[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 1.61 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		46	AnyEvent::MP::Intro - outdated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 $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.
131		154
132	=item initialise_node $noderef, $seednode, $seednode...	155	=item initialise_node $noderef, $seednode, $seednode...
133		156
134	=item initialise_node "slave/", $master, $master...	157	=item initialise_node "slave/", $master, $master...
135		158
…		…
138	it should know the noderefs of some other nodes in the network.	161	it should know the noderefs of some other nodes in the network.
139		162
140	This function initialises a node - it must be called exactly once (or	163	This function initialises a node - it must be called exactly once (or
141	never) before calling other AnyEvent::MP functions.	164	never) before calling other AnyEvent::MP functions.
142		165
143	All arguments are noderefs, which can be either resolved or unresolved.	166	All arguments (optionally except for the first) are noderefs, which can be
		167	either resolved or unresolved.
		168
		169	The first argument will be looked up in the configuration database first
		170	(if it is C<undef> then the current nodename will be used instead) to find
		171	the relevant configuration profile (see L<aemp>). If none is found then
		172	the default configuration is used. The configuration supplies additional
		173	seed/master nodes and can override the actual noderef.
144		174
145	There are two types of networked nodes, public nodes and slave nodes:	175	There are two types of networked nodes, public nodes and slave nodes:
146		176
147	=over 4	177	=over 4
148		178
149	=item public nodes	179	=item public nodes
150		180
151	For public nodes, C<$noderef> must either be a (possibly unresolved)	181	For public nodes, C<$noderef> (supplied either directly to
152	noderef, in which case it will be resolved, or C<undef> (or missing), in	182	C<initialise_node> or indirectly via a profile or the nodename) must be a
153	which case the noderef will be guessed.	183	noderef (possibly unresolved, in which case it will be resolved).
154		184
155	Afterwards, the node will bind itself on all endpoints and try to connect	185	After resolving, the node will bind itself on all endpoints and try to
156	to all additional C<$seednodes> that are specified. Seednodes are optional	186	connect to all additional C<$seednodes> that are specified. Seednodes are
157	and can be used to quickly bootstrap the node into an existing network.	187	optional and can be used to quickly bootstrap the node into an existing
		188	network.
158		189
159	=item slave nodes	190	=item slave nodes
160		191
161	When the C<$noderef> is the special string C<slave/>, then the node will	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
162	become a slave node. Slave nodes cannot be contacted from outside and will	194	node. Slave nodes cannot be contacted from outside and will route most of
163	route most of their traffic to the master node that they attach to.	195	their traffic to the master node that they attach to.
164		196
165	At least one additional noderef is required: The node will try to connect	197	At least one additional noderef is required (either by specifying it
166	to all of them and will become a slave attached to the first node it can	198	directly or because it is part of the configuration profile): The node
167	successfully connect to.	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.
168		206
169	=back	207	=back
170		208
171	This function will block until all nodes have been resolved and, for slave	209	This function will block until all nodes have been resolved and, for slave
172	nodes, until it has successfully established a connection to a master	210	nodes, until it has successfully established a connection to a master
173	server.	211	server.
174		212
		213	All the seednodes will also be specially marked to automatically retry
		214	connecting to them infinitely.
		215
175	Example: become a public node listening on the default node.	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.
176		219
177	initialise_node;	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";
178		231
179	Example: become a public node, and try to contact some well-known master	232	Example: become a public node, and try to contact some well-known master
180	servers to become part of the network.	233	servers to become part of the network.
181		234
182	initialise_node undef, "master1", "master2";	235	initialise_node undef, "master1", "master2";
…		…
185		238
186	initialise_node 4041;	239	initialise_node 4041;
187		240
188	Example: become a public node, only visible on localhost port 4044.	241	Example: become a public node, only visible on localhost port 4044.
189		242
190	initialise_node "locahost:4044";	243	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		244
196	=item $cv = resolve_node $noderef	245	=item $cv = resolve_node $noderef
197		246
198	Takes an unresolved node reference that may contain hostnames and	247	Takes an unresolved node reference that may contain hostnames and
199	abbreviated IDs, resolves all of them and returns a resolved node	248	abbreviated IDs, resolves all of them and returns a resolved node
…		…
236	=item snd $port, type => @data	285	=item snd $port, type => @data
237		286
238	=item snd $port, @msg	287	=item snd $port, @msg
239		288
240	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
241	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.
242	stringifies a sa port ID (such as a port object :).
243		291
244	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
245	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
246	type etc.).	294	type etc.).
247		295
248	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
249	function: modifying any argument is not allowed and can cause many	297	function: modifying any argument is not allowed and can cause many
250	problems.	298	problems.
…		…
255	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
256	node, anything can be passed.	304	node, anything can be passed.
257		305
258	=item $local_port = port	306	=item $local_port = port
259		307
260	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
261	matching port ("full port") or a single-callback port ("miniport"),	309	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		310
264	=item $port = port { my @msg = @_; $finished }	311	=item $local_port = port { my @msg = @_ }
265		312
266	Creates a "miniport", that is, a very lightweight port without any pattern	313	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.	314	creating a port and calling C<rcv $port, $callback> on it.
269		315
270	The block will be called for every message received on the port. When the	316	The block will be called for every message received on the port, with the
271	callback returns a true value its job is considered "done" and the port	317	global variable C<$SELF> set to the port ID. Runtime errors will cause the
272	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.
273		320
274	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:
275	be passed to the callback.
276		322
277	If you need the local port id in the callback, this works nicely:	323	my $port = port {
278		324	my @msg = @_;
279	my $port; $port = port {	325	...
280	snd $otherport, reply => $port;	326	kil $SELF;
281	};	327	};
282		328
283	=cut	329	=cut
284		330
285	sub rcv($@);	331	sub rcv($@);
		332
		333	sub _kilme {
		334	die "received message on port without callback";
		335	}
286		336
287	sub port(;&) {	337	sub port(;&) {
288	my $id = "$UNIQ." . $ID++;	338	my $id = "$UNIQ." . $ID++;
289	my $port = "$NODE#$id";	339	my $port = "$NODE#$id";
290		340
291	if (@_) {	341	rcv $port, shift \|\| \&_kilme;
292	rcv $port, shift;
293	} else {
294	$PORT{$id} = sub { }; # nop
295	}
296		342
297	$port	343	$port
298	}	344	}
299		345
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)	346	=item rcv $local_port, $callback->(@msg)
318		347
319	Replaces the callback on the specified miniport (after converting it to	348	Replaces the default callback on the specified port. There is no way to
320	one if required).	349	remove the default callback: use C<sub { }> to disable it, or better
321		350	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...] => $callback->(@msg), ...
327
328	Register callbacks to be called on matching messages on the given full
329	port (after converting it to one if required).
330
331	The callback has to return a true value when its work is done, after
332	which is will be removed, or a false value in which case it will stay
333	registered.
334		351
335	The global C<$SELF> (exported by this module) contains C<$port> while	352	The global C<$SELF> (exported by this module) contains C<$port> while
336	executing the callback.	353	executing the callback. Runtime errors during callback execution will
		354	result in the port being C<kil>ed.
337		355
338	Runtime errors wdurign callback execution will result in the port being	356	The default callback received all messages not matched by a more specific
339	C<kil>ed.	357	C<tag> match.
340		358
341	If the match is an array reference, then it will be matched against the	359	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
342	first elements of the message, otherwise only the first element is being
343	matched.
344		360
345	Any element in the match that is specified as C<_any_> (a function	361	Register (or replace) callbacks to be called on messages starting with the
346	exported by this module) matches any single element of the message.	362	given tag on the given port (and return the port), or unregister it (when
		363	C<$callback> is C<$undef> or missing). There can only be one callback
		364	registered for each tag.
347		365
348	While not required, it is highly recommended that the first matching	366	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	367	element (the tag) has been removed. The callback will use the same
350	also the most efficient match (by far).	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, $otherport;
		393	};
351		394
352	=cut	395	=cut
353		396
354	sub rcv($@) {	397	sub rcv($@) {
355	my $port = shift;	398	my $port = shift;
356	my ($noderef, $portid) = split /#/, $port, 2;	399	my ($noderef, $portid) = split /#/, $port, 2;
357		400
358	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	401	$NODE{$noderef} == $NODE{""}
359	or Carp::croak "$port: rcv can only be called on local ports, caught";	402	or Carp::croak "$port: rcv can only be called on local ports, caught";
360		403
361	if (@_ == 1) {	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 {
362	my $cb = shift;	412	my $cb = shift;
363	delete $PORT_DATA{$portid};
364	$PORT{$portid} = sub {	413	$PORT{$portid} = sub {
365	local $SELF = $port;	414	local $SELF = $port;
366	eval {	415	eval { &$cb }; _self_die if $@;
367	&$cb	416	};
368	and kil $port;
369	};	417	}
370	_self_die if $@;	418	} elsif (defined $_[0]) {
371	};
372	} else {
373	my $self = $PORT_DATA{$portid} \|\|= do {	419	my $self = $PORT_DATA{$portid} \|\|= do {
374	my $self = bless {	420	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
375	id => $port,
376	}, "AnyEvent::MP::Port";
377		421
378	$PORT{$portid} = sub {	422	$PORT{$portid} = sub {
379	local $SELF = $port;	423	local $SELF = $port;
380		424
381	eval {
382	for (@{ $self->{rc0}{$_[0]} }) {	425	if (my $cb = $self->[1]{$_[0]}) {
383	$_ && &{$_->[0]}	426	shift;
384	&& undef $_;	427	eval { &$cb }; _self_die if $@;
385	}	428	} else {
386
387	for (@{ $self->{rcv}{$_[0]} }) {
388	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
389	&& &{$_->[0]}	429	&{ $self->[0] };
390	&& undef $_;
391	}
392
393	for (@{ $self->{any} }) {
394	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
395	&& &{$_->[0]}
396	&& undef $_;
397	}	430	}
398	};	431	};
399	_self_die if $@;	432
		433	$self
400	};	434	};
401		435
402	$self
403	};
404
405	"AnyEvent::MP::Port" eq ref $self	436	"AnyEvent::MP::Port" eq ref $self
406	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	437	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
407		438
408	while (@_) {
409	my ($match, $cb) = splice @_, 0, 2;	439	my ($tag, $cb) = splice @_, 0, 2;
410		440
411	if (!ref $match) {	441	if (defined $cb) {
412	push @{ $self->{rc0}{$match} }, [$cb];	442	$self->[1]{$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 {	443	} else {
419	push @{ $self->{any} }, [$cb, $match];	444	delete $self->[1]{$tag};
420	}	445	}
421	}	446	}
422	}	447	}
423		448
424	$port	449	$port
…		…
462	}	487	}
463	}	488	}
464		489
465	=item $guard = mon $port, $cb->(@reason)	490	=item $guard = mon $port, $cb->(@reason)
466		491
467	=item $guard = mon $port, $otherport	492	=item $guard = mon $port, $rcvport
468		493
		494	=item $guard = mon $port
		495
469	=item $guard = mon $port, $otherport, @msg	496	=item $guard = mon $port, $rcvport, @msg
470		497
471	Monitor the given port and do something when the port is killed.	498	Monitor the given port and do something when the port is killed or
		499	messages to it were lost, and optionally return a guard that can be used
		500	to stop monitoring again.
472		501
		502	C<mon> effectively guarantees that, in the absence of hardware failures,
		503	that after starting the monitor, either all messages sent to the port
		504	will arrive, or the monitoring action will be invoked after possible
		505	message loss has been detected. No messages will be lost "in between"
		506	(after the first lost message no further messages will be received by the
		507	port). After the monitoring action was invoked, further messages might get
		508	delivered again.
		509
		510	Note that monitoring-actions are one-shot: once released, they are removed
		511	and will not trigger again.
		512
473	In the first form, the callback is simply called with any number	513	In the first form (callback), the callback is simply called with any
474	of C<@reason> elements (no @reason means that the port was deleted	514	number of C<@reason> elements (no @reason means that the port was deleted
475	"normally"). Note also that I<< the callback B<must> never die >>, so use	515	"normally"). Note also that I<< the callback B<must> never die >>, so use
476	C<eval> if unsure.	516	C<eval> if unsure.
477		517
478	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	518	In the second form (another port given), the other port (C<$rcvport>)
479	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
480	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.
481		522
		523	The third form (kill self) is the same as the second form, except that
		524	C<$rvport> defaults to C<$SELF>.
		525
482	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.
483		535
484	Example: call a given callback when C<$port> is killed.	536	Example: call a given callback when C<$port> is killed.
485		537
486	mon $port, sub { warn "port died because of <@_>\n" };	538	mon $port, sub { warn "port died because of <@_>\n" };
487		539
488	Example: kill ourselves when C<$port> is killed abnormally.	540	Example: kill ourselves when C<$port> is killed abnormally.
489		541
490	mon $port, $self;	542	mon $port;
491		543
492	Example: send us a restart message another C<$port> is killed.	544	Example: send us a restart message when another C<$port> is killed.
493		545
494	mon $port, $self => "restart";	546	mon $port, $self => "restart";
495		547
496	=cut	548	=cut
497		549
498	sub mon {	550	sub mon {
499	my ($noderef, $port) = split /#/, shift, 2;	551	my ($noderef, $port) = split /#/, shift, 2;
500		552
501	my $node = $NODE{$noderef} \|\| add_node $noderef;	553	my $node = $NODE{$noderef} \|\| add_node $noderef;
502		554
503	my $cb = shift;	555	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
504		556
505	unless (ref $cb) {	557	unless (ref $cb) {
506	if (@_) {	558	if (@_) {
507	# send a kill info message	559	# send a kill info message
508	my (@msg) = ($cb, @_);	560	my (@msg) = ($cb, @_);
…		…
539	=cut	591	=cut
540		592
541	sub mon_guard {	593	sub mon_guard {
542	my ($port, @refs) = @_;	594	my ($port, @refs) = @_;
543		595
		596	#TODO: mon-less form?
		597
544	mon $port, sub { 0 && @refs }	598	mon $port, sub { 0 && @refs }
545	}	599	}
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		600
557	=item kil $port[, @reason]	601	=item kil $port[, @reason]
558		602
559	Kill the specified port with the given C<@reason>.	603	Kill the specified port with the given C<@reason>.
560		604
…		…
568	will be reported as reason C<< die => $@ >>.	612	will be reported as reason C<< die => $@ >>.
569		613
570	Transport/communication errors are reported as C<< transport_error =>	614	Transport/communication errors are reported as C<< transport_error =>
571	$message >>.	615	$message >>.
572		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	? $action[0]()
		705	: snd @action;
		706	};
		707	}
		708
573	=back	709	=back
574		710
575	=head1 NODE MESSAGES
576
577	Nodes understand the following messages sent to them. Many of them take
578	arguments called C<@reply>, which will simply be used to compose a reply
579	message - C<$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	711	=head1 AnyEvent::MP vs. Distributed Erlang
622		712
623	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
624	== 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
625	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
626	sample:	716	sample:
627		717
628	http://www.erlang.se/doc/programming_rules.shtml	718	http://www.Erlang.se/doc/programming_rules.shtml
629	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
630	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
631	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
632		722
633	Despite the similarities, there are also some important differences:	723	Despite the similarities, there are also some important differences:
634		724
635	=over 4	725	=over 4
636		726
…		…
641	convenience functionality.	731	convenience functionality.
642		732
643	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
644	cost of longer node references and a slightly higher management overhead.	734	cost of longer node references and a slightly higher management overhead.
645		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
646	=item * Erlang uses processes and a mailbox, AEMP does not queue.	751	=item * Erlang uses processes and a mailbox, AEMP does not queue.
647		752
648	Erlang uses processes that selctively receive messages, and therefore	753	Erlang uses processes that selectively receive messages, and therefore
649	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
650	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.
651		758
652	(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).
653		760
654	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	761	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
655		762
656	Sending messages in erlang is synchronous and blocks the process. AEMP	763	Sending messages in Erlang is synchronous and blocks the process (and
657	sends are immediate, connection establishment is handled in the	764	so does not need a queue that can overflow). AEMP sends are immediate,
658	background.	765	connection establishment is handled in the background.
659		766
660	=item * Erlang can silently lose messages, AEMP cannot.	767	=item * Erlang suffers from silent message loss, AEMP does not.
661		768
662	Erlang makes few guarantees on messages delivery - messages can get lost	769	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,	770	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).	771	and c, and the other side only receives messages a and c).
665		772
666	AEMP guarantees correct ordering, and the guarantee that there are no	773	AEMP guarantees correct ordering, and the guarantee that there are no
667	holes in the message sequence.	774	holes in the message sequence.
668		775
669	=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
670	alive.	777	alive.
671		778
672	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
673	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
674	still alive - and can receive messages.	781	still alive - and can receive messages.
675		782
676	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
677	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
678	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.
679		786
680	=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.
681		788
682	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
683	ID known to other nodes for a completely different process, causing	790	known to other nodes for a completely different process, causing messages
684	messages destined for that process to end up in an unrelated process.	791	destined for that process to end up in an unrelated process.
685		792
686	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
687	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.
688		795
689	=item * Erlang uses unprotected connections, AEMP uses secure	796	=item * Erlang uses unprotected connections, AEMP uses secure
…		…
693	securely authenticate nodes.	800	securely authenticate nodes.
694		801
695	=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
696	communications.	803	communications.
697		804
698	The AEMP protocol, unlike the erlang protocol, supports both	805	The AEMP protocol, unlike the Erlang protocol, supports both
699	language-independent text-only protocols (good for debugging) and binary,	806	language-independent text-only protocols (good for debugging) and binary,
700	language-specific serialisers (e.g. Storable).	807	language-specific serialisers (e.g. Storable).
701		808
702	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
703	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
704	protocol simple.	811	protocol simple.
705		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
706	=back	870	=back
707		871
708	=head1 SEE ALSO	872	=head1 SEE ALSO
709		873
710	L<AnyEvent>.	874	L<AnyEvent>.

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