[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 1.55 by root, Fri Aug 14 23:17:17 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		46	AnyEvent::MP::Intro - outdated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 _any_
108	resolve_node initialise_node	132	resolve_node initialise_node
109	snd rcv mon kil reg psub	133	snd rcv mon 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 $port	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	=back
		203
		204	This function will block until all nodes have been resolved and, for slave
		205	nodes, until it has successfully established a connection to a master
		206	server.
		207
		208	Example: become a public node listening on the guessed noderef, or the one
		209	specified via C<aemp> for the current node. This should be the most common
		210	form of invocation for "daemon"-type nodes.
		211
		212	initialise_node;
		213
		214	Example: become a slave node to any of the the seednodes specified via
		215	C<aemp>. This form is often used for commandline clients.
		216
		217	initialise_node "slave/";
		218
		219	Example: become a slave node to any of the specified master servers. This
		220	form is also often used for commandline clients.
		221
		222	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
		223
		224	Example: become a public node, and try to contact some well-known master
		225	servers to become part of the network.
		226
		227	initialise_node undef, "master1", "master2";
		228
		229	Example: become a public node listening on port C<4041>.
		230
		231	initialise_node 4041;
		232
		233	Example: become a public node, only visible on localhost port 4044.
		234
		235	initialise_node "localhost:4044";
131		236
132	=item $cv = resolve_node $noderef	237	=item $cv = resolve_node $noderef
133		238
134	Takes an unresolved node reference that may contain hostnames and	239	Takes an unresolved node reference that may contain hostnames and
135	abbreviated IDs, resolves all of them and returns a resolved node	240	abbreviated IDs, resolves all of them and returns a resolved node
…		…
172	=item snd $port, type => @data	277	=item snd $port, type => @data
173		278
174	=item snd $port, @msg	279	=item snd $port, @msg
175		280
176	Send the given message to the given port ID, which can identify either	281	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	282	a local or a remote port, and must be a port ID.
178	stringifies a sa port ID (such as a port object :).
179		283
180	While the message can be about anything, it is highly recommended to use a	284	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	285	string as first element (a port ID, or some word that indicates a request
182	type etc.).	286	type etc.).
183		287
184	The message data effectively becomes read-only after a call to this	288	The message data effectively becomes read-only after a call to this
185	function: modifying any argument is not allowed and can cause many	289	function: modifying any argument is not allowed and can cause many
186	problems.	290	problems.
…		…
191	that Storable can serialise and deserialise is allowed, and for the local	295	that Storable can serialise and deserialise is allowed, and for the local
192	node, anything can be passed.	296	node, anything can be passed.
193		297
194	=item $local_port = port	298	=item $local_port = port
195		299
196	Create a new local port object that can be used either as a pattern	300	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"),	301	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		302
200	=item $port = port { my @msg = @_; $finished }	303	=item $local_port = port { my @msg = @_ }
201		304
202	Creates a "miniport", that is, a very lightweight port without any pattern	305	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.	306	creating a port and calling C<rcv $port, $callback> on it.
205		307
206	The block will be called for every message received on the port. When the	308	The block will be called for every message received on the port, with the
207	callback returns a true value its job is considered "done" and the port	309	global variable C<$SELF> set to the port ID. Runtime errors will cause the
208	will be destroyed. Otherwise it will stay alive.	310	port to be C<kil>ed. The message will be passed as-is, no extra argument
		311	(i.e. no port ID) will be passed to the callback.
209		312
210	The message will be passed as-is, no extra argument (i.e. no port id) will	313	If you want to stop/destroy the port, simply C<kil> it:
211	be passed to the callback.
212		314
213	If you need the local port id in the callback, this works nicely:	315	my $port = port {
214		316	my @msg = @_;
215	my $port; $port = port {	317	...
216	snd $otherport, reply => $port;	318	kil $SELF;
217	};	319	};
218		320
219	=cut	321	=cut
220		322
221	sub rcv($@);	323	sub rcv($@);
		324
		325	sub _kilme {
		326	die "received message on port without callback";
		327	}
222		328
223	sub port(;&) {	329	sub port(;&) {
224	my $id = "$UNIQ." . $ID++;	330	my $id = "$UNIQ." . $ID++;
225	my $port = "$NODE#$id";	331	my $port = "$NODE#$id";
226		332
227	if (@_) {	333	rcv $port, shift \|\| \&_kilme;
228	rcv $port, shift;
229	} else {
230	$PORT{$id} = sub { }; # nop
231	}
232		334
233	$port	335	$port
234	}	336	}
235		337
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)	338	=item rcv $local_port, $callback->(@msg)
254		339
255	Replaces the callback on the specified miniport (after converting it to	340	Replaces the default callback on the specified port. There is no way to
256	one if required).	341	remove the default callback: use C<sub { }> to disable it, or better
257		342	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...] => $callback->(@msg), ...
263
264	Register callbacks to be called on matching messages on the given full
265	port (after converting it to one if required).
266
267	The callback has to return a true value when its work is done, after
268	which is will be removed, or a false value in which case it will stay
269	registered.
270		343
271	The global C<$SELF> (exported by this module) contains C<$port> while	344	The global C<$SELF> (exported by this module) contains C<$port> while
272	executing the callback.	345	executing the callback. Runtime errors during callback execution will
		346	result in the port being C<kil>ed.
273		347
274	Runtime errors wdurign callback execution will result in the port being	348	The default callback received all messages not matched by a more specific
275	C<kil>ed.	349	C<tag> match.
276		350
277	If the match is an array reference, then it will be matched against the	351	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
278	first elements of the message, otherwise only the first element is being
279	matched.
280		352
281	Any element in the match that is specified as C<_any_> (a function	353	Register (or replace) callbacks to be called on messages starting with the
282	exported by this module) matches any single element of the message.	354	given tag on the given port (and return the port), or unregister it (when
		355	C<$callback> is C<$undef> or missing). There can only be one callback
		356	registered for each tag.
283		357
284	While not required, it is highly recommended that the first matching	358	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	359	element (the tag) has been removed. The callback will use the same
286	also the most efficient match (by far).	360	environment as the default callback (see above).
		361
		362	Example: create a port and bind receivers on it in one go.
		363
		364	my $port = rcv port,
		365	msg1 => sub { ... },
		366	msg2 => sub { ... },
		367	;
		368
		369	Example: create a port, bind receivers and send it in a message elsewhere
		370	in one go:
		371
		372	snd $otherport, reply =>
		373	rcv port,
		374	msg1 => sub { ... },
		375	...
		376	;
		377
		378	Example: temporarily register a rcv callback for a tag matching some port
		379	(e.g. for a rpc reply) and unregister it after a message was received.
		380
		381	rcv $port, $otherport => sub {
		382	my @reply = @_;
		383
		384	rcv $SELF, $otherport;
		385	};
287		386
288	=cut	387	=cut
289		388
290	sub rcv($@) {	389	sub rcv($@) {
291	my $port = shift;	390	my $port = shift;
292	my ($noderef, $portid) = split /#/, $port, 2;	391	my ($noderef, $portid) = split /#/, $port, 2;
293		392
294	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	393	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
295	or Carp::croak "$port: rcv can only be called on local ports, caught";	394	or Carp::croak "$port: rcv can only be called on local ports, caught";
296		395
297	if (@_ == 1) {	396	while (@_) {
		397	if (ref $_[0]) {
		398	if (my $self = $PORT_DATA{$portid}) {
		399	"AnyEvent::MP::Port" eq ref $self
		400	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		401
		402	$self->[2] = shift;
		403	} else {
298	my $cb = shift;	404	my $cb = shift;
299	delete $PORT_DATA{$portid};
300	$PORT{$portid} = sub {	405	$PORT{$portid} = sub {
301	local $SELF = $port;	406	local $SELF = $port;
302	eval {	407	eval { &$cb }; _self_die if $@;
303	&$cb	408	};
304	and kil $port;
305	};	409	}
306	_self_die if $@;	410	} elsif (defined $_[0]) {
307	};
308	} else {
309	my $self = $PORT_DATA{$portid} \|\|= do {	411	my $self = $PORT_DATA{$portid} \|\|= do {
310	my $self = bless {	412	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
311	id => $port,
312	}, "AnyEvent::MP::Port";
313		413
314	$PORT{$portid} = sub {	414	$PORT{$portid} = sub {
315	local $SELF = $port;	415	local $SELF = $port;
316		416
317	eval {
318	for (@{ $self->{rc0}{$_[0]} }) {	417	if (my $cb = $self->[1]{$_[0]}) {
319	$_ && &{$_->[0]}	418	shift;
320	&& undef $_;	419	eval { &$cb }; _self_die if $@;
321	}	420	} else {
322
323	for (@{ $self->{rcv}{$_[0]} }) {
324	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
325	&& &{$_->[0]}	421	&{ $self->[0] };
326	&& undef $_;
327	}
328
329	for (@{ $self->{any} }) {
330	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
331	&& &{$_->[0]}
332	&& undef $_;
333	}	422	}
334	};	423	};
335	_self_die if $@;	424
		425	$self
336	};	426	};
337		427
338	$self
339	};
340
341	"AnyEvent::MP::Port" eq ref $self	428	"AnyEvent::MP::Port" eq ref $self
342	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	429	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
343		430
344	while (@_) {
345	my ($match, $cb) = splice @_, 0, 2;	431	my ($tag, $cb) = splice @_, 0, 2;
346		432
347	if (!ref $match) {	433	if (defined $cb) {
348	push @{ $self->{rc0}{$match} }, [$cb];	434	$self->[1]{$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 {	435	} else {
355	push @{ $self->{any} }, [$cb, $match];	436	delete $self->[1]{$tag};
356	}	437	}
357	}	438	}
358	}	439	}
359		440
360	$port	441	$port
…		…
398	}	479	}
399	}	480	}
400		481
401	=item $guard = mon $port, $cb->(@reason)	482	=item $guard = mon $port, $cb->(@reason)
402		483
403	=item $guard = mon $port, $otherport	484	=item $guard = mon $port, $rcvport
404		485
		486	=item $guard = mon $port
		487
405	=item $guard = mon $port, $otherport, @msg	488	=item $guard = mon $port, $rcvport, @msg
406		489
407	Monitor the given port and do something when the port is killed.	490	Monitor the given port and do something when the port is killed or
		491	messages to it were lost, and optionally return a guard that can be used
		492	to stop monitoring again.
408		493
		494	C<mon> effectively guarantees that, in the absence of hardware failures,
		495	that after starting the monitor, either all messages sent to the port
		496	will arrive, or the monitoring action will be invoked after possible
		497	message loss has been detected. No messages will be lost "in between"
		498	(after the first lost message no further messages will be received by the
		499	port). After the monitoring action was invoked, further messages might get
		500	delivered again.
		501
409	In the first form, the callback is simply called with any number	502	In the first form (callback), the callback is simply called with any
410	of C<@reason> elements (no @reason means that the port was deleted	503	number of C<@reason> elements (no @reason means that the port was deleted
411	"normally"). Note also that I<< the callback B<must> never die >>, so use	504	"normally"). Note also that I<< the callback B<must> never die >>, so use
412	C<eval> if unsure.	505	C<eval> if unsure.
413		506
414	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	507	In the second form (another port given), the other port (C<$rcvport>)
415	a @reason was specified, i.e. on "normal" kils nothing happens, while	508	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.	509	"normal" kils nothing happens, while under all other conditions, the other
		510	port is killed with the same reason.
417		511
		512	The third form (kill self) is the same as the second form, except that
		513	C<$rvport> defaults to C<$SELF>.
		514
418	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	515	In the last form (message), a message of the form C<@msg, @reason> will be
		516	C<snd>.
		517
		518	As a rule of thumb, monitoring requests should always monitor a port from
		519	a local port (or callback). The reason is that kill messages might get
		520	lost, just like any other message. Another less obvious reason is that
		521	even monitoring requests can get lost (for exmaple, when the connection
		522	to the other node goes down permanently). When monitoring a port locally
		523	these problems do not exist.
419		524
420	Example: call a given callback when C<$port> is killed.	525	Example: call a given callback when C<$port> is killed.
421		526
422	mon $port, sub { warn "port died because of <@_>\n" };	527	mon $port, sub { warn "port died because of <@_>\n" };
423		528
424	Example: kill ourselves when C<$port> is killed abnormally.	529	Example: kill ourselves when C<$port> is killed abnormally.
425		530
426	mon $port, $self;	531	mon $port;
427		532
428	Example: send us a restart message another C<$port> is killed.	533	Example: send us a restart message when another C<$port> is killed.
429		534
430	mon $port, $self => "restart";	535	mon $port, $self => "restart";
431		536
432	=cut	537	=cut
433		538
434	sub mon {	539	sub mon {
435	my ($noderef, $port) = split /#/, shift, 2;	540	my ($noderef, $port) = split /#/, shift, 2;
436		541
437	my $node = $NODE{$noderef} \|\| add_node $noderef;	542	my $node = $NODE{$noderef} \|\| add_node $noderef;
438		543
439	my $cb = shift;	544	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
440		545
441	unless (ref $cb) {	546	unless (ref $cb) {
442	if (@_) {	547	if (@_) {
443	# send a kill info message	548	# send a kill info message
444	my (@msg) = ($cb, @_);	549	my (@msg) = ($cb, @_);
…		…
475	=cut	580	=cut
476		581
477	sub mon_guard {	582	sub mon_guard {
478	my ($port, @refs) = @_;	583	my ($port, @refs) = @_;
479		584
		585	#TODO: mon-less form?
		586
480	mon $port, sub { 0 && @refs }	587	mon $port, sub { 0 && @refs }
481	}	588	}
482		589
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
493	=item kil $port[, @reason]	590	=item kil $port[, @reason]
494		591
495	Kill the specified port with the given C<@reason>.	592	Kill the specified port with the given C<@reason>.
496		593
497	If no C<@reason> is specified, then the port is killed "normally" (linked	594	If no C<@reason> is specified, then the port is killed "normally" (linked
…		…
504	will be reported as reason C<< die => $@ >>.	601	will be reported as reason C<< die => $@ >>.
505		602
506	Transport/communication errors are reported as C<< transport_error =>	603	Transport/communication errors are reported as C<< transport_error =>
507	$message >>.	604	$message >>.
508		605
509	=back
510
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	606	=cut
		607
		608	=item $port = spawn $node, $initfunc[, @initdata]
		609
		610	Creates a port on the node C<$node> (which can also be a port ID, in which
		611	case it's the node where that port resides).
		612
		613	The port ID of the newly created port is return immediately, and it is
		614	permissible to immediately start sending messages or monitor the port.
		615
		616	After the port has been created, the init function is
		617	called. This function must be a fully-qualified function name
		618	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		619	program, use C<::name>.
		620
		621	If the function doesn't exist, then the node tries to C<require>
		622	the package, then the package above the package and so on (e.g.
		623	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		624	exists or it runs out of package names.
		625
		626	The init function is then called with the newly-created port as context
		627	object (C<$SELF>) and the C<@initdata> values as arguments.
		628
		629	A common idiom is to pass your own port, monitor the spawned port, and
		630	in the init function, monitor the original port. This two-way monitoring
		631	ensures that both ports get cleaned up when there is a problem.
		632
		633	Example: spawn a chat server port on C<$othernode>.
		634
		635	# this node, executed from within a port context:
		636	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		637	mon $server;
		638
		639	# init function on C<$othernode>
		640	sub connect {
		641	my ($srcport) = @_;
		642
		643	mon $srcport;
		644
		645	rcv $SELF, sub {
		646	...
		647	};
		648	}
		649
		650	=cut
		651
		652	sub _spawn {
		653	my $port = shift;
		654	my $init = shift;
		655
		656	local $SELF = "$NODE#$port";
		657	eval {
		658	&{ load_func $init }
		659	};
		660	_self_die if $@;
		661	}
		662
		663	sub spawn(@) {
		664	my ($noderef, undef) = split /#/, shift, 2;
		665
		666	my $id = "$RUNIQ." . $ID++;
		667
		668	$_[0] =~ /::/
		669	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		670
		671	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
		672
		673	"$noderef#$id"
		674	}
576		675
577	=back	676	=back
578		677
579	=head1 NODE MESSAGES	678	=head1 NODE MESSAGES
580		679
…		…
622		721
623	=back	722	=back
624		723
625	=head1 AnyEvent::MP vs. Distributed Erlang	724	=head1 AnyEvent::MP vs. Distributed Erlang
626		725
627	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node	726	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	727	== 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	728	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
630	sample:	729	sample:
631		730
632	http://www.erlang.se/doc/programming_rules.shtml	731	http://www.Erlang.se/doc/programming_rules.shtml
633	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	732	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	733	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	734	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
636		735
637	Despite the similarities, there are also some important differences:	736	Despite the similarities, there are also some important differences:
638		737
639	=over 4	738	=over 4
640		739
…		…
645	convenience functionality.	744	convenience functionality.
646		745
647	This means that AEMP requires a less tightly controlled environment at the	746	This means that AEMP requires a less tightly controlled environment at the
648	cost of longer node references and a slightly higher management overhead.	747	cost of longer node references and a slightly higher management overhead.
649		748
		749	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
		750	uses "local ports are like remote ports".
		751
		752	The failure modes for local ports are quite different (runtime errors
		753	only) then for remote ports - when a local port dies, you I<know> it dies,
		754	when a connection to another node dies, you know nothing about the other
		755	port.
		756
		757	Erlang pretends remote ports are as reliable as local ports, even when
		758	they are not.
		759
		760	AEMP encourages a "treat remote ports differently" philosophy, with local
		761	ports being the special case/exception, where transport errors cannot
		762	occur.
		763
650	=item * Erlang uses processes and a mailbox, AEMP does not queue.	764	=item * Erlang uses processes and a mailbox, AEMP does not queue.
651		765
652	Erlang uses processes that selctively receive messages, and therefore	766	Erlang uses processes that selectively receive messages, and therefore
653	needs a queue. AEMP is event based, queuing messages would serve no useful	767	needs a queue. AEMP is event based, queuing messages would serve no
654	purpose.	768	useful purpose. For the same reason the pattern-matching abilities of
		769	AnyEvent::MP are more limited, as there is little need to be able to
		770	filter messages without dequeing them.
655		771
656	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	772	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
657		773
658	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	774	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
659		775
660	Sending messages in erlang is synchronous and blocks the process. AEMP	776	Sending messages in Erlang is synchronous and blocks the process (and
661	sends are immediate, connection establishment is handled in the	777	so does not need a queue that can overflow). AEMP sends are immediate,
662	background.	778	connection establishment is handled in the background.
663		779
664	=item * Erlang can silently lose messages, AEMP cannot.	780	=item * Erlang suffers from silent message loss, AEMP does not.
665		781
666	Erlang makes few guarantees on messages delivery - messages can get lost	782	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,	783	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).	784	and c, and the other side only receives messages a and c).
669		785
670	AEMP guarantees correct ordering, and the guarantee that there are no	786	AEMP guarantees correct ordering, and the guarantee that there are no
671	holes in the message sequence.	787	holes in the message sequence.
672		788
673	=item * In erlang, processes can be declared dead and later be found to be	789	=item * In Erlang, processes can be declared dead and later be found to be
674	alive.	790	alive.
675		791
676	In erlang it can happen that a monitored process is declared dead and	792	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	793	linked processes get killed, but later it turns out that the process is
678	still alive - and can receive messages.	794	still alive - and can receive messages.
679		795
680	In AEMP, when port monitoring detects a port as dead, then that port will	796	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	797	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.	798	and then later sends messages to it, finding it is still alive.
683		799
684	=item * Erlang can send messages to the wrong port, AEMP does not.	800	=item * Erlang can send messages to the wrong port, AEMP does not.
685		801
686	In erlang it is quite possible that a node that restarts reuses a process	802	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	803	known to other nodes for a completely different process, causing messages
688	messages destined for that process to end up in an unrelated process.	804	destined for that process to end up in an unrelated process.
689		805
690	AEMP never reuses port IDs, so old messages or old port IDs floating	806	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.	807	around in the network will not be sent to an unrelated port.
692		808
693	=item * Erlang uses unprotected connections, AEMP uses secure	809	=item * Erlang uses unprotected connections, AEMP uses secure
…		…
697	securely authenticate nodes.	813	securely authenticate nodes.
698		814
699	=item * The AEMP protocol is optimised for both text-based and binary	815	=item * The AEMP protocol is optimised for both text-based and binary
700	communications.	816	communications.
701		817
702	The AEMP protocol, unlike the erlang protocol, supports both	818	The AEMP protocol, unlike the Erlang protocol, supports both
703	language-independent text-only protocols (good for debugging) and binary,	819	language-independent text-only protocols (good for debugging) and binary,
704	language-specific serialisers (e.g. Storable).	820	language-specific serialisers (e.g. Storable).
705		821
706	It has also been carefully designed to be implementable in other languages	822	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	823	with a minimum of work while gracefully degrading fucntionality to make the
708	protocol simple.	824	protocol simple.
709		825
		826	=item * AEMP has more flexible monitoring options than Erlang.
		827
		828	In Erlang, you can chose to receive I<all> exit signals as messages
		829	or I<none>, there is no in-between, so monitoring single processes is
		830	difficult to implement. Monitoring in AEMP is more flexible than in
		831	Erlang, as one can choose between automatic kill, exit message or callback
		832	on a per-process basis.
		833
		834	=item * Erlang tries to hide remote/local connections, AEMP does not.
		835
		836	Monitoring in Erlang is not an indicator of process death/crashes,
		837	as linking is (except linking is unreliable in Erlang).
		838
		839	In AEMP, you don't "look up" registered port names or send to named ports
		840	that might or might not be persistent. Instead, you normally spawn a port
		841	on the remote node. The init function monitors the you, and you monitor
		842	the remote port. Since both monitors are local to the node, they are much
		843	more reliable.
		844
		845	This also saves round-trips and avoids sending messages to the wrong port
		846	(hard to do in Erlang).
		847
		848	=back
		849
		850	=head1 RATIONALE
		851
		852	=over 4
		853
		854	=item Why strings for ports and noderefs, why not objects?
		855
		856	We considered "objects", but found that the actual number of methods
		857	thatc an be called are very low. Since port IDs and noderefs travel over
		858	the network frequently, the serialising/deserialising would add lots of
		859	overhead, as well as having to keep a proxy object.
		860
		861	Strings can easily be printed, easily serialised etc. and need no special
		862	procedures to be "valid".
		863
		864	And a a miniport consists of a single closure stored in a global hash - it
		865	can't become much cheaper.
		866
		867	=item Why favour JSON, why not real serialising format such as Storable?
		868
		869	In fact, any AnyEvent::MP node will happily accept Storable as framing
		870	format, but currently there is no way to make a node use Storable by
		871	default.
		872
		873	The default framing protocol is JSON because a) JSON::XS is many times
		874	faster for small messages and b) most importantly, after years of
		875	experience we found that object serialisation is causing more problems
		876	than it gains: Just like function calls, objects simply do not travel
		877	easily over the network, mostly because they will always be a copy, so you
		878	always have to re-think your design.
		879
		880	Keeping your messages simple, concentrating on data structures rather than
		881	objects, will keep your messages clean, tidy and efficient.
		882
710	=back	883	=back
711		884
712	=head1 SEE ALSO	885	=head1 SEE ALSO
713		886
714	L<AnyEvent>.	887	L<AnyEvent>.

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing cvsroot/AnyEvent-MP/MP.pm (file contents): Revision 1.33 by root, Wed Aug 5 22:40:51 2009 UTC vs. Revision 1.55 by root, Fri Aug 14 23:17:17 2009 UTC

Diff Legend

Comparing cvsroot/AnyEvent-MP/MP.pm (file contents):
Revision 1.33 by root, Wed Aug 5 22:40:51 2009 UTC vs.
Revision 1.55 by root, Fri Aug 14 23:17:17 2009 UTC