[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 1.38 by root, Fri Aug 7 22:55:18 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
…		…
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 initialise_node	123	resolve_node initialise_node
109	snd rcv mon kil reg psub	124	snd rcv mon kil reg psub spawn
110	port	125	port
111	);	126	);
112		127
113	our $SELF;	128	our $SELF;
114		129
…		…
123	The C<NODE> function returns, and the C<$NODE> variable contains	138	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	139	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	140	to C<become_public> or C<become_slave>, after which all local port
126	identifiers become invalid.	141	identifiers become invalid.
127		142
128	=item $noderef = node_of $portid	143	=item $noderef = node_of $port
129		144
130	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";
131		210
132	=item $cv = resolve_node $noderef	211	=item $cv = resolve_node $noderef
133		212
134	Takes an unresolved node reference that may contain hostnames and	213	Takes an unresolved node reference that may contain hostnames and
135	abbreviated IDs, resolves all of them and returns a resolved node	214	abbreviated IDs, resolves all of them and returns a resolved node
…		…
167		246
168	Due to some quirks in how perl exports variables, it is impossible to	247	Due to some quirks in how perl exports variables, it is impossible to
169	just export C<$SELF>, all the symbols called C<SELF> are exported by this	248	just export C<$SELF>, all the symbols called C<SELF> are exported by this
170	module, but only C<$SELF> is currently used.	249	module, but only C<$SELF> is currently used.
171		250
172	=item snd $portid, type => @data	251	=item snd $port, type => @data
173		252
174	=item snd $portid, @msg	253	=item snd $port, @msg
175		254
176	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
177	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
178	stringifies a sa port ID (such as a port object :).	257	stringifies a sa port ID (such as a port object :).
179		258
…		…
189	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
190	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
191	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
192	node, anything can be passed.	271	node, anything can be passed.
193		272
194	=item kil $portid[, @reason]
195
196	Kill the specified port with the given C<@reason>.
197
198	If no C<@reason> is specified, then the port is killed "normally" (linked
199	ports will not be kileld, or even notified).
200
201	Otherwise, linked ports get killed with the same reason (second form of
202	C<mon>, see below).
203
204	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
205	will be reported as reason C<< die => $@ >>.
206
207	Transport/communication errors are reported as C<< transport_error =>
208	$message >>.
209
210	=item $guard = mon $portid, $cb->(@reason)
211
212	=item $guard = mon $portid, $otherport
213
214	=item $guard = mon $portid, $otherport, @msg
215
216	Monitor the given port and do something when the port is killed.
217
218	In the first form, the callback is simply called with any number
219	of C<@reason> elements (no @reason means that the port was deleted
220	"normally"). Note also that I<< the callback B<must> never die >>, so use
221	C<eval> if unsure.
222
223	In the second form, the other port will be C<kil>'ed with C<@reason>, iff
224	a @reason was specified, i.e. on "normal" kils nothing happens, while
225	under all other conditions, the other port is killed with the same reason.
226
227	In the last form, a message of the form C<@msg, @reason> will be C<snd>.
228
229	Example: call a given callback when C<$port> is killed.
230
231	mon $port, sub { warn "port died because of <@_>\n" };
232
233	Example: kill ourselves when C<$port> is killed abnormally.
234
235	mon $port, $self;
236
237	Example: send us a restart message another C<$port> is killed.
238
239	mon $port, $self => "restart";
240
241	=cut
242
243	sub mon {
244	my ($noderef, $port) = split /#/, shift, 2;
245
246	my $node = $NODE{$noderef} \|\| add_node $noderef;
247
248	my $cb = shift;
249
250	unless (ref $cb) {
251	if (@_) {
252	# send a kill info message
253	my (@msg) = ($cb, @_);
254	$cb = sub { snd @msg, @_ };
255	} else {
256	# simply kill other port
257	my $port = $cb;
258	$cb = sub { kil $port, @_ if @_ };
259	}
260	}
261
262	$node->monitor ($port, $cb);
263
264	defined wantarray
265	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
266	}
267
268	=item $guard = mon_guard $port, $ref, $ref...
269
270	Monitors the given C<$port> and keeps the passed references. When the port
271	is killed, the references will be freed.
272
273	Optionally returns a guard that will stop the monitoring.
274
275	This function is useful when you create e.g. timers or other watchers and
276	want to free them when the port gets killed:
277
278	$port->rcv (start => sub {
279	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
280	undef $timer if 0.9 < rand;
281	});
282	});
283
284	=cut
285
286	sub mon_guard {
287	my ($port, @refs) = @_;
288
289	mon $port, sub { 0 && @refs }
290	}
291
292	=item lnk $port1, $port2
293
294	Link two ports. This is simply a shorthand for:
295
296	mon $port1, $port2;
297	mon $port2, $port1;
298
299	It means that if either one is killed abnormally, the other one gets
300	killed as well.
301
302	=item $local_port = port	273	=item $local_port = port
303		274
304	Create a new local port object that can be used either as a pattern	275	Create a new local port object that can be used either as a pattern
305	matching port ("full port") or a single-callback port ("miniport"),	276	matching port ("full port") or a single-callback port ("miniport"),
306	depending on how C<rcv> callbacks are bound to the object.	277	depending on how C<rcv> callbacks are bound to the object.
307		278
308	=item $portid = port { my @msg = @_; $finished }	279	=item $port = port { my @msg = @_; $finished }
309		280
310	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
311	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.
312		284
313	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
314	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
315	will be destroyed. Otherwise it will stay alive.	287	will be destroyed. Otherwise it will stay alive.
316		288
…		…
323	snd $otherport, reply => $port;	295	snd $otherport, reply => $port;
324	};	296	};
325		297
326	=cut	298	=cut
327		299
		300	sub rcv($@);
		301
328	sub port(;&) {	302	sub port(;&) {
329	my $id = "$UNIQ." . $ID++;	303	my $id = "$UNIQ." . $ID++;
330	my $port = "$NODE#$id";	304	my $port = "$NODE#$id";
331		305
332	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) {
333	my $cb = shift;	395	my $cb = shift;
		396	delete $PORT_DATA{$portid};
334	$PORT{$id} = sub {	397	$PORT{$portid} = sub {
335	local $SELF = $port;	398	local $SELF = $port;
336	eval {	399	eval {
337	&$cb	400	&$cb
338	and kil $id;	401	and kil $port;
339	};	402	};
340	_self_die if $@;	403	_self_die if $@;
341	};	404	};
342	} else {	405	} else {
		406	my $self = $PORT_DATA{$portid} \|\|= do {
343	my $self = bless {	407	my $self = bless {
344	id => "$NODE#$id",	408	id => $port,
345	}, "AnyEvent::MP::Port";	409	}, "AnyEvent::MP::Port";
346		410
347	$PORT_DATA{$id} = $self;
348	$PORT{$id} = sub {	411	$PORT{$portid} = sub {
349	local $SELF = $port;	412	local $SELF = $port;
350		413
351	eval {	414	eval {
352	for (@{ $self->{rc0}{$_[0]} }) {	415	for (@{ $self->{rc0}{$_[0]} }) {
353	$_ && &{$_->[0]}	416	$_ && &{$_->[0]}
354	&& undef $_;	417	&& undef $_;
355	}	418	}
356		419
357	for (@{ $self->{rcv}{$_[0]} }) {	420	for (@{ $self->{rcv}{$_[0]} }) {
358	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]	421	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
359	&& &{$_->[0]}	422	&& &{$_->[0]}
360	&& undef $_;	423	&& undef $_;
361	}	424	}
362		425
363	for (@{ $self->{any} }) {	426	for (@{ $self->{any} }) {
364	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]	427	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
365	&& &{$_->[0]}	428	&& &{$_->[0]}
366	&& undef $_;	429	&& undef $_;
		430	}
367	}	431	};
		432	_self_die if $@;
368	};	433	};
369	_self_die if $@;	434
		435	$self
370	};	436	};
371	}
372		437
373	$port
374	}
375
376	=item reg $portid, $name
377
378	Registers the given port under the name C<$name>. If the name already
379	exists it is replaced.
380
381	A port can only be registered under one well known name.
382
383	A port automatically becomes unregistered when it is killed.
384
385	=cut
386
387	sub reg(@) {
388	my ($portid, $name) = @_;
389
390	$REG{$name} = $portid;
391	}
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	438	"AnyEvent::MP::Port" eq ref $self
440	or Carp::croak "$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";
441		440
442	while (@_) {	441	while (@_) {
443	my ($match, $cb) = splice @_, 0, 2;	442	my ($match, $cb) = splice @_, 0, 2;
444		443
445	if (!ref $match) {	444	if (!ref $match) {
446	push @{ $self->{rc0}{$match} }, [$cb];	445	push @{ $self->{rc0}{$match} }, [$cb];
447	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {	446	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
448	my ($type, @match) = @$match;	447	my ($type, @match) = @$match;
449	@match	448	@match
450	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]	449	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
451	: push @{ $self->{rc0}{$match->[0]} }, [$cb];	450	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
452	} else {	451	} else {
453	push @{ $self->{any} }, [$cb, $match];	452	push @{ $self->{any} }, [$cb, $match];
		453	}
454	}	454	}
455	}	455	}
456		456
457	$portid	457	$port
458	}	458	}
459		459
460	=item $closure = psub { BLOCK }	460	=item $closure = psub { BLOCK }
461		461
462	Remembers C<$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
…		…
493	$res	493	$res
494	}	494	}
495	}	495	}
496	}	496	}
497		497
498	=back	498	=item $guard = mon $port, $cb->(@reason)
499		499
500	=head1 FUNCTIONS FOR NODES	500	=item $guard = mon $port, $rcvport
501		501
502	=over 4	502	=item $guard = mon $port
503		503
504	=item become_public $noderef	504	=item $guard = mon $port, $rcvport, @msg
505		505
506	Tells the node to become a public node, i.e. reachable from other nodes.	506	Monitor the given port and do something when the port is killed, and
		507	optionally return a guard that can be used to stop monitoring again.
507		508
508	The first argument is the (unresolved) node reference of the local node	509	In the first form (callback), the callback is simply called with any
509	(if missing then the empty string is used).	510	number of C<@reason> elements (no @reason means that the port was deleted
		511	"normally"). Note also that I<< the callback B<must> never die >>, so use
		512	C<eval> if unsure.
510		513
511	It is quite common to not specify anything, in which case the local node	514	In the second form (another port given), the other port (C<$rcvport)
512	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
513	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.
514		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, $self => "restart";
		543
515	=cut	544	=cut
		545
		546	sub mon {
		547	my ($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 fucntion 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." . $ID++;
		673
		674	($NODE{$noderef} \|\| add_node $noderef)
		675	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
		676
		677	"$noderef#$id"
		678	}
516		679
517	=back	680	=back
518		681
519	=head1 NODE MESSAGES	682	=head1 NODE MESSAGES
520		683
…		…
562		725
563	=back	726	=back
564		727
565	=head1 AnyEvent::MP vs. Distributed Erlang	728	=head1 AnyEvent::MP vs. Distributed Erlang
566		729
567	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node	730	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	731	== 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	732	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
570	sample:	733	sample:
571		734
572	http://www.erlang.se/doc/programming_rules.shtml	735	http://www.Erlang.se/doc/programming_rules.shtml
573	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	736	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	737	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	738	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
576		739
577	Despite the similarities, there are also some important differences:	740	Despite the similarities, there are also some important differences:
578		741
579	=over 4	742	=over 4
580		743
…		…
591		754
592	Erlang uses processes that selctively receive messages, and therefore	755	Erlang uses processes that selctively receive messages, and therefore
593	needs a queue. AEMP is event based, queuing messages would serve no useful	756	needs a queue. AEMP is event based, queuing messages would serve no useful
594	purpose.	757	purpose.
595		758
596	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	759	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
597		760
598	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	761	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
599		762
600	Sending messages in erlang is synchronous and blocks the process. AEMP	763	Sending messages in Erlang is synchronous and blocks the process. AEMP
601	sends are immediate, connection establishment is handled in the	764	sends are immediate, connection establishment is handled in the
602	background.	765	background.
603		766
604	=item * Erlang can silently lose messages, AEMP cannot.	767	=item * Erlang can silently lose messages, AEMP cannot.
605		768
…		…
608	and c, and the other side only receives messages a and c).	771	and c, and the other side only receives messages a and c).
609		772
610	AEMP guarantees correct ordering, and the guarantee that there are no	773	AEMP guarantees correct ordering, and the guarantee that there are no
611	holes in the message sequence.	774	holes in the message sequence.
612		775
613	=item * In erlang, processes can be declared dead and later be found to be	776	=item * In Erlang, processes can be declared dead and later be found to be
614	alive.	777	alive.
615		778
616	In erlang it can happen that a monitored process is declared dead and	779	In Erlang it can happen that a monitored process is declared dead and
617	linked processes get killed, but later it turns out that the process is	780	linked processes get killed, but later it turns out that the process is
618	still alive - and can receive messages.	781	still alive - and can receive messages.
619		782
620	In AEMP, when port monitoring detects a port as dead, then that port will	783	In AEMP, when port monitoring detects a port as dead, then that port will
621	eventually be killed - it cannot happen that a node detects a port as dead	784	eventually be killed - it cannot happen that a node detects a port as dead
622	and then later sends messages to it, finding it is still alive.	785	and then later sends messages to it, finding it is still alive.
623		786
624	=item * Erlang can send messages to the wrong port, AEMP does not.	787	=item * Erlang can send messages to the wrong port, AEMP does not.
625		788
626	In erlang it is quite possible that a node that restarts reuses a process	789	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	790	ID known to other nodes for a completely different process, causing
628	messages destined for that process to end up in an unrelated process.	791	messages destined for that process to end up in an unrelated process.
629		792
630	AEMP never reuses port IDs, so old messages or old port IDs floating	793	AEMP never reuses port IDs, so old messages or old port IDs floating
631	around in the network will not be sent to an unrelated port.	794	around in the network will not be sent to an unrelated port.
…		…
637	securely authenticate nodes.	800	securely authenticate nodes.
638		801
639	=item * The AEMP protocol is optimised for both text-based and binary	802	=item * The AEMP protocol is optimised for both text-based and binary
640	communications.	803	communications.
641		804
642	The AEMP protocol, unlike the erlang protocol, supports both	805	The AEMP protocol, unlike the Erlang protocol, supports both
643	language-independent text-only protocols (good for debugging) and binary,	806	language-independent text-only protocols (good for debugging) and binary,
644	language-specific serialisers (e.g. Storable).	807	language-specific serialisers (e.g. Storable).
645		808
646	It has also been carefully designed to be implementable in other languages	809	It has also been carefully designed to be implementable in other languages
647	with a minimum of work while gracefully degrading fucntionality to make the	810	with a minimum of work while gracefully degrading fucntionality to make the
648	protocol simple.	811	protocol simple.
649		812
		813	=item * AEMP has more flexible monitoring options than Erlang.
		814
		815	In Erlang, you can chose to receive I<all> exit signals as messages
		816	or I<none>, there is no in-between, so monitoring single processes is
		817	difficult to implement. Monitoring in AEMP is more flexible than in
		818	Erlang, as one can choose between automatic kill, exit message or callback
		819	on a per-process basis.
		820
		821	=item * Erlang tries to hide remote/local connections, AEMP does not.
		822
		823	Monitoring in Erlang is not an indicator of process death/crashes,
		824	as linking is (except linking is unreliable in Erlang).
		825
		826	In AEMP, you don't "look up" registered port names or send to named ports
		827	that might or might not be persistent. Instead, you normally spawn a port
		828	on the remote node. The init function monitors the you, and you monitor
		829	the remote port. Since both monitors are local to the node, they are much
		830	more reliable.
		831
		832	This also saves round-trips and avoids sending messages to the wrong port
		833	(hard to do in Erlang).
		834
650	=back	835	=back
651		836
652	=head1 SEE ALSO	837	=head1 SEE ALSO
653		838
654	L<AnyEvent>.	839	L<AnyEvent>.

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Revision 1.38 by root, Fri Aug 7 22:55:18 2009 UTC