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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.32 by root, Wed Aug 5 19:58:46 2009 UTC vs.
Revision 1.45 by root, Thu Aug 13 01:16:24 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		46	AnyEvent::MP::Intro - outdated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
…		…
195		284
196	Create a new local port object that can be used either as a pattern	285	Create a new local port object that can be used either as a pattern
197	matching port ("full port") or a single-callback port ("miniport"),	286	matching port ("full port") or a single-callback port ("miniport"),
198	depending on how C<rcv> callbacks are bound to the object.	287	depending on how C<rcv> callbacks are bound to the object.
199		288
200	=item $portid = port { my @msg = @_; $finished }	289	=item $port = port { my @msg = @_; $finished }
201		290
202	Creates a "mini port", that is, a very lightweight port without any	291	Creates a "miniport", that is, a very lightweight port without any pattern
203	pattern matching behind it, and returns its ID.	292	matching behind it, and returns its ID. Semantically the same as creating
		293	a port and calling C<rcv $port, $callback> on it.
204		294
205	The block will be called for every message received on the port. When the	295	The block will be called for every message received on the port. When the
206	callback returns a true value its job is considered "done" and the port	296	callback returns a true value its job is considered "done" and the port
207	will be destroyed. Otherwise it will stay alive.	297	will be destroyed. Otherwise it will stay alive.
208		298
…		…
215	snd $otherport, reply => $port;	305	snd $otherport, reply => $port;
216	};	306	};
217		307
218	=cut	308	=cut
219		309
		310	sub rcv($@);
		311
220	sub port(;&) {	312	sub port(;&) {
221	my $id = "$UNIQ." . $ID++;	313	my $id = "$UNIQ." . $ID++;
222	my $port = "$NODE#$id";	314	my $port = "$NODE#$id";
223		315
224	if (@_) {	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) {
225	my $cb = shift;	405	my $cb = shift;
		406	delete $PORT_DATA{$portid};
226	$PORT{$id} = sub {	407	$PORT{$portid} = sub {
227	local $SELF = $port;	408	local $SELF = $port;
228	eval {	409	eval {
229	&$cb	410	&$cb
230	and kil $id;	411	and kil $port;
231	};	412	};
232	_self_die if $@;	413	_self_die if $@;
233	};	414	};
234	} else {	415	} else {
		416	my $self = $PORT_DATA{$portid} \|\|= do {
235	my $self = bless {	417	my $self = bless {
236	id => "$NODE#$id",	418	id => $port,
237	}, "AnyEvent::MP::Port";	419	}, "AnyEvent::MP::Port";
238		420
239	$PORT_DATA{$id} = $self;
240	$PORT{$id} = sub {	421	$PORT{$portid} = sub {
241	local $SELF = $port;	422	local $SELF = $port;
242		423
243	eval {	424	eval {
244	for (@{ $self->{rc0}{$_[0]} }) {	425	for (@{ $self->{rc0}{$_[0]} }) {
245	$_ && &{$_->[0]}	426	$_ && &{$_->[0]}
246	&& undef $_;	427	&& undef $_;
247	}	428	}
248		429
249	for (@{ $self->{rcv}{$_[0]} }) {	430	for (@{ $self->{rcv}{$_[0]} }) {
250	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]	431	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
251	&& &{$_->[0]}	432	&& &{$_->[0]}
252	&& undef $_;	433	&& undef $_;
253	}	434	}
254		435
255	for (@{ $self->{any} }) {	436	for (@{ $self->{any} }) {
256	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]	437	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
257	&& &{$_->[0]}	438	&& &{$_->[0]}
258	&& undef $_;	439	&& undef $_;
		440	}
259	}	441	};
		442	_self_die if $@;
260	};	443	};
261	_self_die if $@;	444
		445	$self
262	};	446	};
263	}
264		447
265	$port
266	}
267
268	=item reg $portid, $name
269
270	Registers the given port under the name C<$name>. If the name already
271	exists it is replaced.
272
273	A port can only be registered under one well known name.
274
275	A port automatically becomes unregistered when it is killed.
276
277	=cut
278
279	sub reg(@) {
280	my ($portid, $name) = @_;
281
282	$REG{$name} = $portid;
283	}
284
285	=item rcv $portid, $callback->(@msg)
286
287	Replaces the callback on the specified miniport (or newly created port
288	object, see C<port>). Full ports are configured with the following calls:
289
290	=item rcv $portid, tagstring => $callback->(@msg), ...
291
292	=item rcv $portid, $smartmatch => $callback->(@msg), ...
293
294	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
295
296	Register callbacks to be called on matching messages on the given full
297	port (or newly created port).
298
299	The callback has to return a true value when its work is done, after
300	which is will be removed, or a false value in which case it will stay
301	registered.
302
303	The global C<$SELF> (exported by this module) contains C<$portid> while
304	executing the callback.
305
306	Runtime errors wdurign callback execution will result in the port being
307	C<kil>ed.
308
309	If the match is an array reference, then it will be matched against the
310	first elements of the message, otherwise only the first element is being
311	matched.
312
313	Any element in the match that is specified as C<_any_> (a function
314	exported by this module) matches any single element of the message.
315
316	While not required, it is highly recommended that the first matching
317	element is a string identifying the message. The one-string-only match is
318	also the most efficient match (by far).
319
320	=cut
321
322	sub rcv($@) {
323	my $portid = shift;
324	my ($noderef, $port) = split /#/, $port, 2;
325
326	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
327	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";
328
329	my $self = $PORT_DATA{$port}
330	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
331
332	"AnyEvent::MP::Port" eq ref $self	448	"AnyEvent::MP::Port" eq ref $self
333	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";	449	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
334		450
335	while (@_) {	451	while (@_) {
336	my ($match, $cb) = splice @_, 0, 2;	452	my ($match, $cb) = splice @_, 0, 2;
337		453
338	if (!ref $match) {	454	if (!ref $match) {
339	push @{ $self->{rc0}{$match} }, [$cb];	455	push @{ $self->{rc0}{$match} }, [$cb];
340	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {	456	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
341	my ($type, @match) = @$match;	457	my ($type, @match) = @$match;
342	@match	458	@match
343	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]	459	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
344	: push @{ $self->{rc0}{$match->[0]} }, [$cb];	460	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
345	} else {	461	} else {
346	push @{ $self->{any} }, [$cb, $match];	462	push @{ $self->{any} }, [$cb, $match];
		463	}
347	}	464	}
348	}	465	}
349		466
350	$portid	467	$port
351	}	468	}
352		469
353	=item $closure = psub { BLOCK }	470	=item $closure = psub { BLOCK }
354		471
355	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	472	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
…		…
386	$res	503	$res
387	}	504	}
388	}	505	}
389	}	506	}
390		507
391	=item $guard = mon $portid, $cb->(@reason)	508	=item $guard = mon $port, $cb->(@reason)
392		509
393	=item $guard = mon $portid, $otherport	510	=item $guard = mon $port, $rcvport
394		511
		512	=item $guard = mon $port
		513
395	=item $guard = mon $portid, $otherport, @msg	514	=item $guard = mon $port, $rcvport, @msg
396		515
397	Monitor the given port and do something when the port is killed.	516	Monitor the given port and do something when the port is killed or
		517	messages to it were lost, and optionally return a guard that can be used
		518	to stop monitoring again.
398		519
		520	C<mon> effectively guarantees that, in the absence of hardware failures,
		521	that after starting the monitor, either all messages sent to the port
		522	will arrive, or the monitoring action will be invoked after possible
		523	message loss has been detected. No messages will be lost "in between"
		524	(after the first lost message no further messages will be received by the
		525	port). After the monitoring action was invoked, further messages might get
		526	delivered again.
		527
399	In the first form, the callback is simply called with any number	528	In the first form (callback), the callback is simply called with any
400	of C<@reason> elements (no @reason means that the port was deleted	529	number of C<@reason> elements (no @reason means that the port was deleted
401	"normally"). Note also that I<< the callback B<must> never die >>, so use	530	"normally"). Note also that I<< the callback B<must> never die >>, so use
402	C<eval> if unsure.	531	C<eval> if unsure.
403		532
404	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	533	In the second form (another port given), the other port (C<$rcvport>)
405	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
406	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.
407		537
		538	The third form (kill self) is the same as the second form, except that
		539	C<$rvport> defaults to C<$SELF>.
		540
408	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.
409		550
410	Example: call a given callback when C<$port> is killed.	551	Example: call a given callback when C<$port> is killed.
411		552
412	mon $port, sub { warn "port died because of <@_>\n" };	553	mon $port, sub { warn "port died because of <@_>\n" };
413		554
414	Example: kill ourselves when C<$port> is killed abnormally.	555	Example: kill ourselves when C<$port> is killed abnormally.
415		556
416	mon $port, $self;	557	mon $port;
417		558
418	Example: send us a restart message another C<$port> is killed.	559	Example: send us a restart message when another C<$port> is killed.
419		560
420	mon $port, $self => "restart";	561	mon $port, $self => "restart";
421		562
422	=cut	563	=cut
423		564
424	sub mon {	565	sub mon {
425	my ($noderef, $port) = split /#/, shift, 2;	566	my ($noderef, $port) = split /#/, shift, 2;
426		567
427	my $node = $NODE{$noderef} \|\| add_node $noderef;	568	my $node = $NODE{$noderef} \|\| add_node $noderef;
428		569
429	my $cb = shift;	570	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
430		571
431	unless (ref $cb) {	572	unless (ref $cb) {
432	if (@_) {	573	if (@_) {
433	# send a kill info message	574	# send a kill info message
434	my (@msg) = ($cb, @_);	575	my (@msg) = ($cb, @_);
…		…
465	=cut	606	=cut
466		607
467	sub mon_guard {	608	sub mon_guard {
468	my ($port, @refs) = @_;	609	my ($port, @refs) = @_;
469		610
		611	#TODO: mon-less form?
		612
470	mon $port, sub { 0 && @refs }	613	mon $port, sub { 0 && @refs }
471	}	614	}
472		615
473	=item lnk $port1, $port2
474
475	Link two ports. This is simply a shorthand for:
476
477	mon $port1, $port2;
478	mon $port2, $port1;
479
480	It means that if either one is killed abnormally, the other one gets
481	killed as well.
482
483	=item kil $portid[, @reason]	616	=item kil $port[, @reason]
484		617
485	Kill the specified port with the given C<@reason>.	618	Kill the specified port with the given C<@reason>.
486		619
487	If no C<@reason> is specified, then the port is killed "normally" (linked	620	If no C<@reason> is specified, then the port is killed "normally" (linked
488	ports will not be kileld, or even notified).	621	ports will not be kileld, or even notified).
…		…
494	will be reported as reason C<< die => $@ >>.	627	will be reported as reason C<< die => $@ >>.
495		628
496	Transport/communication errors are reported as C<< transport_error =>	629	Transport/communication errors are reported as C<< transport_error =>
497	$message >>.	630	$message >>.
498		631
499	=back
500
501	=head1 FUNCTIONS FOR NODES
502
503	=over 4
504
505	=item become_public $noderef
506
507	Tells the node to become a public node, i.e. reachable from other nodes.
508
509	The first argument is the (unresolved) node reference of the local node
510	(if missing then the empty string is used).
511
512	It is quite common to not specify anything, in which case the local node
513	tries to listen on the default port, or to only specify a port number, in
514	which case AnyEvent::MP tries to guess the local addresses.
515
516	=cut	632	=cut
		633
		634	=item $port = spawn $node, $initfunc[, @initdata]
		635
		636	Creates a port on the node C<$node> (which can also be a port ID, in which
		637	case it's the node where that port resides).
		638
		639	The port ID of the newly created port is return immediately, and it is
		640	permissible to immediately start sending messages or monitor the port.
		641
		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 {
		672	...
		673	};
		674	}
		675
		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 $@;
		687	}
		688
		689	sub spawn(@) {
		690	my ($noderef, undef) = split /#/, shift, 2;
		691
		692	my $id = "$RUNIQ." . $ID++;
		693
		694	$_[0] =~ /::/
		695	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		696
		697	($NODE{$noderef} \|\| add_node $noderef)
		698	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
		699
		700	"$noderef#$id"
		701	}
517		702
518	=back	703	=back
519		704
520	=head1 NODE MESSAGES	705	=head1 NODE MESSAGES
521		706
…		…
563		748
564	=back	749	=back
565		750
566	=head1 AnyEvent::MP vs. Distributed Erlang	751	=head1 AnyEvent::MP vs. Distributed Erlang
567		752
568	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
569	== 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
570	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
571	sample:	756	sample:
572		757
573	http://www.erlang.se/doc/programming_rules.shtml	758	http://www.Erlang.se/doc/programming_rules.shtml
574	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
575	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
576	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
577		762
578	Despite the similarities, there are also some important differences:	763	Despite the similarities, there are also some important differences:
579		764
580	=over 4	765	=over 4
581		766
…		…
592		777
593	Erlang uses processes that selctively receive messages, and therefore	778	Erlang uses processes that selctively receive messages, and therefore
594	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
595	purpose.	780	purpose.
596		781
597	(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).
598		783
599	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	784	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
600		785
601	Sending messages in erlang is synchronous and blocks the process. AEMP	786	Sending messages in Erlang is synchronous and blocks the process. AEMP
602	sends are immediate, connection establishment is handled in the	787	sends are immediate, connection establishment is handled in the
603	background.	788	background.
604		789
605	=item * Erlang can silently lose messages, AEMP cannot.	790	=item * Erlang can silently lose messages, AEMP cannot.
606		791
…		…
609	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).
610		795
611	AEMP guarantees correct ordering, and the guarantee that there are no	796	AEMP guarantees correct ordering, and the guarantee that there are no
612	holes in the message sequence.	797	holes in the message sequence.
613		798
614	=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
615	alive.	800	alive.
616		801
617	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
618	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
619	still alive - and can receive messages.	804	still alive - and can receive messages.
620		805
621	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
622	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
623	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.
624		809
625	=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.
626		811
627	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
628	ID known to other nodes for a completely different process, causing	813	ID known to other nodes for a completely different process, causing
629	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.
630		815
631	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
632	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.
…		…
638	securely authenticate nodes.	823	securely authenticate nodes.
639		824
640	=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
641	communications.	826	communications.
642		827
643	The AEMP protocol, unlike the erlang protocol, supports both	828	The AEMP protocol, unlike the Erlang protocol, supports both
644	language-independent text-only protocols (good for debugging) and binary,	829	language-independent text-only protocols (good for debugging) and binary,
645	language-specific serialisers (e.g. Storable).	830	language-specific serialisers (e.g. Storable).
646		831
647	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
648	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
649	protocol simple.	834	protocol simple.
650		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
651	=back	858	=back
652		859
653	=head1 SEE ALSO	860	=head1 SEE ALSO
654		861
655	L<AnyEvent>.	862	L<AnyEvent>.

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Revision 1.45 by root, Thu Aug 13 01:16:24 2009 UTC