[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 1.48 by root, Thu Aug 13 02:59:42 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	# initialise the node so it can send/receive messages
		16	initialise_node; # -OR-
		17	initialise_node "localhost:4040"; # -OR-
		18	initialise_node "slave/", "localhost:4040"
		19
		20	# ports are message endpoints
		21
		22	# sending messages
13	snd $port, type => data...;	23	snd $port, type => data...;
		24	snd $port, @msg;
		25	snd @msg_with_first_element_being_a_port;
14		26
15	$SELF # receiving/own port id in rcv callbacks	27	# creating/using miniports
		28	my $miniport = port { my @msg = @_; 0 };
16		29
		30	# creating/using full ports
		31	my $port = port;
17	rcv $port, smartmatch => $cb->($port, @msg);	32	rcv $port, smartmatch => $cb->(@msg);
18
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	33	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
21	rcv $port1, pong => sub { warn "pong received\n" };	34	rcv $port, pong => sub { warn "pong received\n"; 0 };
22	snd $port2, ping => $port1;
23		35
24	# more, smarter, matches (_any_ is exported by this module)	36	# more, smarter, matches (_any_ is exported by this module)
25	rcv $port, [child_died => $pid] => sub { ...	37	rcv $port, [child_died => $pid] => sub { ...
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	38	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
27		39
		40	# create a port on another node
		41	my $port = spawn $node, $initfunc, @initdata;
		42
		43	# monitoring
		44	mon $port, $cb->(@msg) # callback is invoked on death
		45	mon $port, $otherport # kill otherport on abnormal death
		46	mon $port, $otherport, @msg # send message on death
		47
		48	=head1 CURRENT STATUS
		49
		50	AnyEvent::MP - stable API, should work
		51	AnyEvent::MP::Intro - outdated
		52	AnyEvent::MP::Kernel - WIP
		53	AnyEvent::MP::Transport - mostly stable
		54
		55	stay tuned.
		56
28	=head1 DESCRIPTION	57	=head1 DESCRIPTION
29		58
30	This module (-family) implements a simple message passing framework.	59	This module (-family) implements a simple message passing framework.
31		60
32	Despite its simplicity, you can securely message other processes running	61	Despite its simplicity, you can securely message other processes running
…		…
35	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	64	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
36	manual page.	65	manual page.
37		66
38	At the moment, this module family is severly broken and underdocumented,	67	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 -	68	so do not use. This was uploaded mainly to reserve the CPAN namespace -
40	stay tuned! The basic API should be finished, however.	69	stay tuned!
41		70
42	=head1 CONCEPTS	71	=head1 CONCEPTS
43		72
44	=over 4	73	=over 4
45		74
…		…
53		82
54	=item port id - C<noderef#portname>	83	=item port id - C<noderef#portname>
55		84
56	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	85	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	86	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	87	exception is the the node port, whose ID is identical to its node
59	reference.	88	reference.
60		89
61	=item node	90	=item node
62		91
63	A node is a single process containing at least one port - the node	92	A node is a single process containing at least one port - the node
…		…
90		119
91	=cut	120	=cut
92		121
93	package AnyEvent::MP;	122	package AnyEvent::MP;
94		123
95	use AnyEvent::MP::Base;	124	use AnyEvent::MP::Kernel;
96		125
97	use common::sense;	126	use common::sense;
98		127
99	use Carp ();	128	use Carp ();
100		129
101	use AE ();	130	use AE ();
102		131
103	use base "Exporter";	132	use base "Exporter";
104		133
105	our $VERSION = '0.1';	134	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		135
106	our @EXPORT = qw(	136	our @EXPORT = qw(
107	NODE $NODE *SELF node_of _any_	137	NODE $NODE *SELF node_of _any_
108	resolve_node	138	resolve_node initialise_node
109	become_slave become_public
110	snd rcv mon kil reg psub	139	snd rcv mon kil reg psub spawn
111	port	140	port
112	);	141	);
113		142
114	our $SELF;	143	our $SELF;
115		144
…		…
124	The C<NODE> function returns, and the C<$NODE> variable contains	153	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	154	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	155	to C<become_public> or C<become_slave>, after which all local port
127	identifiers become invalid.	156	identifiers become invalid.
128		157
129	=item $noderef = node_of $portid	158	=item $noderef = node_of $port
130		159
131	Extracts and returns the noderef from a portid or a noderef.	160	Extracts and returns the noderef from a portid or a noderef.
		161
		162	=item initialise_node $noderef, $seednode, $seednode...
		163
		164	=item initialise_node "slave/", $master, $master...
		165
		166	Before a node can talk to other nodes on the network it has to initialise
		167	itself - the minimum a node needs to know is it's own name, and optionally
		168	it should know the noderefs of some other nodes in the network.
		169
		170	This function initialises a node - it must be called exactly once (or
		171	never) before calling other AnyEvent::MP functions.
		172
		173	All arguments are noderefs, which can be either resolved or unresolved.
		174
		175	There are two types of networked nodes, public nodes and slave nodes:
		176
		177	=over 4
		178
		179	=item public nodes
		180
		181	For public nodes, C<$noderef> must either be a (possibly unresolved)
		182	noderef, in which case it will be resolved, or C<undef> (or missing), in
		183	which case the noderef will be guessed.
		184
		185	Afterwards, the node will bind itself on all endpoints and try to connect
		186	to all additional C<$seednodes> that are specified. Seednodes are optional
		187	and can be used to quickly bootstrap the node into an existing network.
		188
		189	=item slave nodes
		190
		191	When the C<$noderef> is the special string C<slave/>, then the node will
		192	become a slave node. Slave nodes cannot be contacted from outside and will
		193	route most of their traffic to the master node that they attach to.
		194
		195	At least one additional noderef is required: The node will try to connect
		196	to all of them and will become a slave attached to the first node it can
		197	successfully connect to.
		198
		199	=back
		200
		201	This function will block until all nodes have been resolved and, for slave
		202	nodes, until it has successfully established a connection to a master
		203	server.
		204
		205	Example: become a public node listening on the default node.
		206
		207	initialise_node;
		208
		209	Example: become a public node, and try to contact some well-known master
		210	servers to become part of the network.
		211
		212	initialise_node undef, "master1", "master2";
		213
		214	Example: become a public node listening on port C<4041>.
		215
		216	initialise_node 4041;
		217
		218	Example: become a public node, only visible on localhost port 4044.
		219
		220	initialise_node "locahost:4044";
		221
		222	Example: become a slave node to any of the specified master servers.
		223
		224	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
132		225
133	=item $cv = resolve_node $noderef	226	=item $cv = resolve_node $noderef
134		227
135	Takes an unresolved node reference that may contain hostnames and	228	Takes an unresolved node reference that may contain hostnames and
136	abbreviated IDs, resolves all of them and returns a resolved node	229	abbreviated IDs, resolves all of them and returns a resolved node
…		…
168		261
169	Due to some quirks in how perl exports variables, it is impossible to	262	Due to some quirks in how perl exports variables, it is impossible to
170	just export C<$SELF>, all the symbols called C<SELF> are exported by this	263	just export C<$SELF>, all the symbols called C<SELF> are exported by this
171	module, but only C<$SELF> is currently used.	264	module, but only C<$SELF> is currently used.
172		265
173	=item snd $portid, type => @data	266	=item snd $port, type => @data
174		267
175	=item snd $portid, @msg	268	=item snd $port, @msg
176		269
177	Send the given message to the given port ID, which can identify either	270	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	271	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 :).	272	stringifies a sa port ID (such as a port object :).
180		273
…		…
190	JSON is used, then only strings, numbers and arrays and hashes consisting	283	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	284	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	285	that Storable can serialise and deserialise is allowed, and for the local
193	node, anything can be passed.	286	node, anything can be passed.
194		287
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	288	=item $local_port = port
303		289
304	Create a new local port object that supports message matching.	290	Create a new local port object that can be used either as a pattern
		291	matching port ("full port") or a single-callback port ("miniport"),
		292	depending on how C<rcv> callbacks are bound to the object.
305		293
306	=item $portid = port { my @msg = @_; $finished }	294	=item $port = port { my @msg = @_; $finished }
307		295
308	Creates a "mini port", that is, a very lightweight port without any	296	Creates a "miniport", that is, a very lightweight port without any pattern
309	pattern matching behind it, and returns its ID.	297	matching behind it, and returns its ID. Semantically the same as creating
		298	a port and calling C<rcv $port, $callback> on it.
310		299
311	The block will be called for every message received on the port. When the	300	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	301	callback returns a true value its job is considered "done" and the port
313	will be destroyed. Otherwise it will stay alive.	302	will be destroyed. Otherwise it will stay alive.
314		303
315	The message will be passed as-is, no extra argument (i.e. no port id) will	304	The message will be passed as-is, no extra argument (i.e. no port id) will
316	be passed to the callback.	305	be passed to the callback.
317		306
318	If you need the local port id in the callback, this works nicely:	307	If you need the local port id in the callback, this works nicely:
319		308
320	my $port; $port = miniport {	309	my $port; $port = port {
321	snd $otherport, reply => $port;	310	snd $otherport, reply => $port;
322	};	311	};
323		312
324	=cut	313	=cut
		314
		315	sub rcv($@);
325		316
326	sub port(;&) {	317	sub port(;&) {
327	my $id = "$UNIQ." . $ID++;	318	my $id = "$UNIQ." . $ID++;
328	my $port = "$NODE#$id";	319	my $port = "$NODE#$id";
329		320
330	if (@_) {	321	if (@_) {
		322	rcv $port, shift;
		323	} else {
		324	$PORT{$id} = sub { }; # nop
		325	}
		326
		327	$port
		328	}
		329
		330	=item reg $port, $name
		331
		332	=item reg $name
		333
		334	Registers the given port (or C<$SELF><<< if missing) under the name
		335	C<$name>. If the name already exists it is replaced.
		336
		337	A port can only be registered under one well known name.
		338
		339	A port automatically becomes unregistered when it is killed.
		340
		341	=cut
		342
		343	sub reg(@) {
		344	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
		345
		346	$REG{$_[0]} = $port;
		347	}
		348
		349	=item rcv $port, $callback->(@msg)
		350
		351	Replaces the callback on the specified miniport (after converting it to
		352	one if required).
		353
		354	=item rcv $port, tagstring => $callback->(@msg), ...
		355
		356	=item rcv $port, $smartmatch => $callback->(@msg), ...
		357
		358	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
		359
		360	Register callbacks to be called on matching messages on the given full
		361	port (after converting it to one if required) and return the port.
		362
		363	The callback has to return a true value when its work is done, after
		364	which is will be removed, or a false value in which case it will stay
		365	registered.
		366
		367	The global C<$SELF> (exported by this module) contains C<$port> while
		368	executing the callback.
		369
		370	Runtime errors during callback execution will result in the port being
		371	C<kil>ed.
		372
		373	If the match is an array reference, then it will be matched against the
		374	first elements of the message, otherwise only the first element is being
		375	matched.
		376
		377	Any element in the match that is specified as C<_any_> (a function
		378	exported by this module) matches any single element of the message.
		379
		380	While not required, it is highly recommended that the first matching
		381	element is a string identifying the message. The one-string-only match is
		382	also the most efficient match (by far).
		383
		384	Example: create a port and bind receivers on it in one go.
		385
		386	my $port = rcv port,
		387	msg1 => sub { ...; 0 },
		388	msg2 => sub { ...; 0 },
		389	;
		390
		391	Example: create a port, bind receivers and send it in a message elsewhere
		392	in one go:
		393
		394	snd $otherport, reply =>
		395	rcv port,
		396	msg1 => sub { ...; 0 },
		397	...
		398	;
		399
		400	=cut
		401
		402	sub rcv($@) {
		403	my $port = shift;
		404	my ($noderef, $portid) = split /#/, $port, 2;
		405
		406	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
		407	or Carp::croak "$port: rcv can only be called on local ports, caught";
		408
		409	if (@_ == 1) {
331	my $cb = shift;	410	my $cb = shift;
		411	delete $PORT_DATA{$portid};
332	$PORT{$id} = sub {	412	$PORT{$portid} = sub {
333	local $SELF = $port;	413	local $SELF = $port;
334	eval {	414	eval {
335	&$cb	415	&$cb
336	and kil $id;	416	and kil $port;
337	};	417	};
338	_self_die if $@;	418	_self_die if $@;
339	};	419	};
340	} else {	420	} else {
		421	my $self = $PORT_DATA{$portid} \|\|= do {
341	my $self = bless {	422	my $self = bless {
342	id => "$NODE#$id",	423	id => $port,
343	}, "AnyEvent::MP::Port";	424	}, "AnyEvent::MP::Port";
344		425
345	$PORT_DATA{$id} = $self;
346	$PORT{$id} = sub {	426	$PORT{$portid} = sub {
347	local $SELF = $port;	427	local $SELF = $port;
348		428
349	eval {	429	eval {
350	for (@{ $self->{rc0}{$_[0]} }) {	430	for (@{ $self->{rc0}{$_[0]} }) {
351	$_ && &{$_->[0]}	431	$_ && &{$_->[0]}
352	&& undef $_;	432	&& undef $_;
353	}	433	}
354		434
355	for (@{ $self->{rcv}{$_[0]} }) {	435	for (@{ $self->{rcv}{$_[0]} }) {
356	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]	436	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
357	&& &{$_->[0]}	437	&& &{$_->[0]}
358	&& undef $_;	438	&& undef $_;
359	}	439	}
360		440
361	for (@{ $self->{any} }) {	441	for (@{ $self->{any} }) {
362	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]	442	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
363	&& &{$_->[0]}	443	&& &{$_->[0]}
364	&& undef $_;	444	&& undef $_;
		445	}
365	}	446	};
		447	_self_die if $@;
366	};	448	};
367	_self_die if $@;	449
		450	$self
368	};	451	};
369	}
370		452
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	453	"AnyEvent::MP::Port" eq ref $self
432	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";	454	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
433		455
434	while (@_) {	456	while (@_) {
435	my ($match, $cb) = splice @_, 0, 2;	457	my ($match, $cb) = splice @_, 0, 2;
436		458
437	if (!ref $match) {	459	if (!ref $match) {
438	push @{ $self->{rc0}{$match} }, [$cb];	460	push @{ $self->{rc0}{$match} }, [$cb];
439	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {	461	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
440	my ($type, @match) = @$match;	462	my ($type, @match) = @$match;
441	@match	463	@match
442	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]	464	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
443	: push @{ $self->{rc0}{$match->[0]} }, [$cb];	465	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
444	} else {	466	} else {
445	push @{ $self->{any} }, [$cb, $match];	467	push @{ $self->{any} }, [$cb, $match];
		468	}
446	}	469	}
447	}	470	}
		471
		472	$port
448	}	473	}
449		474
450	=item $closure = psub { BLOCK }	475	=item $closure = psub { BLOCK }
451		476
452	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	477	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
…		…
483	$res	508	$res
484	}	509	}
485	}	510	}
486	}	511	}
487		512
488	=back	513	=item $guard = mon $port, $cb->(@reason)
489		514
490	=head1 FUNCTIONS FOR NODES	515	=item $guard = mon $port, $rcvport
491		516
492	=over 4	517	=item $guard = mon $port
493		518
494	=item become_public $noderef	519	=item $guard = mon $port, $rcvport, @msg
495		520
496	Tells the node to become a public node, i.e. reachable from other nodes.	521	Monitor the given port and do something when the port is killed or
		522	messages to it were lost, and optionally return a guard that can be used
		523	to stop monitoring again.
497		524
498	The first argument is the (unresolved) node reference of the local node	525	C<mon> effectively guarantees that, in the absence of hardware failures,
499	(if missing then the empty string is used).	526	that after starting the monitor, either all messages sent to the port
		527	will arrive, or the monitoring action will be invoked after possible
		528	message loss has been detected. No messages will be lost "in between"
		529	(after the first lost message no further messages will be received by the
		530	port). After the monitoring action was invoked, further messages might get
		531	delivered again.
500		532
501	It is quite common to not specify anything, in which case the local node	533	In the first form (callback), the callback is simply called with any
502	tries to listen on the default port, or to only specify a port number, in	534	number of C<@reason> elements (no @reason means that the port was deleted
503	which case AnyEvent::MP tries to guess the local addresses.	535	"normally"). Note also that I<< the callback B<must> never die >>, so use
		536	C<eval> if unsure.
504		537
		538	In the second form (another port given), the other port (C<$rcvport>)
		539	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
		540	"normal" kils nothing happens, while under all other conditions, the other
		541	port is killed with the same reason.
		542
		543	The third form (kill self) is the same as the second form, except that
		544	C<$rvport> defaults to C<$SELF>.
		545
		546	In the last form (message), a message of the form C<@msg, @reason> will be
		547	C<snd>.
		548
		549	As a rule of thumb, monitoring requests should always monitor a port from
		550	a local port (or callback). The reason is that kill messages might get
		551	lost, just like any other message. Another less obvious reason is that
		552	even monitoring requests can get lost (for exmaple, when the connection
		553	to the other node goes down permanently). When monitoring a port locally
		554	these problems do not exist.
		555
		556	Example: call a given callback when C<$port> is killed.
		557
		558	mon $port, sub { warn "port died because of <@_>\n" };
		559
		560	Example: kill ourselves when C<$port> is killed abnormally.
		561
		562	mon $port;
		563
		564	Example: send us a restart message when another C<$port> is killed.
		565
		566	mon $port, $self => "restart";
		567
505	=cut	568	=cut
		569
		570	sub mon {
		571	my ($noderef, $port) = split /#/, shift, 2;
		572
		573	my $node = $NODE{$noderef} \|\| add_node $noderef;
		574
		575	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
		576
		577	unless (ref $cb) {
		578	if (@_) {
		579	# send a kill info message
		580	my (@msg) = ($cb, @_);
		581	$cb = sub { snd @msg, @_ };
		582	} else {
		583	# simply kill other port
		584	my $port = $cb;
		585	$cb = sub { kil $port, @_ if @_ };
		586	}
		587	}
		588
		589	$node->monitor ($port, $cb);
		590
		591	defined wantarray
		592	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
		593	}
		594
		595	=item $guard = mon_guard $port, $ref, $ref...
		596
		597	Monitors the given C<$port> and keeps the passed references. When the port
		598	is killed, the references will be freed.
		599
		600	Optionally returns a guard that will stop the monitoring.
		601
		602	This function is useful when you create e.g. timers or other watchers and
		603	want to free them when the port gets killed:
		604
		605	$port->rcv (start => sub {
		606	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
		607	undef $timer if 0.9 < rand;
		608	});
		609	});
		610
		611	=cut
		612
		613	sub mon_guard {
		614	my ($port, @refs) = @_;
		615
		616	#TODO: mon-less form?
		617
		618	mon $port, sub { 0 && @refs }
		619	}
		620
		621	=item kil $port[, @reason]
		622
		623	Kill the specified port with the given C<@reason>.
		624
		625	If no C<@reason> is specified, then the port is killed "normally" (linked
		626	ports will not be kileld, or even notified).
		627
		628	Otherwise, linked ports get killed with the same reason (second form of
		629	C<mon>, see below).
		630
		631	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		632	will be reported as reason C<< die => $@ >>.
		633
		634	Transport/communication errors are reported as C<< transport_error =>
		635	$message >>.
		636
		637	=cut
		638
		639	=item $port = spawn $node, $initfunc[, @initdata]
		640
		641	Creates a port on the node C<$node> (which can also be a port ID, in which
		642	case it's the node where that port resides).
		643
		644	The port ID of the newly created port is return immediately, and it is
		645	permissible to immediately start sending messages or monitor the port.
		646
		647	After the port has been created, the init function is
		648	called. This function must be a fully-qualified function name
		649	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		650	program, use C<::name>.
		651
		652	If the function doesn't exist, then the node tries to C<require>
		653	the package, then the package above the package and so on (e.g.
		654	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		655	exists or it runs out of package names.
		656
		657	The init function is then called with the newly-created port as context
		658	object (C<$SELF>) and the C<@initdata> values as arguments.
		659
		660	A common idiom is to pass your own port, monitor the spawned port, and
		661	in the init function, monitor the original port. This two-way monitoring
		662	ensures that both ports get cleaned up when there is a problem.
		663
		664	Example: spawn a chat server port on C<$othernode>.
		665
		666	# this node, executed from within a port context:
		667	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		668	mon $server;
		669
		670	# init function on C<$othernode>
		671	sub connect {
		672	my ($srcport) = @_;
		673
		674	mon $srcport;
		675
		676	rcv $SELF, sub {
		677	...
		678	};
		679	}
		680
		681	=cut
		682
		683	sub _spawn {
		684	my $port = shift;
		685	my $init = shift;
		686
		687	local $SELF = "$NODE#$port";
		688	eval {
		689	&{ load_func $init }
		690	};
		691	_self_die if $@;
		692	}
		693
		694	sub spawn(@) {
		695	my ($noderef, undef) = split /#/, shift, 2;
		696
		697	my $id = "$RUNIQ." . $ID++;
		698
		699	$_[0] =~ /::/
		700	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		701
		702	($NODE{$noderef} \|\| add_node $noderef)
		703	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
		704
		705	"$noderef#$id"
		706	}
506		707
507	=back	708	=back
508		709
509	=head1 NODE MESSAGES	710	=head1 NODE MESSAGES
510		711
…		…
552		753
553	=back	754	=back
554		755
555	=head1 AnyEvent::MP vs. Distributed Erlang	756	=head1 AnyEvent::MP vs. Distributed Erlang
556		757
557	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node	758	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	759	== 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	760	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
560	sample:	761	sample:
561		762
562	http://www.erlang.se/doc/programming_rules.shtml	763	http://www.Erlang.se/doc/programming_rules.shtml
563	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	764	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	765	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	766	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
566		767
567	Despite the similarities, there are also some important differences:	768	Despite the similarities, there are also some important differences:
568		769
569	=over 4	770	=over 4
570		771
…		…
581		782
582	Erlang uses processes that selctively receive messages, and therefore	783	Erlang uses processes that selctively receive messages, and therefore
583	needs a queue. AEMP is event based, queuing messages would serve no useful	784	needs a queue. AEMP is event based, queuing messages would serve no useful
584	purpose.	785	purpose.
585		786
586	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	787	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
587		788
588	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	789	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
589		790
590	Sending messages in erlang is synchronous and blocks the process. AEMP	791	Sending messages in Erlang is synchronous and blocks the process. AEMP
591	sends are immediate, connection establishment is handled in the	792	sends are immediate, connection establishment is handled in the
592	background.	793	background.
593		794
594	=item * Erlang can silently lose messages, AEMP cannot.	795	=item * Erlang can silently lose messages, AEMP cannot.
595		796
…		…
598	and c, and the other side only receives messages a and c).	799	and c, and the other side only receives messages a and c).
599		800
600	AEMP guarantees correct ordering, and the guarantee that there are no	801	AEMP guarantees correct ordering, and the guarantee that there are no
601	holes in the message sequence.	802	holes in the message sequence.
602		803
603	=item * In erlang, processes can be declared dead and later be found to be	804	=item * In Erlang, processes can be declared dead and later be found to be
604	alive.	805	alive.
605		806
606	In erlang it can happen that a monitored process is declared dead and	807	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	808	linked processes get killed, but later it turns out that the process is
608	still alive - and can receive messages.	809	still alive - and can receive messages.
609		810
610	In AEMP, when port monitoring detects a port as dead, then that port will	811	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	812	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.	813	and then later sends messages to it, finding it is still alive.
613		814
614	=item * Erlang can send messages to the wrong port, AEMP does not.	815	=item * Erlang can send messages to the wrong port, AEMP does not.
615		816
616	In erlang it is quite possible that a node that restarts reuses a process	817	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	818	ID known to other nodes for a completely different process, causing
618	messages destined for that process to end up in an unrelated process.	819	messages destined for that process to end up in an unrelated process.
619		820
620	AEMP never reuses port IDs, so old messages or old port IDs floating	821	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.	822	around in the network will not be sent to an unrelated port.
…		…
627	securely authenticate nodes.	828	securely authenticate nodes.
628		829
629	=item * The AEMP protocol is optimised for both text-based and binary	830	=item * The AEMP protocol is optimised for both text-based and binary
630	communications.	831	communications.
631		832
632	The AEMP protocol, unlike the erlang protocol, supports both	833	The AEMP protocol, unlike the Erlang protocol, supports both
633	language-independent text-only protocols (good for debugging) and binary,	834	language-independent text-only protocols (good for debugging) and binary,
634	language-specific serialisers (e.g. Storable).	835	language-specific serialisers (e.g. Storable).
635		836
636	It has also been carefully designed to be implementable in other languages	837	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	838	with a minimum of work while gracefully degrading fucntionality to make the
638	protocol simple.	839	protocol simple.
639		840
		841	=item * AEMP has more flexible monitoring options than Erlang.
		842
		843	In Erlang, you can chose to receive I<all> exit signals as messages
		844	or I<none>, there is no in-between, so monitoring single processes is
		845	difficult to implement. Monitoring in AEMP is more flexible than in
		846	Erlang, as one can choose between automatic kill, exit message or callback
		847	on a per-process basis.
		848
		849	=item * Erlang tries to hide remote/local connections, AEMP does not.
		850
		851	Monitoring in Erlang is not an indicator of process death/crashes,
		852	as linking is (except linking is unreliable in Erlang).
		853
		854	In AEMP, you don't "look up" registered port names or send to named ports
		855	that might or might not be persistent. Instead, you normally spawn a port
		856	on the remote node. The init function monitors the you, and you monitor
		857	the remote port. Since both monitors are local to the node, they are much
		858	more reliable.
		859
		860	This also saves round-trips and avoids sending messages to the wrong port
		861	(hard to do in Erlang).
		862
		863	=back
		864
		865	=head1 RATIONALE
		866
		867	=over 4
		868
		869	=item Why strings for ports and noderefs, why not objects?
		870
		871	We considered "objects", but found that the actual number of methods
		872	thatc an be called are very low. Since port IDs and noderefs travel over
		873	the network frequently, the serialising/deserialising would add lots of
		874	overhead, as well as having to keep a proxy object.
		875
		876	Strings can easily be printed, easily serialised etc. and need no special
		877	procedures to be "valid".
		878
		879	And a a miniport consists of a single closure stored in a global hash - it
		880	can't become much cheaper.
		881
		882	=item Why favour JSON, why not real serialising format such as Storable?
		883
		884	In fact, any AnyEvent::MP node will happily accept Storable as framing
		885	format, but currently there is no way to make a node use Storable by
		886	default.
		887
		888	The default framing protocol is JSON because a) JSON::XS is many times
		889	faster for small messages and b) most importantly, after years of
		890	experience we found that object serialisation is causing more problems
		891	than it gains: Just like function calls, objects simply do not travel
		892	easily over the network, mostly because they will always be a copy, so you
		893	always have to re-think your design.
		894
		895	Keeping your messages simple, concentrating on data structures rather than
		896	objects, will keep your messages clean, tidy and efficient.
		897
640	=back	898	=back
641		899
642	=head1 SEE ALSO	900	=head1 SEE ALSO
643		901
644	L<AnyEvent>.	902	L<AnyEvent>.

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Revision 1.29 by root, Tue Aug 4 23:16:57 2009 UTC vs.
Revision 1.48 by root, Thu Aug 13 02:59:42 2009 UTC