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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.25 by root, Tue Aug 4 21:07:37 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		44	AnyEvent::MP::Intro - outdated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, and	70	A port is something you can send messages to (with the C<snd> function).
49	you can register C<rcv> handlers with. All C<rcv> handlers will receive
50	messages they match, messages will not be queued.
51		71
		72	Ports allow you to register C<rcv> handlers that can match all or just
		73	some messages. Messages send to ports will not be queued, regardless of
		74	anything was listening for them or not.
		75
52	=item port id - C<noderef#portname>	76	=item port ID - C<nodeid#portname>
53		77
54	A port id is always the noderef, a hash-mark (C<#>) as separator, followed	78	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as
55	by a port name (a printable string of unspecified format).	79	separator, and a port name (a printable string of unspecified format).
56		80
57	=item node	81	=item node
58		82
59	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,
60	port. You can send messages to node ports to let them create new ports,	84	which enables nodes to manage each other remotely, and to create new
61	among other things.	85	ports.
62		86
63	Initially, nodes are either private (single-process only) or hidden	87	Nodes are either public (have one or more listening ports) or private
64	(connected to a master node only). Only when they epxlicitly "become	88	(no listening ports). Private nodes cannot talk to other private nodes
65	public" can you send them messages from unrelated other nodes.	89	currently.
66		90
67	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	91	=item node ID - C<[a-za-Z0-9_\-.:]+>
68		92
69	A noderef is a string that either uniquely identifies a given node (for	93	A node ID is a string that uniquely identifies the node within a
70	private and hidden nodes), or contains a recipe on how to reach a given	94	network. Depending on the configuration used, node IDs can look like a
71	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.
		97
		98	=item binds - C<ip:port>
		99
		100	Nodes can only talk to each other by creating some kind of connection to
		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.
		104
		105	=item seeds - C<host:port>
		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.
72		119
73	=back	120	=back
74		121
75	=head1 VARIABLES/FUNCTIONS	122	=head1 VARIABLES/FUNCTIONS
76		123
…		…
78		125
79	=cut	126	=cut
80		127
81	package AnyEvent::MP;	128	package AnyEvent::MP;
82		129
83	use AnyEvent::MP::Base;	130	use AnyEvent::MP::Kernel;
84		131
85	use common::sense;	132	use common::sense;
86		133
87	use Carp ();	134	use Carp ();
88		135
89	use AE ();	136	use AE ();
90		137
91	use base "Exporter";	138	use base "Exporter";
92		139
93	our $VERSION = '0.1';	140	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		141
94	our @EXPORT = qw(	142	our @EXPORT = qw(
95	NODE $NODE *SELF node_of _any_	143	NODE $NODE *SELF node_of after
96	become_slave become_public	144	initialise_node
97	snd rcv mon kil reg psub	145	snd rcv mon mon_guard kil reg psub spawn
98	port	146	port
99	);	147	);
100		148
101	our $SELF;	149	our $SELF;
102		150
…		…
106	kil $SELF, die => $msg;	154	kil $SELF, die => $msg;
107	}	155	}
108		156
109	=item $thisnode = NODE / $NODE	157	=item $thisnode = NODE / $NODE
110		158
111	The C<NODE> function returns, and the C<$NODE> variable contains	159	The C<NODE> function returns, and the C<$NODE> variable contains, the node
112	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
113	to C<become_public> or C<become_slave>, after which all local port	161	a call to C<initialise_node>.
114	identifiers become invalid.
115		162
116	=item $noderef = node_of $portid	163	=item $nodeid = node_of $port
117		164
118	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.
		166
		167	=item initialise_node $profile_name, key => value...
		168
		169	Before a node can talk to other nodes on the network (i.e. enter
		170	"distributed mode") it has to initialise itself - the minimum a node needs
		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.
		173
		174	This function initialises a node - it must be called exactly once (or
		175	never) before calling other AnyEvent::MP functions.
		176
		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>).
		179
		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:
		182
		183	First, all remaining key => value pairs will be used. Then they will be
		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.
		189
		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.
		193
		194	The next step is to look up the binds in the profile, followed by binding
		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).
		199
		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.
		203
		204	Lastly, the seeds list from the profile is passed to the
		205	L<AnyEvent::MP::Global> module, which will then use it to keep
		206	connectivity with at least on of those seed nodes at any point in time.
		207
		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";
119		224
120	=item $SELF	225	=item $SELF
121		226
122	Contains the current port id while executing C<rcv> callbacks or C<psub>	227	Contains the current port id while executing C<rcv> callbacks or C<psub>
123	blocks.	228	blocks.
124		229
125	=item SELF, %SELF, @SELF...	230	=item *SELF, SELF, %SELF, @SELF...
126		231
127	Due to some quirks in how perl exports variables, it is impossible to	232	Due to some quirks in how perl exports variables, it is impossible to
128	just export C<$SELF>, all the symbols called C<SELF> are exported by this	233	just export C<$SELF>, all the symbols named C<SELF> are exported by this
129	module, but only C<$SELF> is currently used.	234	module, but only C<$SELF> is currently used.
130		235
131	=item snd $portid, type => @data	236	=item snd $port, type => @data
132		237
133	=item snd $portid, @msg	238	=item snd $port, @msg
134		239
135	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
136	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.
137	stringifies a sa port ID (such as a port object :).
138		242
139	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
140	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
141	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.
142		247
143	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
144	function: modifying any argument is not allowed and can cause many	249	function: modifying any argument (or values referenced by them) is
145	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.
146		254
147	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
148	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
149	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
150	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
151	node, anything can be passed.	259	node, anything can be passed. Best rely only on the common denominator of
		260	these.
152		261
153	=item kil $portid[, @reason]	262	=item $local_port = port
154		263
155	Kill the specified port with the given C<@reason>.	264	Create a new local port object and returns its port ID. Initially it has
		265	no callbacks set and will throw an error when it receives messages.
156		266
157	If no C<@reason> is specified, then the port is killed "normally" (linked	267	=item $local_port = port { my @msg = @_ }
158	ports will not be kileld, or even notified).
159		268
160	Otherwise, linked ports get killed with the same reason (second form of	269	Creates a new local port, and returns its ID. Semantically the same as
161	C<mon>, see below).	270	creating a port and calling C<rcv $port, $callback> on it.
162		271
163	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	272	The block will be called for every message received on the port, with the
164	will be reported as reason C<< die => $@ >>.	273	global variable C<$SELF> set to the port ID. Runtime errors will cause the
		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.
165		276
166	Transport/communication errors are reported as C<< transport_error =>	277	If you want to stop/destroy the port, simply C<kil> it:
167	$message >>.
168		278
169	=item $guard = mon $portid, $cb->(@reason)	279	my $port = port {
		280	my @msg = @_;
		281	...
		282	kil $SELF;
		283	};
170		284
171	=item $guard = mon $portid, $otherport	285	=cut
172		286
173	=item $guard = mon $portid, $otherport, @msg	287	sub rcv($@);
174		288
		289	sub _kilme {
		290	die "received message on port without callback";
		291	}
		292
		293	sub port(;&) {
		294	my $id = "$UNIQ." . $ID++;
		295	my $port = "$NODE#$id";
		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
		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 {
		368	my $cb = shift;
		369	$PORT{$portid} = sub {
		370	local $SELF = $port;
		371	eval { &$cb }; _self_die if $@;
		372	};
		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
		390	};
		391
		392	"AnyEvent::MP::Port" eq ref $self
		393	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		394
		395	my ($tag, $cb) = splice @_, 0, 2;
		396
		397	if (defined $cb) {
		398	$self->[1]{$tag} = $cb;
		399	} else {
		400	delete $self->[1]{$tag};
		401	}
		402	}
		403	}
		404
		405	$port
		406	}
		407
		408	=item $closure = psub { BLOCK }
		409
		410	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
		411	closure is executed, sets up the environment in the same way as in C<rcv>
		412	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		413
		414	This is useful when you register callbacks from C<rcv> callbacks:
		415
		416	rcv delayed_reply => sub {
		417	my ($delay, @reply) = @_;
		418	my $timer = AE::timer $delay, 0, psub {
		419	snd @reply, $SELF;
		420	};
		421	};
		422
		423	=cut
		424
		425	sub psub(&) {
		426	my $cb = shift;
		427
		428	my $port = $SELF
		429	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
		430
		431	sub {
		432	local $SELF = $port;
		433
		434	if (wantarray) {
		435	my @res = eval { &$cb };
		436	_self_die if $@;
		437	@res
		438	} else {
		439	my $res = eval { &$cb };
		440	_self_die if $@;
		441	$res
		442	}
		443	}
		444	}
		445
		446	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
		447
		448	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
		449
		450	=item $guard = mon $port # kill $SELF when $port dies
		451
		452	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
		453
175	Monitor the given port and do something when the port is killed.	454	Monitor the given port and do something when the port is killed or
		455	messages to it were lost, and optionally return a guard that can be used
		456	to stop monitoring again.
176		457
		458	C<mon> effectively guarantees that, in the absence of hardware failures,
		459	after starting the monitor, either all messages sent to the port will
		460	arrive, or the monitoring action will be invoked after possible message
		461	loss has been detected. No messages will be lost "in between" (after
		462	the first lost message no further messages will be received by the
		463	port). After the monitoring action was invoked, further messages might get
		464	delivered again.
		465
		466	Note that monitoring-actions are one-shot: once messages are lost (and a
		467	monitoring alert was raised), they are removed and will not trigger again.
		468
177	In the first form, the callback is simply called with any number	469	In the first form (callback), the callback is simply called with any
178	of C<@reason> elements (no @reason means that the port was deleted	470	number of C<@reason> elements (no @reason means that the port was deleted
179	"normally"). Note also that I<< the callback B<must> never die >>, so use	471	"normally"). Note also that I<< the callback B<must> never die >>, so use
180	C<eval> if unsure.	472	C<eval> if unsure.
181		473
182	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	474	In the second form (another port given), the other port (C<$rcvport>)
183	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
184	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.
185		478
		479	The third form (kill self) is the same as the second form, except that
		480	C<$rvport> defaults to C<$SELF>.
		481
186	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.
187		491
188	Example: call a given callback when C<$port> is killed.	492	Example: call a given callback when C<$port> is killed.
189		493
190	mon $port, sub { warn "port died because of <@_>\n" };	494	mon $port, sub { warn "port died because of <@_>\n" };
191		495
192	Example: kill ourselves when C<$port> is killed abnormally.	496	Example: kill ourselves when C<$port> is killed abnormally.
193		497
194	mon $port, $self;	498	mon $port;
195		499
196	Example: send us a restart message another C<$port> is killed.	500	Example: send us a restart message when another C<$port> is killed.
197		501
198	mon $port, $self => "restart";	502	mon $port, $self => "restart";
199		503
200	=cut	504	=cut
201		505
202	sub mon {	506	sub mon {
203	my ($noderef, $port, $cb) = ((split /#/, shift, 2), shift);	507	my ($noderef, $port) = split /#/, shift, 2;
204		508
205	my $node = $NODE{$noderef} \|\| add_node $noderef;	509	my $node = $NODE{$noderef} \|\| add_node $noderef;
206		510
207	#TODO: ports must not be references	511	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
208	if (!ref $cb or "AnyEvent::MP::Port" eq ref $cb) {	512
		513	unless (ref $cb) {
209	if (@_) {	514	if (@_) {
210	# send a kill info message	515	# send a kill info message
211	my (@msg) = ($cb, @_);	516	my (@msg) = ($cb, @_);
212	$cb = sub { snd @msg, @_ };	517	$cb = sub { snd @msg, @_ };
213	} else {	518	} else {
…		…
229	is killed, the references will be freed.	534	is killed, the references will be freed.
230		535
231	Optionally returns a guard that will stop the monitoring.	536	Optionally returns a guard that will stop the monitoring.
232		537
233	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
234	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>):
235		540
236	$port->rcv (start => sub {	541	$port->rcv (start => sub {
237	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	542	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
238	undef $timer if 0.9 < rand;	543	undef $timer if 0.9 < rand;
239	});	544	});
240	});	545	});
241		546
242	=cut	547	=cut
243		548
244	sub mon_guard {	549	sub mon_guard {
245	my ($port, @refs) = @_;	550	my ($port, @refs) = @_;
246		551
		552	#TODO: mon-less form?
		553
247	mon $port, sub { 0 && @refs }	554	mon $port, sub { 0 && @refs }
248	}	555	}
249		556
250	=item lnk $port1, $port2	557	=item kil $port[, @reason]
251		558
252	Link two ports. This is simply a shorthand for:	559	Kill the specified port with the given C<@reason>.
253		560
254	mon $port1, $port2;	561	If no C<@reason> is specified, then the port is killed "normally" (ports
255	mon $port2, $port1;	562	monitoring other ports will not necessarily die because a port dies
		563	"normally").
256		564
257	It means that if either one is killed abnormally, the other one gets	565	Otherwise, linked ports get killed with the same reason (second form of
258	killed as well.	566	C<mon>, see above).
259		567
260	=item $local_port = port	568	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		569	will be reported as reason C<< die => $@ >>.
261		570
262	Create a new local port object that supports message matching.	571	Transport/communication errors are reported as C<< transport_error =>
		572	$message >>.
263		573
264	=item $portid = port { my @msg = @_; $finished }
265
266	Creates a "mini port", that is, a very lightweight port without any
267	pattern matching behind it, and returns its ID.
268
269	The block will be called for every message received on the port. When the
270	callback returns a true value its job is considered "done" and the port
271	will be destroyed. Otherwise it will stay alive.
272
273	The message will be passed as-is, no extra argument (i.e. no port id) will
274	be passed to the callback.
275
276	If you need the local port id in the callback, this works nicely:
277
278	my $port; $port = miniport {
279	snd $otherport, reply => $port;
280	};
281
282	=cut	574	=cut
283		575
284	sub port(;&) {	576	=item $port = spawn $node, $initfunc[, @initdata]
285	my $id = "$UNIQ." . $ID++;
286	my $port = "$NODE#$id";
287		577
288	if (@_) {	578	Creates a port on the node C<$node> (which can also be a port ID, in which
289	my $cb = shift;	579	case it's the node where that port resides).
290	$PORT{$id} = sub {	580
291	local $SELF = $port;	581	The port ID of the newly created port is returned immediately, and it is
292	eval {	582	possible to immediately start sending messages or to monitor the port.
293	&$cb	583
294	and kil $id;	584	After the port has been created, the init function is called on the remote
		585	node, in the same context as a C<rcv> callback. This function must be a
		586	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
		587	specify a function in the main program, use C<::name>.
		588
		589	If the function doesn't exist, then the node tries to C<require>
		590	the package, then the package above the package and so on (e.g.
		591	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		592	exists or it runs out of package names.
		593
		594	The init function is then called with the newly-created port as context
		595	object (C<$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 {
295	};	615	...
296	_self_die if $@;
297	};
298	} else {
299	my $self = bless {
300	id => "$NODE#$id",
301	}, "AnyEvent::MP::Port";
302
303	$PORT_DATA{$id} = $self;
304	$PORT{$id} = sub {
305	local $SELF = $port;
306
307	eval {
308	for (@{ $self->{rc0}{$_[0]} }) {
309	$_ && &{$_->[0]}
310	&& undef $_;
311	}
312
313	for (@{ $self->{rcv}{$_[0]} }) {
314	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
315	&& &{$_->[0]}
316	&& undef $_;
317	}
318
319	for (@{ $self->{any} }) {
320	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
321	&& &{$_->[0]}
322	&& undef $_;
323	}
324	};
325	_self_die if $@;
326	};	616	};
327	}	617	}
328		618
329	$port
330	}
331
332	=item reg $portid, $name
333
334	Registers the given port under the name C<$name>. If the name already
335	exists it is replaced.
336
337	A port can only be registered under one well known name.
338
339	A port automatically becomes unregistered when it is killed.
340
341	=cut	619	=cut
342		620
343	sub reg(@) {	621	sub _spawn {
344	my ($portid, $name) = @_;	622	my $port = shift;
		623	my $init = shift;
345		624
346	$REG{$name} = $portid;	625	local $SELF = "$NODE#$port";
347	}	626	eval {
348		627	&{ load_func $init }
349	=item rcv $portid, tagstring => $callback->(@msg), ...
350
351	=item rcv $portid, $smartmatch => $callback->(@msg), ...
352
353	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
354
355	Register callbacks to be called on matching messages on the given port.
356
357	The callback has to return a true value when its work is done, after
358	which is will be removed, or a false value in which case it will stay
359	registered.
360
361	The global C<$SELF> (exported by this module) contains C<$portid> while
362	executing the callback.
363
364	Runtime errors wdurign callback execution will result in the port being
365	C<kil>ed.
366
367	If the match is an array reference, then it will be matched against the
368	first elements of the message, otherwise only the first element is being
369	matched.
370
371	Any element in the match that is specified as C<_any_> (a function
372	exported by this module) matches any single element of the message.
373
374	While not required, it is highly recommended that the first matching
375	element is a string identifying the message. The one-string-only match is
376	also the most efficient match (by far).
377
378	=cut
379
380	sub rcv($@) {
381	my ($noderef, $port) = split /#/, shift, 2;
382
383	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
384	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";
385
386	my $self = $PORT_DATA{$port}
387	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
388
389	"AnyEvent::MP::Port" eq ref $self
390	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
391
392	while (@_) {
393	my ($match, $cb) = splice @_, 0, 2;
394
395	if (!ref $match) {
396	push @{ $self->{rc0}{$match} }, [$cb];
397	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
398	my ($type, @match) = @$match;
399	@match
400	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
401	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
402	} else {
403	push @{ $self->{any} }, [$cb, $match];
404	}
405	}
406	}
407
408	=item $closure = psub { BLOCK }
409
410	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
411	closure is executed, sets up the environment in the same way as in C<rcv>
412	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
413
414	This is useful when you register callbacks from C<rcv> callbacks:
415
416	rcv delayed_reply => sub {
417	my ($delay, @reply) = @_;
418	my $timer = AE::timer $delay, 0, psub {
419	snd @reply, $SELF;
420	};
421	};	628	};
422
423	=cut
424
425	sub psub(&) {
426	my $cb = shift;
427
428	my $port = $SELF
429	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
430
431	sub {
432	local $SELF = $port;
433
434	if (wantarray) {
435	my @res = eval { &$cb };
436	_self_die if $@;	629	_self_die if $@;
437	@res	630	}
438	} else {	631
439	my $res = eval { &$cb };	632	sub spawn(@) {
440	_self_die if $@;	633	my ($noderef, undef) = split /#/, shift, 2;
441	$res	634
442	}	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;
443	}	666	};
444	}	667	}
445		668
446	=back	669	=back
447		670
448	=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:
449		684
450	=over 4	685	=over 4
451		686
452	=item become_public endpoint...	687	=item * Node IDs are arbitrary strings in AEMP.
453		688
454	Tells the node to become a public node, i.e. reachable from other nodes.	689	Erlang relies on special naming and DNS to work everywhere in the same
		690	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
		691	configuraiton or DNS), but will otherwise discover other odes itself.
455		692
456	If no arguments are given, or the first argument is C<undef>, then	693	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
457	AnyEvent::MP tries to bind on port C<4040> on all IP addresses that the	694	uses "local ports are like remote ports".
458	local nodename resolves to.
459		695
460	Otherwise the first argument must be an array-reference with transport	696	The failure modes for local ports are quite different (runtime errors
461	endpoints ("ip:port", "hostname:port") or port numbers (in which case the	697	only) then for remote ports - when a local port dies, you I<know> it dies,
462	local nodename is used as hostname). The endpoints are all resolved and	698	when a connection to another node dies, you know nothing about the other
463	will become the node reference.	699	port.
464		700
465	=cut	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.
		707
		708	=item * Erlang uses processes and a mailbox, AEMP does not queue.
		709
		710	Erlang uses processes that selectively receive messages, and therefore
		711	needs a queue. AEMP is event based, queuing messages would serve no
		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.
		715
		716	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
		717
		718	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
		719
		720	Sending messages in Erlang is synchronous and blocks the process (and
		721	so does not need a queue that can overflow). AEMP sends are immediate,
		722	connection establishment is handled in the background.
		723
		724	=item * Erlang suffers from silent message loss, AEMP does not.
		725
		726	Erlang makes few guarantees on messages delivery - messages can get lost
		727	without any of the processes realising it (i.e. you send messages a, b,
		728	and c, and the other side only receives messages a and c).
		729
		730	AEMP guarantees correct ordering, and the guarantee that after one message
		731	is lost, all following ones sent to the same port are lost as well, until
		732	monitoring raises an error, so there are no silent "holes" in the message
		733	sequence.
		734
		735	=item * Erlang can send messages to the wrong port, AEMP does not.
		736
		737	In Erlang it is quite likely that a node that restarts reuses a process ID
		738	known to other nodes for a completely different process, causing messages
		739	destined for that process to end up in an unrelated process.
		740
		741	AEMP never reuses port IDs, so old messages or old port IDs floating
		742	around in the network will not be sent to an unrelated port.
		743
		744	=item * Erlang uses unprotected connections, AEMP uses secure
		745	authentication and can use TLS.
		746
		747	AEMP can use a proven protocol - TLS - to protect connections and
		748	securely authenticate nodes.
		749
		750	=item * The AEMP protocol is optimised for both text-based and binary
		751	communications.
		752
		753	The AEMP protocol, unlike the Erlang protocol, supports both programming
		754	language independent text-only protocols (good for debugging) and binary,
		755	language-specific serialisers (e.g. Storable). By default, unless TLS is
		756	used, the protocol is actually completely text-based.
		757
		758	It has also been carefully designed to be implementable in other languages
		759	with a minimum of work while gracefully degrading functionality to make the
		760	protocol simple.
		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).
466		783
467	=back	784	=back
468		785
469	=head1 NODE MESSAGES	786	=head1 RATIONALE
470
471	Nodes understand the following messages sent to them. Many of them take
472	arguments called C<@reply>, which will simply be used to compose a reply
473	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
474	the remaining arguments are simply the message data.
475		787
476	=over 4	788	=over 4
477		789
478	=cut	790	=item Why strings for port and node IDs, why not objects?
479		791
480	=item lookup => $name, @reply	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.
481		796
482	Replies with the port ID of the specified well-known port, or C<undef>.	797	Strings can easily be printed, easily serialised etc. and need no special
		798	procedures to be "valid".
483		799
484	=item devnull => ...	800	And as a result, a miniport consists of a single closure stored in a
		801	global hash - it can't become much cheaper.
485		802
486	Generic data sink/CPU heat conversion.	803	=item Why favour JSON, why not a real serialising format such as Storable?
487		804
488	=item relay => $port, @msg	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).
489		808
490	Simply forwards the message to the given port.	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.
491		815
492	=item eval => $string[ @reply]	816	Keeping your messages simple, concentrating on data structures rather than
493		817	objects, will keep your messages clean, tidy and efficient.
494	Evaluates the given string. If C<@reply> is given, then a message of the
495	form C<@reply, $@, @evalres> is sent.
496
497	Example: crash another node.
498
499	snd $othernode, eval => "exit";
500
501	=item time => @reply
502
503	Replies the the current node time to C<@reply>.
504
505	Example: tell the current node to send the current time to C<$myport> in a
506	C<timereply> message.
507
508	snd $NODE, time => $myport, timereply => 1, 2;
509	# => snd $myport, timereply => 1, 2, <time>
510		818
511	=back	819	=back
512		820
513	=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.
514		829
515	L<AnyEvent>.	830	L<AnyEvent>.
516		831
517	=head1 AUTHOR	832	=head1 AUTHOR
518		833

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Revision 1.69 by root, Sun Aug 30 18:51:49 2009 UTC