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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.22 by root, Tue Aug 4 18:33:30 2009 UTC vs.
Revision 1.51 by root, Fri Aug 14 14:07:44 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 ports, the simple way
		28	my $somple_port = port { my @msg = @_; 0 };
16		29
17	rcv $port, smartmatch => $cb->($port, @msg);	30	# creating/using ports, type matching
18		31	my $port = port;
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	32	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
21	rcv $port1, pong => sub { warn "pong received\n" };	33	rcv $port, pong => sub { warn "pong received\n"; 0 };
22	snd $port2, ping => $port1;
23		34
24	# more, smarter, matches (_any_ is exported by this module)	35	# create a port on another node
25	rcv $port, [child_died => $pid] => sub { ...	36	my $port = spawn $node, $initfunc, @initdata;
26	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
		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		46	AnyEvent::MP::Intro - outdated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.
27		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
33	on the same or other hosts.	57	on the same or other hosts.
34		58
		59	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
		60	manual page.
		61
35	At the moment, this module family is severly brokena nd underdocumented,	62	At the moment, this module family is severly broken and underdocumented,
36	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 -
37	stay tuned!	64	stay tuned!
38		65
39	=head1 CONCEPTS	66	=head1 CONCEPTS
40		67
41	=over 4	68	=over 4
42		69
43	=item port	70	=item port
44		71
45	A port is something you can send messages to with the C<snd> function, and	72	A port is something you can send messages to (with the C<snd> function).
46	you can register C<rcv> handlers with. All C<rcv> handlers will receive	73
47	messages they match, messages will not be queued.	74	Some ports allow you to register C<rcv> handlers that can match specific
		75	messages. All C<rcv> handlers will receive messages they match, messages
		76	will not be queued.
48		77
49	=item port id - C<noderef#portname>	78	=item port id - C<noderef#portname>
50		79
51	A port id is always the noderef, a hash-mark (C<#>) as separator, followed	80	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as
52	by a port name (a printable string of unspecified format).	81	separator, and a port name (a printable string of unspecified format). An
		82	exception is the the node port, whose ID is identical to its node
		83	reference.
53		84
54	=item node	85	=item node
55		86
56	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
57	port. You can send messages to node ports to let them create new ports,	88	port. You can send messages to node ports to find existing ports or to
58	among other things.	89	create new ports, among other things.
59		90
60	Initially, nodes are either private (single-process only) or hidden	91	Nodes are either private (single-process only), slaves (connected to a
61	(connected to a master node only). Only when they epxlicitly "become	92	master node only) or public nodes (connectable from unrelated nodes).
62	public" can you send them messages from unrelated other nodes.
63		93
64	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	94	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>
65		95
66	A noderef is a string that either uniquely identifies a given node (for	96	A node reference is a string that either simply identifies the node (for
67	private and hidden nodes), or contains a recipe on how to reach a given	97	private and slave nodes), or contains a recipe on how to reach a given
68	node (for public nodes).	98	node (for public nodes).
69		99
		100	This recipe is simply a comma-separated list of C<address:port> pairs (for
		101	TCP/IP, other protocols might look different).
		102
		103	Node references come in two flavours: resolved (containing only numerical
		104	addresses) or unresolved (where hostnames are used instead of addresses).
		105
		106	Before using an unresolved node reference in a message you first have to
		107	resolve it.
		108
70	=back	109	=back
71		110
72	=head1 VARIABLES/FUNCTIONS	111	=head1 VARIABLES/FUNCTIONS
73		112
74	=over 4	113	=over 4
75		114
76	=cut	115	=cut
77		116
78	package AnyEvent::MP;	117	package AnyEvent::MP;
79		118
80	use AnyEvent::MP::Base;	119	use AnyEvent::MP::Kernel;
81		120
82	use common::sense;	121	use common::sense;
83		122
84	use Carp ();	123	use Carp ();
85		124
86	use AE ();	125	use AE ();
87		126
88	use base "Exporter";	127	use base "Exporter";
89		128
90	our $VERSION = '0.02';	129	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		130
91	our @EXPORT = qw(	131	our @EXPORT = qw(
92	NODE $NODE *SELF node_of _any_	132	NODE $NODE *SELF node_of _any_
93	become_slave become_public	133	resolve_node initialise_node
94	snd rcv mon kil reg psub	134	snd rcv mon kil reg psub spawn
95	port	135	port
96	);	136	);
97		137
98	our $SELF;	138	our $SELF;
99		139
…		…
108	The C<NODE> function returns, and the C<$NODE> variable contains	148	The C<NODE> function returns, and the C<$NODE> variable contains
109	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
110	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
111	identifiers become invalid.	151	identifiers become invalid.
112		152
113	=item $noderef = node_of $portid	153	=item $noderef = node_of $port
114		154
115	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, $master...
		160
		161	Before a node can talk to other nodes on the network it has to initialise
		162	itself - the minimum a node needs to know is it's own name, and optionally
		163	it should know the noderefs of some other nodes in the network.
		164
		165	This function initialises a node - it must be called exactly once (or
		166	never) before calling other AnyEvent::MP functions.
		167
		168	All arguments (optionally except for the first) are noderefs, which can be
		169	either resolved or unresolved.
		170
		171	The first argument will be looked up in the configuration database first
		172	(if it is C<undef> then the current nodename will be used instead) to find
		173	the relevant configuration profile (see L<aemp>). If none is found then
		174	the default configuration is used. The configuration supplies additional
		175	seed/master nodes and can override the actual noderef.
		176
		177	There are two types of networked nodes, public nodes and slave nodes:
		178
		179	=over 4
		180
		181	=item public nodes
		182
		183	For public nodes, C<$noderef> (supplied either directly to
		184	C<initialise_node> or indirectly via a profile or the nodename) must be a
		185	noderef (possibly unresolved, in which case it will be resolved).
		186
		187	After resolving, the node will bind itself on all endpoints and try to
		188	connect to all additional C<$seednodes> that are specified. Seednodes are
		189	optional and can be used to quickly bootstrap the node into an existing
		190	network.
		191
		192	=item slave nodes
		193
		194	When the C<$noderef> (either as given or overriden by the config file)
		195	is the special string C<slave/>, then the node will become a slave
		196	node. Slave nodes cannot be contacted from outside and will route most of
		197	their traffic to the master node that they attach to.
		198
		199	At least one additional noderef is required (either by specifying it
		200	directly or because it is part of the configuration profile): The node
		201	will try to connect to all of them and will become a slave attached to the
		202	first node it can successfully connect to.
		203
		204	=back
		205
		206	This function will block until all nodes have been resolved and, for slave
		207	nodes, until it has successfully established a connection to a master
		208	server.
		209
		210	Example: become a public node listening on the guessed noderef, or the one
		211	specified via C<aemp> for the current node. This should be the most common
		212	form of invocation for "daemon"-type nodes.
		213
		214	initialise_node;
		215
		216	Example: become a slave node to any of the the seednodes specified via
		217	C<aemp>. This form is often used for commandline clients.
		218
		219	initialise_node "slave/";
		220
		221	Example: become a slave node to any of the specified master servers. This
		222	form is also often used for commandline clients.
		223
		224	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
		225
		226	Example: become a public node, and try to contact some well-known master
		227	servers to become part of the network.
		228
		229	initialise_node undef, "master1", "master2";
		230
		231	Example: become a public node listening on port C<4041>.
		232
		233	initialise_node 4041;
		234
		235	Example: become a public node, only visible on localhost port 4044.
		236
		237	initialise_node "localhost:4044";
		238
		239	=item $cv = resolve_node $noderef
		240
		241	Takes an unresolved node reference that may contain hostnames and
		242	abbreviated IDs, resolves all of them and returns a resolved node
		243	reference.
		244
		245	In addition to C<address:port> pairs allowed in resolved noderefs, the
		246	following forms are supported:
		247
		248	=over 4
		249
		250	=item the empty string
		251
		252	An empty-string component gets resolved as if the default port (4040) was
		253	specified.
		254
		255	=item naked port numbers (e.g. C<1234>)
		256
		257	These are resolved by prepending the local nodename and a colon, to be
		258	further resolved.
		259
		260	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
		261
		262	These are resolved by using AnyEvent::DNS to resolve them, optionally
		263	looking up SRV records for the C<aemp=4040> port, if no port was
		264	specified.
		265
		266	=back
116		267
117	=item $SELF	268	=item $SELF
118		269
119	Contains the current port id while executing C<rcv> callbacks or C<psub>	270	Contains the current port id while executing C<rcv> callbacks or C<psub>
120	blocks.	271	blocks.
…		…
123		274
124	Due to some quirks in how perl exports variables, it is impossible to	275	Due to some quirks in how perl exports variables, it is impossible to
125	just export C<$SELF>, all the symbols called C<SELF> are exported by this	276	just export C<$SELF>, all the symbols called C<SELF> are exported by this
126	module, but only C<$SELF> is currently used.	277	module, but only C<$SELF> is currently used.
127		278
128	=item snd $portid, type => @data	279	=item snd $port, type => @data
129		280
130	=item snd $portid, @msg	281	=item snd $port, @msg
131		282
132	Send the given message to the given port ID, which can identify either	283	Send the given message to the given port ID, which can identify either
133	a local or a remote port, and can be either a string or soemthignt hat	284	a local or a remote port, and can be either a string or soemthignt hat
134	stringifies a sa port ID (such as a port object :).	285	stringifies a sa port ID (such as a port object :).
135		286
…		…
145	JSON is used, then only strings, numbers and arrays and hashes consisting	296	JSON is used, then only strings, numbers and arrays and hashes consisting
146	of those are allowed (no objects). When Storable is used, then anything	297	of those are allowed (no objects). When Storable is used, then anything
147	that Storable can serialise and deserialise is allowed, and for the local	298	that Storable can serialise and deserialise is allowed, and for the local
148	node, anything can be passed.	299	node, anything can be passed.
149		300
150	=item kil $portid[, @reason]	301	=item $local_port = port
151		302
152	Kill the specified port with the given C<@reason>.	303	Create a new local port object and returns its port ID. Initially it has
		304	no callbacks set and will throw an error when it receives messages.
153		305
154	If no C<@reason> is specified, then the port is killed "normally" (linked	306	=item $local_port = port { my @msg = @_ }
155	ports will not be kileld, or even notified).
156		307
157	Otherwise, linked ports get killed with the same reason (second form of	308	Creates a new local port, and returns its ID. Semantically the same as
158	C<mon>, see below).	309	creating a port and calling C<rcv $port, $callback> on it.
159		310
160	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	311	The block will be called for every message received on the port, with the
161	will be reported as reason C<< die => $@ >>.	312	global variable C<$SELF> set to the port ID. Runtime errors will cause the
		313	port to be C<kil>ed. The message will be passed as-is, no extra argument
		314	(i.e. no port ID) will be passed to the callback.
162		315
163	Transport/communication errors are reported as C<< transport_error =>	316	If you want to stop/destroy the port, simply C<kil> it:
164	$message >>.
165		317
166	=item $guard = mon $portid, $cb->(@reason)	318	my $port = port {
167
168	=item $guard = mon $portid, $otherport
169
170	=item $guard = mon $portid, $otherport, @msg
171
172	Monitor the given port and do something when the port is killed.
173
174	In the first form, the callback is simply called with any number
175	of C<@reason> elements (no @reason means that the port was deleted
176	"normally"). Note also that I<< the callback B<must> never die >>, so use
177	C<eval> if unsure.
178
179	In the second form, the other port will be C<kil>'ed with C<@reason>, iff
180	a @reason was specified, i.e. on "normal" kils nothing happens, while
181	under all other conditions, the other port is killed with the same reason.
182
183	In the last form, a message of the form C<@msg, @reason> will be C<snd>.
184
185	Example: call a given callback when C<$port> is killed.
186
187	mon $port, sub { warn "port died because of <@_>\n" };
188
189	Example: kill ourselves when C<$port> is killed abnormally.
190
191	mon $port, $self;
192
193	Example: send us a restart message another C<$port> is killed.
194
195	mon $port, $self => "restart";
196
197	=cut
198
199	sub mon {
200	my ($noderef, $port, $cb) = ((split /#/, shift, 2), shift);
201
202	my $node = $NODE{$noderef} \|\| add_node $noderef;
203
204	#TODO: ports must not be references
205	if (!ref $cb or "AnyEvent::MP::Port" eq ref $cb) {
206	if (@_) {
207	# send a kill info message
208	my (@msg) = ($cb, @_);	319	my @msg = @_;
209	$cb = sub { snd @msg, @_ };
210	} else {
211	# simply kill other port
212	my $port = $cb;
213	$cb = sub { kil $port, @_ if @_ };
214	}	320	...
		321	kil $SELF;
215	}	322	};
216		323
217	$node->monitor ($port, $cb);	324	=cut
218		325
219	defined wantarray	326	sub rcv($@);
220	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }	327
		328	sub _kilme {
		329	die "received message on port without callback";
221	}	330	}
222
223	=item $guard = mon_guard $port, $ref, $ref...
224
225	Monitors the given C<$port> and keeps the passed references. When the port
226	is killed, the references will be freed.
227
228	Optionally returns a guard that will stop the monitoring.
229
230	This function is useful when you create e.g. timers or other watchers and
231	want to free them when the port gets killed:
232
233	$port->rcv (start => sub {
234	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
235	undef $timer if 0.9 < rand;
236	});
237	});
238
239	=cut
240
241	sub mon_guard {
242	my ($port, @refs) = @_;
243
244	mon $port, sub { 0 && @refs }
245	}
246
247	=item $local_port = port
248
249	Create a new local port object that supports message matching.
250
251	=item $portid = port { my @msg = @_; $finished }
252
253	Creates a "mini port", that is, a very lightweight port without any
254	pattern matching behind it, and returns its ID.
255
256	The block will be called for every message received on the port. When the
257	callback returns a true value its job is considered "done" and the port
258	will be destroyed. Otherwise it will stay alive.
259
260	The message will be passed as-is, no extra argument (i.e. no port id) will
261	be passed to the callback.
262
263	If you need the local port id in the callback, this works nicely:
264
265	my $port; $port = miniport {
266	snd $otherport, reply => $port;
267	};
268
269	=cut
270		331
271	sub port(;&) {	332	sub port(;&) {
272	my $id = "$UNIQ." . $ID++;	333	my $id = "$UNIQ." . $ID++;
273	my $port = "$NODE#$id";	334	my $port = "$NODE#$id";
274		335
275	if (@_) {	336	rcv $port, shift \|\| \&_kilme;
276	my $cb = shift;
277	$PORT{$id} = sub {
278	local $SELF = $port;
279	eval {
280	&$cb
281	and kil $id;
282	};
283	_self_die if $@;
284	};
285	} else {
286	my $self = bless {
287	id => "$NODE#$id",
288	}, "AnyEvent::MP::Port";
289
290	$PORT_DATA{$id} = $self;
291	$PORT{$id} = sub {
292	local $SELF = $port;
293
294	eval {
295	for (@{ $self->{rc0}{$_[0]} }) {
296	$_ && &{$_->[0]}
297	&& undef $_;
298	}
299
300	for (@{ $self->{rcv}{$_[0]} }) {
301	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
302	&& &{$_->[0]}
303	&& undef $_;
304	}
305
306	for (@{ $self->{any} }) {
307	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
308	&& &{$_->[0]}
309	&& undef $_;
310	}
311	};
312	_self_die if $@;
313	};
314	}
315		337
316	$port	338	$port
317	}	339	}
318		340
319	=item reg $portid, $name	341	=item rcv $local_port, $callback->(@msg)
320		342
321	Registers the given port under the name C<$name>. If the name already	343	Replaces the default callback on the specified port. There is no way to
322	exists it is replaced.	344	remove the default callback: use C<sub { }> to disable it, or better
		345	C<kil> the port when it is no longer needed.
323		346
324	A port can only be registered under one well known name.
325
326	A port automatically becomes unregistered when it is killed.
327
328	=cut
329
330	sub reg(@) {
331	my ($portid, $name) = @_;
332
333	$REG{$name} = $portid;
334	}
335
336	=item rcv $portid, tagstring => $callback->(@msg), ...
337
338	=item rcv $portid, $smartmatch => $callback->(@msg), ...
339
340	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
341
342	Register callbacks to be called on matching messages on the given port.
343
344	The callback has to return a true value when its work is done, after
345	which is will be removed, or a false value in which case it will stay
346	registered.
347
348	The global C<$SELF> (exported by this module) contains C<$portid> while	347	The global C<$SELF> (exported by this module) contains C<$port> while
349	executing the callback.	348	executing the callback. Runtime errors during callback execution will
		349	result in the port being C<kil>ed.
350		350
351	Runtime errors wdurign callback execution will result in the port being	351	The default callback received all messages not matched by a more specific
352	C<kil>ed.	352	C<tag> match.
353		353
354	If the match is an array reference, then it will be matched against the	354	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
355	first elements of the message, otherwise only the first element is being
356	matched.
357		355
358	Any element in the match that is specified as C<_any_> (a function	356	Register callbacks to be called on messages starting with the given tag on
359	exported by this module) matches any single element of the message.	357	the given port (and return the port), or unregister it (when C<$callback>
		358	is C<$undef>).
360		359
361	While not required, it is highly recommended that the first matching	360	The original message will be passed to the callback, after the first
362	element is a string identifying the message. The one-string-only match is	361	element (the tag) has been removed. The callback will use the same
363	also the most efficient match (by far).	362	environment as the default callback (see above).
		363
		364	Example: create a port and bind receivers on it in one go.
		365
		366	my $port = rcv port,
		367	msg1 => sub { ... },
		368	msg2 => sub { ... },
		369	;
		370
		371	Example: create a port, bind receivers and send it in a message elsewhere
		372	in one go:
		373
		374	snd $otherport, reply =>
		375	rcv port,
		376	msg1 => sub { ... },
		377	...
		378	;
364		379
365	=cut	380	=cut
366		381
367	sub rcv($@) {	382	sub rcv($@) {
		383	my $port = shift;
368	my ($noderef, $port) = split /#/, shift, 2;	384	my ($noderef, $portid) = split /#/, $port, 2;
369		385
370	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	386	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
371	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";	387	or Carp::croak "$port: rcv can only be called on local ports, caught";
372
373	my $self = $PORT_DATA{$port}
374	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
375
376	"AnyEvent::MP::Port" eq ref $self
377	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
378		388
379	while (@_) {	389	while (@_) {
380	my ($match, $cb) = splice @_, 0, 2;
381
382	if (!ref $match) {	390	if (ref $_[0]) {
383	push @{ $self->{rc0}{$match} }, [$cb];	391	if (my $self = $PORT_DATA{$portid}) {
384	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {	392	"AnyEvent::MP::Port" eq ref $self
385	my ($type, @match) = @$match;	393	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
386	@match	394
387	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]	395	$self->[2] = shift;
388	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
389	} else {	396	} else {
390	push @{ $self->{any} }, [$cb, $match];	397	my $cb = shift;
		398	$PORT{$portid} = sub {
		399	local $SELF = $port;
		400	eval { &$cb }; _self_die if $@;
		401	};
		402	}
		403	} elsif (defined $_[0]) {
		404	my $self = $PORT_DATA{$portid} \|\|= do {
		405	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
		406
		407	$PORT{$portid} = sub {
		408	local $SELF = $port;
		409
		410	if (my $cb = $self->[1]{$_[0]}) {
		411	shift;
		412	eval { &$cb }; _self_die if $@;
		413	} else {
		414	&{ $self->[0] };
		415	}
		416	};
		417
		418	$self
		419	};
		420
		421	"AnyEvent::MP::Port" eq ref $self
		422	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		423
		424	my ($tag, $cb) = splice @_, 0, 2;
		425
		426	if (defined $cb) {
		427	$self->[1]{$tag} = $cb;
		428	} else {
		429	delete $self->[1]{$tag};
		430	}
391	}	431	}
392	}	432	}
		433
		434	$port
393	}	435	}
394		436
395	=item $closure = psub { BLOCK }	437	=item $closure = psub { BLOCK }
396		438
397	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	439	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
…		…
428	$res	470	$res
429	}	471	}
430	}	472	}
431	}	473	}
432		474
433	=back	475	=item $guard = mon $port, $cb->(@reason)
434		476
435	=head1 FUNCTIONS FOR NODES	477	=item $guard = mon $port, $rcvport
436		478
437	=over 4	479	=item $guard = mon $port
438		480
439	=item become_public endpoint...	481	=item $guard = mon $port, $rcvport, @msg
440		482
441	Tells the node to become a public node, i.e. reachable from other nodes.	483	Monitor the given port and do something when the port is killed or
		484	messages to it were lost, and optionally return a guard that can be used
		485	to stop monitoring again.
442		486
443	If no arguments are given, or the first argument is C<undef>, then	487	C<mon> effectively guarantees that, in the absence of hardware failures,
444	AnyEvent::MP tries to bind on port C<4040> on all IP addresses that the	488	that after starting the monitor, either all messages sent to the port
445	local nodename resolves to.	489	will arrive, or the monitoring action will be invoked after possible
		490	message loss has been detected. No messages will be lost "in between"
		491	(after the first lost message no further messages will be received by the
		492	port). After the monitoring action was invoked, further messages might get
		493	delivered again.
446		494
447	Otherwise the first argument must be an array-reference with transport	495	In the first form (callback), the callback is simply called with any
448	endpoints ("ip:port", "hostname:port") or port numbers (in which case the	496	number of C<@reason> elements (no @reason means that the port was deleted
449	local nodename is used as hostname). The endpoints are all resolved and	497	"normally"). Note also that I<< the callback B<must> never die >>, so use
450	will become the node reference.	498	C<eval> if unsure.
451		499
		500	In the second form (another port given), the other port (C<$rcvport>)
		501	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
		502	"normal" kils nothing happens, while under all other conditions, the other
		503	port is killed with the same reason.
		504
		505	The third form (kill self) is the same as the second form, except that
		506	C<$rvport> defaults to C<$SELF>.
		507
		508	In the last form (message), a message of the form C<@msg, @reason> will be
		509	C<snd>.
		510
		511	As a rule of thumb, monitoring requests should always monitor a port from
		512	a local port (or callback). The reason is that kill messages might get
		513	lost, just like any other message. Another less obvious reason is that
		514	even monitoring requests can get lost (for exmaple, when the connection
		515	to the other node goes down permanently). When monitoring a port locally
		516	these problems do not exist.
		517
		518	Example: call a given callback when C<$port> is killed.
		519
		520	mon $port, sub { warn "port died because of <@_>\n" };
		521
		522	Example: kill ourselves when C<$port> is killed abnormally.
		523
		524	mon $port;
		525
		526	Example: send us a restart message when another C<$port> is killed.
		527
		528	mon $port, $self => "restart";
		529
452	=cut	530	=cut
		531
		532	sub mon {
		533	my ($noderef, $port) = split /#/, shift, 2;
		534
		535	my $node = $NODE{$noderef} \|\| add_node $noderef;
		536
		537	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
		538
		539	unless (ref $cb) {
		540	if (@_) {
		541	# send a kill info message
		542	my (@msg) = ($cb, @_);
		543	$cb = sub { snd @msg, @_ };
		544	} else {
		545	# simply kill other port
		546	my $port = $cb;
		547	$cb = sub { kil $port, @_ if @_ };
		548	}
		549	}
		550
		551	$node->monitor ($port, $cb);
		552
		553	defined wantarray
		554	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
		555	}
		556
		557	=item $guard = mon_guard $port, $ref, $ref...
		558
		559	Monitors the given C<$port> and keeps the passed references. When the port
		560	is killed, the references will be freed.
		561
		562	Optionally returns a guard that will stop the monitoring.
		563
		564	This function is useful when you create e.g. timers or other watchers and
		565	want to free them when the port gets killed:
		566
		567	$port->rcv (start => sub {
		568	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
		569	undef $timer if 0.9 < rand;
		570	});
		571	});
		572
		573	=cut
		574
		575	sub mon_guard {
		576	my ($port, @refs) = @_;
		577
		578	#TODO: mon-less form?
		579
		580	mon $port, sub { 0 && @refs }
		581	}
		582
		583	=item kil $port[, @reason]
		584
		585	Kill the specified port with the given C<@reason>.
		586
		587	If no C<@reason> is specified, then the port is killed "normally" (linked
		588	ports will not be kileld, or even notified).
		589
		590	Otherwise, linked ports get killed with the same reason (second form of
		591	C<mon>, see below).
		592
		593	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		594	will be reported as reason C<< die => $@ >>.
		595
		596	Transport/communication errors are reported as C<< transport_error =>
		597	$message >>.
		598
		599	=cut
		600
		601	=item $port = spawn $node, $initfunc[, @initdata]
		602
		603	Creates a port on the node C<$node> (which can also be a port ID, in which
		604	case it's the node where that port resides).
		605
		606	The port ID of the newly created port is return immediately, and it is
		607	permissible to immediately start sending messages or monitor the port.
		608
		609	After the port has been created, the init function is
		610	called. This function must be a fully-qualified function name
		611	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		612	program, use C<::name>.
		613
		614	If the function doesn't exist, then the node tries to C<require>
		615	the package, then the package above the package and so on (e.g.
		616	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		617	exists or it runs out of package names.
		618
		619	The init function is then called with the newly-created port as context
		620	object (C<$SELF>) and the C<@initdata> values as arguments.
		621
		622	A common idiom is to pass your own port, monitor the spawned port, and
		623	in the init function, monitor the original port. This two-way monitoring
		624	ensures that both ports get cleaned up when there is a problem.
		625
		626	Example: spawn a chat server port on C<$othernode>.
		627
		628	# this node, executed from within a port context:
		629	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		630	mon $server;
		631
		632	# init function on C<$othernode>
		633	sub connect {
		634	my ($srcport) = @_;
		635
		636	mon $srcport;
		637
		638	rcv $SELF, sub {
		639	...
		640	};
		641	}
		642
		643	=cut
		644
		645	sub _spawn {
		646	my $port = shift;
		647	my $init = shift;
		648
		649	local $SELF = "$NODE#$port";
		650	eval {
		651	&{ load_func $init }
		652	};
		653	_self_die if $@;
		654	}
		655
		656	sub spawn(@) {
		657	my ($noderef, undef) = split /#/, shift, 2;
		658
		659	my $id = "$RUNIQ." . $ID++;
		660
		661	$_[0] =~ /::/
		662	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		663
		664	($NODE{$noderef} \|\| add_node $noderef)
		665	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
		666
		667	"$noderef#$id"
		668	}
453		669
454	=back	670	=back
455		671
456	=head1 NODE MESSAGES	672	=head1 NODE MESSAGES
457		673
458	Nodes understand the following messages sent to them. Many of them take	674	Nodes understand the following messages sent to them. Many of them take
459	arguments called C<@reply>, which will simply be used to compose a reply	675	arguments called C<@reply>, which will simply be used to compose a reply
460	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and	676	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
461	the remaining arguments are simply the message data.	677	the remaining arguments are simply the message data.
462		678
		679	While other messages exist, they are not public and subject to change.
		680
463	=over 4	681	=over 4
464		682
465	=cut	683	=cut
466		684
467	=item lookup => $name, @reply	685	=item lookup => $name, @reply
…		…
495	snd $NODE, time => $myport, timereply => 1, 2;	713	snd $NODE, time => $myport, timereply => 1, 2;
496	# => snd $myport, timereply => 1, 2, <time>	714	# => snd $myport, timereply => 1, 2, <time>
497		715
498	=back	716	=back
499		717
		718	=head1 AnyEvent::MP vs. Distributed Erlang
		719
		720	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
		721	== aemp node, Erlang process == aemp port), so many of the documents and
		722	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		723	sample:
		724
		725	http://www.Erlang.se/doc/programming_rules.shtml
		726	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		727	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		728	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		729
		730	Despite the similarities, there are also some important differences:
		731
		732	=over 4
		733
		734	=item * Node references contain the recipe on how to contact them.
		735
		736	Erlang relies on special naming and DNS to work everywhere in the
		737	same way. AEMP relies on each node knowing it's own address(es), with
		738	convenience functionality.
		739
		740	This means that AEMP requires a less tightly controlled environment at the
		741	cost of longer node references and a slightly higher management overhead.
		742
		743	=item Erlang has a "remote ports are like local ports" philosophy, AEMP
		744	uses "local ports are like remote ports".
		745
		746	The failure modes for local ports are quite different (runtime errors
		747	only) then for remote ports - when a local port dies, you I<know> it dies,
		748	when a connection to another node dies, you know nothing about the other
		749	port.
		750
		751	Erlang pretends remote ports are as reliable as local ports, even when
		752	they are not.
		753
		754	AEMP encourages a "treat remote ports differently" philosophy, with local
		755	ports being the special case/exception, where transport errors cannot
		756	occur.
		757
		758	=item * Erlang uses processes and a mailbox, AEMP does not queue.
		759
		760	Erlang uses processes that selectively receive messages, and therefore
		761	needs a queue. AEMP is event based, queuing messages would serve no
		762	useful purpose. For the same reason the pattern-matching abilities of
		763	AnyEvent::MP are more limited, as there is little need to be able to
		764	filter messages without dequeing them.
		765
		766	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
		767
		768	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
		769
		770	Sending messages in Erlang is synchronous and blocks the process (and
		771	so does not need a queue that can overflow). AEMP sends are immediate,
		772	connection establishment is handled in the background.
		773
		774	=item * Erlang suffers from silent message loss, AEMP does not.
		775
		776	Erlang makes few guarantees on messages delivery - messages can get lost
		777	without any of the processes realising it (i.e. you send messages a, b,
		778	and c, and the other side only receives messages a and c).
		779
		780	AEMP guarantees correct ordering, and the guarantee that there are no
		781	holes in the message sequence.
		782
		783	=item * In Erlang, processes can be declared dead and later be found to be
		784	alive.
		785
		786	In Erlang it can happen that a monitored process is declared dead and
		787	linked processes get killed, but later it turns out that the process is
		788	still alive - and can receive messages.
		789
		790	In AEMP, when port monitoring detects a port as dead, then that port will
		791	eventually be killed - it cannot happen that a node detects a port as dead
		792	and then later sends messages to it, finding it is still alive.
		793
		794	=item * Erlang can send messages to the wrong port, AEMP does not.
		795
		796	In Erlang it is quite likely that a node that restarts reuses a process ID
		797	known to other nodes for a completely different process, causing messages
		798	destined for that process to end up in an unrelated process.
		799
		800	AEMP never reuses port IDs, so old messages or old port IDs floating
		801	around in the network will not be sent to an unrelated port.
		802
		803	=item * Erlang uses unprotected connections, AEMP uses secure
		804	authentication and can use TLS.
		805
		806	AEMP can use a proven protocol - SSL/TLS - to protect connections and
		807	securely authenticate nodes.
		808
		809	=item * The AEMP protocol is optimised for both text-based and binary
		810	communications.
		811
		812	The AEMP protocol, unlike the Erlang protocol, supports both
		813	language-independent text-only protocols (good for debugging) and binary,
		814	language-specific serialisers (e.g. Storable).
		815
		816	It has also been carefully designed to be implementable in other languages
		817	with a minimum of work while gracefully degrading fucntionality to make the
		818	protocol simple.
		819
		820	=item * AEMP has more flexible monitoring options than Erlang.
		821
		822	In Erlang, you can chose to receive I<all> exit signals as messages
		823	or I<none>, there is no in-between, so monitoring single processes is
		824	difficult to implement. Monitoring in AEMP is more flexible than in
		825	Erlang, as one can choose between automatic kill, exit message or callback
		826	on a per-process basis.
		827
		828	=item * Erlang tries to hide remote/local connections, AEMP does not.
		829
		830	Monitoring in Erlang is not an indicator of process death/crashes,
		831	as linking is (except linking is unreliable in Erlang).
		832
		833	In AEMP, you don't "look up" registered port names or send to named ports
		834	that might or might not be persistent. Instead, you normally spawn a port
		835	on the remote node. The init function monitors the you, and you monitor
		836	the remote port. Since both monitors are local to the node, they are much
		837	more reliable.
		838
		839	This also saves round-trips and avoids sending messages to the wrong port
		840	(hard to do in Erlang).
		841
		842	=back
		843
		844	=head1 RATIONALE
		845
		846	=over 4
		847
		848	=item Why strings for ports and noderefs, why not objects?
		849
		850	We considered "objects", but found that the actual number of methods
		851	thatc an be called are very low. Since port IDs and noderefs travel over
		852	the network frequently, the serialising/deserialising would add lots of
		853	overhead, as well as having to keep a proxy object.
		854
		855	Strings can easily be printed, easily serialised etc. and need no special
		856	procedures to be "valid".
		857
		858	And a a miniport consists of a single closure stored in a global hash - it
		859	can't become much cheaper.
		860
		861	=item Why favour JSON, why not real serialising format such as Storable?
		862
		863	In fact, any AnyEvent::MP node will happily accept Storable as framing
		864	format, but currently there is no way to make a node use Storable by
		865	default.
		866
		867	The default framing protocol is JSON because a) JSON::XS is many times
		868	faster for small messages and b) most importantly, after years of
		869	experience we found that object serialisation is causing more problems
		870	than it gains: Just like function calls, objects simply do not travel
		871	easily over the network, mostly because they will always be a copy, so you
		872	always have to re-think your design.
		873
		874	Keeping your messages simple, concentrating on data structures rather than
		875	objects, will keep your messages clean, tidy and efficient.
		876
		877	=back
		878
500	=head1 SEE ALSO	879	=head1 SEE ALSO
501		880
502	L<AnyEvent>.	881	L<AnyEvent>.
503		882
504	=head1 AUTHOR	883	=head1 AUTHOR

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.22 by root, Tue Aug 4 18:33:30 2009 UTC vs. Revision 1.51 by root, Fri Aug 14 14:07:44 2009 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.22 by root, Tue Aug 4 18:33:30 2009 UTC vs.
Revision 1.51 by root, Fri Aug 14 14:07:44 2009 UTC