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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.31 by root, Wed Aug 5 19:55:58 2009 UTC vs.
Revision 1.47 by root, Thu Aug 13 01:57:10 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	# ports are message endpoints
		16
		17	# sending messages
13	snd $port, type => data...;	18	snd $port, type => data...;
		19	snd $port, @msg;
		20	snd @msg_with_first_element_being_a_port;
14		21
15	$SELF # receiving/own port id in rcv callbacks	22	# miniports
		23	my $miniport = port { my @msg = @_; 0 };
16		24
		25	# full ports
		26	my $port = port;
17	rcv $port, smartmatch => $cb->($port, @msg);	27	rcv $port, smartmatch => $cb->(@msg);
18
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	28	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
21	rcv $port1, pong => sub { warn "pong received\n" };	29	rcv $port, pong => sub { warn "pong received\n"; 0 };
22	snd $port2, ping => $port1;	30
		31	# remote ports
		32	my $port = spawn $node, $initfunc, @initdata;
23		33
24	# more, smarter, matches (_any_ is exported by this module)	34	# more, smarter, matches (_any_ is exported by this module)
25	rcv $port, [child_died => $pid] => sub { ...	35	rcv $port, [child_died => $pid] => sub { ...
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	36	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
27		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		46	AnyEvent::MP::Intro - outdated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.
		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
32	Despite its simplicity, you can securely message other processes running	56	Despite its simplicity, you can securely message other processes running
…		…
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
…		…
90		114
91	=cut	115	=cut
92		116
93	package AnyEvent::MP;	117	package AnyEvent::MP;
94		118
95	use AnyEvent::MP::Base;	119	use AnyEvent::MP::Kernel;
96		120
97	use common::sense;	121	use common::sense;
98		122
99	use Carp ();	123	use Carp ();
100		124
101	use AE ();	125	use AE ();
102		126
103	use base "Exporter";	127	use base "Exporter";
104		128
105	our $VERSION = '0.1';	129	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		130
106	our @EXPORT = qw(	131	our @EXPORT = qw(
107	NODE $NODE *SELF node_of _any_	132	NODE $NODE *SELF node_of _any_
108	resolve_node initialise_node	133	resolve_node initialise_node
109	snd rcv mon kil reg psub	134	snd rcv mon kil reg psub spawn
110	port	135	port
111	);	136	);
112		137
113	our $SELF;	138	our $SELF;
114		139
…		…
123	The C<NODE> function returns, and the C<$NODE> variable contains	148	The C<NODE> function returns, and the C<$NODE> variable contains
124	the noderef of the local node. The value is initialised by a call	149	the noderef of the local node. The value is initialised by a call
125	to C<become_public> or C<become_slave>, after which all local port	150	to C<become_public> or C<become_slave>, after which all local port
126	identifiers become invalid.	151	identifiers become invalid.
127		152
128	=item $noderef = node_of $portid	153	=item $noderef = node_of $port
129		154
130	Extracts and returns the noderef from a portid or a noderef.	155	Extracts and returns the noderef from a portid or a noderef.
		156
		157	=item initialise_node $noderef, $seednode, $seednode...
		158
		159	=item initialise_node "slave/", $master, $master...
		160
		161	Before a node can talk to other nodes on the network it has to initialise
		162	itself - the minimum a node needs to know is it's own name, and optionally
		163	it should know the noderefs of some other nodes in the network.
		164
		165	This function initialises a node - it must be called exactly once (or
		166	never) before calling other AnyEvent::MP functions.
		167
		168	All arguments are noderefs, which can be either resolved or unresolved.
		169
		170	There are two types of networked nodes, public nodes and slave nodes:
		171
		172	=over 4
		173
		174	=item public nodes
		175
		176	For public nodes, C<$noderef> must either be a (possibly unresolved)
		177	noderef, in which case it will be resolved, or C<undef> (or missing), in
		178	which case the noderef will be guessed.
		179
		180	Afterwards, the node will bind itself on all endpoints and try to connect
		181	to all additional C<$seednodes> that are specified. Seednodes are optional
		182	and can be used to quickly bootstrap the node into an existing network.
		183
		184	=item slave nodes
		185
		186	When the C<$noderef> is the special string C<slave/>, then the node will
		187	become a slave node. Slave nodes cannot be contacted from outside and will
		188	route most of their traffic to the master node that they attach to.
		189
		190	At least one additional noderef is required: The node will try to connect
		191	to all of them and will become a slave attached to the first node it can
		192	successfully connect to.
		193
		194	=back
		195
		196	This function will block until all nodes have been resolved and, for slave
		197	nodes, until it has successfully established a connection to a master
		198	server.
		199
		200	Example: become a public node listening on the default node.
		201
		202	initialise_node;
		203
		204	Example: become a public node, and try to contact some well-known master
		205	servers to become part of the network.
		206
		207	initialise_node undef, "master1", "master2";
		208
		209	Example: become a public node listening on port C<4041>.
		210
		211	initialise_node 4041;
		212
		213	Example: become a public node, only visible on localhost port 4044.
		214
		215	initialise_node "locahost:4044";
		216
		217	Example: become a slave node to any of the specified master servers.
		218
		219	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
131		220
132	=item $cv = resolve_node $noderef	221	=item $cv = resolve_node $noderef
133		222
134	Takes an unresolved node reference that may contain hostnames and	223	Takes an unresolved node reference that may contain hostnames and
135	abbreviated IDs, resolves all of them and returns a resolved node	224	abbreviated IDs, resolves all of them and returns a resolved node
…		…
167		256
168	Due to some quirks in how perl exports variables, it is impossible to	257	Due to some quirks in how perl exports variables, it is impossible to
169	just export C<$SELF>, all the symbols called C<SELF> are exported by this	258	just export C<$SELF>, all the symbols called C<SELF> are exported by this
170	module, but only C<$SELF> is currently used.	259	module, but only C<$SELF> is currently used.
171		260
172	=item snd $portid, type => @data	261	=item snd $port, type => @data
173		262
174	=item snd $portid, @msg	263	=item snd $port, @msg
175		264
176	Send the given message to the given port ID, which can identify either	265	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	266	a local or a remote port, and can be either a string or soemthignt hat
178	stringifies a sa port ID (such as a port object :).	267	stringifies a sa port ID (such as a port object :).
179		268
…		…
189	JSON is used, then only strings, numbers and arrays and hashes consisting	278	JSON is used, then only strings, numbers and arrays and hashes consisting
190	of those are allowed (no objects). When Storable is used, then anything	279	of those are allowed (no objects). When Storable is used, then anything
191	that Storable can serialise and deserialise is allowed, and for the local	280	that Storable can serialise and deserialise is allowed, and for the local
192	node, anything can be passed.	281	node, anything can be passed.
193		282
194	=item kil $portid[, @reason]	283	=item $local_port = port
195		284
196	Kill the specified port with the given C<@reason>.	285	Create a new local port object that can be used either as a pattern
		286	matching port ("full port") or a single-callback port ("miniport"),
		287	depending on how C<rcv> callbacks are bound to the object.
197		288
198	If no C<@reason> is specified, then the port is killed "normally" (linked	289	=item $port = port { my @msg = @_; $finished }
199	ports will not be kileld, or even notified).
200		290
201	Otherwise, linked ports get killed with the same reason (second form of	291	Creates a "miniport", that is, a very lightweight port without any pattern
202	C<mon>, see below).	292	matching behind it, and returns its ID. Semantically the same as creating
		293	a port and calling C<rcv $port, $callback> on it.
203		294
204	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	295	The block will be called for every message received on the port. When the
205	will be reported as reason C<< die => $@ >>.	296	callback returns a true value its job is considered "done" and the port
		297	will be destroyed. Otherwise it will stay alive.
206		298
207	Transport/communication errors are reported as C<< transport_error =>	299	The message will be passed as-is, no extra argument (i.e. no port id) will
208	$message >>.	300	be passed to the callback.
209		301
		302	If you need the local port id in the callback, this works nicely:
		303
		304	my $port; $port = port {
		305	snd $otherport, reply => $port;
		306	};
		307
		308	=cut
		309
		310	sub rcv($@);
		311
		312	sub port(;&) {
		313	my $id = "$UNIQ." . $ID++;
		314	my $port = "$NODE#$id";
		315
		316	if (@_) {
		317	rcv $port, shift;
		318	} else {
		319	$PORT{$id} = sub { }; # nop
		320	}
		321
		322	$port
		323	}
		324
		325	=item reg $port, $name
		326
		327	=item reg $name
		328
		329	Registers the given port (or C<$SELF><<< if missing) under the name
		330	C<$name>. If the name already exists it is replaced.
		331
		332	A port can only be registered under one well known name.
		333
		334	A port automatically becomes unregistered when it is killed.
		335
		336	=cut
		337
		338	sub reg(@) {
		339	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
		340
		341	$REG{$_[0]} = $port;
		342	}
		343
		344	=item rcv $port, $callback->(@msg)
		345
		346	Replaces the callback on the specified miniport (after converting it to
		347	one if required).
		348
		349	=item rcv $port, tagstring => $callback->(@msg), ...
		350
		351	=item rcv $port, $smartmatch => $callback->(@msg), ...
		352
		353	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
		354
		355	Register callbacks to be called on matching messages on the given full
		356	port (after converting it to one if required) and return the port.
		357
		358	The callback has to return a true value when its work is done, after
		359	which is will be removed, or a false value in which case it will stay
		360	registered.
		361
		362	The global C<$SELF> (exported by this module) contains C<$port> while
		363	executing the callback.
		364
		365	Runtime errors during callback execution will result in the port being
		366	C<kil>ed.
		367
		368	If the match is an array reference, then it will be matched against the
		369	first elements of the message, otherwise only the first element is being
		370	matched.
		371
		372	Any element in the match that is specified as C<_any_> (a function
		373	exported by this module) matches any single element of the message.
		374
		375	While not required, it is highly recommended that the first matching
		376	element is a string identifying the message. The one-string-only match is
		377	also the most efficient match (by far).
		378
		379	Example: create a port and bind receivers on it in one go.
		380
		381	my $port = rcv port,
		382	msg1 => sub { ...; 0 },
		383	msg2 => sub { ...; 0 },
		384	;
		385
		386	Example: create a port, bind receivers and send it in a message elsewhere
		387	in one go:
		388
		389	snd $otherport, reply =>
		390	rcv port,
		391	msg1 => sub { ...; 0 },
		392	...
		393	;
		394
		395	=cut
		396
		397	sub rcv($@) {
		398	my $port = shift;
		399	my ($noderef, $portid) = split /#/, $port, 2;
		400
		401	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
		402	or Carp::croak "$port: rcv can only be called on local ports, caught";
		403
		404	if (@_ == 1) {
		405	my $cb = shift;
		406	delete $PORT_DATA{$portid};
		407	$PORT{$portid} = sub {
		408	local $SELF = $port;
		409	eval {
		410	&$cb
		411	and kil $port;
		412	};
		413	_self_die if $@;
		414	};
		415	} else {
		416	my $self = $PORT_DATA{$portid} \|\|= do {
		417	my $self = bless {
		418	id => $port,
		419	}, "AnyEvent::MP::Port";
		420
		421	$PORT{$portid} = sub {
		422	local $SELF = $port;
		423
		424	eval {
		425	for (@{ $self->{rc0}{$_[0]} }) {
		426	$_ && &{$_->[0]}
		427	&& undef $_;
		428	}
		429
		430	for (@{ $self->{rcv}{$_[0]} }) {
		431	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
		432	&& &{$_->[0]}
		433	&& undef $_;
		434	}
		435
		436	for (@{ $self->{any} }) {
		437	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
		438	&& &{$_->[0]}
		439	&& undef $_;
		440	}
		441	};
		442	_self_die if $@;
		443	};
		444
		445	$self
		446	};
		447
		448	"AnyEvent::MP::Port" eq ref $self
		449	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		450
		451	while (@_) {
		452	my ($match, $cb) = splice @_, 0, 2;
		453
		454	if (!ref $match) {
		455	push @{ $self->{rc0}{$match} }, [$cb];
		456	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
		457	my ($type, @match) = @$match;
		458	@match
		459	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
		460	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
		461	} else {
		462	push @{ $self->{any} }, [$cb, $match];
		463	}
		464	}
		465	}
		466
		467	$port
		468	}
		469
		470	=item $closure = psub { BLOCK }
		471
		472	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
		473	closure is executed, sets up the environment in the same way as in C<rcv>
		474	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		475
		476	This is useful when you register callbacks from C<rcv> callbacks:
		477
		478	rcv delayed_reply => sub {
		479	my ($delay, @reply) = @_;
		480	my $timer = AE::timer $delay, 0, psub {
		481	snd @reply, $SELF;
		482	};
		483	};
		484
		485	=cut
		486
		487	sub psub(&) {
		488	my $cb = shift;
		489
		490	my $port = $SELF
		491	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
		492
		493	sub {
		494	local $SELF = $port;
		495
		496	if (wantarray) {
		497	my @res = eval { &$cb };
		498	_self_die if $@;
		499	@res
		500	} else {
		501	my $res = eval { &$cb };
		502	_self_die if $@;
		503	$res
		504	}
		505	}
		506	}
		507
210	=item $guard = mon $portid, $cb->(@reason)	508	=item $guard = mon $port, $cb->(@reason)
211		509
212	=item $guard = mon $portid, $otherport	510	=item $guard = mon $port, $rcvport
213		511
		512	=item $guard = mon $port
		513
214	=item $guard = mon $portid, $otherport, @msg	514	=item $guard = mon $port, $rcvport, @msg
215		515
216	Monitor the given port and do something when the port is killed.	516	Monitor the given port and do something when the port is killed or
		517	messages to it were lost, and optionally return a guard that can be used
		518	to stop monitoring again.
217		519
		520	C<mon> effectively guarantees that, in the absence of hardware failures,
		521	that after starting the monitor, either all messages sent to the port
		522	will arrive, or the monitoring action will be invoked after possible
		523	message loss has been detected. No messages will be lost "in between"
		524	(after the first lost message no further messages will be received by the
		525	port). After the monitoring action was invoked, further messages might get
		526	delivered again.
		527
218	In the first form, the callback is simply called with any number	528	In the first form (callback), the callback is simply called with any
219	of C<@reason> elements (no @reason means that the port was deleted	529	number of C<@reason> elements (no @reason means that the port was deleted
220	"normally"). Note also that I<< the callback B<must> never die >>, so use	530	"normally"). Note also that I<< the callback B<must> never die >>, so use
221	C<eval> if unsure.	531	C<eval> if unsure.
222		532
223	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	533	In the second form (another port given), the other port (C<$rcvport>)
224	a @reason was specified, i.e. on "normal" kils nothing happens, while	534	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
225	under all other conditions, the other port is killed with the same reason.	535	"normal" kils nothing happens, while under all other conditions, the other
		536	port is killed with the same reason.
226		537
		538	The third form (kill self) is the same as the second form, except that
		539	C<$rvport> defaults to C<$SELF>.
		540
227	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	541	In the last form (message), a message of the form C<@msg, @reason> will be
		542	C<snd>.
		543
		544	As a rule of thumb, monitoring requests should always monitor a port from
		545	a local port (or callback). The reason is that kill messages might get
		546	lost, just like any other message. Another less obvious reason is that
		547	even monitoring requests can get lost (for exmaple, when the connection
		548	to the other node goes down permanently). When monitoring a port locally
		549	these problems do not exist.
228		550
229	Example: call a given callback when C<$port> is killed.	551	Example: call a given callback when C<$port> is killed.
230		552
231	mon $port, sub { warn "port died because of <@_>\n" };	553	mon $port, sub { warn "port died because of <@_>\n" };
232		554
233	Example: kill ourselves when C<$port> is killed abnormally.	555	Example: kill ourselves when C<$port> is killed abnormally.
234		556
235	mon $port, $self;	557	mon $port;
236		558
237	Example: send us a restart message another C<$port> is killed.	559	Example: send us a restart message when another C<$port> is killed.
238		560
239	mon $port, $self => "restart";	561	mon $port, $self => "restart";
240		562
241	=cut	563	=cut
242		564
243	sub mon {	565	sub mon {
244	my ($noderef, $port) = split /#/, shift, 2;	566	my ($noderef, $port) = split /#/, shift, 2;
245		567
246	my $node = $NODE{$noderef} \|\| add_node $noderef;	568	my $node = $NODE{$noderef} \|\| add_node $noderef;
247		569
248	my $cb = shift;	570	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
249		571
250	unless (ref $cb) {	572	unless (ref $cb) {
251	if (@_) {	573	if (@_) {
252	# send a kill info message	574	# send a kill info message
253	my (@msg) = ($cb, @_);	575	my (@msg) = ($cb, @_);
…		…
284	=cut	606	=cut
285		607
286	sub mon_guard {	608	sub mon_guard {
287	my ($port, @refs) = @_;	609	my ($port, @refs) = @_;
288		610
		611	#TODO: mon-less form?
		612
289	mon $port, sub { 0 && @refs }	613	mon $port, sub { 0 && @refs }
290	}	614	}
291		615
292	=item lnk $port1, $port2	616	=item kil $port[, @reason]
293		617
294	Link two ports. This is simply a shorthand for:	618	Kill the specified port with the given C<@reason>.
295		619
296	mon $port1, $port2;	620	If no C<@reason> is specified, then the port is killed "normally" (linked
297	mon $port2, $port1;	621	ports will not be kileld, or even notified).
298		622
299	It means that if either one is killed abnormally, the other one gets	623	Otherwise, linked ports get killed with the same reason (second form of
300	killed as well.	624	C<mon>, see below).
301		625
302	=item $local_port = port	626	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		627	will be reported as reason C<< die => $@ >>.
303		628
304	Create a new local port object that can be used either as a pattern	629	Transport/communication errors are reported as C<< transport_error =>
305	matching port ("full port") or a single-callback port ("miniport"),	630	$message >>.
306	depending on how C<rcv> callbacks are bound to the object.
307		631
308	=item $portid = port { my @msg = @_; $finished }
309
310	Creates a "mini port", that is, a very lightweight port without any
311	pattern matching behind it, and returns its ID.
312
313	The block will be called for every message received on the port. When the
314	callback returns a true value its job is considered "done" and the port
315	will be destroyed. Otherwise it will stay alive.
316
317	The message will be passed as-is, no extra argument (i.e. no port id) will
318	be passed to the callback.
319
320	If you need the local port id in the callback, this works nicely:
321
322	my $port; $port = port {
323	snd $otherport, reply => $port;
324	};
325
326	=cut	632	=cut
327		633
328	sub port(;&) {	634	=item $port = spawn $node, $initfunc[, @initdata]
329	my $id = "$UNIQ." . $ID++;
330	my $port = "$NODE#$id";
331		635
332	if (@_) {	636	Creates a port on the node C<$node> (which can also be a port ID, in which
333	my $cb = shift;	637	case it's the node where that port resides).
334	$PORT{$id} = sub {	638
335	local $SELF = $port;	639	The port ID of the newly created port is return immediately, and it is
336	eval {	640	permissible to immediately start sending messages or monitor the port.
337	&$cb	641
338	and kil $id;	642	After the port has been created, the init function is
		643	called. This function must be a fully-qualified function name
		644	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		645	program, use C<::name>.
		646
		647	If the function doesn't exist, then the node tries to C<require>
		648	the package, then the package above the package and so on (e.g.
		649	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		650	exists or it runs out of package names.
		651
		652	The init function is then called with the newly-created port as context
		653	object (C<$SELF>) and the C<@initdata> values as arguments.
		654
		655	A common idiom is to pass your own port, monitor the spawned port, and
		656	in the init function, monitor the original port. This two-way monitoring
		657	ensures that both ports get cleaned up when there is a problem.
		658
		659	Example: spawn a chat server port on C<$othernode>.
		660
		661	# this node, executed from within a port context:
		662	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		663	mon $server;
		664
		665	# init function on C<$othernode>
		666	sub connect {
		667	my ($srcport) = @_;
		668
		669	mon $srcport;
		670
		671	rcv $SELF, sub {
339	};	672	...
340	_self_die if $@;
341	};
342	} else {
343	my $self = bless {
344	id => "$NODE#$id",
345	}, "AnyEvent::MP::Port";
346
347	$PORT_DATA{$id} = $self;
348	$PORT{$id} = sub {
349	local $SELF = $port;
350
351	eval {
352	for (@{ $self->{rc0}{$_[0]} }) {
353	$_ && &{$_->[0]}
354	&& undef $_;
355	}
356
357	for (@{ $self->{rcv}{$_[0]} }) {
358	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
359	&& &{$_->[0]}
360	&& undef $_;
361	}
362
363	for (@{ $self->{any} }) {
364	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
365	&& &{$_->[0]}
366	&& undef $_;
367	}
368	};
369	_self_die if $@;
370	};	673	};
371	}	674	}
372		675
373	$port	676	=cut
		677
		678	sub _spawn {
		679	my $port = shift;
		680	my $init = shift;
		681
		682	local $SELF = "$NODE#$port";
		683	eval {
		684	&{ load_func $init }
		685	};
		686	_self_die if $@;
374	}	687	}
375		688
376	=item reg $portid, $name	689	sub spawn(@) {
		690	my ($noderef, undef) = split /#/, shift, 2;
377		691
378	Registers the given port under the name C<$name>. If the name already	692	my $id = "$RUNIQ." . $ID++;
379	exists it is replaced.
380		693
381	A port can only be registered under one well known name.	694	$_[0] =~ /::/
		695	or Carp::croak "spawn init function must be a fully-qualified name, caught";
382		696
383	A port automatically becomes unregistered when it is killed.	697	($NODE{$noderef} \|\| add_node $noderef)
		698	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
384		699
385	=cut	700	"$noderef#$id"
386
387	sub reg(@) {
388	my ($portid, $name) = @_;
389
390	$REG{$name} = $portid;
391	}	701	}
392
393	=item rcv $portid, $callback->(@msg)
394
395	Replaces the callback on the specified miniport (or newly created port
396	object, see C<port>). Full ports are configured with the following calls:
397
398	=item rcv $portid, tagstring => $callback->(@msg), ...
399
400	=item rcv $portid, $smartmatch => $callback->(@msg), ...
401
402	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
403
404	Register callbacks to be called on matching messages on the given port.
405
406	The callback has to return a true value when its work is done, after
407	which is will be removed, or a false value in which case it will stay
408	registered.
409
410	The global C<$SELF> (exported by this module) contains C<$portid> while
411	executing the callback.
412
413	Runtime errors wdurign callback execution will result in the port being
414	C<kil>ed.
415
416	If the match is an array reference, then it will be matched against the
417	first elements of the message, otherwise only the first element is being
418	matched.
419
420	Any element in the match that is specified as C<_any_> (a function
421	exported by this module) matches any single element of the message.
422
423	While not required, it is highly recommended that the first matching
424	element is a string identifying the message. The one-string-only match is
425	also the most efficient match (by far).
426
427	=cut
428
429	sub rcv($@) {
430	my $portid = shift;
431	my ($noderef, $port) = split /#/, $port, 2;
432
433	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
434	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";
435
436	my $self = $PORT_DATA{$port}
437	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
438
439	"AnyEvent::MP::Port" eq ref $self
440	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
441
442	while (@_) {
443	my ($match, $cb) = splice @_, 0, 2;
444
445	if (!ref $match) {
446	push @{ $self->{rc0}{$match} }, [$cb];
447	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
448	my ($type, @match) = @$match;
449	@match
450	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
451	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
452	} else {
453	push @{ $self->{any} }, [$cb, $match];
454	}
455	}
456
457	$portid
458	}
459
460	=item $closure = psub { BLOCK }
461
462	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
463	closure is executed, sets up the environment in the same way as in C<rcv>
464	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
465
466	This is useful when you register callbacks from C<rcv> callbacks:
467
468	rcv delayed_reply => sub {
469	my ($delay, @reply) = @_;
470	my $timer = AE::timer $delay, 0, psub {
471	snd @reply, $SELF;
472	};
473	};
474
475	=cut
476
477	sub psub(&) {
478	my $cb = shift;
479
480	my $port = $SELF
481	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
482
483	sub {
484	local $SELF = $port;
485
486	if (wantarray) {
487	my @res = eval { &$cb };
488	_self_die if $@;
489	@res
490	} else {
491	my $res = eval { &$cb };
492	_self_die if $@;
493	$res
494	}
495	}
496	}
497
498	=back
499
500	=head1 FUNCTIONS FOR NODES
501
502	=over 4
503
504	=item become_public $noderef
505
506	Tells the node to become a public node, i.e. reachable from other nodes.
507
508	The first argument is the (unresolved) node reference of the local node
509	(if missing then the empty string is used).
510
511	It is quite common to not specify anything, in which case the local node
512	tries to listen on the default port, or to only specify a port number, in
513	which case AnyEvent::MP tries to guess the local addresses.
514
515	=cut
516		702
517	=back	703	=back
518		704
519	=head1 NODE MESSAGES	705	=head1 NODE MESSAGES
520		706
…		…
562		748
563	=back	749	=back
564		750
565	=head1 AnyEvent::MP vs. Distributed Erlang	751	=head1 AnyEvent::MP vs. Distributed Erlang
566		752
567	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node	753	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
568	== aemp node, erlang process == aemp port), so many of the documents and	754	== aemp node, Erlang process == aemp port), so many of the documents and
569	programming techniques employed by erlang apply to AnyEvent::MP. Here is a	755	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
570	sample:	756	sample:
571		757
572	http://www.erlang.se/doc/programming_rules.shtml	758	http://www.Erlang.se/doc/programming_rules.shtml
573	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	759	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
574	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6	760	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
575	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5	761	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
576		762
577	Despite the similarities, there are also some important differences:	763	Despite the similarities, there are also some important differences:
578		764
579	=over 4	765	=over 4
580		766
…		…
591		777
592	Erlang uses processes that selctively receive messages, and therefore	778	Erlang uses processes that selctively receive messages, and therefore
593	needs a queue. AEMP is event based, queuing messages would serve no useful	779	needs a queue. AEMP is event based, queuing messages would serve no useful
594	purpose.	780	purpose.
595		781
596	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	782	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
597		783
598	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	784	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
599		785
600	Sending messages in erlang is synchronous and blocks the process. AEMP	786	Sending messages in Erlang is synchronous and blocks the process. AEMP
601	sends are immediate, connection establishment is handled in the	787	sends are immediate, connection establishment is handled in the
602	background.	788	background.
603		789
604	=item * Erlang can silently lose messages, AEMP cannot.	790	=item * Erlang can silently lose messages, AEMP cannot.
605		791
…		…
608	and c, and the other side only receives messages a and c).	794	and c, and the other side only receives messages a and c).
609		795
610	AEMP guarantees correct ordering, and the guarantee that there are no	796	AEMP guarantees correct ordering, and the guarantee that there are no
611	holes in the message sequence.	797	holes in the message sequence.
612		798
613	=item * In erlang, processes can be declared dead and later be found to be	799	=item * In Erlang, processes can be declared dead and later be found to be
614	alive.	800	alive.
615		801
616	In erlang it can happen that a monitored process is declared dead and	802	In Erlang it can happen that a monitored process is declared dead and
617	linked processes get killed, but later it turns out that the process is	803	linked processes get killed, but later it turns out that the process is
618	still alive - and can receive messages.	804	still alive - and can receive messages.
619		805
620	In AEMP, when port monitoring detects a port as dead, then that port will	806	In AEMP, when port monitoring detects a port as dead, then that port will
621	eventually be killed - it cannot happen that a node detects a port as dead	807	eventually be killed - it cannot happen that a node detects a port as dead
622	and then later sends messages to it, finding it is still alive.	808	and then later sends messages to it, finding it is still alive.
623		809
624	=item * Erlang can send messages to the wrong port, AEMP does not.	810	=item * Erlang can send messages to the wrong port, AEMP does not.
625		811
626	In erlang it is quite possible that a node that restarts reuses a process	812	In Erlang it is quite possible that a node that restarts reuses a process
627	ID known to other nodes for a completely different process, causing	813	ID known to other nodes for a completely different process, causing
628	messages destined for that process to end up in an unrelated process.	814	messages destined for that process to end up in an unrelated process.
629		815
630	AEMP never reuses port IDs, so old messages or old port IDs floating	816	AEMP never reuses port IDs, so old messages or old port IDs floating
631	around in the network will not be sent to an unrelated port.	817	around in the network will not be sent to an unrelated port.
…		…
637	securely authenticate nodes.	823	securely authenticate nodes.
638		824
639	=item * The AEMP protocol is optimised for both text-based and binary	825	=item * The AEMP protocol is optimised for both text-based and binary
640	communications.	826	communications.
641		827
642	The AEMP protocol, unlike the erlang protocol, supports both	828	The AEMP protocol, unlike the Erlang protocol, supports both
643	language-independent text-only protocols (good for debugging) and binary,	829	language-independent text-only protocols (good for debugging) and binary,
644	language-specific serialisers (e.g. Storable).	830	language-specific serialisers (e.g. Storable).
645		831
646	It has also been carefully designed to be implementable in other languages	832	It has also been carefully designed to be implementable in other languages
647	with a minimum of work while gracefully degrading fucntionality to make the	833	with a minimum of work while gracefully degrading fucntionality to make the
648	protocol simple.	834	protocol simple.
649		835
		836	=item * AEMP has more flexible monitoring options than Erlang.
		837
		838	In Erlang, you can chose to receive I<all> exit signals as messages
		839	or I<none>, there is no in-between, so monitoring single processes is
		840	difficult to implement. Monitoring in AEMP is more flexible than in
		841	Erlang, as one can choose between automatic kill, exit message or callback
		842	on a per-process basis.
		843
		844	=item * Erlang tries to hide remote/local connections, AEMP does not.
		845
		846	Monitoring in Erlang is not an indicator of process death/crashes,
		847	as linking is (except linking is unreliable in Erlang).
		848
		849	In AEMP, you don't "look up" registered port names or send to named ports
		850	that might or might not be persistent. Instead, you normally spawn a port
		851	on the remote node. The init function monitors the you, and you monitor
		852	the remote port. Since both monitors are local to the node, they are much
		853	more reliable.
		854
		855	This also saves round-trips and avoids sending messages to the wrong port
		856	(hard to do in Erlang).
		857
		858	=back
		859
		860	=head1 RATIONALE
		861
		862	=over 4
		863
		864	=item Why strings for ports and noderefs, why not objects?
		865
		866	We considered "objects", but found that the actual number of methods
		867	thatc an be called are very low. Since port IDs and noderefs travel over
		868	the network frequently, the serialising/deserialising would add lots of
		869	overhead, as well as having to keep a proxy object.
		870
		871	Strings can easily be printed, easily serialised etc. and need no special
		872	procedures to be "valid".
		873
		874	And a a miniport consists of a single closure stored in a global hash - it
		875	can't become much cheaper.
		876
		877	=item Why favour JSON, why not real serialising format such as Storable?
		878
		879	In fact, any AnyEvent::MP node will happily accept Storable as framing
		880	format, but currently there is no way to make a node use Storable by
		881	default.
		882
		883	The default framing protocol is JSON because a) JSON::XS is many times
		884	faster for small messages and b) most importantly, after years of
		885	experience we found that object serialisation is causing more problems
		886	than it gains: Just like function calls, objects simply do not travel
		887	easily over the network, mostly because they will always be a copy, so you
		888	always have to re-think your design.
		889
		890	Keeping your messages simple, concentrating on data structures rather than
		891	objects, will keep your messages clean, tidy and efficient.
		892
650	=back	893	=back
651		894
652	=head1 SEE ALSO	895	=head1 SEE ALSO
653		896
654	L<AnyEvent>.	897	L<AnyEvent>.

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Revision 1.47 by root, Thu Aug 13 01:57:10 2009 UTC