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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.32 by root, Wed Aug 5 19:58:46 2009 UTC vs.
Revision 1.69 by root, Sun Aug 30 18:51:49 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;
		17
		18	# ports are message endpoints
		19
		20	# sending messages
13	snd $port, type => data...;	21	snd $port, type => data...;
		22	snd $port, @msg;
		23	snd @msg_with_first_element_being_a_port;
14		24
15	$SELF # receiving/own port id in rcv callbacks	25	# creating/using ports, the simple way
		26	my $simple_port = port { my @msg = @_; 0 };
16		27
17	rcv $port, smartmatch => $cb->($port, @msg);	28	# creating/using ports, tagged message matching
18		29	my $port = port;
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	30	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
21	rcv $port1, pong => sub { warn "pong received\n" };	31	rcv $port, pong => sub { warn "pong received\n"; 0 };
22	snd $port2, ping => $port1;
23		32
24	# more, smarter, matches (_any_ is exported by this module)	33	# create a port on another node
25	rcv $port, [child_died => $pid] => sub { ...	34	my $port = spawn $node, $initfunc, @initdata;
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	35
		36	# monitoring
		37	mon $port, $cb->(@msg) # callback is invoked on death
		38	mon $port, $otherport # kill otherport on abnormal death
		39	mon $port, $otherport, @msg # send message on death
		40
		41	=head1 CURRENT STATUS
		42
		43	AnyEvent::MP - stable API, should work
		44	AnyEvent::MP::Intro - outdated
		45	AnyEvent::MP::Kernel - mostly stable
		46	AnyEvent::MP::Global - mostly stable
		47	AnyEvent::MP::Node - mostly stable, but internal anyways
		48	AnyEvent::MP::Transport - mostly stable, but internal anyways
		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, and you can supervise entities remotely.
34		58
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 and the examples under F<eg/>.
37		61
38	At the moment, this module family is severly broken and underdocumented,	62	At the moment, this module family is a bit underdocumented.
39	so do not use. This was uploaded mainly to reserve the CPAN namespace -
40	stay tuned! The basic API should be finished, however.
41		63
42	=head1 CONCEPTS	64	=head1 CONCEPTS
43		65
44	=over 4	66	=over 4
45		67
46	=item port	68	=item port
47		69
48	A port is something you can send messages to (with the C<snd> function).	70	A port is something you can send messages to (with the C<snd> function).
49		71
50	Some ports allow you to register C<rcv> handlers that can match specific	72	Ports allow you to register C<rcv> handlers that can match all or just
51	messages. All C<rcv> handlers will receive messages they match, messages	73	some messages. Messages send to ports will not be queued, regardless of
52	will not be queued.	74	anything was listening for them or not.
53		75
54	=item port id - C<noderef#portname>	76	=item port ID - C<nodeid#portname>
55		77
56	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	78	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as
57	separator, and a port name (a printable string of unspecified format). An	79	separator, and a port name (a printable string of unspecified format).
58	exception is the the node port, whose ID is identical to its node
59	reference.
60		80
61	=item node	81	=item node
62		82
63	A node is a single process containing at least one port - the node	83	A node is a single process containing at least one port - the node port,
64	port. You can send messages to node ports to find existing ports or to	84	which enables nodes to manage each other remotely, and to create new
65	create new ports, among other things.	85	ports.
66		86
67	Nodes are either private (single-process only), slaves (connected to a	87	Nodes are either public (have one or more listening ports) or private
68	master node only) or public nodes (connectable from unrelated nodes).	88	(no listening ports). Private nodes cannot talk to other private nodes
		89	currently.
69		90
70	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	91	=item node ID - C<[a-za-Z0-9_\-.:]+>
71		92
72	A node reference is a string that either simply identifies the node (for	93	A node ID is a string that uniquely identifies the node within a
73	private and slave nodes), or contains a recipe on how to reach a given	94	network. Depending on the configuration used, node IDs can look like a
74	node (for public nodes).	95	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
		96	doesn't interpret node IDs in any way.
75		97
76	This recipe is simply a comma-separated list of C<address:port> pairs (for	98	=item binds - C<ip:port>
77	TCP/IP, other protocols might look different).
78		99
79	Node references come in two flavours: resolved (containing only numerical	100	Nodes can only talk to each other by creating some kind of connection to
80	addresses) or unresolved (where hostnames are used instead of addresses).	101	each other. To do this, nodes should listen on one or more local transport
		102	endpoints - binds. Currently, only standard C<ip:port> specifications can
		103	be used, which specify TCP ports to listen on.
81		104
82	Before using an unresolved node reference in a message you first have to	105	=item seeds - C<host:port>
83	resolve it.	106
		107	When a node starts, it knows nothing about the network. To teach the node
		108	about the network it first has to contact some other node within the
		109	network. This node is called a seed.
		110
		111	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes
		112	are expected to be long-running, and at least one of those should always
		113	be available. When nodes run out of connections (e.g. due to a network
		114	error), they try to re-establish connections to some seednodes again to
		115	join the network.
		116
		117	Apart from being sued for seeding, seednodes are not special in any way -
		118	every public node can be a seednode.
84		119
85	=back	120	=back
86		121
87	=head1 VARIABLES/FUNCTIONS	122	=head1 VARIABLES/FUNCTIONS
88		123
…		…
90		125
91	=cut	126	=cut
92		127
93	package AnyEvent::MP;	128	package AnyEvent::MP;
94		129
95	use AnyEvent::MP::Base;	130	use AnyEvent::MP::Kernel;
96		131
97	use common::sense;	132	use common::sense;
98		133
99	use Carp ();	134	use Carp ();
100		135
101	use AE ();	136	use AE ();
102		137
103	use base "Exporter";	138	use base "Exporter";
104		139
105	our $VERSION = '0.1';	140	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		141
106	our @EXPORT = qw(	142	our @EXPORT = qw(
107	NODE $NODE *SELF node_of _any_	143	NODE $NODE *SELF node_of after
108	resolve_node initialise_node	144	initialise_node
109	snd rcv mon kil reg psub	145	snd rcv mon mon_guard kil reg psub spawn
110	port	146	port
111	);	147	);
112		148
113	our $SELF;	149	our $SELF;
114		150
…		…
118	kil $SELF, die => $msg;	154	kil $SELF, die => $msg;
119	}	155	}
120		156
121	=item $thisnode = NODE / $NODE	157	=item $thisnode = NODE / $NODE
122		158
123	The C<NODE> function returns, and the C<$NODE> variable contains	159	The C<NODE> function returns, and the C<$NODE> variable contains, the node
124	the noderef of the local node. The value is initialised by a call	160	ID of the node running in the current process. This value is initialised by
125	to C<become_public> or C<become_slave>, after which all local port	161	a call to C<initialise_node>.
126	identifiers become invalid.
127		162
128	=item $noderef = node_of $portid	163	=item $nodeid = node_of $port
129		164
130	Extracts and returns the noderef from a portid or a noderef.	165	Extracts and returns the node ID from a port ID or a node ID.
131		166
132	=item $cv = resolve_node $noderef	167	=item initialise_node $profile_name, key => value...
133		168
134	Takes an unresolved node reference that may contain hostnames and	169	Before a node can talk to other nodes on the network (i.e. enter
135	abbreviated IDs, resolves all of them and returns a resolved node	170	"distributed mode") it has to initialise itself - the minimum a node needs
136	reference.	171	to know is its own name, and optionally it should know the addresses of
		172	some other nodes in the network to discover other nodes.
137		173
138	In addition to C<address:port> pairs allowed in resolved noderefs, the	174	This function initialises a node - it must be called exactly once (or
139	following forms are supported:	175	never) before calling other AnyEvent::MP functions.
140		176
141	=over 4	177	The first argument is a profile name. If it is C<undef> or missing, then
		178	the current nodename will be used instead (i.e. F<uname -n>).
142		179
143	=item the empty string	180	The function first looks up the profile in the aemp configuration (see the
		181	L<aemp> commandline utility). the profile is calculated as follows:
144		182
145	An empty-string component gets resolved as if the default port (4040) was	183	First, all remaining key => value pairs will be used. Then they will be
146	specified.	184	overwritten by any values specified in the global default configuration
		185	(see the F<aemp> utility), then the chain of profiles selected, if
		186	any. That means that the values specified in the profile have highest
		187	priority and the values specified via C<initialise_node> have lowest
		188	priority.
147		189
148	=item naked port numbers (e.g. C<1234>)	190	If the profile specifies a node ID, then this will become the node ID of
		191	this process. If not, then the profile name will be used as node ID. The
		192	special node ID of C<anon/> will be replaced by a random node ID.
149		193
150	These are resolved by prepending the local nodename and a colon, to be	194	The next step is to look up the binds in the profile, followed by binding
151	further resolved.	195	aemp protocol listeners on all binds specified (it is possible and valid
		196	to have no binds, meaning that the node cannot be contacted form the
		197	outside. This means the node cannot talk to other nodes that also have no
		198	binds, but it can still talk to all "normal" nodes).
152		199
153	=item hostnames (e.g. C<localhost:1234>, C<localhost>)	200	If the profile does not specify a binds list, then the node ID will be
		201	treated as if it were of the form C<host:port>, which will be resolved and
		202	used as binds list.
154		203
155	These are resolved by using AnyEvent::DNS to resolve them, optionally	204	Lastly, the seeds list from the profile is passed to the
156	looking up SRV records for the C<aemp=4040> port, if no port was	205	L<AnyEvent::MP::Global> module, which will then use it to keep
157	specified.	206	connectivity with at least on of those seed nodes at any point in time.
158		207
159	=back	208	Example: become a distributed node listening on the guessed noderef, or
		209	the one specified via C<aemp> for the current node. This should be the
		210	most common form of invocation for "daemon"-type nodes.
		211
		212	initialise_node;
		213
		214	Example: become an anonymous node. This form is often used for commandline
		215	clients.
		216
		217	initialise_node "anon/";
		218
		219	Example: become a distributed node. If there is no profile of the given
		220	name, or no binds list was specified, resolve C<localhost:4044> and bind
		221	on the resulting addresses.
		222
		223	initialise_node "localhost:4044";
160		224
161	=item $SELF	225	=item $SELF
162		226
163	Contains the current port id while executing C<rcv> callbacks or C<psub>	227	Contains the current port id while executing C<rcv> callbacks or C<psub>
164	blocks.	228	blocks.
165		229
166	=item SELF, %SELF, @SELF...	230	=item *SELF, SELF, %SELF, @SELF...
167		231
168	Due to some quirks in how perl exports variables, it is impossible to	232	Due to some quirks in how perl exports variables, it is impossible to
169	just export C<$SELF>, all the symbols called C<SELF> are exported by this	233	just export C<$SELF>, all the symbols named C<SELF> are exported by this
170	module, but only C<$SELF> is currently used.	234	module, but only C<$SELF> is currently used.
171		235
172	=item snd $portid, type => @data	236	=item snd $port, type => @data
173		237
174	=item snd $portid, @msg	238	=item snd $port, @msg
175		239
176	Send the given message to the given port ID, which can identify either	240	Send the given message to the given port, which can identify either a
177	a local or a remote port, and can be either a string or soemthignt hat	241	local or a remote port, and must be a port ID.
178	stringifies a sa port ID (such as a port object :).
179		242
180	While the message can be about anything, it is highly recommended to use a	243	While the message can be almost anything, it is highly recommended to
181	string as first element (a portid, or some word that indicates a request	244	use a string as first element (a port ID, or some word that indicates a
182	type etc.).	245	request type etc.) and to consist if only simple perl values (scalars,
		246	arrays, hashes) - if you think you need to pass an object, think again.
183		247
184	The message data effectively becomes read-only after a call to this	248	The message data logically becomes read-only after a call to this
185	function: modifying any argument is not allowed and can cause many	249	function: modifying any argument (or values referenced by them) is
186	problems.	250	forbidden, as there can be considerable time between the call to C<snd>
		251	and the time the message is actually being serialised - in fact, it might
		252	never be copied as within the same process it is simply handed to the
		253	receiving port.
187		254
188	The type of data you can transfer depends on the transport protocol: when	255	The type of data you can transfer depends on the transport protocol: when
189	JSON is used, then only strings, numbers and arrays and hashes consisting	256	JSON is used, then only strings, numbers and arrays and hashes consisting
190	of those are allowed (no objects). When Storable is used, then anything	257	of those are allowed (no objects). When Storable is used, then anything
191	that Storable can serialise and deserialise is allowed, and for the local	258	that Storable can serialise and deserialise is allowed, and for the local
192	node, anything can be passed.	259	node, anything can be passed. Best rely only on the common denominator of
		260	these.
193		261
194	=item $local_port = port	262	=item $local_port = port
195		263
196	Create a new local port object that can be used either as a pattern	264	Create a new local port object and returns its port ID. Initially it has
197	matching port ("full port") or a single-callback port ("miniport"),	265	no callbacks set and will throw an error when it receives messages.
198	depending on how C<rcv> callbacks are bound to the object.
199		266
200	=item $portid = port { my @msg = @_; $finished }	267	=item $local_port = port { my @msg = @_ }
201		268
202	Creates a "mini port", that is, a very lightweight port without any	269	Creates a new local port, and returns its ID. Semantically the same as
203	pattern matching behind it, and returns its ID.	270	creating a port and calling C<rcv $port, $callback> on it.
204		271
205	The block will be called for every message received on the port. When the	272	The block will be called for every message received on the port, with the
206	callback returns a true value its job is considered "done" and the port	273	global variable C<$SELF> set to the port ID. Runtime errors will cause the
207	will be destroyed. Otherwise it will stay alive.	274	port to be C<kil>ed. The message will be passed as-is, no extra argument
		275	(i.e. no port ID) will be passed to the callback.
208		276
209	The message will be passed as-is, no extra argument (i.e. no port id) will	277	If you want to stop/destroy the port, simply C<kil> it:
210	be passed to the callback.
211		278
212	If you need the local port id in the callback, this works nicely:	279	my $port = port {
213		280	my @msg = @_;
214	my $port; $port = port {	281	...
215	snd $otherport, reply => $port;	282	kil $SELF;
216	};	283	};
217		284
218	=cut	285	=cut
		286
		287	sub rcv($@);
		288
		289	sub _kilme {
		290	die "received message on port without callback";
		291	}
219		292
220	sub port(;&) {	293	sub port(;&) {
221	my $id = "$UNIQ." . $ID++;	294	my $id = "$UNIQ." . $ID++;
222	my $port = "$NODE#$id";	295	my $port = "$NODE#$id";
223		296
		297	rcv $port, shift \|\| \&_kilme;
		298
		299	$port
		300	}
		301
		302	=item rcv $local_port, $callback->(@msg)
		303
		304	Replaces the default callback on the specified port. There is no way to
		305	remove the default callback: use C<sub { }> to disable it, or better
		306	C<kil> the port when it is no longer needed.
		307
		308	The global C<$SELF> (exported by this module) contains C<$port> while
		309	executing the callback. Runtime errors during callback execution will
		310	result in the port being C<kil>ed.
		311
		312	The default callback received all messages not matched by a more specific
		313	C<tag> match.
		314
		315	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
		316
		317	Register (or replace) callbacks to be called on messages starting with the
		318	given tag on the given port (and return the port), or unregister it (when
		319	C<$callback> is C<$undef> or missing). There can only be one callback
		320	registered for each tag.
		321
		322	The original message will be passed to the callback, after the first
		323	element (the tag) has been removed. The callback will use the same
		324	environment as the default callback (see above).
		325
		326	Example: create a port and bind receivers on it in one go.
		327
		328	my $port = rcv port,
		329	msg1 => sub { ... },
		330	msg2 => sub { ... },
		331	;
		332
		333	Example: create a port, bind receivers and send it in a message elsewhere
		334	in one go:
		335
		336	snd $otherport, reply =>
		337	rcv port,
		338	msg1 => sub { ... },
		339	...
		340	;
		341
		342	Example: temporarily register a rcv callback for a tag matching some port
		343	(e.g. for a rpc reply) and unregister it after a message was received.
		344
		345	rcv $port, $otherport => sub {
		346	my @reply = @_;
		347
		348	rcv $SELF, $otherport;
		349	};
		350
		351	=cut
		352
		353	sub rcv($@) {
		354	my $port = shift;
		355	my ($noderef, $portid) = split /#/, $port, 2;
		356
		357	$NODE{$noderef} == $NODE{""}
		358	or Carp::croak "$port: rcv can only be called on local ports, caught";
		359
224	if (@_) {	360	while (@_) {
		361	if (ref $_[0]) {
		362	if (my $self = $PORT_DATA{$portid}) {
		363	"AnyEvent::MP::Port" eq ref $self
		364	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		365
		366	$self->[2] = shift;
		367	} else {
225	my $cb = shift;	368	my $cb = shift;
226	$PORT{$id} = sub {	369	$PORT{$portid} = sub {
227	local $SELF = $port;	370	local $SELF = $port;
228	eval {	371	eval { &$cb }; _self_die if $@;
229	&$cb	372	};
230	and kil $id;	373	}
		374	} elsif (defined $_[0]) {
		375	my $self = $PORT_DATA{$portid} \|\|= do {
		376	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
		377
		378	$PORT{$portid} = sub {
		379	local $SELF = $port;
		380
		381	if (my $cb = $self->[1]{$_[0]}) {
		382	shift;
		383	eval { &$cb }; _self_die if $@;
		384	} else {
		385	&{ $self->[0] };
		386	}
		387	};
		388
		389	$self
231	};	390	};
232	_self_die if $@;	391
233	};
234	} else {
235	my $self = bless {
236	id => "$NODE#$id",
237	}, "AnyEvent::MP::Port";	392	"AnyEvent::MP::Port" eq ref $self
		393	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
238		394
239	$PORT_DATA{$id} = $self;	395	my ($tag, $cb) = splice @_, 0, 2;
240	$PORT{$id} = sub {
241	local $SELF = $port;
242		396
		397	if (defined $cb) {
		398	$self->[1]{$tag} = $cb;
243	eval {	399	} else {
244	for (@{ $self->{rc0}{$_[0]} }) {	400	delete $self->[1]{$tag};
245	$_ && &{$_->[0]}
246	&& undef $_;
247	}
248
249	for (@{ $self->{rcv}{$_[0]} }) {
250	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
251	&& &{$_->[0]}
252	&& undef $_;
253	}
254
255	for (@{ $self->{any} }) {
256	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
257	&& &{$_->[0]}
258	&& undef $_;
259	}
260	};	401	}
261	_self_die if $@;
262	};
263	}
264
265	$port
266	}
267
268	=item reg $portid, $name
269
270	Registers the given port under the name C<$name>. If the name already
271	exists it is replaced.
272
273	A port can only be registered under one well known name.
274
275	A port automatically becomes unregistered when it is killed.
276
277	=cut
278
279	sub reg(@) {
280	my ($portid, $name) = @_;
281
282	$REG{$name} = $portid;
283	}
284
285	=item rcv $portid, $callback->(@msg)
286
287	Replaces the callback on the specified miniport (or newly created port
288	object, see C<port>). Full ports are configured with the following calls:
289
290	=item rcv $portid, tagstring => $callback->(@msg), ...
291
292	=item rcv $portid, $smartmatch => $callback->(@msg), ...
293
294	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
295
296	Register callbacks to be called on matching messages on the given full
297	port (or newly created port).
298
299	The callback has to return a true value when its work is done, after
300	which is will be removed, or a false value in which case it will stay
301	registered.
302
303	The global C<$SELF> (exported by this module) contains C<$portid> while
304	executing the callback.
305
306	Runtime errors wdurign callback execution will result in the port being
307	C<kil>ed.
308
309	If the match is an array reference, then it will be matched against the
310	first elements of the message, otherwise only the first element is being
311	matched.
312
313	Any element in the match that is specified as C<_any_> (a function
314	exported by this module) matches any single element of the message.
315
316	While not required, it is highly recommended that the first matching
317	element is a string identifying the message. The one-string-only match is
318	also the most efficient match (by far).
319
320	=cut
321
322	sub rcv($@) {
323	my $portid = shift;
324	my ($noderef, $port) = split /#/, $port, 2;
325
326	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
327	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";
328
329	my $self = $PORT_DATA{$port}
330	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
331
332	"AnyEvent::MP::Port" eq ref $self
333	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
334
335	while (@_) {
336	my ($match, $cb) = splice @_, 0, 2;
337
338	if (!ref $match) {
339	push @{ $self->{rc0}{$match} }, [$cb];
340	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
341	my ($type, @match) = @$match;
342	@match
343	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
344	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
345	} else {
346	push @{ $self->{any} }, [$cb, $match];
347	}	402	}
348	}	403	}
349		404
350	$portid	405	$port
351	}	406	}
352		407
353	=item $closure = psub { BLOCK }	408	=item $closure = psub { BLOCK }
354		409
355	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	410	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
…		…
386	$res	441	$res
387	}	442	}
388	}	443	}
389	}	444	}
390		445
391	=item $guard = mon $portid, $cb->(@reason)	446	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
392		447
393	=item $guard = mon $portid, $otherport	448	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
394		449
395	=item $guard = mon $portid, $otherport, @msg	450	=item $guard = mon $port # kill $SELF when $port dies
396		451
		452	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
		453
397	Monitor the given port and do something when the port is killed.	454	Monitor the given port and do something when the port is killed or
		455	messages to it were lost, and optionally return a guard that can be used
		456	to stop monitoring again.
398		457
		458	C<mon> effectively guarantees that, in the absence of hardware failures,
		459	after starting the monitor, either all messages sent to the port will
		460	arrive, or the monitoring action will be invoked after possible message
		461	loss has been detected. No messages will be lost "in between" (after
		462	the first lost message no further messages will be received by the
		463	port). After the monitoring action was invoked, further messages might get
		464	delivered again.
		465
		466	Note that monitoring-actions are one-shot: once messages are lost (and a
		467	monitoring alert was raised), they are removed and will not trigger again.
		468
399	In the first form, the callback is simply called with any number	469	In the first form (callback), the callback is simply called with any
400	of C<@reason> elements (no @reason means that the port was deleted	470	number of C<@reason> elements (no @reason means that the port was deleted
401	"normally"). Note also that I<< the callback B<must> never die >>, so use	471	"normally"). Note also that I<< the callback B<must> never die >>, so use
402	C<eval> if unsure.	472	C<eval> if unsure.
403		473
404	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	474	In the second form (another port given), the other port (C<$rcvport>)
405	a @reason was specified, i.e. on "normal" kils nothing happens, while	475	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
406	under all other conditions, the other port is killed with the same reason.	476	"normal" kils nothing happens, while under all other conditions, the other
		477	port is killed with the same reason.
407		478
		479	The third form (kill self) is the same as the second form, except that
		480	C<$rvport> defaults to C<$SELF>.
		481
408	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	482	In the last form (message), a message of the form C<@msg, @reason> will be
		483	C<snd>.
		484
		485	As a rule of thumb, monitoring requests should always monitor a port from
		486	a local port (or callback). The reason is that kill messages might get
		487	lost, just like any other message. Another less obvious reason is that
		488	even monitoring requests can get lost (for exmaple, when the connection
		489	to the other node goes down permanently). When monitoring a port locally
		490	these problems do not exist.
409		491
410	Example: call a given callback when C<$port> is killed.	492	Example: call a given callback when C<$port> is killed.
411		493
412	mon $port, sub { warn "port died because of <@_>\n" };	494	mon $port, sub { warn "port died because of <@_>\n" };
413		495
414	Example: kill ourselves when C<$port> is killed abnormally.	496	Example: kill ourselves when C<$port> is killed abnormally.
415		497
416	mon $port, $self;	498	mon $port;
417		499
418	Example: send us a restart message another C<$port> is killed.	500	Example: send us a restart message when another C<$port> is killed.
419		501
420	mon $port, $self => "restart";	502	mon $port, $self => "restart";
421		503
422	=cut	504	=cut
423		505
424	sub mon {	506	sub mon {
425	my ($noderef, $port) = split /#/, shift, 2;	507	my ($noderef, $port) = split /#/, shift, 2;
426		508
427	my $node = $NODE{$noderef} \|\| add_node $noderef;	509	my $node = $NODE{$noderef} \|\| add_node $noderef;
428		510
429	my $cb = shift;	511	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
430		512
431	unless (ref $cb) {	513	unless (ref $cb) {
432	if (@_) {	514	if (@_) {
433	# send a kill info message	515	# send a kill info message
434	my (@msg) = ($cb, @_);	516	my (@msg) = ($cb, @_);
…		…
452	is killed, the references will be freed.	534	is killed, the references will be freed.
453		535
454	Optionally returns a guard that will stop the monitoring.	536	Optionally returns a guard that will stop the monitoring.
455		537
456	This function is useful when you create e.g. timers or other watchers and	538	This function is useful when you create e.g. timers or other watchers and
457	want to free them when the port gets killed:	539	want to free them when the port gets killed (note the use of C<psub>):
458		540
459	$port->rcv (start => sub {	541	$port->rcv (start => sub {
460	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	542	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
461	undef $timer if 0.9 < rand;	543	undef $timer if 0.9 < rand;
462	});	544	});
463	});	545	});
464		546
465	=cut	547	=cut
466		548
467	sub mon_guard {	549	sub mon_guard {
468	my ($port, @refs) = @_;	550	my ($port, @refs) = @_;
469		551
		552	#TODO: mon-less form?
		553
470	mon $port, sub { 0 && @refs }	554	mon $port, sub { 0 && @refs }
471	}	555	}
472		556
473	=item lnk $port1, $port2
474
475	Link two ports. This is simply a shorthand for:
476
477	mon $port1, $port2;
478	mon $port2, $port1;
479
480	It means that if either one is killed abnormally, the other one gets
481	killed as well.
482
483	=item kil $portid[, @reason]	557	=item kil $port[, @reason]
484		558
485	Kill the specified port with the given C<@reason>.	559	Kill the specified port with the given C<@reason>.
486		560
487	If no C<@reason> is specified, then the port is killed "normally" (linked	561	If no C<@reason> is specified, then the port is killed "normally" (ports
488	ports will not be kileld, or even notified).	562	monitoring other ports will not necessarily die because a port dies
		563	"normally").
489		564
490	Otherwise, linked ports get killed with the same reason (second form of	565	Otherwise, linked ports get killed with the same reason (second form of
491	C<mon>, see below).	566	C<mon>, see above).
492		567
493	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	568	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
494	will be reported as reason C<< die => $@ >>.	569	will be reported as reason C<< die => $@ >>.
495		570
496	Transport/communication errors are reported as C<< transport_error =>	571	Transport/communication errors are reported as C<< transport_error =>
497	$message >>.	572	$message >>.
498		573
		574	=cut
		575
		576	=item $port = spawn $node, $initfunc[, @initdata]
		577
		578	Creates a port on the node C<$node> (which can also be a port ID, in which
		579	case it's the node where that port resides).
		580
		581	The port ID of the newly created port is returned immediately, and it is
		582	possible to immediately start sending messages or to monitor the port.
		583
		584	After the port has been created, the init function is called on the remote
		585	node, in the same context as a C<rcv> callback. This function must be a
		586	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
		587	specify a function in the main program, use C<::name>.
		588
		589	If the function doesn't exist, then the node tries to C<require>
		590	the package, then the package above the package and so on (e.g.
		591	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		592	exists or it runs out of package names.
		593
		594	The init function is then called with the newly-created port as context
		595	object (C<$SELF>) and the C<@initdata> values as arguments.
		596
		597	A common idiom is to pass a local port, immediately monitor the spawned
		598	port, and in the remote init function, immediately monitor the passed
		599	local port. This two-way monitoring ensures that both ports get cleaned up
		600	when there is a problem.
		601
		602	Example: spawn a chat server port on C<$othernode>.
		603
		604	# this node, executed from within a port context:
		605	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		606	mon $server;
		607
		608	# init function on C<$othernode>
		609	sub connect {
		610	my ($srcport) = @_;
		611
		612	mon $srcport;
		613
		614	rcv $SELF, sub {
		615	...
		616	};
		617	}
		618
		619	=cut
		620
		621	sub _spawn {
		622	my $port = shift;
		623	my $init = shift;
		624
		625	local $SELF = "$NODE#$port";
		626	eval {
		627	&{ load_func $init }
		628	};
		629	_self_die if $@;
		630	}
		631
		632	sub spawn(@) {
		633	my ($noderef, undef) = split /#/, shift, 2;
		634
		635	my $id = "$RUNIQ." . $ID++;
		636
		637	$_[0] =~ /::/
		638	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		639
		640	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
		641
		642	"$noderef#$id"
		643	}
		644
		645	=item after $timeout, @msg
		646
		647	=item after $timeout, $callback
		648
		649	Either sends the given message, or call the given callback, after the
		650	specified number of seconds.
		651
		652	This is simply a utility function that comes in handy at times - the
		653	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		654	so it may go away in the future.
		655
		656	=cut
		657
		658	sub after($@) {
		659	my ($timeout, @action) = @_;
		660
		661	my $t; $t = AE::timer $timeout, 0, sub {
		662	undef $t;
		663	ref $action[0]
		664	? $action[0]()
		665	: snd @action;
		666	};
		667	}
		668
499	=back	669	=back
500		670
501	=head1 FUNCTIONS FOR NODES	671	=head1 AnyEvent::MP vs. Distributed Erlang
		672
		673	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
		674	== aemp node, Erlang process == aemp port), so many of the documents and
		675	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		676	sample:
		677
		678	http://www.Erlang.se/doc/programming_rules.shtml
		679	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		680	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		681	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		682
		683	Despite the similarities, there are also some important differences:
502		684
503	=over 4	685	=over 4
504		686
505	=item become_public $noderef	687	=item * Node IDs are arbitrary strings in AEMP.
506		688
507	Tells the node to become a public node, i.e. reachable from other nodes.
508
509	The first argument is the (unresolved) node reference of the local node
510	(if missing then the empty string is used).
511
512	It is quite common to not specify anything, in which case the local node
513	tries to listen on the default port, or to only specify a port number, in
514	which case AnyEvent::MP tries to guess the local addresses.
515
516	=cut
517
518	=back
519
520	=head1 NODE MESSAGES
521
522	Nodes understand the following messages sent to them. Many of them take
523	arguments called C<@reply>, which will simply be used to compose a reply
524	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
525	the remaining arguments are simply the message data.
526
527	While other messages exist, they are not public and subject to change.
528
529	=over 4
530
531	=cut
532
533	=item lookup => $name, @reply
534
535	Replies with the port ID of the specified well-known port, or C<undef>.
536
537	=item devnull => ...
538
539	Generic data sink/CPU heat conversion.
540
541	=item relay => $port, @msg
542
543	Simply forwards the message to the given port.
544
545	=item eval => $string[ @reply]
546
547	Evaluates the given string. If C<@reply> is given, then a message of the
548	form C<@reply, $@, @evalres> is sent.
549
550	Example: crash another node.
551
552	snd $othernode, eval => "exit";
553
554	=item time => @reply
555
556	Replies the the current node time to C<@reply>.
557
558	Example: tell the current node to send the current time to C<$myport> in a
559	C<timereply> message.
560
561	snd $NODE, time => $myport, timereply => 1, 2;
562	# => snd $myport, timereply => 1, 2, <time>
563
564	=back
565
566	=head1 AnyEvent::MP vs. Distributed Erlang
567
568	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node
569	== aemp node, erlang process == aemp port), so many of the documents and
570	programming techniques employed by erlang apply to AnyEvent::MP. Here is a
571	sample:
572
573	http://www.erlang.se/doc/programming_rules.shtml
574	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
575	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6
576	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
577
578	Despite the similarities, there are also some important differences:
579
580	=over 4
581
582	=item * Node references contain the recipe on how to contact them.
583
584	Erlang relies on special naming and DNS to work everywhere in the	689	Erlang relies on special naming and DNS to work everywhere in the same
585	same way. AEMP relies on each node knowing it's own address(es), with	690	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
586	convenience functionality.	691	configuraiton or DNS), but will otherwise discover other odes itself.
587		692
588	This means that AEMP requires a less tightly controlled environment at the	693	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
589	cost of longer node references and a slightly higher management overhead.	694	uses "local ports are like remote ports".
		695
		696	The failure modes for local ports are quite different (runtime errors
		697	only) then for remote ports - when a local port dies, you I<know> it dies,
		698	when a connection to another node dies, you know nothing about the other
		699	port.
		700
		701	Erlang pretends remote ports are as reliable as local ports, even when
		702	they are not.
		703
		704	AEMP encourages a "treat remote ports differently" philosophy, with local
		705	ports being the special case/exception, where transport errors cannot
		706	occur.
590		707
591	=item * Erlang uses processes and a mailbox, AEMP does not queue.	708	=item * Erlang uses processes and a mailbox, AEMP does not queue.
592		709
593	Erlang uses processes that selctively receive messages, and therefore	710	Erlang uses processes that selectively receive messages, and therefore
594	needs a queue. AEMP is event based, queuing messages would serve no useful	711	needs a queue. AEMP is event based, queuing messages would serve no
595	purpose.	712	useful purpose. For the same reason the pattern-matching abilities of
		713	AnyEvent::MP are more limited, as there is little need to be able to
		714	filter messages without dequeing them.
596		715
597	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	716	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
598		717
599	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	718	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
600		719
601	Sending messages in erlang is synchronous and blocks the process. AEMP	720	Sending messages in Erlang is synchronous and blocks the process (and
602	sends are immediate, connection establishment is handled in the	721	so does not need a queue that can overflow). AEMP sends are immediate,
603	background.	722	connection establishment is handled in the background.
604		723
605	=item * Erlang can silently lose messages, AEMP cannot.	724	=item * Erlang suffers from silent message loss, AEMP does not.
606		725
607	Erlang makes few guarantees on messages delivery - messages can get lost	726	Erlang makes few guarantees on messages delivery - messages can get lost
608	without any of the processes realising it (i.e. you send messages a, b,	727	without any of the processes realising it (i.e. you send messages a, b,
609	and c, and the other side only receives messages a and c).	728	and c, and the other side only receives messages a and c).
610		729
611	AEMP guarantees correct ordering, and the guarantee that there are no	730	AEMP guarantees correct ordering, and the guarantee that after one message
612	holes in the message sequence.	731	is lost, all following ones sent to the same port are lost as well, until
613		732	monitoring raises an error, so there are no silent "holes" in the message
614	=item * In erlang, processes can be declared dead and later be found to be	733	sequence.
615	alive.
616
617	In erlang it can happen that a monitored process is declared dead and
618	linked processes get killed, but later it turns out that the process is
619	still alive - and can receive messages.
620
621	In AEMP, when port monitoring detects a port as dead, then that port will
622	eventually be killed - it cannot happen that a node detects a port as dead
623	and then later sends messages to it, finding it is still alive.
624		734
625	=item * Erlang can send messages to the wrong port, AEMP does not.	735	=item * Erlang can send messages to the wrong port, AEMP does not.
626		736
627	In erlang it is quite possible that a node that restarts reuses a process	737	In Erlang it is quite likely that a node that restarts reuses a process ID
628	ID known to other nodes for a completely different process, causing	738	known to other nodes for a completely different process, causing messages
629	messages destined for that process to end up in an unrelated process.	739	destined for that process to end up in an unrelated process.
630		740
631	AEMP never reuses port IDs, so old messages or old port IDs floating	741	AEMP never reuses port IDs, so old messages or old port IDs floating
632	around in the network will not be sent to an unrelated port.	742	around in the network will not be sent to an unrelated port.
633		743
634	=item * Erlang uses unprotected connections, AEMP uses secure	744	=item * Erlang uses unprotected connections, AEMP uses secure
635	authentication and can use TLS.	745	authentication and can use TLS.
636		746
637	AEMP can use a proven protocol - SSL/TLS - to protect connections and	747	AEMP can use a proven protocol - TLS - to protect connections and
638	securely authenticate nodes.	748	securely authenticate nodes.
639		749
640	=item * The AEMP protocol is optimised for both text-based and binary	750	=item * The AEMP protocol is optimised for both text-based and binary
641	communications.	751	communications.
642		752
643	The AEMP protocol, unlike the erlang protocol, supports both	753	The AEMP protocol, unlike the Erlang protocol, supports both programming
644	language-independent text-only protocols (good for debugging) and binary,	754	language independent text-only protocols (good for debugging) and binary,
645	language-specific serialisers (e.g. Storable).	755	language-specific serialisers (e.g. Storable). By default, unless TLS is
		756	used, the protocol is actually completely text-based.
646		757
647	It has also been carefully designed to be implementable in other languages	758	It has also been carefully designed to be implementable in other languages
648	with a minimum of work while gracefully degrading fucntionality to make the	759	with a minimum of work while gracefully degrading functionality to make the
649	protocol simple.	760	protocol simple.
650		761
		762	=item * AEMP has more flexible monitoring options than Erlang.
		763
		764	In Erlang, you can chose to receive I<all> exit signals as messages
		765	or I<none>, there is no in-between, so monitoring single processes is
		766	difficult to implement. Monitoring in AEMP is more flexible than in
		767	Erlang, as one can choose between automatic kill, exit message or callback
		768	on a per-process basis.
		769
		770	=item * Erlang tries to hide remote/local connections, AEMP does not.
		771
		772	Monitoring in Erlang is not an indicator of process death/crashes, in the
		773	same way as linking is (except linking is unreliable in Erlang).
		774
		775	In AEMP, you don't "look up" registered port names or send to named ports
		776	that might or might not be persistent. Instead, you normally spawn a port
		777	on the remote node. The init function monitors you, and you monitor the
		778	remote port. Since both monitors are local to the node, they are much more
		779	reliable (no need for C<spawn_link>).
		780
		781	This also saves round-trips and avoids sending messages to the wrong port
		782	(hard to do in Erlang).
		783
651	=back	784	=back
652		785
		786	=head1 RATIONALE
		787
		788	=over 4
		789
		790	=item Why strings for port and node IDs, why not objects?
		791
		792	We considered "objects", but found that the actual number of methods
		793	that can be called are quite low. Since port and node IDs travel over
		794	the network frequently, the serialising/deserialising would add lots of
		795	overhead, as well as having to keep a proxy object everywhere.
		796
		797	Strings can easily be printed, easily serialised etc. and need no special
		798	procedures to be "valid".
		799
		800	And as a result, a miniport consists of a single closure stored in a
		801	global hash - it can't become much cheaper.
		802
		803	=item Why favour JSON, why not a real serialising format such as Storable?
		804
		805	In fact, any AnyEvent::MP node will happily accept Storable as framing
		806	format, but currently there is no way to make a node use Storable by
		807	default (although all nodes will accept it).
		808
		809	The default framing protocol is JSON because a) JSON::XS is many times
		810	faster for small messages and b) most importantly, after years of
		811	experience we found that object serialisation is causing more problems
		812	than it solves: Just like function calls, objects simply do not travel
		813	easily over the network, mostly because they will always be a copy, so you
		814	always have to re-think your design.
		815
		816	Keeping your messages simple, concentrating on data structures rather than
		817	objects, will keep your messages clean, tidy and efficient.
		818
		819	=back
		820
653	=head1 SEE ALSO	821	=head1 SEE ALSO
		822
		823	L<AnyEvent::MP::Intro> - a gentle introduction.
		824
		825	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		826
		827	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		828	your applications.
654		829
655	L<AnyEvent>.	830	L<AnyEvent>.
656		831
657	=head1 AUTHOR	832	=head1 AUTHOR
658		833

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.32 by root, Wed Aug 5 19:58:46 2009 UTC vs. Revision 1.69 by root, Sun Aug 30 18:51:49 2009 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.32 by root, Wed Aug 5 19:58:46 2009 UTC vs.
Revision 1.69 by root, Sun Aug 30 18:51:49 2009 UTC