[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 1.71 by root, Sun Aug 30 19:52:56 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	bin/aemp - stable.
		44	AnyEvent::MP - stable API, should work.
		45	AnyEvent::MP::Intro - uptodate, but incomplete.
		46	AnyEvent::MP::Kernel - mostly stable.
		47	AnyEvent::MP::Global - stable API, protocol not yet final.
		48
		49	stay tuned.
27		50
28	=head1 DESCRIPTION	51	=head1 DESCRIPTION
29		52
30	This module (-family) implements a simple message passing framework.	53	This module (-family) implements a simple message passing framework.
31		54
32	Despite its simplicity, you can securely message other processes running	55	Despite its simplicity, you can securely message other processes running
33	on the same or other hosts.	56	on the same or other hosts, and you can supervise entities remotely.
34		57
35	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	58	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
36	manual page.	59	manual page and the examples under F<eg/>.
37		60
38	At the moment, this module family is severly broken and underdocumented,	61	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		62
42	=head1 CONCEPTS	63	=head1 CONCEPTS
43		64
44	=over 4	65	=over 4
45		66
46	=item port	67	=item port
47		68
48	A port is something you can send messages to (with the C<snd> function).	69	A port is something you can send messages to (with the C<snd> function).
49		70
50	Some ports allow you to register C<rcv> handlers that can match specific	71	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	72	some messages. Messages send to ports will not be queued, regardless of
52	will not be queued.	73	anything was listening for them or not.
53		74
54	=item port id - C<noderef#portname>	75	=item port ID - C<nodeid#portname>
55		76
56	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	77	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	78	separator, and a port name (a printable string of unspecified format).
58	exception is the the node port, whose ID is identical to it's node
59	reference.
60		79
61	=item node	80	=item node
62		81
63	A node is a single process containing at least one port - the node	82	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	83	which enables nodes to manage each other remotely, and to create new
65	create new ports, among other things.	84	ports.
66		85
67	Nodes are either private (single-process only), slaves (connected to a	86	Nodes are either public (have one or more listening ports) or private
68	master node only) or public nodes (connectable from unrelated nodes).	87	(no listening ports). Private nodes cannot talk to other private nodes
		88	currently.
69		89
70	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	90	=item node ID - C<[a-za-Z0-9_\-.:]+>
71		91
72	A node reference is a string that either simply identifies the node (for	92	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	93	network. Depending on the configuration used, node IDs can look like a
74	node (for public nodes).	94	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
		95	doesn't interpret node IDs in any way.
75		96
76	This recipe is simply a comma-separated list of C<address:port> pairs (for	97	=item binds - C<ip:port>
77	TCP/IP, other protocols might look different).
78		98
79	Node references come in two flavours: resolved (containing only numerical	99	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).	100	each other. To do this, nodes should listen on one or more local transport
		101	endpoints - binds. Currently, only standard C<ip:port> specifications can
		102	be used, which specify TCP ports to listen on.
81		103
82	Before using an unresolved node reference in a message you first have to	104	=item seeds - C<host:port>
83	resolve it.	105
		106	When a node starts, it knows nothing about the network. To teach the node
		107	about the network it first has to contact some other node within the
		108	network. This node is called a seed.
		109
		110	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes
		111	are expected to be long-running, and at least one of those should always
		112	be available. When nodes run out of connections (e.g. due to a network
		113	error), they try to re-establish connections to some seednodes again to
		114	join the network.
		115
		116	Apart from being sued for seeding, seednodes are not special in any way -
		117	every public node can be a seednode.
84		118
85	=back	119	=back
86		120
87	=head1 VARIABLES/FUNCTIONS	121	=head1 VARIABLES/FUNCTIONS
88		122
…		…
90		124
91	=cut	125	=cut
92		126
93	package AnyEvent::MP;	127	package AnyEvent::MP;
94		128
95	use AnyEvent::MP::Base;	129	use AnyEvent::MP::Kernel;
96		130
97	use common::sense;	131	use common::sense;
98		132
99	use Carp ();	133	use Carp ();
100		134
101	use AE ();	135	use AE ();
102		136
103	use base "Exporter";	137	use base "Exporter";
104		138
105	our $VERSION = '0.1';	139	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		140
106	our @EXPORT = qw(	141	our @EXPORT = qw(
107	NODE $NODE *SELF node_of _any_	142	NODE $NODE *SELF node_of after
108	resolve_node	143	initialise_node
109	become_slave become_public
110	snd rcv mon kil reg psub	144	snd rcv mon mon_guard kil reg psub spawn
111	port	145	port
112	);	146	);
113		147
114	our $SELF;	148	our $SELF;
115		149
…		…
119	kil $SELF, die => $msg;	153	kil $SELF, die => $msg;
120	}	154	}
121		155
122	=item $thisnode = NODE / $NODE	156	=item $thisnode = NODE / $NODE
123		157
124	The C<NODE> function returns, and the C<$NODE> variable contains	158	The C<NODE> function returns, and the C<$NODE> variable contains, the node
125	the noderef of the local node. The value is initialised by a call	159	ID of the node running in the current process. This value is initialised by
126	to C<become_public> or C<become_slave>, after which all local port	160	a call to C<initialise_node>.
127	identifiers become invalid.
128		161
129	=item $noderef = node_of $portid	162	=item $nodeid = node_of $port
130		163
131	Extracts and returns the noderef from a portid or a noderef.	164	Extracts and returns the node ID from a port ID or a node ID.
132		165
133	=item $cv = resolve_node $noderef	166	=item initialise_node $profile_name, key => value...
134		167
135	Takes an unresolved node reference that may contain hostnames and	168	Before a node can talk to other nodes on the network (i.e. enter
136	abbreviated IDs, resolves all of them and returns a resolved node	169	"distributed mode") it has to initialise itself - the minimum a node needs
137	reference.	170	to know is its own name, and optionally it should know the addresses of
		171	some other nodes in the network to discover other nodes.
138		172
139	In addition to C<address:port> pairs allowed in resolved noderefs, the	173	This function initialises a node - it must be called exactly once (or
140	following forms are supported:	174	never) before calling other AnyEvent::MP functions.
141		175
142	=over 4	176	The first argument is a profile name. If it is C<undef> or missing, then
		177	the current nodename will be used instead (i.e. F<uname -n>).
143		178
144	=item the empty string	179	The function first looks up the profile in the aemp configuration (see the
		180	L<aemp> commandline utility). the profile is calculated as follows:
145		181
146	An empty-string component gets resolved as if the default port (4040) was	182	First, all remaining key => value pairs (all of which are conviniently
147	specified.	183	undocumented at the moment) will be used. Then they will be overwritten by
		184	any values specified in the global default configuration (see the F<aemp>
		185	utility), then the chain of profiles selected, if any. That means that
		186	the values specified in the profile have highest priority and the values
		187	specified via C<initialise_node> have lowest priority.
148		188
149	=item naked port numbers (e.g. C<1234>)	189	If the profile specifies a node ID, then this will become the node ID of
		190	this process. If not, then the profile name will be used as node ID. The
		191	special node ID of C<anon/> will be replaced by a random node ID.
150		192
151	These are resolved by prepending the local nodename and a colon, to be	193	The next step is to look up the binds in the profile, followed by binding
152	further resolved.	194	aemp protocol listeners on all binds specified (it is possible and valid
		195	to have no binds, meaning that the node cannot be contacted form the
		196	outside. This means the node cannot talk to other nodes that also have no
		197	binds, but it can still talk to all "normal" nodes).
153		198
154	=item hostnames (e.g. C<localhost:1234>, C<localhost>)	199	If the profile does not specify a binds list, then a default of C<*> is
		200	used.
155		201
156	These are resolved by using AnyEvent::DNS to resolve them, optionally	202	Lastly, the seeds list from the profile is passed to the
157	looking up SRV records for the C<aemp=4040> port, if no port was	203	L<AnyEvent::MP::Global> module, which will then use it to keep
158	specified.	204	connectivity with at least on of those seed nodes at any point in time.
159		205
160	=back	206	Example: become a distributed node listening on the guessed noderef, or
		207	the one specified via C<aemp> for the current node. This should be the
		208	most common form of invocation for "daemon"-type nodes.
		209
		210	initialise_node;
		211
		212	Example: become an anonymous node. This form is often used for commandline
		213	clients.
		214
		215	initialise_node "anon/";
		216
		217	Example: become a distributed node. If there is no profile of the given
		218	name, or no binds list was specified, resolve C<localhost:4044> and bind
		219	on the resulting addresses.
		220
		221	initialise_node "localhost:4044";
161		222
162	=item $SELF	223	=item $SELF
163		224
164	Contains the current port id while executing C<rcv> callbacks or C<psub>	225	Contains the current port id while executing C<rcv> callbacks or C<psub>
165	blocks.	226	blocks.
166		227
167	=item SELF, %SELF, @SELF...	228	=item *SELF, SELF, %SELF, @SELF...
168		229
169	Due to some quirks in how perl exports variables, it is impossible to	230	Due to some quirks in how perl exports variables, it is impossible to
170	just export C<$SELF>, all the symbols called C<SELF> are exported by this	231	just export C<$SELF>, all the symbols named C<SELF> are exported by this
171	module, but only C<$SELF> is currently used.	232	module, but only C<$SELF> is currently used.
172		233
173	=item snd $portid, type => @data	234	=item snd $port, type => @data
174		235
175	=item snd $portid, @msg	236	=item snd $port, @msg
176		237
177	Send the given message to the given port ID, which can identify either	238	Send the given message to the given port, which can identify either a
178	a local or a remote port, and can be either a string or soemthignt hat	239	local or a remote port, and must be a port ID.
179	stringifies a sa port ID (such as a port object :).
180		240
181	While the message can be about anything, it is highly recommended to use a	241	While the message can be almost anything, it is highly recommended to
182	string as first element (a portid, or some word that indicates a request	242	use a string as first element (a port ID, or some word that indicates a
183	type etc.).	243	request type etc.) and to consist if only simple perl values (scalars,
		244	arrays, hashes) - if you think you need to pass an object, think again.
184		245
185	The message data effectively becomes read-only after a call to this	246	The message data logically becomes read-only after a call to this
186	function: modifying any argument is not allowed and can cause many	247	function: modifying any argument (or values referenced by them) is
187	problems.	248	forbidden, as there can be considerable time between the call to C<snd>
		249	and the time the message is actually being serialised - in fact, it might
		250	never be copied as within the same process it is simply handed to the
		251	receiving port.
188		252
189	The type of data you can transfer depends on the transport protocol: when	253	The type of data you can transfer depends on the transport protocol: when
190	JSON is used, then only strings, numbers and arrays and hashes consisting	254	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	255	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	256	that Storable can serialise and deserialise is allowed, and for the local
193	node, anything can be passed.	257	node, anything can be passed. Best rely only on the common denominator of
		258	these.
194		259
195	=item kil $portid[, @reason]	260	=item $local_port = port
196		261
197	Kill the specified port with the given C<@reason>.	262	Create a new local port object and returns its port ID. Initially it has
		263	no callbacks set and will throw an error when it receives messages.
198		264
199	If no C<@reason> is specified, then the port is killed "normally" (linked	265	=item $local_port = port { my @msg = @_ }
200	ports will not be kileld, or even notified).
201		266
202	Otherwise, linked ports get killed with the same reason (second form of	267	Creates a new local port, and returns its ID. Semantically the same as
203	C<mon>, see below).	268	creating a port and calling C<rcv $port, $callback> on it.
204		269
205	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	270	The block will be called for every message received on the port, with the
206	will be reported as reason C<< die => $@ >>.	271	global variable C<$SELF> set to the port ID. Runtime errors will cause the
		272	port to be C<kil>ed. The message will be passed as-is, no extra argument
		273	(i.e. no port ID) will be passed to the callback.
207		274
208	Transport/communication errors are reported as C<< transport_error =>	275	If you want to stop/destroy the port, simply C<kil> it:
209	$message >>.
210		276
211	=item $guard = mon $portid, $cb->(@reason)	277	my $port = port {
		278	my @msg = @_;
		279	...
		280	kil $SELF;
		281	};
212		282
213	=item $guard = mon $portid, $otherport	283	=cut
214		284
215	=item $guard = mon $portid, $otherport, @msg	285	sub rcv($@);
216		286
		287	sub _kilme {
		288	die "received message on port without callback";
		289	}
		290
		291	sub port(;&) {
		292	my $id = "$UNIQ." . $ID++;
		293	my $port = "$NODE#$id";
		294
		295	rcv $port, shift \|\| \&_kilme;
		296
		297	$port
		298	}
		299
		300	=item rcv $local_port, $callback->(@msg)
		301
		302	Replaces the default callback on the specified port. There is no way to
		303	remove the default callback: use C<sub { }> to disable it, or better
		304	C<kil> the port when it is no longer needed.
		305
		306	The global C<$SELF> (exported by this module) contains C<$port> while
		307	executing the callback. Runtime errors during callback execution will
		308	result in the port being C<kil>ed.
		309
		310	The default callback received all messages not matched by a more specific
		311	C<tag> match.
		312
		313	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
		314
		315	Register (or replace) callbacks to be called on messages starting with the
		316	given tag on the given port (and return the port), or unregister it (when
		317	C<$callback> is C<$undef> or missing). There can only be one callback
		318	registered for each tag.
		319
		320	The original message will be passed to the callback, after the first
		321	element (the tag) has been removed. The callback will use the same
		322	environment as the default callback (see above).
		323
		324	Example: create a port and bind receivers on it in one go.
		325
		326	my $port = rcv port,
		327	msg1 => sub { ... },
		328	msg2 => sub { ... },
		329	;
		330
		331	Example: create a port, bind receivers and send it in a message elsewhere
		332	in one go:
		333
		334	snd $otherport, reply =>
		335	rcv port,
		336	msg1 => sub { ... },
		337	...
		338	;
		339
		340	Example: temporarily register a rcv callback for a tag matching some port
		341	(e.g. for a rpc reply) and unregister it after a message was received.
		342
		343	rcv $port, $otherport => sub {
		344	my @reply = @_;
		345
		346	rcv $SELF, $otherport;
		347	};
		348
		349	=cut
		350
		351	sub rcv($@) {
		352	my $port = shift;
		353	my ($noderef, $portid) = split /#/, $port, 2;
		354
		355	$NODE{$noderef} == $NODE{""}
		356	or Carp::croak "$port: rcv can only be called on local ports, caught";
		357
		358	while (@_) {
		359	if (ref $_[0]) {
		360	if (my $self = $PORT_DATA{$portid}) {
		361	"AnyEvent::MP::Port" eq ref $self
		362	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		363
		364	$self->[2] = shift;
		365	} else {
		366	my $cb = shift;
		367	$PORT{$portid} = sub {
		368	local $SELF = $port;
		369	eval { &$cb }; _self_die if $@;
		370	};
		371	}
		372	} elsif (defined $_[0]) {
		373	my $self = $PORT_DATA{$portid} \|\|= do {
		374	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
		375
		376	$PORT{$portid} = sub {
		377	local $SELF = $port;
		378
		379	if (my $cb = $self->[1]{$_[0]}) {
		380	shift;
		381	eval { &$cb }; _self_die if $@;
		382	} else {
		383	&{ $self->[0] };
		384	}
		385	};
		386
		387	$self
		388	};
		389
		390	"AnyEvent::MP::Port" eq ref $self
		391	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		392
		393	my ($tag, $cb) = splice @_, 0, 2;
		394
		395	if (defined $cb) {
		396	$self->[1]{$tag} = $cb;
		397	} else {
		398	delete $self->[1]{$tag};
		399	}
		400	}
		401	}
		402
		403	$port
		404	}
		405
		406	=item $closure = psub { BLOCK }
		407
		408	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
		409	closure is executed, sets up the environment in the same way as in C<rcv>
		410	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		411
		412	This is useful when you register callbacks from C<rcv> callbacks:
		413
		414	rcv delayed_reply => sub {
		415	my ($delay, @reply) = @_;
		416	my $timer = AE::timer $delay, 0, psub {
		417	snd @reply, $SELF;
		418	};
		419	};
		420
		421	=cut
		422
		423	sub psub(&) {
		424	my $cb = shift;
		425
		426	my $port = $SELF
		427	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
		428
		429	sub {
		430	local $SELF = $port;
		431
		432	if (wantarray) {
		433	my @res = eval { &$cb };
		434	_self_die if $@;
		435	@res
		436	} else {
		437	my $res = eval { &$cb };
		438	_self_die if $@;
		439	$res
		440	}
		441	}
		442	}
		443
		444	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
		445
		446	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
		447
		448	=item $guard = mon $port # kill $SELF when $port dies
		449
		450	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
		451
217	Monitor the given port and do something when the port is killed.	452	Monitor the given port and do something when the port is killed or
		453	messages to it were lost, and optionally return a guard that can be used
		454	to stop monitoring again.
218		455
		456	C<mon> effectively guarantees that, in the absence of hardware failures,
		457	after starting the monitor, either all messages sent to the port will
		458	arrive, or the monitoring action will be invoked after possible message
		459	loss has been detected. No messages will be lost "in between" (after
		460	the first lost message no further messages will be received by the
		461	port). After the monitoring action was invoked, further messages might get
		462	delivered again.
		463
		464	Note that monitoring-actions are one-shot: once messages are lost (and a
		465	monitoring alert was raised), they are removed and will not trigger again.
		466
219	In the first form, the callback is simply called with any number	467	In the first form (callback), the callback is simply called with any
220	of C<@reason> elements (no @reason means that the port was deleted	468	number of C<@reason> elements (no @reason means that the port was deleted
221	"normally"). Note also that I<< the callback B<must> never die >>, so use	469	"normally"). Note also that I<< the callback B<must> never die >>, so use
222	C<eval> if unsure.	470	C<eval> if unsure.
223		471
224	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	472	In the second form (another port given), the other port (C<$rcvport>)
225	a @reason was specified, i.e. on "normal" kils nothing happens, while	473	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
226	under all other conditions, the other port is killed with the same reason.	474	"normal" kils nothing happens, while under all other conditions, the other
		475	port is killed with the same reason.
227		476
		477	The third form (kill self) is the same as the second form, except that
		478	C<$rvport> defaults to C<$SELF>.
		479
228	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	480	In the last form (message), a message of the form C<@msg, @reason> will be
		481	C<snd>.
		482
		483	As a rule of thumb, monitoring requests should always monitor a port from
		484	a local port (or callback). The reason is that kill messages might get
		485	lost, just like any other message. Another less obvious reason is that
		486	even monitoring requests can get lost (for exmaple, when the connection
		487	to the other node goes down permanently). When monitoring a port locally
		488	these problems do not exist.
229		489
230	Example: call a given callback when C<$port> is killed.	490	Example: call a given callback when C<$port> is killed.
231		491
232	mon $port, sub { warn "port died because of <@_>\n" };	492	mon $port, sub { warn "port died because of <@_>\n" };
233		493
234	Example: kill ourselves when C<$port> is killed abnormally.	494	Example: kill ourselves when C<$port> is killed abnormally.
235		495
236	mon $port, $self;	496	mon $port;
237		497
238	Example: send us a restart message another C<$port> is killed.	498	Example: send us a restart message when another C<$port> is killed.
239		499
240	mon $port, $self => "restart";	500	mon $port, $self => "restart";
241		501
242	=cut	502	=cut
243		503
244	sub mon {	504	sub mon {
245	my ($noderef, $port, $cb) = ((split /#/, shift, 2), shift);	505	my ($noderef, $port) = split /#/, shift, 2;
246		506
247	my $node = $NODE{$noderef} \|\| add_node $noderef;	507	my $node = $NODE{$noderef} \|\| add_node $noderef;
248		508
249	#TODO: ports must not be references	509	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
250	if (!ref $cb or "AnyEvent::MP::Port" eq ref $cb) {	510
		511	unless (ref $cb) {
251	if (@_) {	512	if (@_) {
252	# send a kill info message	513	# send a kill info message
253	my (@msg) = ($cb, @_);	514	my (@msg) = ($cb, @_);
254	$cb = sub { snd @msg, @_ };	515	$cb = sub { snd @msg, @_ };
255	} else {	516	} else {
…		…
271	is killed, the references will be freed.	532	is killed, the references will be freed.
272		533
273	Optionally returns a guard that will stop the monitoring.	534	Optionally returns a guard that will stop the monitoring.
274		535
275	This function is useful when you create e.g. timers or other watchers and	536	This function is useful when you create e.g. timers or other watchers and
276	want to free them when the port gets killed:	537	want to free them when the port gets killed (note the use of C<psub>):
277		538
278	$port->rcv (start => sub {	539	$port->rcv (start => sub {
279	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	540	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
280	undef $timer if 0.9 < rand;	541	undef $timer if 0.9 < rand;
281	});	542	});
282	});	543	});
283		544
284	=cut	545	=cut
285		546
286	sub mon_guard {	547	sub mon_guard {
287	my ($port, @refs) = @_;	548	my ($port, @refs) = @_;
288		549
		550	#TODO: mon-less form?
		551
289	mon $port, sub { 0 && @refs }	552	mon $port, sub { 0 && @refs }
290	}	553	}
291		554
292	=item lnk $port1, $port2	555	=item kil $port[, @reason]
293		556
294	Link two ports. This is simply a shorthand for:	557	Kill the specified port with the given C<@reason>.
295		558
296	mon $port1, $port2;	559	If no C<@reason> is specified, then the port is killed "normally" (ports
297	mon $port2, $port1;	560	monitoring other ports will not necessarily die because a port dies
		561	"normally").
298		562
299	It means that if either one is killed abnormally, the other one gets	563	Otherwise, linked ports get killed with the same reason (second form of
300	killed as well.	564	C<mon>, see above).
301		565
302	=item $local_port = port	566	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		567	will be reported as reason C<< die => $@ >>.
303		568
304	Create a new local port object that supports message matching.	569	Transport/communication errors are reported as C<< transport_error =>
		570	$message >>.
305		571
306	=item $portid = port { my @msg = @_; $finished }
307
308	Creates a "mini port", that is, a very lightweight port without any
309	pattern matching behind it, and returns its ID.
310
311	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
313	will be destroyed. Otherwise it will stay alive.
314
315	The message will be passed as-is, no extra argument (i.e. no port id) will
316	be passed to the callback.
317
318	If you need the local port id in the callback, this works nicely:
319
320	my $port; $port = miniport {
321	snd $otherport, reply => $port;
322	};
323
324	=cut	572	=cut
325		573
326	sub port(;&) {	574	=item $port = spawn $node, $initfunc[, @initdata]
327	my $id = "$UNIQ." . $ID++;
328	my $port = "$NODE#$id";
329		575
330	if (@_) {	576	Creates a port on the node C<$node> (which can also be a port ID, in which
331	my $cb = shift;	577	case it's the node where that port resides).
332	$PORT{$id} = sub {	578
333	local $SELF = $port;	579	The port ID of the newly created port is returned immediately, and it is
334	eval {	580	possible to immediately start sending messages or to monitor the port.
335	&$cb	581
336	and kil $id;	582	After the port has been created, the init function is called on the remote
		583	node, in the same context as a C<rcv> callback. This function must be a
		584	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
		585	specify a function in the main program, use C<::name>.
		586
		587	If the function doesn't exist, then the node tries to C<require>
		588	the package, then the package above the package and so on (e.g.
		589	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		590	exists or it runs out of package names.
		591
		592	The init function is then called with the newly-created port as context
		593	object (C<$SELF>) and the C<@initdata> values as arguments.
		594
		595	A common idiom is to pass a local port, immediately monitor the spawned
		596	port, and in the remote init function, immediately monitor the passed
		597	local port. This two-way monitoring ensures that both ports get cleaned up
		598	when there is a problem.
		599
		600	Example: spawn a chat server port on C<$othernode>.
		601
		602	# this node, executed from within a port context:
		603	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		604	mon $server;
		605
		606	# init function on C<$othernode>
		607	sub connect {
		608	my ($srcport) = @_;
		609
		610	mon $srcport;
		611
		612	rcv $SELF, sub {
337	};	613	...
338	_self_die if $@;
339	};
340	} else {
341	my $self = bless {
342	id => "$NODE#$id",
343	}, "AnyEvent::MP::Port";
344
345	$PORT_DATA{$id} = $self;
346	$PORT{$id} = sub {
347	local $SELF = $port;
348
349	eval {
350	for (@{ $self->{rc0}{$_[0]} }) {
351	$_ && &{$_->[0]}
352	&& undef $_;
353	}
354
355	for (@{ $self->{rcv}{$_[0]} }) {
356	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
357	&& &{$_->[0]}
358	&& undef $_;
359	}
360
361	for (@{ $self->{any} }) {
362	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
363	&& &{$_->[0]}
364	&& undef $_;
365	}
366	};
367	_self_die if $@;
368	};	614	};
369	}	615	}
370		616
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	617	=cut
384		618
385	sub reg(@) {	619	sub _spawn {
386	my ($portid, $name) = @_;	620	my $port = shift;
		621	my $init = shift;
387		622
388	$REG{$name} = $portid;	623	local $SELF = "$NODE#$port";
389	}	624	eval {
390		625	&{ load_func $init }
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 $self
432	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
433
434	while (@_) {
435	my ($match, $cb) = splice @_, 0, 2;
436
437	if (!ref $match) {
438	push @{ $self->{rc0}{$match} }, [$cb];
439	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
440	my ($type, @match) = @$match;
441	@match
442	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
443	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
444	} else {
445	push @{ $self->{any} }, [$cb, $match];
446	}
447	}
448	}
449
450	=item $closure = psub { BLOCK }
451
452	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
453	closure is executed, sets up the environment in the same way as in C<rcv>
454	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
455
456	This is useful when you register callbacks from C<rcv> callbacks:
457
458	rcv delayed_reply => sub {
459	my ($delay, @reply) = @_;
460	my $timer = AE::timer $delay, 0, psub {
461	snd @reply, $SELF;
462	};
463	};	626	};
464
465	=cut
466
467	sub psub(&) {
468	my $cb = shift;
469
470	my $port = $SELF
471	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
472
473	sub {
474	local $SELF = $port;
475
476	if (wantarray) {
477	my @res = eval { &$cb };
478	_self_die if $@;	627	_self_die if $@;
479	@res	628	}
480	} else {	629
481	my $res = eval { &$cb };	630	sub spawn(@) {
482	_self_die if $@;	631	my ($noderef, undef) = split /#/, shift, 2;
483	$res	632
484	}	633	my $id = "$RUNIQ." . $ID++;
		634
		635	$_[0] =~ /::/
		636	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		637
		638	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
		639
		640	"$noderef#$id"
		641	}
		642
		643	=item after $timeout, @msg
		644
		645	=item after $timeout, $callback
		646
		647	Either sends the given message, or call the given callback, after the
		648	specified number of seconds.
		649
		650	This is simply a utility function that comes in handy at times - the
		651	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		652	so it may go away in the future.
		653
		654	=cut
		655
		656	sub after($@) {
		657	my ($timeout, @action) = @_;
		658
		659	my $t; $t = AE::timer $timeout, 0, sub {
		660	undef $t;
		661	ref $action[0]
		662	? $action[0]()
		663	: snd @action;
485	}	664	};
486	}	665	}
487		666
488	=back	667	=back
489		668
490	=head1 FUNCTIONS FOR NODES	669	=head1 AnyEvent::MP vs. Distributed Erlang
		670
		671	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
		672	== aemp node, Erlang process == aemp port), so many of the documents and
		673	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		674	sample:
		675
		676	http://www.Erlang.se/doc/programming_rules.shtml
		677	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		678	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		679	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		680
		681	Despite the similarities, there are also some important differences:
491		682
492	=over 4	683	=over 4
493		684
494	=item become_public $noderef	685	=item * Node IDs are arbitrary strings in AEMP.
495		686
496	Tells the node to become a public node, i.e. reachable from other nodes.
497
498	The first argument is the (unresolved) node reference of the local node
499	(if missing then the empty string is used).
500
501	It is quite common to not specify anything, in which case the local node
502	tries to listen on the default port, or to only specify a port number, in
503	which case AnyEvent::MP tries to guess the local addresses.
504
505	=cut
506
507	=back
508
509	=head1 NODE MESSAGES
510
511	Nodes understand the following messages sent to them. Many of them take
512	arguments called C<@reply>, which will simply be used to compose a reply
513	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
514	the remaining arguments are simply the message data.
515
516	While other messages exist, they are not public and subject to change.
517
518	=over 4
519
520	=cut
521
522	=item lookup => $name, @reply
523
524	Replies with the port ID of the specified well-known port, or C<undef>.
525
526	=item devnull => ...
527
528	Generic data sink/CPU heat conversion.
529
530	=item relay => $port, @msg
531
532	Simply forwards the message to the given port.
533
534	=item eval => $string[ @reply]
535
536	Evaluates the given string. If C<@reply> is given, then a message of the
537	form C<@reply, $@, @evalres> is sent.
538
539	Example: crash another node.
540
541	snd $othernode, eval => "exit";
542
543	=item time => @reply
544
545	Replies the the current node time to C<@reply>.
546
547	Example: tell the current node to send the current time to C<$myport> in a
548	C<timereply> message.
549
550	snd $NODE, time => $myport, timereply => 1, 2;
551	# => snd $myport, timereply => 1, 2, <time>
552
553	=back
554
555	=head1 AnyEvent::MP vs. Distributed Erlang
556
557	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
559	programming techniques employed by erlang apply to AnyEvent::MP. Here is a
560	sample:
561
562	http://www.erlang.se/doc/programming_rules.shtml
563	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
565	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
566
567	Despite the similarities, there are also some important differences:
568
569	=over 4
570
571	=item * Node references contain the recipe on how to contact them.
572
573	Erlang relies on special naming and DNS to work everywhere in the	687	Erlang relies on special naming and DNS to work everywhere in the same
574	same way. AEMP relies on each node knowing it's own address(es), with	688	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
575	convenience functionality.	689	configuraiton or DNS), but will otherwise discover other odes itself.
576		690
577	This means that AEMP requires a less tightly controlled environment at the	691	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
578	cost of longer node references and a slightly higher management overhead.	692	uses "local ports are like remote ports".
		693
		694	The failure modes for local ports are quite different (runtime errors
		695	only) then for remote ports - when a local port dies, you I<know> it dies,
		696	when a connection to another node dies, you know nothing about the other
		697	port.
		698
		699	Erlang pretends remote ports are as reliable as local ports, even when
		700	they are not.
		701
		702	AEMP encourages a "treat remote ports differently" philosophy, with local
		703	ports being the special case/exception, where transport errors cannot
		704	occur.
579		705
580	=item * Erlang uses processes and a mailbox, AEMP does not queue.	706	=item * Erlang uses processes and a mailbox, AEMP does not queue.
581		707
582	Erlang uses processes that selctively receive messages, and therefore	708	Erlang uses processes that selectively receive messages, and therefore
583	needs a queue. AEMP is event based, queuing messages would serve no useful	709	needs a queue. AEMP is event based, queuing messages would serve no
584	purpose.	710	useful purpose. For the same reason the pattern-matching abilities of
		711	AnyEvent::MP are more limited, as there is little need to be able to
		712	filter messages without dequeing them.
585		713
586	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	714	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
587		715
588	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	716	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
589		717
590	Sending messages in erlang is synchronous and blocks the process. AEMP	718	Sending messages in Erlang is synchronous and blocks the process (and
591	sends are immediate, connection establishment is handled in the	719	so does not need a queue that can overflow). AEMP sends are immediate,
592	background.	720	connection establishment is handled in the background.
593		721
594	=item * Erlang can silently lose messages, AEMP cannot.	722	=item * Erlang suffers from silent message loss, AEMP does not.
595		723
596	Erlang makes few guarantees on messages delivery - messages can get lost	724	Erlang makes few guarantees on messages delivery - messages can get lost
597	without any of the processes realising it (i.e. you send messages a, b,	725	without any of the processes realising it (i.e. you send messages a, b,
598	and c, and the other side only receives messages a and c).	726	and c, and the other side only receives messages a and c).
599		727
600	AEMP guarantees correct ordering, and the guarantee that there are no	728	AEMP guarantees correct ordering, and the guarantee that after one message
601	holes in the message sequence.	729	is lost, all following ones sent to the same port are lost as well, until
602		730	monitoring raises an error, so there are no silent "holes" in the message
603	=item * In erlang, processes can be declared dead and later be found to be	731	sequence.
604	alive.
605
606	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
608	still alive - and can receive messages.
609
610	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
612	and then later sends messages to it, finding it is still alive.
613		732
614	=item * Erlang can send messages to the wrong port, AEMP does not.	733	=item * Erlang can send messages to the wrong port, AEMP does not.
615		734
616	In erlang it is quite possible that a node that restarts reuses a process	735	In Erlang it is quite likely that a node that restarts reuses a process ID
617	ID known to other nodes for a completely different process, causing	736	known to other nodes for a completely different process, causing messages
618	messages destined for that process to end up in an unrelated process.	737	destined for that process to end up in an unrelated process.
619		738
620	AEMP never reuses port IDs, so old messages or old port IDs floating	739	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.	740	around in the network will not be sent to an unrelated port.
622		741
623	=item * Erlang uses unprotected connections, AEMP uses secure	742	=item * Erlang uses unprotected connections, AEMP uses secure
624	authentication and can use TLS.	743	authentication and can use TLS.
625		744
626	AEMP can use a proven protocol - SSL/TLS - to protect connections and	745	AEMP can use a proven protocol - TLS - to protect connections and
627	securely authenticate nodes.	746	securely authenticate nodes.
628		747
629	=item * The AEMP protocol is optimised for both text-based and binary	748	=item * The AEMP protocol is optimised for both text-based and binary
630	communications.	749	communications.
631		750
632	The AEMP protocol, unlike the erlang protocol, supports both	751	The AEMP protocol, unlike the Erlang protocol, supports both programming
633	language-independent text-only protocols (good for debugging) and binary,	752	language independent text-only protocols (good for debugging) and binary,
634	language-specific serialisers (e.g. Storable).	753	language-specific serialisers (e.g. Storable). By default, unless TLS is
		754	used, the protocol is actually completely text-based.
635		755
636	It has also been carefully designed to be implementable in other languages	756	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	757	with a minimum of work while gracefully degrading functionality to make the
638	protocol simple.	758	protocol simple.
639		759
		760	=item * AEMP has more flexible monitoring options than Erlang.
		761
		762	In Erlang, you can chose to receive I<all> exit signals as messages
		763	or I<none>, there is no in-between, so monitoring single processes is
		764	difficult to implement. Monitoring in AEMP is more flexible than in
		765	Erlang, as one can choose between automatic kill, exit message or callback
		766	on a per-process basis.
		767
		768	=item * Erlang tries to hide remote/local connections, AEMP does not.
		769
		770	Monitoring in Erlang is not an indicator of process death/crashes, in the
		771	same way as linking is (except linking is unreliable in Erlang).
		772
		773	In AEMP, you don't "look up" registered port names or send to named ports
		774	that might or might not be persistent. Instead, you normally spawn a port
		775	on the remote node. The init function monitors you, and you monitor the
		776	remote port. Since both monitors are local to the node, they are much more
		777	reliable (no need for C<spawn_link>).
		778
		779	This also saves round-trips and avoids sending messages to the wrong port
		780	(hard to do in Erlang).
		781
640	=back	782	=back
641		783
		784	=head1 RATIONALE
		785
		786	=over 4
		787
		788	=item Why strings for port and node IDs, why not objects?
		789
		790	We considered "objects", but found that the actual number of methods
		791	that can be called are quite low. Since port and node IDs travel over
		792	the network frequently, the serialising/deserialising would add lots of
		793	overhead, as well as having to keep a proxy object everywhere.
		794
		795	Strings can easily be printed, easily serialised etc. and need no special
		796	procedures to be "valid".
		797
		798	And as a result, a miniport consists of a single closure stored in a
		799	global hash - it can't become much cheaper.
		800
		801	=item Why favour JSON, why not a real serialising format such as Storable?
		802
		803	In fact, any AnyEvent::MP node will happily accept Storable as framing
		804	format, but currently there is no way to make a node use Storable by
		805	default (although all nodes will accept it).
		806
		807	The default framing protocol is JSON because a) JSON::XS is many times
		808	faster for small messages and b) most importantly, after years of
		809	experience we found that object serialisation is causing more problems
		810	than it solves: Just like function calls, objects simply do not travel
		811	easily over the network, mostly because they will always be a copy, so you
		812	always have to re-think your design.
		813
		814	Keeping your messages simple, concentrating on data structures rather than
		815	objects, will keep your messages clean, tidy and efficient.
		816
		817	=back
		818
642	=head1 SEE ALSO	819	=head1 SEE ALSO
		820
		821	L<AnyEvent::MP::Intro> - a gentle introduction.
		822
		823	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		824
		825	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		826	your applications.
643		827
644	L<AnyEvent>.	828	L<AnyEvent>.
645		829
646	=head1 AUTHOR	830	=head1 AUTHOR
647		831

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.29 by root, Tue Aug 4 23:16:57 2009 UTC vs. Revision 1.71 by root, Sun Aug 30 19:52:56 2009 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.29 by root, Tue Aug 4 23:16:57 2009 UTC vs.
Revision 1.71 by root, Sun Aug 30 19:52:56 2009 UTC