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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.30 by root, Tue Aug 4 23:35:51 2009 UTC vs.
Revision 1.39 by root, Fri Aug 7 23:21:48 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
		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
27		42
28	=head1 DESCRIPTION	43	=head1 DESCRIPTION
29		44
30	This module (-family) implements a simple message passing framework.	45	This module (-family) implements a simple message passing framework.
31		46
…		…
103	use base "Exporter";	118	use base "Exporter";
104		119
105	our $VERSION = '0.1';	120	our $VERSION = '0.1';
106	our @EXPORT = qw(	121	our @EXPORT = qw(
107	NODE $NODE *SELF node_of _any_	122	NODE $NODE *SELF node_of _any_
108	resolve_node	123	resolve_node initialise_node
109	become_slave become_public
110	snd rcv mon kil reg psub	124	snd rcv mon kil reg psub spawn
111	port	125	port
112	);	126	);
113		127
114	our $SELF;	128	our $SELF;
115		129
…		…
124	The C<NODE> function returns, and the C<$NODE> variable contains	138	The C<NODE> function returns, and the C<$NODE> variable contains
125	the noderef of the local node. The value is initialised by a call	139	the noderef of the local node. The value is initialised by a call
126	to C<become_public> or C<become_slave>, after which all local port	140	to C<become_public> or C<become_slave>, after which all local port
127	identifiers become invalid.	141	identifiers become invalid.
128		142
129	=item $noderef = node_of $portid	143	=item $noderef = node_of $port
130		144
131	Extracts and returns the noderef from a portid or a noderef.	145	Extracts and returns the noderef from a portid or a noderef.
		146
		147	=item initialise_node $noderef, $seednode, $seednode...
		148
		149	=item initialise_node "slave/", $master, $master...
		150
		151	Before a node can talk to other nodes on the network it has to initialise
		152	itself - the minimum a node needs to know is it's own name, and optionally
		153	it should know the noderefs of some other nodes in the network.
		154
		155	This function initialises a node - it must be called exactly once (or
		156	never) before calling other AnyEvent::MP functions.
		157
		158	All arguments are noderefs, which can be either resolved or unresolved.
		159
		160	There are two types of networked nodes, public nodes and slave nodes:
		161
		162	=over 4
		163
		164	=item public nodes
		165
		166	For public nodes, C<$noderef> must either be a (possibly unresolved)
		167	noderef, in which case it will be resolved, or C<undef> (or missing), in
		168	which case the noderef will be guessed.
		169
		170	Afterwards, the node will bind itself on all endpoints and try to connect
		171	to all additional C<$seednodes> that are specified. Seednodes are optional
		172	and can be used to quickly bootstrap the node into an existing network.
		173
		174	=item slave nodes
		175
		176	When the C<$noderef> is the special string C<slave/>, then the node will
		177	become a slave node. Slave nodes cannot be contacted from outside and will
		178	route most of their traffic to the master node that they attach to.
		179
		180	At least one additional noderef is required: The node will try to connect
		181	to all of them and will become a slave attached to the first node it can
		182	successfully connect to.
		183
		184	=back
		185
		186	This function will block until all nodes have been resolved and, for slave
		187	nodes, until it has successfully established a connection to a master
		188	server.
		189
		190	Example: become a public node listening on the default node.
		191
		192	initialise_node;
		193
		194	Example: become a public node, and try to contact some well-known master
		195	servers to become part of the network.
		196
		197	initialise_node undef, "master1", "master2";
		198
		199	Example: become a public node listening on port C<4041>.
		200
		201	initialise_node 4041;
		202
		203	Example: become a public node, only visible on localhost port 4044.
		204
		205	initialise_node "locahost:4044";
		206
		207	Example: become a slave node to any of the specified master servers.
		208
		209	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
132		210
133	=item $cv = resolve_node $noderef	211	=item $cv = resolve_node $noderef
134		212
135	Takes an unresolved node reference that may contain hostnames and	213	Takes an unresolved node reference that may contain hostnames and
136	abbreviated IDs, resolves all of them and returns a resolved node	214	abbreviated IDs, resolves all of them and returns a resolved node
…		…
168		246
169	Due to some quirks in how perl exports variables, it is impossible to	247	Due to some quirks in how perl exports variables, it is impossible to
170	just export C<$SELF>, all the symbols called C<SELF> are exported by this	248	just export C<$SELF>, all the symbols called C<SELF> are exported by this
171	module, but only C<$SELF> is currently used.	249	module, but only C<$SELF> is currently used.
172		250
173	=item snd $portid, type => @data	251	=item snd $port, type => @data
174		252
175	=item snd $portid, @msg	253	=item snd $port, @msg
176		254
177	Send the given message to the given port ID, which can identify either	255	Send the given message to the given port ID, which can identify either
178	a local or a remote port, and can be either a string or soemthignt hat	256	a local or a remote port, and can be either a string or soemthignt hat
179	stringifies a sa port ID (such as a port object :).	257	stringifies a sa port ID (such as a port object :).
180		258
…		…
190	JSON is used, then only strings, numbers and arrays and hashes consisting	268	JSON is used, then only strings, numbers and arrays and hashes consisting
191	of those are allowed (no objects). When Storable is used, then anything	269	of those are allowed (no objects). When Storable is used, then anything
192	that Storable can serialise and deserialise is allowed, and for the local	270	that Storable can serialise and deserialise is allowed, and for the local
193	node, anything can be passed.	271	node, anything can be passed.
194		272
195	=item kil $portid[, @reason]
196
197	Kill the specified port with the given C<@reason>.
198
199	If no C<@reason> is specified, then the port is killed "normally" (linked
200	ports will not be kileld, or even notified).
201
202	Otherwise, linked ports get killed with the same reason (second form of
203	C<mon>, see below).
204
205	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
206	will be reported as reason C<< die => $@ >>.
207
208	Transport/communication errors are reported as C<< transport_error =>
209	$message >>.
210
211	=item $guard = mon $portid, $cb->(@reason)
212
213	=item $guard = mon $portid, $otherport
214
215	=item $guard = mon $portid, $otherport, @msg
216
217	Monitor the given port and do something when the port is killed.
218
219	In the first form, the callback is simply called with any number
220	of C<@reason> elements (no @reason means that the port was deleted
221	"normally"). Note also that I<< the callback B<must> never die >>, so use
222	C<eval> if unsure.
223
224	In the second form, the other port will be C<kil>'ed with C<@reason>, iff
225	a @reason was specified, i.e. on "normal" kils nothing happens, while
226	under all other conditions, the other port is killed with the same reason.
227
228	In the last form, a message of the form C<@msg, @reason> will be C<snd>.
229
230	Example: call a given callback when C<$port> is killed.
231
232	mon $port, sub { warn "port died because of <@_>\n" };
233
234	Example: kill ourselves when C<$port> is killed abnormally.
235
236	mon $port, $self;
237
238	Example: send us a restart message another C<$port> is killed.
239
240	mon $port, $self => "restart";
241
242	=cut
243
244	sub mon {
245	my ($noderef, $port) = split /#/, shift, 2;
246
247	my $node = $NODE{$noderef} \|\| add_node $noderef;
248
249	my $cb = shift;
250
251	unless (ref $cb) {
252	if (@_) {
253	# send a kill info message
254	my (@msg) = ($cb, @_);
255	$cb = sub { snd @msg, @_ };
256	} else {
257	# simply kill other port
258	my $port = $cb;
259	$cb = sub { kil $port, @_ if @_ };
260	}
261	}
262
263	$node->monitor ($port, $cb);
264
265	defined wantarray
266	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
267	}
268
269	=item $guard = mon_guard $port, $ref, $ref...
270
271	Monitors the given C<$port> and keeps the passed references. When the port
272	is killed, the references will be freed.
273
274	Optionally returns a guard that will stop the monitoring.
275
276	This function is useful when you create e.g. timers or other watchers and
277	want to free them when the port gets killed:
278
279	$port->rcv (start => sub {
280	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
281	undef $timer if 0.9 < rand;
282	});
283	});
284
285	=cut
286
287	sub mon_guard {
288	my ($port, @refs) = @_;
289
290	mon $port, sub { 0 && @refs }
291	}
292
293	=item lnk $port1, $port2
294
295	Link two ports. This is simply a shorthand for:
296
297	mon $port1, $port2;
298	mon $port2, $port1;
299
300	It means that if either one is killed abnormally, the other one gets
301	killed as well.
302
303	=item $local_port = port	273	=item $local_port = port
304		274
305	Create a new local port object that supports message matching.	275	Create a new local port object that can be used either as a pattern
		276	matching port ("full port") or a single-callback port ("miniport"),
		277	depending on how C<rcv> callbacks are bound to the object.
306		278
307	=item $portid = port { my @msg = @_; $finished }	279	=item $port = port { my @msg = @_; $finished }
308		280
309	Creates a "mini port", that is, a very lightweight port without any	281	Creates a "miniport", that is, a very lightweight port without any pattern
310	pattern matching behind it, and returns its ID.	282	matching behind it, and returns its ID. Semantically the same as creating
		283	a port and calling C<rcv $port, $callback> on it.
311		284
312	The block will be called for every message received on the port. When the	285	The block will be called for every message received on the port. When the
313	callback returns a true value its job is considered "done" and the port	286	callback returns a true value its job is considered "done" and the port
314	will be destroyed. Otherwise it will stay alive.	287	will be destroyed. Otherwise it will stay alive.
315		288
316	The message will be passed as-is, no extra argument (i.e. no port id) will	289	The message will be passed as-is, no extra argument (i.e. no port id) will
317	be passed to the callback.	290	be passed to the callback.
318		291
319	If you need the local port id in the callback, this works nicely:	292	If you need the local port id in the callback, this works nicely:
320		293
321	my $port; $port = miniport {	294	my $port; $port = port {
322	snd $otherport, reply => $port;	295	snd $otherport, reply => $port;
323	};	296	};
324		297
325	=cut	298	=cut
		299
		300	sub rcv($@);
326		301
327	sub port(;&) {	302	sub port(;&) {
328	my $id = "$UNIQ." . $ID++;	303	my $id = "$UNIQ." . $ID++;
329	my $port = "$NODE#$id";	304	my $port = "$NODE#$id";
330		305
331	if (@_) {	306	if (@_) {
		307	rcv $port, shift;
		308	} else {
		309	$PORT{$id} = sub { }; # nop
		310	}
		311
		312	$port
		313	}
		314
		315	=item reg $port, $name
		316
		317	=item reg $name
		318
		319	Registers the given port (or C<$SELF><<< if missing) under the name
		320	C<$name>. If the name already exists it is replaced.
		321
		322	A port can only be registered under one well known name.
		323
		324	A port automatically becomes unregistered when it is killed.
		325
		326	=cut
		327
		328	sub reg(@) {
		329	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
		330
		331	$REG{$_[0]} = $port;
		332	}
		333
		334	=item rcv $port, $callback->(@msg)
		335
		336	Replaces the callback on the specified miniport (after converting it to
		337	one if required).
		338
		339	=item rcv $port, tagstring => $callback->(@msg), ...
		340
		341	=item rcv $port, $smartmatch => $callback->(@msg), ...
		342
		343	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
		344
		345	Register callbacks to be called on matching messages on the given full
		346	port (after converting it to one if required) and return the port.
		347
		348	The callback has to return a true value when its work is done, after
		349	which is will be removed, or a false value in which case it will stay
		350	registered.
		351
		352	The global C<$SELF> (exported by this module) contains C<$port> while
		353	executing the callback.
		354
		355	Runtime errors during callback execution will result in the port being
		356	C<kil>ed.
		357
		358	If the match is an array reference, then it will be matched against the
		359	first elements of the message, otherwise only the first element is being
		360	matched.
		361
		362	Any element in the match that is specified as C<_any_> (a function
		363	exported by this module) matches any single element of the message.
		364
		365	While not required, it is highly recommended that the first matching
		366	element is a string identifying the message. The one-string-only match is
		367	also the most efficient match (by far).
		368
		369	Example: create a port and bind receivers on it in one go.
		370
		371	my $port = rcv port,
		372	msg1 => sub { ...; 0 },
		373	msg2 => sub { ...; 0 },
		374	;
		375
		376	Example: create a port, bind receivers and send it in a message elsewhere
		377	in one go:
		378
		379	snd $otherport, reply =>
		380	rcv port,
		381	msg1 => sub { ...; 0 },
		382	...
		383	;
		384
		385	=cut
		386
		387	sub rcv($@) {
		388	my $port = shift;
		389	my ($noderef, $portid) = split /#/, $port, 2;
		390
		391	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
		392	or Carp::croak "$port: rcv can only be called on local ports, caught";
		393
		394	if (@_ == 1) {
332	my $cb = shift;	395	my $cb = shift;
		396	delete $PORT_DATA{$portid};
333	$PORT{$id} = sub {	397	$PORT{$portid} = sub {
334	local $SELF = $port;	398	local $SELF = $port;
335	eval {	399	eval {
336	&$cb	400	&$cb
337	and kil $id;	401	and kil $port;
338	};	402	};
339	_self_die if $@;	403	_self_die if $@;
340	};	404	};
341	} else {	405	} else {
		406	my $self = $PORT_DATA{$portid} \|\|= do {
342	my $self = bless {	407	my $self = bless {
343	id => "$NODE#$id",	408	id => $port,
344	}, "AnyEvent::MP::Port";	409	}, "AnyEvent::MP::Port";
345		410
346	$PORT_DATA{$id} = $self;
347	$PORT{$id} = sub {	411	$PORT{$portid} = sub {
348	local $SELF = $port;	412	local $SELF = $port;
349		413
350	eval {	414	eval {
351	for (@{ $self->{rc0}{$_[0]} }) {	415	for (@{ $self->{rc0}{$_[0]} }) {
352	$_ && &{$_->[0]}	416	$_ && &{$_->[0]}
353	&& undef $_;	417	&& undef $_;
354	}	418	}
355		419
356	for (@{ $self->{rcv}{$_[0]} }) {	420	for (@{ $self->{rcv}{$_[0]} }) {
357	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]	421	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
358	&& &{$_->[0]}	422	&& &{$_->[0]}
359	&& undef $_;	423	&& undef $_;
360	}	424	}
361		425
362	for (@{ $self->{any} }) {	426	for (@{ $self->{any} }) {
363	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]	427	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
364	&& &{$_->[0]}	428	&& &{$_->[0]}
365	&& undef $_;	429	&& undef $_;
		430	}
366	}	431	};
		432	_self_die if $@;
367	};	433	};
368	_self_die if $@;	434
		435	$self
369	};	436	};
370	}
371		437
372	$port
373	}
374
375	=item reg $portid, $name
376
377	Registers the given port under the name C<$name>. If the name already
378	exists it is replaced.
379
380	A port can only be registered under one well known name.
381
382	A port automatically becomes unregistered when it is killed.
383
384	=cut
385
386	sub reg(@) {
387	my ($portid, $name) = @_;
388
389	$REG{$name} = $portid;
390	}
391
392	=item rcv $portid, tagstring => $callback->(@msg), ...
393
394	=item rcv $portid, $smartmatch => $callback->(@msg), ...
395
396	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
397
398	Register callbacks to be called on matching messages on the given port.
399
400	The callback has to return a true value when its work is done, after
401	which is will be removed, or a false value in which case it will stay
402	registered.
403
404	The global C<$SELF> (exported by this module) contains C<$portid> while
405	executing the callback.
406
407	Runtime errors wdurign callback execution will result in the port being
408	C<kil>ed.
409
410	If the match is an array reference, then it will be matched against the
411	first elements of the message, otherwise only the first element is being
412	matched.
413
414	Any element in the match that is specified as C<_any_> (a function
415	exported by this module) matches any single element of the message.
416
417	While not required, it is highly recommended that the first matching
418	element is a string identifying the message. The one-string-only match is
419	also the most efficient match (by far).
420
421	=cut
422
423	sub rcv($@) {
424	my ($noderef, $port) = split /#/, shift, 2;
425
426	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
427	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";
428
429	my $self = $PORT_DATA{$port}
430	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
431
432	"AnyEvent::MP::Port" eq ref $self	438	"AnyEvent::MP::Port" eq ref $self
433	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";	439	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
434		440
435	while (@_) {	441	while (@_) {
436	my ($match, $cb) = splice @_, 0, 2;	442	my ($match, $cb) = splice @_, 0, 2;
437		443
438	if (!ref $match) {	444	if (!ref $match) {
439	push @{ $self->{rc0}{$match} }, [$cb];	445	push @{ $self->{rc0}{$match} }, [$cb];
440	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {	446	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
441	my ($type, @match) = @$match;	447	my ($type, @match) = @$match;
442	@match	448	@match
443	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]	449	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
444	: push @{ $self->{rc0}{$match->[0]} }, [$cb];	450	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
445	} else {	451	} else {
446	push @{ $self->{any} }, [$cb, $match];	452	push @{ $self->{any} }, [$cb, $match];
		453	}
447	}	454	}
448	}	455	}
		456
		457	$port
449	}	458	}
450		459
451	=item $closure = psub { BLOCK }	460	=item $closure = psub { BLOCK }
452		461
453	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	462	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
…		…
484	$res	493	$res
485	}	494	}
486	}	495	}
487	}	496	}
488		497
489	=back	498	=item $guard = mon $port, $cb->(@reason)
490		499
491	=head1 FUNCTIONS FOR NODES	500	=item $guard = mon $port, $rcvport
492		501
493	=over 4	502	=item $guard = mon $port
494		503
495	=item become_public $noderef	504	=item $guard = mon $port, $rcvport, @msg
496		505
497	Tells the node to become a public node, i.e. reachable from other nodes.	506	Monitor the given port and do something when the port is killed, and
		507	optionally return a guard that can be used to stop monitoring again.
498		508
499	The first argument is the (unresolved) node reference of the local node	509	In the first form (callback), the callback is simply called with any
500	(if missing then the empty string is used).	510	number of C<@reason> elements (no @reason means that the port was deleted
		511	"normally"). Note also that I<< the callback B<must> never die >>, so use
		512	C<eval> if unsure.
501		513
502	It is quite common to not specify anything, in which case the local node	514	In the second form (another port given), the other port (C<$rcvport)
503	tries to listen on the default port, or to only specify a port number, in	515	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
504	which case AnyEvent::MP tries to guess the local addresses.	516	"normal" kils nothing happens, while under all other conditions, the other
		517	port is killed with the same reason.
505		518
		519	The third form (kill self) is the same as the second form, except that
		520	C<$rvport> defaults to C<$SELF>.
		521
		522	In the last form (message), a message of the form C<@msg, @reason> will be
		523	C<snd>.
		524
		525	As a rule of thumb, monitoring requests should always monitor a port from
		526	a local port (or callback). The reason is that kill messages might get
		527	lost, just like any other message. Another less obvious reason is that
		528	even monitoring requests can get lost (for exmaple, when the connection
		529	to the other node goes down permanently). When monitoring a port locally
		530	these problems do not exist.
		531
		532	Example: call a given callback when C<$port> is killed.
		533
		534	mon $port, sub { warn "port died because of <@_>\n" };
		535
		536	Example: kill ourselves when C<$port> is killed abnormally.
		537
		538	mon $port;
		539
		540	Example: send us a restart message when another C<$port> is killed.
		541
		542	mon $port, $self => "restart";
		543
506	=cut	544	=cut
		545
		546	sub mon {
		547	my ($noderef, $port) = split /#/, shift, 2;
		548
		549	my $node = $NODE{$noderef} \|\| add_node $noderef;
		550
		551	my $cb = @_ ? $_[0] : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
		552
		553	unless (ref $cb) {
		554	if (@_) {
		555	# send a kill info message
		556	my (@msg) = @_;
		557	$cb = sub { snd @msg, @_ };
		558	} else {
		559	# simply kill other port
		560	my $port = $cb;
		561	$cb = sub { kil $port, @_ if @_ };
		562	}
		563	}
		564
		565	$node->monitor ($port, $cb);
		566
		567	defined wantarray
		568	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
		569	}
		570
		571	=item $guard = mon_guard $port, $ref, $ref...
		572
		573	Monitors the given C<$port> and keeps the passed references. When the port
		574	is killed, the references will be freed.
		575
		576	Optionally returns a guard that will stop the monitoring.
		577
		578	This function is useful when you create e.g. timers or other watchers and
		579	want to free them when the port gets killed:
		580
		581	$port->rcv (start => sub {
		582	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
		583	undef $timer if 0.9 < rand;
		584	});
		585	});
		586
		587	=cut
		588
		589	sub mon_guard {
		590	my ($port, @refs) = @_;
		591
		592	#TODO: mon-less form?
		593
		594	mon $port, sub { 0 && @refs }
		595	}
		596
		597	=item kil $port[, @reason]
		598
		599	Kill the specified port with the given C<@reason>.
		600
		601	If no C<@reason> is specified, then the port is killed "normally" (linked
		602	ports will not be kileld, or even notified).
		603
		604	Otherwise, linked ports get killed with the same reason (second form of
		605	C<mon>, see below).
		606
		607	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		608	will be reported as reason C<< die => $@ >>.
		609
		610	Transport/communication errors are reported as C<< transport_error =>
		611	$message >>.
		612
		613	=cut
		614
		615	=item $port = spawn $node, $initfunc[, @initdata]
		616
		617	Creates a port on the node C<$node> (which can also be a port ID, in which
		618	case it's the node where that port resides).
		619
		620	The port ID of the newly created port is return immediately, and it is
		621	permissible to immediately start sending messages or monitor the port.
		622
		623	After the port has been created, the init function is
		624	called. This function must be a fully-qualified function name
		625	(e.g. C<MyApp::Chat::Server::init>).
		626
		627	If the function doesn't exist, then the node tries to C<require>
		628	the package, then the package above the package and so on (e.g.
		629	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		630	exists or it runs out of package names.
		631
		632	The init function is then called with the newly-created port as context
		633	object (C<$SELF>) and the C<@initdata> values as arguments.
		634
		635	A common idiom is to pass your own port, monitor the spawned port, and
		636	in the init function, monitor the original port. This two-way monitoring
		637	ensures that both ports get cleaned up when there is a problem.
		638
		639	Example: spawn a chat server port on C<$othernode>.
		640
		641	# this node, executed from within a port context:
		642	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		643	mon $server;
		644
		645	# init function on C<$othernode>
		646	sub connect {
		647	my ($srcport) = @_;
		648
		649	mon $srcport;
		650
		651	rcv $SELF, sub {
		652	...
		653	};
		654	}
		655
		656	=cut
		657
		658	sub _spawn {
		659	my $port = shift;
		660	my $init = shift;
		661
		662	local $SELF = "$NODE#$port";
		663	eval {
		664	&{ load_func $init }
		665	};
		666	_self_die if $@;
		667	}
		668
		669	sub spawn(@) {
		670	my ($noderef, undef) = split /#/, shift, 2;
		671
		672	my $id = "$RUNIQ." . $ID++;
		673
		674	$_[0] =~ /::/
		675	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		676
		677	($NODE{$noderef} \|\| add_node $noderef)
		678	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
		679
		680	"$noderef#$id"
		681	}
507		682
508	=back	683	=back
509		684
510	=head1 NODE MESSAGES	685	=head1 NODE MESSAGES
511		686
…		…
553		728
554	=back	729	=back
555		730
556	=head1 AnyEvent::MP vs. Distributed Erlang	731	=head1 AnyEvent::MP vs. Distributed Erlang
557		732
558	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node	733	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
559	== aemp node, erlang process == aemp port), so many of the documents and	734	== aemp node, Erlang process == aemp port), so many of the documents and
560	programming techniques employed by erlang apply to AnyEvent::MP. Here is a	735	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
561	sample:	736	sample:
562		737
563	http://www.erlang.se/doc/programming_rules.shtml	738	http://www.Erlang.se/doc/programming_rules.shtml
564	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	739	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
565	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6	740	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
566	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5	741	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
567		742
568	Despite the similarities, there are also some important differences:	743	Despite the similarities, there are also some important differences:
569		744
570	=over 4	745	=over 4
571		746
…		…
582		757
583	Erlang uses processes that selctively receive messages, and therefore	758	Erlang uses processes that selctively receive messages, and therefore
584	needs a queue. AEMP is event based, queuing messages would serve no useful	759	needs a queue. AEMP is event based, queuing messages would serve no useful
585	purpose.	760	purpose.
586		761
587	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	762	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
588		763
589	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	764	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
590		765
591	Sending messages in erlang is synchronous and blocks the process. AEMP	766	Sending messages in Erlang is synchronous and blocks the process. AEMP
592	sends are immediate, connection establishment is handled in the	767	sends are immediate, connection establishment is handled in the
593	background.	768	background.
594		769
595	=item * Erlang can silently lose messages, AEMP cannot.	770	=item * Erlang can silently lose messages, AEMP cannot.
596		771
…		…
599	and c, and the other side only receives messages a and c).	774	and c, and the other side only receives messages a and c).
600		775
601	AEMP guarantees correct ordering, and the guarantee that there are no	776	AEMP guarantees correct ordering, and the guarantee that there are no
602	holes in the message sequence.	777	holes in the message sequence.
603		778
604	=item * In erlang, processes can be declared dead and later be found to be	779	=item * In Erlang, processes can be declared dead and later be found to be
605	alive.	780	alive.
606		781
607	In erlang it can happen that a monitored process is declared dead and	782	In Erlang it can happen that a monitored process is declared dead and
608	linked processes get killed, but later it turns out that the process is	783	linked processes get killed, but later it turns out that the process is
609	still alive - and can receive messages.	784	still alive - and can receive messages.
610		785
611	In AEMP, when port monitoring detects a port as dead, then that port will	786	In AEMP, when port monitoring detects a port as dead, then that port will
612	eventually be killed - it cannot happen that a node detects a port as dead	787	eventually be killed - it cannot happen that a node detects a port as dead
613	and then later sends messages to it, finding it is still alive.	788	and then later sends messages to it, finding it is still alive.
614		789
615	=item * Erlang can send messages to the wrong port, AEMP does not.	790	=item * Erlang can send messages to the wrong port, AEMP does not.
616		791
617	In erlang it is quite possible that a node that restarts reuses a process	792	In Erlang it is quite possible that a node that restarts reuses a process
618	ID known to other nodes for a completely different process, causing	793	ID known to other nodes for a completely different process, causing
619	messages destined for that process to end up in an unrelated process.	794	messages destined for that process to end up in an unrelated process.
620		795
621	AEMP never reuses port IDs, so old messages or old port IDs floating	796	AEMP never reuses port IDs, so old messages or old port IDs floating
622	around in the network will not be sent to an unrelated port.	797	around in the network will not be sent to an unrelated port.
…		…
628	securely authenticate nodes.	803	securely authenticate nodes.
629		804
630	=item * The AEMP protocol is optimised for both text-based and binary	805	=item * The AEMP protocol is optimised for both text-based and binary
631	communications.	806	communications.
632		807
633	The AEMP protocol, unlike the erlang protocol, supports both	808	The AEMP protocol, unlike the Erlang protocol, supports both
634	language-independent text-only protocols (good for debugging) and binary,	809	language-independent text-only protocols (good for debugging) and binary,
635	language-specific serialisers (e.g. Storable).	810	language-specific serialisers (e.g. Storable).
636		811
637	It has also been carefully designed to be implementable in other languages	812	It has also been carefully designed to be implementable in other languages
638	with a minimum of work while gracefully degrading fucntionality to make the	813	with a minimum of work while gracefully degrading fucntionality to make the
639	protocol simple.	814	protocol simple.
640		815
		816	=item * AEMP has more flexible monitoring options than Erlang.
		817
		818	In Erlang, you can chose to receive I<all> exit signals as messages
		819	or I<none>, there is no in-between, so monitoring single processes is
		820	difficult to implement. Monitoring in AEMP is more flexible than in
		821	Erlang, as one can choose between automatic kill, exit message or callback
		822	on a per-process basis.
		823
		824	=item * Erlang tries to hide remote/local connections, AEMP does not.
		825
		826	Monitoring in Erlang is not an indicator of process death/crashes,
		827	as linking is (except linking is unreliable in Erlang).
		828
		829	In AEMP, you don't "look up" registered port names or send to named ports
		830	that might or might not be persistent. Instead, you normally spawn a port
		831	on the remote node. The init function monitors the you, and you monitor
		832	the remote port. Since both monitors are local to the node, they are much
		833	more reliable.
		834
		835	This also saves round-trips and avoids sending messages to the wrong port
		836	(hard to do in Erlang).
		837
641	=back	838	=back
642		839
643	=head1 SEE ALSO	840	=head1 SEE ALSO
644		841
645	L<AnyEvent>.	842	L<AnyEvent>.

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Revision 1.39 by root, Fri Aug 7 23:21:48 2009 UTC