
		224
		225	initialise_node "slave/";
		226
		227	Example: become a slave node to any of the specified master servers. This
		228	form is also often used for commandline clients.
		229
		230	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
		231
		232	Example: become a public node, and try to contact some well-known master
		233	servers to become part of the network.
		234
		235	initialise_node undef, "master1", "master2";
		236
		237	Example: become a public node listening on port C<4041>.
		238
		239	initialise_node 4041;
		240
		241	Example: become a public node, only visible on localhost port 4044.
		242
		243	initialise_node "localhost:4044";
131		244
132	=item $cv = resolve_node $noderef	245	=item $cv = resolve_node $noderef
133		246
134	Takes an unresolved node reference that may contain hostnames and	247	Takes an unresolved node reference that may contain hostnames and
135	abbreviated IDs, resolves all of them and returns a resolved node	248	abbreviated IDs, resolves all of them and returns a resolved node
…		…
167		280
168	Due to some quirks in how perl exports variables, it is impossible to	281	Due to some quirks in how perl exports variables, it is impossible to
169	just export C<$SELF>, all the symbols called C<SELF> are exported by this	282	just export C<$SELF>, all the symbols called C<SELF> are exported by this
170	module, but only C<$SELF> is currently used.	283	module, but only C<$SELF> is currently used.
171		284
172	=item snd $portid, type => @data	285	=item snd $port, type => @data
173		286
174	=item snd $portid, @msg	287	=item snd $port, @msg
175		288
176	Send the given message to the given port ID, which can identify either	289	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	290	a local or a remote port, and must be a port ID.
178	stringifies a sa port ID (such as a port object :).
179		291
180	While the message can be about anything, it is highly recommended to use a	292	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	293	string as first element (a port ID, or some word that indicates a request
182	type etc.).	294	type etc.).
183		295
184	The message data effectively becomes read-only after a call to this	296	The message data effectively becomes read-only after a call to this
185	function: modifying any argument is not allowed and can cause many	297	function: modifying any argument is not allowed and can cause many
186	problems.	298	problems.
…		…
191	that Storable can serialise and deserialise is allowed, and for the local	303	that Storable can serialise and deserialise is allowed, and for the local
192	node, anything can be passed.	304	node, anything can be passed.
193		305
194	=item $local_port = port	306	=item $local_port = port
195		307
196	Create a new local port object that can be used either as a pattern	308	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"),	309	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		310
200	=item $portid = port { my @msg = @_; $finished }	311	=item $local_port = port { my @msg = @_ }
201		312
202	Creates a "mini port", that is, a very lightweight port without any	313	Creates a new local port, and returns its ID. Semantically the same as
203	pattern matching behind it, and returns its ID.	314	creating a port and calling C<rcv $port, $callback> on it.
204		315
205	The block will be called for every message received on the port. When the	316	The block will be called for every message received on the port, with the
206	callback returns a true value its job is considered "done" and the port	317	global variable C<$SELF> set to the port ID. Runtime errors will cause the
207	will be destroyed. Otherwise it will stay alive.	318	port to be C<kil>ed. The message will be passed as-is, no extra argument
		319	(i.e. no port ID) will be passed to the callback.
208		320
209	The message will be passed as-is, no extra argument (i.e. no port id) will	321	If you want to stop/destroy the port, simply C<kil> it:
210	be passed to the callback.
211		322
212	If you need the local port id in the callback, this works nicely:	323	my $port = port {
213		324	my @msg = @_;
214	my $port; $port = port {	325	...
215	snd $otherport, reply => $port;	326	kil $SELF;
216	};	327	};
217		328
218	=cut	329	=cut
		330
		331	sub rcv($@);
		332
		333	sub _kilme {
		334	die "received message on port without callback";
		335	}
219		336
220	sub port(;&) {	337	sub port(;&) {
221	my $id = "$UNIQ." . $ID++;	338	my $id = "$UNIQ." . $ID++;
222	my $port = "$NODE#$id";	339	my $port = "$NODE#$id";
223		340
		341	rcv $port, shift \|\| \&_kilme;
		342
		343	$port
		344	}
		345
		346	=item rcv $local_port, $callback->(@msg)
		347
		348	Replaces the default callback on the specified port. There is no way to
		349	remove the default callback: use C<sub { }> to disable it, or better
		350	C<kil> the port when it is no longer needed.
		351
		352	The global C<$SELF> (exported by this module) contains C<$port> while
		353	executing the callback. Runtime errors during callback execution will
		354	result in the port being C<kil>ed.
		355
		356	The default callback received all messages not matched by a more specific
		357	C<tag> match.
		358
		359	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
		360
		361	Register (or replace) callbacks to be called on messages starting with the
		362	given tag on the given port (and return the port), or unregister it (when
		363	C<$callback> is C<$undef> or missing). There can only be one callback
		364	registered for each tag.
		365
		366	The original message will be passed to the callback, after the first
		367	element (the tag) has been removed. The callback will use the same
		368	environment as the default callback (see above).
		369
		370	Example: create a port and bind receivers on it in one go.
		371
		372	my $port = rcv port,
		373	msg1 => sub { ... },
		374	msg2 => sub { ... },
		375	;
		376
		377	Example: create a port, bind receivers and send it in a message elsewhere
		378	in one go:
		379
		380	snd $otherport, reply =>
		381	rcv port,
		382	msg1 => sub { ... },
		383	...
		384	;
		385
		386	Example: temporarily register a rcv callback for a tag matching some port
		387	(e.g. for a rpc reply) and unregister it after a message was received.
		388
		389	rcv $port, $otherport => sub {
		390	my @reply = @_;
		391
		392	rcv $SELF, $otherport;
		393	};
		394
		395	=cut
		396
		397	sub rcv($@) {
		398	my $port = shift;
		399	my ($noderef, $portid) = split /#/, $port, 2;
		400
		401	$NODE{$noderef} == $NODE{""}
		402	or Carp::croak "$port: rcv can only be called on local ports, caught";
		403
224	if (@_) {	404	while (@_) {
		405	if (ref $_[0]) {
		406	if (my $self = $PORT_DATA{$portid}) {
		407	"AnyEvent::MP::Port" eq ref $self
		408	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		409
		410	$self->[2] = shift;
		411	} else {
225	my $cb = shift;	412	my $cb = shift;
226	$PORT{$id} = sub {	413	$PORT{$portid} = sub {
227	local $SELF = $port;	414	local $SELF = $port;
228	eval {	415	eval { &$cb }; _self_die if $@;
229	&$cb	416	};
230	and kil $id;	417	}
		418	} elsif (defined $_[0]) {
		419	my $self = $PORT_DATA{$portid} \|\|= do {
		420	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
		421
		422	$PORT{$portid} = sub {
		423	local $SELF = $port;
		424
		425	if (my $cb = $self->[1]{$_[0]}) {
		426	shift;
		427	eval { &$cb }; _self_die if $@;
		428	} else {
		429	&{ $self->[0] };
		430	}
		431	};
		432
		433	$self
231	};	434	};
232	_self_die if $@;	435
233	};
234	} else {
235	my $self = bless {
236	id => "$NODE#$id",
237	}, "AnyEvent::MP::Port";	436	"AnyEvent::MP::Port" eq ref $self
		437	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
238		438
239	$PORT_DATA{$id} = $self;	439	my ($tag, $cb) = splice @_, 0, 2;
240	$PORT{$id} = sub {
241	local $SELF = $port;
242		440
		441	if (defined $cb) {
		442	$self->[1]{$tag} = $cb;
243	eval {	443	} else {
244	for (@{ $self->{rc0}{$_[0]} }) {	444	delete $self->[1]{$tag};
245	$_ && &{$_->[0]}
246	&& undef $_;
247	}
248
249	for (@{ $self->{rcv}{$_[0]} }) {
250	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
251	&& &{$_->[0]}
252	&& undef $_;
253	}
254
255	for (@{ $self->{any} }) {
256	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
257	&& &{$_->[0]}
258	&& undef $_;
259	}
260	};	445	}
261	_self_die if $@;
262	};
263	}
264
265	$port
266	}
267
268	=item reg $portid, $name
269
270	Registers the given port under the name C<$name>. If the name already
271	exists it is replaced.
272
273	A port can only be registered under one well known name.
274
275	A port automatically becomes unregistered when it is killed.
276
277	=cut
278
279	sub reg(@) {
280	my ($portid, $name) = @_;
281
282	$REG{$name} = $portid;
283	}
284
285	=item rcv $portid, $callback->(@msg)
286
287	Replaces the callback on the specified miniport (or newly created port
288	object, see C<port>). Full ports are configured with the following calls:
289
290	=item rcv $portid, tagstring => $callback->(@msg), ...
291
292	=item rcv $portid, $smartmatch => $callback->(@msg), ...
293
294	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
295
296	Register callbacks to be called on matching messages on the given full
297	port (or newly created port).
298
299	The callback has to return a true value when its work is done, after
300	which is will be removed, or a false value in which case it will stay
301	registered.
302
303	The global C<$SELF> (exported by this module) contains C<$portid> while
304	executing the callback.
305
306	Runtime errors wdurign callback execution will result in the port being
307	C<kil>ed.
308
309	If the match is an array reference, then it will be matched against the
310	first elements of the message, otherwise only the first element is being
311	matched.
312
313	Any element in the match that is specified as C<_any_> (a function
314	exported by this module) matches any single element of the message.
315
316	While not required, it is highly recommended that the first matching
317	element is a string identifying the message. The one-string-only match is
318	also the most efficient match (by far).
319
320	=cut
321
322	sub rcv($@) {
323	my $portid = shift;
324	my ($noderef, $port) = split /#/, $port, 2;
325
326	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
327	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";
328
329	my $self = $PORT_DATA{$port}
330	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
331
332	"AnyEvent::MP::Port" eq ref $self
333	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
334
335	while (@_) {
336	my ($match, $cb) = splice @_, 0, 2;
337
338	if (!ref $match) {
339	push @{ $self->{rc0}{$match} }, [$cb];
340	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
341	my ($type, @match) = @$match;
342	@match
343	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
344	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
345	} else {
346	push @{ $self->{any} }, [$cb, $match];
347	}	446	}
348	}	447	}
349		448
350	$portid	449	$port
351	}	450	}
352		451
353	=item $closure = psub { BLOCK }	452	=item $closure = psub { BLOCK }
354		453
355	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	454	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
…		…
386	$res	485	$res
387	}	486	}
388	}	487	}
389	}	488	}
390		489
391	=item $guard = mon $portid, $cb->(@reason)	490	=item $guard = mon $port, $cb->(@reason)
392		491
393	=item $guard = mon $portid, $otherport	492	=item $guard = mon $port, $rcvport
394		493
		494	=item $guard = mon $port
		495
395	=item $guard = mon $portid, $otherport, @msg	496	=item $guard = mon $port, $rcvport, @msg
396		497
397	Monitor the given port and do something when the port is killed.	498	Monitor the given port and do something when the port is killed or
		499	messages to it were lost, and optionally return a guard that can be used
		500	to stop monitoring again.
398		501
		502	C<mon> effectively guarantees that, in the absence of hardware failures,
		503	that after starting the monitor, either all messages sent to the port
		504	will arrive, or the monitoring action will be invoked after possible
		505	message loss has been detected. No messages will be lost "in between"
		506	(after the first lost message no further messages will be received by the
		507	port). After the monitoring action was invoked, further messages might get
		508	delivered again.
		509
		510	Note that monitoring-actions are one-shot: once released, they are removed
		511	and will not trigger again.
		512
399	In the first form, the callback is simply called with any number	513	In the first form (callback), the callback is simply called with any
400	of C<@reason> elements (no @reason means that the port was deleted	514	number of C<@reason> elements (no @reason means that the port was deleted
401	"normally"). Note also that I<< the callback B<must> never die >>, so use	515	"normally"). Note also that I<< the callback B<must> never die >>, so use
402	C<eval> if unsure.	516	C<eval> if unsure.
403		517
404	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	518	In the second form (another port given), the other port (C<$rcvport>)
405	a @reason was specified, i.e. on "normal" kils nothing happens, while	519	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
406	under all other conditions, the other port is killed with the same reason.	520	"normal" kils nothing happens, while under all other conditions, the other
		521	port is killed with the same reason.
407		522
		523	The third form (kill self) is the same as the second form, except that
		524	C<$rvport> defaults to C<$SELF>.
		525
408	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	526	In the last form (message), a message of the form C<@msg, @reason> will be
		527	C<snd>.
		528
		529	As a rule of thumb, monitoring requests should always monitor a port from
		530	a local port (or callback). The reason is that kill messages might get
		531	lost, just like any other message. Another less obvious reason is that
		532	even monitoring requests can get lost (for exmaple, when the connection
		533	to the other node goes down permanently). When monitoring a port locally
		534	these problems do not exist.
409		535
410	Example: call a given callback when C<$port> is killed.	536	Example: call a given callback when C<$port> is killed.
411		537
412	mon $port, sub { warn "port died because of <@_>\n" };	538	mon $port, sub { warn "port died because of <@_>\n" };
413		539
414	Example: kill ourselves when C<$port> is killed abnormally.	540	Example: kill ourselves when C<$port> is killed abnormally.
415		541
416	mon $port, $self;	542	mon $port;
417		543
418	Example: send us a restart message another C<$port> is killed.	544	Example: send us a restart message when another C<$port> is killed.
419		545
420	mon $port, $self => "restart";	546	mon $port, $self => "restart";
421		547
422	=cut	548	=cut
423		549
424	sub mon {	550	sub mon {
425	my ($noderef, $port) = split /#/, shift, 2;	551	my ($noderef, $port) = split /#/, shift, 2;
426		552
427	my $node = $NODE{$noderef} \|\| add_node $noderef;	553	my $node = $NODE{$noderef} \|\| add_node $noderef;
428		554
429	my $cb = shift;	555	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
430		556
431	unless (ref $cb) {	557	unless (ref $cb) {
432	if (@_) {	558	if (@_) {
433	# send a kill info message	559	# send a kill info message
434	my (@msg) = ($cb, @_);	560	my (@msg) = ($cb, @_);
…		…
465	=cut	591	=cut
466		592
467	sub mon_guard {	593	sub mon_guard {
468	my ($port, @refs) = @_;	594	my ($port, @refs) = @_;
469		595
		596	#TODO: mon-less form?
		597
470	mon $port, sub { 0 && @refs }	598	mon $port, sub { 0 && @refs }
471	}	599	}
472		600
473	=item lnk $port1, $port2
474
475	Link two ports. This is simply a shorthand for:
476
477	mon $port1, $port2;
478	mon $port2, $port1;
479
480	It means that if either one is killed abnormally, the other one gets
481	killed as well.
482
483	=item kil $portid[, @reason]	601	=item kil $port[, @reason]
484		602
485	Kill the specified port with the given C<@reason>.	603	Kill the specified port with the given C<@reason>.
486		604
487	If no C<@reason> is specified, then the port is killed "normally" (linked	605	If no C<@reason> is specified, then the port is killed "normally" (linked
488	ports will not be kileld, or even notified).	606	ports will not be kileld, or even notified).
…		…
494	will be reported as reason C<< die => $@ >>.	612	will be reported as reason C<< die => $@ >>.
495		613
496	Transport/communication errors are reported as C<< transport_error =>	614	Transport/communication errors are reported as C<< transport_error =>
497	$message >>.	615	$message >>.
498		616
		617	=cut
		618
		619	=item $port = spawn $node, $initfunc[, @initdata]
		620
		621	Creates a port on the node C<$node> (which can also be a port ID, in which
		622	case it's the node where that port resides).
		623
		624	The port ID of the newly created port is return immediately, and it is
		625	permissible to immediately start sending messages or monitor the port.
		626
		627	After the port has been created, the init function is
		628	called. This function must be a fully-qualified function name
		629	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		630	program, use C<::name>.
		631
		632	If the function doesn't exist, then the node tries to C<require>
		633	the package, then the package above the package and so on (e.g.
		634	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		635	exists or it runs out of package names.
		636
		637	The init function is then called with the newly-created port as context
		638	object (C<$SELF>) and the C<@initdata> values as arguments.
		639
		640	A common idiom is to pass your own port, monitor the spawned port, and
		641	in the init function, monitor the original port. This two-way monitoring
		642	ensures that both ports get cleaned up when there is a problem.
		643
		644	Example: spawn a chat server port on C<$othernode>.
		645
		646	# this node, executed from within a port context:
		647	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		648	mon $server;
		649
		650	# init function on C<$othernode>
		651	sub connect {
		652	my ($srcport) = @_;
		653
		654	mon $srcport;
		655
		656	rcv $SELF, sub {
		657	...
		658	};
		659	}
		660
		661	=cut
		662
		663	sub _spawn {
		664	my $port = shift;
		665	my $init = shift;
		666
		667	local $SELF = "$NODE#$port";
		668	eval {
		669	&{ load_func $init }
		670	};
		671	_self_die if $@;
		672	}
		673
		674	sub spawn(@) {
		675	my ($noderef, undef) = split /#/, shift, 2;
		676
		677	my $id = "$RUNIQ." . $ID++;
		678
		679	$_[0] =~ /::/
		680	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		681
		682	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
		683
		684	"$noderef#$id"
		685	}
		686
		687	=item after $timeout, @msg
		688
		689	=item after $timeout, $callback
		690
		691	Either sends the given message, or call the given callback, after the
		692	specified number of seconds.
		693
		694	This is simply a utility function that come sin handy at times.
		695
		696	=cut
		697
		698	sub after($@) {
		699	my ($timeout, @action) = @_;
		700
		701	my $t; $t = AE::timer $timeout, 0, sub {
		702	undef $t;
		703	ref $action[0]
		704	? $action[0]()
		705	: snd @action;
		706	};
		707	}
		708
499	=back	709	=back
500		710
501	=head1 FUNCTIONS FOR NODES
502
503	=over 4
504
505	=item become_public $noderef
506
507	Tells the node to become a public node, i.e. reachable from other nodes.
508
509	The first argument is the (unresolved) node reference of the local node
510	(if missing then the empty string is used).
511
512	It is quite common to not specify anything, in which case the local node
513	tries to listen on the default port, or to only specify a port number, in
514	which case AnyEvent::MP tries to guess the local addresses.
515
516	=cut
517
518	=back
519
520	=head1 NODE MESSAGES
521
522	Nodes understand the following messages sent to them. Many of them take
523	arguments called C<@reply>, which will simply be used to compose a reply
524	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
525	the remaining arguments are simply the message data.
526
527	While other messages exist, they are not public and subject to change.
528
529	=over 4
530
531	=cut
532
533	=item lookup => $name, @reply
534
535	Replies with the port ID of the specified well-known port, or C<undef>.
536
537	=item devnull => ...
538
539	Generic data sink/CPU heat conversion.
540
541	=item relay => $port, @msg
542
543	Simply forwards the message to the given port.
544
545	=item eval => $string[ @reply]
546
547	Evaluates the given string. If C<@reply> is given, then a message of the
548	form C<@reply, $@, @evalres> is sent.
549
550	Example: crash another node.
551
552	snd $othernode, eval => "exit";
553
554	=item time => @reply
555
556	Replies the the current node time to C<@reply>.
557
558	Example: tell the current node to send the current time to C<$myport> in a
559	C<timereply> message.
560
561	snd $NODE, time => $myport, timereply => 1, 2;
562	# => snd $myport, timereply => 1, 2, <time>
563
564	=back
565
566	=head1 AnyEvent::MP vs. Distributed Erlang	711	=head1 AnyEvent::MP vs. Distributed Erlang
567		712
568	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node	713	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
569	== aemp node, erlang process == aemp port), so many of the documents and	714	== aemp node, Erlang process == aemp port), so many of the documents and
570	programming techniques employed by erlang apply to AnyEvent::MP. Here is a	715	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
571	sample:	716	sample:
572		717
573	http://www.erlang.se/doc/programming_rules.shtml	718	http://www.Erlang.se/doc/programming_rules.shtml
574	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	719	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
575	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6	720	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
576	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5	721	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
577		722
578	Despite the similarities, there are also some important differences:	723	Despite the similarities, there are also some important differences:
579		724
580	=over 4	725	=over 4
581		726
…		…
586	convenience functionality.	731	convenience functionality.
587		732
588	This means that AEMP requires a less tightly controlled environment at the	733	This means that AEMP requires a less tightly controlled environment at the
589	cost of longer node references and a slightly higher management overhead.	734	cost of longer node references and a slightly higher management overhead.
590		735
		736	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
		737	uses "local ports are like remote ports".
		738
		739	The failure modes for local ports are quite different (runtime errors
		740	only) then for remote ports - when a local port dies, you I<know> it dies,
		741	when a connection to another node dies, you know nothing about the other
		742	port.
		743
		744	Erlang pretends remote ports are as reliable as local ports, even when
		745	they are not.
		746
		747	AEMP encourages a "treat remote ports differently" philosophy, with local
		748	ports being the special case/exception, where transport errors cannot
		749	occur.
		750
591	=item * Erlang uses processes and a mailbox, AEMP does not queue.	751	=item * Erlang uses processes and a mailbox, AEMP does not queue.
592		752
593	Erlang uses processes that selctively receive messages, and therefore	753	Erlang uses processes that selectively receive messages, and therefore
594	needs a queue. AEMP is event based, queuing messages would serve no useful	754	needs a queue. AEMP is event based, queuing messages would serve no
595	purpose.	755	useful purpose. For the same reason the pattern-matching abilities of
		756	AnyEvent::MP are more limited, as there is little need to be able to
		757	filter messages without dequeing them.
596		758
597	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	759	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
598		760
599	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	761	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
600		762
601	Sending messages in erlang is synchronous and blocks the process. AEMP	763	Sending messages in Erlang is synchronous and blocks the process (and
602	sends are immediate, connection establishment is handled in the	764	so does not need a queue that can overflow). AEMP sends are immediate,
603	background.	765	connection establishment is handled in the background.
604		766
605	=item * Erlang can silently lose messages, AEMP cannot.	767	=item * Erlang suffers from silent message loss, AEMP does not.
606		768
607	Erlang makes few guarantees on messages delivery - messages can get lost	769	Erlang makes few guarantees on messages delivery - messages can get lost
608	without any of the processes realising it (i.e. you send messages a, b,	770	without any of the processes realising it (i.e. you send messages a, b,
609	and c, and the other side only receives messages a and c).	771	and c, and the other side only receives messages a and c).
610		772
611	AEMP guarantees correct ordering, and the guarantee that there are no	773	AEMP guarantees correct ordering, and the guarantee that there are no
612	holes in the message sequence.	774	holes in the message sequence.
613		775
614	=item * In erlang, processes can be declared dead and later be found to be	776	=item * In Erlang, processes can be declared dead and later be found to be
615	alive.	777	alive.
616		778
617	In erlang it can happen that a monitored process is declared dead and	779	In Erlang it can happen that a monitored process is declared dead and
618	linked processes get killed, but later it turns out that the process is	780	linked processes get killed, but later it turns out that the process is
619	still alive - and can receive messages.	781	still alive - and can receive messages.
620		782
621	In AEMP, when port monitoring detects a port as dead, then that port will	783	In AEMP, when port monitoring detects a port as dead, then that port will
622	eventually be killed - it cannot happen that a node detects a port as dead	784	eventually be killed - it cannot happen that a node detects a port as dead
623	and then later sends messages to it, finding it is still alive.	785	and then later sends messages to it, finding it is still alive.
624		786
625	=item * Erlang can send messages to the wrong port, AEMP does not.	787	=item * Erlang can send messages to the wrong port, AEMP does not.
626		788
627	In erlang it is quite possible that a node that restarts reuses a process	789	In Erlang it is quite likely that a node that restarts reuses a process ID
628	ID known to other nodes for a completely different process, causing	790	known to other nodes for a completely different process, causing messages
629	messages destined for that process to end up in an unrelated process.	791	destined for that process to end up in an unrelated process.
630		792
631	AEMP never reuses port IDs, so old messages or old port IDs floating	793	AEMP never reuses port IDs, so old messages or old port IDs floating
632	around in the network will not be sent to an unrelated port.	794	around in the network will not be sent to an unrelated port.
633		795
634	=item * Erlang uses unprotected connections, AEMP uses secure	796	=item * Erlang uses unprotected connections, AEMP uses secure
…		…
638	securely authenticate nodes.	800	securely authenticate nodes.
639		801
640	=item * The AEMP protocol is optimised for both text-based and binary	802	=item * The AEMP protocol is optimised for both text-based and binary
641	communications.	803	communications.
642		804
643	The AEMP protocol, unlike the erlang protocol, supports both	805	The AEMP protocol, unlike the Erlang protocol, supports both
644	language-independent text-only protocols (good for debugging) and binary,	806	language-independent text-only protocols (good for debugging) and binary,
645	language-specific serialisers (e.g. Storable).	807	language-specific serialisers (e.g. Storable).
646		808
647	It has also been carefully designed to be implementable in other languages	809	It has also been carefully designed to be implementable in other languages
648	with a minimum of work while gracefully degrading fucntionality to make the	810	with a minimum of work while gracefully degrading fucntionality to make the
649	protocol simple.	811	protocol simple.
650		812
		813	=item * AEMP has more flexible monitoring options than Erlang.
		814
		815	In Erlang, you can chose to receive I<all> exit signals as messages
		816	or I<none>, there is no in-between, so monitoring single processes is
		817	difficult to implement. Monitoring in AEMP is more flexible than in
		818	Erlang, as one can choose between automatic kill, exit message or callback
		819	on a per-process basis.
		820
		821	=item * Erlang tries to hide remote/local connections, AEMP does not.
		822
		823	Monitoring in Erlang is not an indicator of process death/crashes,
		824	as linking is (except linking is unreliable in Erlang).
		825
		826	In AEMP, you don't "look up" registered port names or send to named ports
		827	that might or might not be persistent. Instead, you normally spawn a port
		828	on the remote node. The init function monitors the you, and you monitor
		829	the remote port. Since both monitors are local to the node, they are much
		830	more reliable.
		831
		832	This also saves round-trips and avoids sending messages to the wrong port
		833	(hard to do in Erlang).
		834
		835	=back
		836
		837	=head1 RATIONALE
		838
		839	=over 4
		840
		841	=item Why strings for ports and noderefs, why not objects?
		842
		843	We considered "objects", but found that the actual number of methods
		844	thatc an be called are very low. Since port IDs and noderefs travel over
		845	the network frequently, the serialising/deserialising would add lots of
		846	overhead, as well as having to keep a proxy object.
		847
		848	Strings can easily be printed, easily serialised etc. and need no special
		849	procedures to be "valid".
		850
		851	And a a miniport consists of a single closure stored in a global hash - it
		852	can't become much cheaper.
		853
		854	=item Why favour JSON, why not real serialising format such as Storable?
		855
		856	In fact, any AnyEvent::MP node will happily accept Storable as framing
		857	format, but currently there is no way to make a node use Storable by
		858	default.
		859
		860	The default framing protocol is JSON because a) JSON::XS is many times
		861	faster for small messages and b) most importantly, after years of
		862	experience we found that object serialisation is causing more problems
		863	than it gains: Just like function calls, objects simply do not travel
		864	easily over the network, mostly because they will always be a copy, so you
		865	always have to re-think your design.
		866
		867	Keeping your messages simple, concentrating on data structures rather than
		868	objects, will keep your messages clean, tidy and efficient.
		869
651	=back	870	=back
652		871
653	=head1 SEE ALSO	872	=head1 SEE ALSO
654		873
655	L<AnyEvent>.	874	L<AnyEvent>.

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Revision 1.61 by root, Mon Aug 24 08:06:49 2009 UTC