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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.29 by root, Tue Aug 4 23:16:57 2009 UTC vs.
Revision 1.47 by root, Thu Aug 13 01:57:10 2009 UTC

…		…
8		8
9	$NODE # contains this node's noderef	9	$NODE # contains this node's noderef
10	NODE # returns this node's noderef	10	NODE # returns this node's noderef
11	NODE $port # returns the noderef of the port	11	NODE $port # returns the noderef of the port
12		12
		13	$SELF # receiving/own port id in rcv callbacks
		14
		15	# ports are message endpoints
		16
		17	# sending messages
13	snd $port, type => data...;	18	snd $port, type => data...;
		19	snd $port, @msg;
		20	snd @msg_with_first_element_being_a_port;
14		21
15	$SELF # receiving/own port id in rcv callbacks	22	# miniports
		23	my $miniport = port { my @msg = @_; 0 };
16		24
		25	# full ports
		26	my $port = port;
17	rcv $port, smartmatch => $cb->($port, @msg);	27	rcv $port, smartmatch => $cb->(@msg);
18
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	28	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
21	rcv $port1, pong => sub { warn "pong received\n" };	29	rcv $port, pong => sub { warn "pong received\n"; 0 };
22	snd $port2, ping => $port1;	30
		31	# remote ports
		32	my $port = spawn $node, $initfunc, @initdata;
23		33
24	# more, smarter, matches (_any_ is exported by this module)	34	# more, smarter, matches (_any_ is exported by this module)
25	rcv $port, [child_died => $pid] => sub { ...	35	rcv $port, [child_died => $pid] => sub { ...
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	36	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
27		37
		38	# monitoring
		39	mon $port, $cb->(@msg) # callback is invoked on death
		40	mon $port, $otherport # kill otherport on abnormal death
		41	mon $port, $otherport, @msg # send message on death
		42
		43	=head1 CURRENT STATUS
		44
		45	AnyEvent::MP - stable API, should work
		46	AnyEvent::MP::Intro - outdated
		47	AnyEvent::MP::Kernel - WIP
		48	AnyEvent::MP::Transport - mostly stable
		49
		50	stay tuned.
		51
28	=head1 DESCRIPTION	52	=head1 DESCRIPTION
29		53
30	This module (-family) implements a simple message passing framework.	54	This module (-family) implements a simple message passing framework.
31		55
32	Despite its simplicity, you can securely message other processes running	56	Despite its simplicity, you can securely message other processes running
…		…
35	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	59	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
36	manual page.	60	manual page.
37		61
38	At the moment, this module family is severly broken and underdocumented,	62	At the moment, this module family is severly broken and underdocumented,
39	so do not use. This was uploaded mainly to reserve the CPAN namespace -	63	so do not use. This was uploaded mainly to reserve the CPAN namespace -
40	stay tuned! The basic API should be finished, however.	64	stay tuned!
41		65
42	=head1 CONCEPTS	66	=head1 CONCEPTS
43		67
44	=over 4	68	=over 4
45		69
…		…
53		77
54	=item port id - C<noderef#portname>	78	=item port id - C<noderef#portname>
55		79
56	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	80	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as
57	separator, and a port name (a printable string of unspecified format). An	81	separator, and a port name (a printable string of unspecified format). An
58	exception is the the node port, whose ID is identical to it's node	82	exception is the the node port, whose ID is identical to its node
59	reference.	83	reference.
60		84
61	=item node	85	=item node
62		86
63	A node is a single process containing at least one port - the node	87	A node is a single process containing at least one port - the node
…		…
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	133	resolve_node initialise_node
109	become_slave become_public
110	snd rcv mon kil reg psub	134	snd rcv mon kil reg psub spawn
111	port	135	port
112	);	136	);
113		137
114	our $SELF;	138	our $SELF;
115		139
…		…
124	The C<NODE> function returns, and the C<$NODE> variable contains	148	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	149	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	150	to C<become_public> or C<become_slave>, after which all local port
127	identifiers become invalid.	151	identifiers become invalid.
128		152
129	=item $noderef = node_of $portid	153	=item $noderef = node_of $port
130		154
131	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";
132		220
133	=item $cv = resolve_node $noderef	221	=item $cv = resolve_node $noderef
134		222
135	Takes an unresolved node reference that may contain hostnames and	223	Takes an unresolved node reference that may contain hostnames and
136	abbreviated IDs, resolves all of them and returns a resolved node	224	abbreviated IDs, resolves all of them and returns a resolved node
…		…
168		256
169	Due to some quirks in how perl exports variables, it is impossible to	257	Due to some quirks in how perl exports variables, it is impossible to
170	just export C<$SELF>, all the symbols called C<SELF> are exported by this	258	just export C<$SELF>, all the symbols called C<SELF> are exported by this
171	module, but only C<$SELF> is currently used.	259	module, but only C<$SELF> is currently used.
172		260
173	=item snd $portid, type => @data	261	=item snd $port, type => @data
174		262
175	=item snd $portid, @msg	263	=item snd $port, @msg
176		264
177	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
178	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
179	stringifies a sa port ID (such as a port object :).	267	stringifies a sa port ID (such as a port object :).
180		268
…		…
190	JSON is used, then only strings, numbers and arrays and hashes consisting	278	JSON is used, then only strings, numbers and arrays and hashes consisting
191	of those are allowed (no objects). When Storable is used, then anything	279	of those are allowed (no objects). When Storable is used, then anything
192	that Storable can serialise and deserialise is allowed, and for the local	280	that Storable can serialise and deserialise is allowed, and for the local
193	node, anything can be passed.	281	node, anything can be passed.
194		282
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, $cb) = ((split /#/, shift, 2), shift);
246
247	my $node = $NODE{$noderef} \|\| add_node $noderef;
248
249	#TODO: ports must not be references
250	if (!ref $cb or "AnyEvent::MP::Port" eq 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	283	=item $local_port = port
303		284
304	Create a new local port object that supports message matching.	285	Create a new local port object that can be used either as a pattern
		286	matching port ("full port") or a single-callback port ("miniport"),
		287	depending on how C<rcv> callbacks are bound to the object.
305		288
306	=item $portid = port { my @msg = @_; $finished }	289	=item $port = port { my @msg = @_; $finished }
307		290
308	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
309	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.
310		294
311	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
312	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
313	will be destroyed. Otherwise it will stay alive.	297	will be destroyed. Otherwise it will stay alive.
314		298
315	The message will be passed as-is, no extra argument (i.e. no port id) will	299	The message will be passed as-is, no extra argument (i.e. no port id) will
316	be passed to the callback.	300	be passed to the callback.
317		301
318	If you need the local port id in the callback, this works nicely:	302	If you need the local port id in the callback, this works nicely:
319		303
320	my $port; $port = miniport {	304	my $port; $port = port {
321	snd $otherport, reply => $port;	305	snd $otherport, reply => $port;
322	};	306	};
323		307
324	=cut	308	=cut
		309
		310	sub rcv($@);
325		311
326	sub port(;&) {	312	sub port(;&) {
327	my $id = "$UNIQ." . $ID++;	313	my $id = "$UNIQ." . $ID++;
328	my $port = "$NODE#$id";	314	my $port = "$NODE#$id";
329		315
330	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) {
331	my $cb = shift;	405	my $cb = shift;
		406	delete $PORT_DATA{$portid};
332	$PORT{$id} = sub {	407	$PORT{$portid} = sub {
333	local $SELF = $port;	408	local $SELF = $port;
334	eval {	409	eval {
335	&$cb	410	&$cb
336	and kil $id;	411	and kil $port;
337	};	412	};
338	_self_die if $@;	413	_self_die if $@;
339	};	414	};
340	} else {	415	} else {
		416	my $self = $PORT_DATA{$portid} \|\|= do {
341	my $self = bless {	417	my $self = bless {
342	id => "$NODE#$id",	418	id => $port,
343	}, "AnyEvent::MP::Port";	419	}, "AnyEvent::MP::Port";
344		420
345	$PORT_DATA{$id} = $self;
346	$PORT{$id} = sub {	421	$PORT{$portid} = sub {
347	local $SELF = $port;	422	local $SELF = $port;
348		423
349	eval {	424	eval {
350	for (@{ $self->{rc0}{$_[0]} }) {	425	for (@{ $self->{rc0}{$_[0]} }) {
351	$_ && &{$_->[0]}	426	$_ && &{$_->[0]}
352	&& undef $_;	427	&& undef $_;
353	}	428	}
354		429
355	for (@{ $self->{rcv}{$_[0]} }) {	430	for (@{ $self->{rcv}{$_[0]} }) {
356	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]	431	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
357	&& &{$_->[0]}	432	&& &{$_->[0]}
358	&& undef $_;	433	&& undef $_;
359	}	434	}
360		435
361	for (@{ $self->{any} }) {	436	for (@{ $self->{any} }) {
362	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]	437	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
363	&& &{$_->[0]}	438	&& &{$_->[0]}
364	&& undef $_;	439	&& undef $_;
		440	}
365	}	441	};
		442	_self_die if $@;
366	};	443	};
367	_self_die if $@;	444
		445	$self
368	};	446	};
369	}
370		447
371	$port
372	}
373
374	=item reg $portid, $name
375
376	Registers the given port under the name C<$name>. If the name already
377	exists it is replaced.
378
379	A port can only be registered under one well known name.
380
381	A port automatically becomes unregistered when it is killed.
382
383	=cut
384
385	sub reg(@) {
386	my ($portid, $name) = @_;
387
388	$REG{$name} = $portid;
389	}
390
391	=item rcv $portid, tagstring => $callback->(@msg), ...
392
393	=item rcv $portid, $smartmatch => $callback->(@msg), ...
394
395	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
396
397	Register callbacks to be called on matching messages on the given port.
398
399	The callback has to return a true value when its work is done, after
400	which is will be removed, or a false value in which case it will stay
401	registered.
402
403	The global C<$SELF> (exported by this module) contains C<$portid> while
404	executing the callback.
405
406	Runtime errors wdurign callback execution will result in the port being
407	C<kil>ed.
408
409	If the match is an array reference, then it will be matched against the
410	first elements of the message, otherwise only the first element is being
411	matched.
412
413	Any element in the match that is specified as C<_any_> (a function
414	exported by this module) matches any single element of the message.
415
416	While not required, it is highly recommended that the first matching
417	element is a string identifying the message. The one-string-only match is
418	also the most efficient match (by far).
419
420	=cut
421
422	sub rcv($@) {
423	my ($noderef, $port) = split /#/, shift, 2;
424
425	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
426	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";
427
428	my $self = $PORT_DATA{$port}
429	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
430
431	"AnyEvent::MP::Port" eq ref $self	448	"AnyEvent::MP::Port" eq ref $self
432	or Carp::croak "$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";
433		450
434	while (@_) {	451	while (@_) {
435	my ($match, $cb) = splice @_, 0, 2;	452	my ($match, $cb) = splice @_, 0, 2;
436		453
437	if (!ref $match) {	454	if (!ref $match) {
438	push @{ $self->{rc0}{$match} }, [$cb];	455	push @{ $self->{rc0}{$match} }, [$cb];
439	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {	456	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
440	my ($type, @match) = @$match;	457	my ($type, @match) = @$match;
441	@match	458	@match
442	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]	459	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
443	: push @{ $self->{rc0}{$match->[0]} }, [$cb];	460	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
444	} else {	461	} else {
445	push @{ $self->{any} }, [$cb, $match];	462	push @{ $self->{any} }, [$cb, $match];
		463	}
446	}	464	}
447	}	465	}
		466
		467	$port
448	}	468	}
449		469
450	=item $closure = psub { BLOCK }	470	=item $closure = psub { BLOCK }
451		471
452	Remembers C<$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
…		…
483	$res	503	$res
484	}	504	}
485	}	505	}
486	}	506	}
487		507
488	=back	508	=item $guard = mon $port, $cb->(@reason)
489		509
490	=head1 FUNCTIONS FOR NODES	510	=item $guard = mon $port, $rcvport
491		511
492	=over 4	512	=item $guard = mon $port
493		513
494	=item become_public $noderef	514	=item $guard = mon $port, $rcvport, @msg
495		515
496	Tells the node to become a public node, i.e. reachable from other nodes.	516	Monitor the given port and do something when the port is killed or
		517	messages to it were lost, and optionally return a guard that can be used
		518	to stop monitoring again.
497		519
498	The first argument is the (unresolved) node reference of the local node	520	C<mon> effectively guarantees that, in the absence of hardware failures,
499	(if missing then the empty string is used).	521	that after starting the monitor, either all messages sent to the port
		522	will arrive, or the monitoring action will be invoked after possible
		523	message loss has been detected. No messages will be lost "in between"
		524	(after the first lost message no further messages will be received by the
		525	port). After the monitoring action was invoked, further messages might get
		526	delivered again.
500		527
501	It is quite common to not specify anything, in which case the local node	528	In the first form (callback), the callback is simply called with any
502	tries to listen on the default port, or to only specify a port number, in	529	number of C<@reason> elements (no @reason means that the port was deleted
503	which case AnyEvent::MP tries to guess the local addresses.	530	"normally"). Note also that I<< the callback B<must> never die >>, so use
		531	C<eval> if unsure.
504		532
		533	In the second form (another port given), the other port (C<$rcvport>)
		534	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
		535	"normal" kils nothing happens, while under all other conditions, the other
		536	port is killed with the same reason.
		537
		538	The third form (kill self) is the same as the second form, except that
		539	C<$rvport> defaults to C<$SELF>.
		540
		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.
		550
		551	Example: call a given callback when C<$port> is killed.
		552
		553	mon $port, sub { warn "port died because of <@_>\n" };
		554
		555	Example: kill ourselves when C<$port> is killed abnormally.
		556
		557	mon $port;
		558
		559	Example: send us a restart message when another C<$port> is killed.
		560
		561	mon $port, $self => "restart";
		562
505	=cut	563	=cut
		564
		565	sub mon {
		566	my ($noderef, $port) = split /#/, shift, 2;
		567
		568	my $node = $NODE{$noderef} \|\| add_node $noderef;
		569
		570	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
		571
		572	unless (ref $cb) {
		573	if (@_) {
		574	# send a kill info message
		575	my (@msg) = ($cb, @_);
		576	$cb = sub { snd @msg, @_ };
		577	} else {
		578	# simply kill other port
		579	my $port = $cb;
		580	$cb = sub { kil $port, @_ if @_ };
		581	}
		582	}
		583
		584	$node->monitor ($port, $cb);
		585
		586	defined wantarray
		587	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
		588	}
		589
		590	=item $guard = mon_guard $port, $ref, $ref...
		591
		592	Monitors the given C<$port> and keeps the passed references. When the port
		593	is killed, the references will be freed.
		594
		595	Optionally returns a guard that will stop the monitoring.
		596
		597	This function is useful when you create e.g. timers or other watchers and
		598	want to free them when the port gets killed:
		599
		600	$port->rcv (start => sub {
		601	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
		602	undef $timer if 0.9 < rand;
		603	});
		604	});
		605
		606	=cut
		607
		608	sub mon_guard {
		609	my ($port, @refs) = @_;
		610
		611	#TODO: mon-less form?
		612
		613	mon $port, sub { 0 && @refs }
		614	}
		615
		616	=item kil $port[, @reason]
		617
		618	Kill the specified port with the given C<@reason>.
		619
		620	If no C<@reason> is specified, then the port is killed "normally" (linked
		621	ports will not be kileld, or even notified).
		622
		623	Otherwise, linked ports get killed with the same reason (second form of
		624	C<mon>, see below).
		625
		626	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		627	will be reported as reason C<< die => $@ >>.
		628
		629	Transport/communication errors are reported as C<< transport_error =>
		630	$message >>.
		631
		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	}
506		702
507	=back	703	=back
508		704
509	=head1 NODE MESSAGES	705	=head1 NODE MESSAGES
510		706
…		…
552		748
553	=back	749	=back
554		750
555	=head1 AnyEvent::MP vs. Distributed Erlang	751	=head1 AnyEvent::MP vs. Distributed Erlang
556		752
557	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
558	== 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
559	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
560	sample:	756	sample:
561		757
562	http://www.erlang.se/doc/programming_rules.shtml	758	http://www.Erlang.se/doc/programming_rules.shtml
563	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
564	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
565	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
566		762
567	Despite the similarities, there are also some important differences:	763	Despite the similarities, there are also some important differences:
568		764
569	=over 4	765	=over 4
570		766
…		…
581		777
582	Erlang uses processes that selctively receive messages, and therefore	778	Erlang uses processes that selctively receive messages, and therefore
583	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
584	purpose.	780	purpose.
585		781
586	(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).
587		783
588	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	784	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
589		785
590	Sending messages in erlang is synchronous and blocks the process. AEMP	786	Sending messages in Erlang is synchronous and blocks the process. AEMP
591	sends are immediate, connection establishment is handled in the	787	sends are immediate, connection establishment is handled in the
592	background.	788	background.
593		789
594	=item * Erlang can silently lose messages, AEMP cannot.	790	=item * Erlang can silently lose messages, AEMP cannot.
595		791
…		…
598	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).
599		795
600	AEMP guarantees correct ordering, and the guarantee that there are no	796	AEMP guarantees correct ordering, and the guarantee that there are no
601	holes in the message sequence.	797	holes in the message sequence.
602		798
603	=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
604	alive.	800	alive.
605		801
606	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
607	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
608	still alive - and can receive messages.	804	still alive - and can receive messages.
609		805
610	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
611	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
612	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.
613		809
614	=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.
615		811
616	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
617	ID known to other nodes for a completely different process, causing	813	ID known to other nodes for a completely different process, causing
618	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.
619		815
620	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
621	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.
…		…
627	securely authenticate nodes.	823	securely authenticate nodes.
628		824
629	=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
630	communications.	826	communications.
631		827
632	The AEMP protocol, unlike the erlang protocol, supports both	828	The AEMP protocol, unlike the Erlang protocol, supports both
633	language-independent text-only protocols (good for debugging) and binary,	829	language-independent text-only protocols (good for debugging) and binary,
634	language-specific serialisers (e.g. Storable).	830	language-specific serialisers (e.g. Storable).
635		831
636	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
637	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
638	protocol simple.	834	protocol simple.
639		835
		836	=item * AEMP has more flexible monitoring options than Erlang.
		837
		838	In Erlang, you can chose to receive I<all> exit signals as messages
		839	or I<none>, there is no in-between, so monitoring single processes is
		840	difficult to implement. Monitoring in AEMP is more flexible than in
		841	Erlang, as one can choose between automatic kill, exit message or callback
		842	on a per-process basis.
		843
		844	=item * Erlang tries to hide remote/local connections, AEMP does not.
		845
		846	Monitoring in Erlang is not an indicator of process death/crashes,
		847	as linking is (except linking is unreliable in Erlang).
		848
		849	In AEMP, you don't "look up" registered port names or send to named ports
		850	that might or might not be persistent. Instead, you normally spawn a port
		851	on the remote node. The init function monitors the you, and you monitor
		852	the remote port. Since both monitors are local to the node, they are much
		853	more reliable.
		854
		855	This also saves round-trips and avoids sending messages to the wrong port
		856	(hard to do in Erlang).
		857
		858	=back
		859
		860	=head1 RATIONALE
		861
		862	=over 4
		863
		864	=item Why strings for ports and noderefs, why not objects?
		865
		866	We considered "objects", but found that the actual number of methods
		867	thatc an be called are very low. Since port IDs and noderefs travel over
		868	the network frequently, the serialising/deserialising would add lots of
		869	overhead, as well as having to keep a proxy object.
		870
		871	Strings can easily be printed, easily serialised etc. and need no special
		872	procedures to be "valid".
		873
		874	And a a miniport consists of a single closure stored in a global hash - it
		875	can't become much cheaper.
		876
		877	=item Why favour JSON, why not real serialising format such as Storable?
		878
		879	In fact, any AnyEvent::MP node will happily accept Storable as framing
		880	format, but currently there is no way to make a node use Storable by
		881	default.
		882
		883	The default framing protocol is JSON because a) JSON::XS is many times
		884	faster for small messages and b) most importantly, after years of
		885	experience we found that object serialisation is causing more problems
		886	than it gains: Just like function calls, objects simply do not travel
		887	easily over the network, mostly because they will always be a copy, so you
		888	always have to re-think your design.
		889
		890	Keeping your messages simple, concentrating on data structures rather than
		891	objects, will keep your messages clean, tidy and efficient.
		892
640	=back	893	=back
641		894
642	=head1 SEE ALSO	895	=head1 SEE ALSO
643		896
644	L<AnyEvent>.	897	L<AnyEvent>.

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