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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.22 by root, Tue Aug 4 18:33:30 2009 UTC vs.
Revision 1.77 by elmex, Thu Sep 3 07:57:30 2009 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use AnyEvent::MP;	7	use AnyEvent::MP;
8		8
9	$NODE # contains this node's noderef	9	$NODE # contains this node's node ID
10	NODE # returns this node's noderef	10	NODE # returns this node's node ID
11	NODE $port # returns the noderef of the port
12		11
		12	$SELF # receiving/own port id in rcv callbacks
		13
		14	# initialise the node so it can send/receive messages
		15	configure;
		16
		17	# ports are message destinations
		18
		19	# sending messages
13	snd $port, type => data...;	20	snd $port, type => data...;
		21	snd $port, @msg;
		22	snd @msg_with_first_element_being_a_port;
14		23
15	$SELF # receiving/own port id in rcv callbacks	24	# creating/using ports, the simple way
		25	my $simple_port = port { my @msg = @_ };
16		26
17	rcv $port, smartmatch => $cb->($port, @msg);	27	# creating/using ports, tagged message matching
18		28	my $port = port;
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	29	rcv $port, ping => sub { snd $_[0], "pong" };
21	rcv $port1, pong => sub { warn "pong received\n" };	30	rcv $port, pong => sub { warn "pong received\n" };
22	snd $port2, ping => $port1;
23		31
24	# more, smarter, matches (_any_ is exported by this module)	32	# create a port on another node
25	rcv $port, [child_died => $pid] => sub { ...	33	my $port = spawn $node, $initfunc, @initdata;
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	34
		35	# monitoring
		36	mon $port, $cb->(@msg) # callback is invoked on death
		37	mon $port, $otherport # kill otherport on abnormal death
		38	mon $port, $otherport, @msg # send message on death
		39
		40	=head1 CURRENT STATUS
		41
		42	bin/aemp - stable.
		43	AnyEvent::MP - stable API, should work.
		44	AnyEvent::MP::Intro - explains most concepts.
		45	AnyEvent::MP::Kernel - mostly stable.
		46	AnyEvent::MP::Global - stable API, protocol not yet final.
		47
		48	stay tuned.
27		49
28	=head1 DESCRIPTION	50	=head1 DESCRIPTION
29		51
30	This module (-family) implements a simple message passing framework.	52	This module (-family) implements a simple message passing framework.
31		53
32	Despite its simplicity, you can securely message other processes running	54	Despite its simplicity, you can securely message other processes running
33	on the same or other hosts.	55	on the same or other hosts, and you can supervise entities remotely.
34		56
35	At the moment, this module family is severly brokena nd underdocumented,	57	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
36	so do not use. This was uploaded mainly to reserve the CPAN namespace -	58	manual page and the examples under F<eg/>.
37	stay tuned!
38		59
39	=head1 CONCEPTS	60	=head1 CONCEPTS
40		61
41	=over 4	62	=over 4
42		63
43	=item port	64	=item port
44		65
45	A port is something you can send messages to with the C<snd> function, and	66	A port is something you can send messages to (with the C<snd> function).
46	you can register C<rcv> handlers with. All C<rcv> handlers will receive
47	messages they match, messages will not be queued.
48		67
		68	Ports allow you to register C<rcv> handlers that can match all or just
		69	some messages. Messages send to ports will not be queued, regardless of
		70	anything was listening for them or not.
		71
49	=item port id - C<noderef#portname>	72	=item port ID - C<nodeid#portname>
50		73
51	A port id is always the noderef, a hash-mark (C<#>) as separator, followed	74	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as
52	by a port name (a printable string of unspecified format).	75	separator, and a port name (a printable string of unspecified format).
53		76
54	=item node	77	=item node
55		78
56	A node is a single process containing at least one port - the node	79	A node is a single process containing at least one port - the node port,
57	port. You can send messages to node ports to let them create new ports,	80	which enables nodes to manage each other remotely, and to create new
58	among other things.	81	ports.
59		82
60	Initially, nodes are either private (single-process only) or hidden	83	Nodes are either public (have one or more listening ports) or private
61	(connected to a master node only). Only when they epxlicitly "become	84	(no listening ports). Private nodes cannot talk to other private nodes
62	public" can you send them messages from unrelated other nodes.	85	currently.
63		86
64	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	87	=item node ID - C<[a-za-Z0-9_\-.:]+>
65		88
66	A noderef is a string that either uniquely identifies a given node (for	89	A node ID is a string that uniquely identifies the node within a
67	private and hidden nodes), or contains a recipe on how to reach a given	90	network. Depending on the configuration used, node IDs can look like a
68	node (for public nodes).	91	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
		92	doesn't interpret node IDs in any way.
		93
		94	=item binds - C<ip:port>
		95
		96	Nodes can only talk to each other by creating some kind of connection to
		97	each other. To do this, nodes should listen on one or more local transport
		98	endpoints - binds. Currently, only standard C<ip:port> specifications can
		99	be used, which specify TCP ports to listen on.
		100
		101	=item seeds - C<host:port>
		102
		103	When a node starts, it knows nothing about the network. To teach the node
		104	about the network it first has to contact some other node within the
		105	network. This node is called a seed.
		106
		107	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes
		108	are expected to be long-running, and at least one of those should always
		109	be available. When nodes run out of connections (e.g. due to a network
		110	error), they try to re-establish connections to some seednodes again to
		111	join the network.
		112
		113	Apart from being sued for seeding, seednodes are not special in any way -
		114	every public node can be a seednode.
69		115
70	=back	116	=back
71		117
72	=head1 VARIABLES/FUNCTIONS	118	=head1 VARIABLES/FUNCTIONS
73		119
…		…
75		121
76	=cut	122	=cut
77		123
78	package AnyEvent::MP;	124	package AnyEvent::MP;
79		125
80	use AnyEvent::MP::Base;	126	use AnyEvent::MP::Kernel;
81		127
82	use common::sense;	128	use common::sense;
83		129
84	use Carp ();	130	use Carp ();
85		131
86	use AE ();	132	use AE ();
87		133
88	use base "Exporter";	134	use base "Exporter";
89		135
90	our $VERSION = '0.02';	136	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		137
91	our @EXPORT = qw(	138	our @EXPORT = qw(
92	NODE $NODE *SELF node_of _any_	139	NODE $NODE *SELF node_of after
93	become_slave become_public	140	configure
94	snd rcv mon kil reg psub	141	snd rcv mon mon_guard kil reg psub spawn
95	port	142	port
96	);	143	);
97		144
98	our $SELF;	145	our $SELF;
99		146
…		…
103	kil $SELF, die => $msg;	150	kil $SELF, die => $msg;
104	}	151	}
105		152
106	=item $thisnode = NODE / $NODE	153	=item $thisnode = NODE / $NODE
107		154
108	The C<NODE> function returns, and the C<$NODE> variable contains	155	The C<NODE> function returns, and the C<$NODE> variable contains, the node
109	the noderef of the local node. The value is initialised by a call	156	ID of the node running in the current process. This value is initialised by
110	to C<become_public> or C<become_slave>, after which all local port	157	a call to C<configure>.
111	identifiers become invalid.
112		158
113	=item $noderef = node_of $portid	159	=item $nodeid = node_of $port
114		160
115	Extracts and returns the noderef from a portid or a noderef.	161	Extracts and returns the node ID from a port ID or a node ID.
		162
		163	=item configure key => value...
		164
		165	Before a node can talk to other nodes on the network (i.e. enter
		166	"distributed mode") it has to configure itself - the minimum a node needs
		167	to know is its own name, and optionally it should know the addresses of
		168	some other nodes in the network to discover other nodes.
		169
		170	This function configures a node - it must be called exactly once (or
		171	never) before calling other AnyEvent::MP functions.
		172
		173	=over 4
		174
		175	=item step 1, gathering configuration from profiles
		176
		177	The function first looks up a profile in the aemp configuration (see the
		178	L<aemp> commandline utility). The profile name can be specified via the
		179	named C<profile> parameter. If it is missing, then the nodename (F<uname
		180	-n>) will be used as profile name.
		181
		182	The profile data is then gathered as follows:
		183
		184	First, all remaining key => value pairs (all of which are conveniently
		185	undocumented at the moment) will be interpreted as configuration
		186	data. Then they will be overwritten by any values specified in the global
		187	default configuration (see the F<aemp> utility), then the chain of
		188	profiles chosen by the profile name (and any C<parent> attributes).
		189
		190	That means that the values specified in the profile have highest priority
		191	and the values specified directly via C<configure> have lowest priority,
		192	and can only be used to specify defaults.
		193
		194	If the profile specifies a node ID, then this will become the node ID of
		195	this process. If not, then the profile name will be used as node ID. The
		196	special node ID of C<anon/> will be replaced by a random node ID.
		197
		198	=item step 2, bind listener sockets
		199
		200	The next step is to look up the binds in the profile, followed by binding
		201	aemp protocol listeners on all binds specified (it is possible and valid
		202	to have no binds, meaning that the node cannot be contacted form the
		203	outside. This means the node cannot talk to other nodes that also have no
		204	binds, but it can still talk to all "normal" nodes).
		205
		206	If the profile does not specify a binds list, then a default of C<*> is
		207	used, meaning the node will bind on a dynamically-assigned port on every
		208	local IP address it finds.
		209
		210	=item step 3, connect to seed nodes
		211
		212	As the last step, the seeds list from the profile is passed to the
		213	L<AnyEvent::MP::Global> module, which will then use it to keep
		214	connectivity with at least one node at any point in time.
		215
		216	=back
		217
		218	Example: become a distributed node using the locla node name as profile.
		219	This should be the most common form of invocation for "daemon"-type nodes.
		220
		221	configure
		222
		223	Example: become an anonymous node. This form is often used for commandline
		224	clients.
		225
		226	configure nodeid => "anon/";
		227
		228	Example: configure a node using a profile called seed, which si suitable
		229	for a seed node as it binds on all local addresses on a fixed port (4040,
		230	customary for aemp).
		231
		232	# use the aemp commandline utility
		233	# aemp profile seed nodeid anon/ binds '*:4040'
		234
		235	# then use it
		236	configure profile => "seed";
		237
		238	# or simply use aemp from the shell again:
		239	# aemp run profile seed
		240
		241	# or provide a nicer-to-remember nodeid
		242	# aemp run profile seed nodeid "$(hostname)"
116		243
117	=item $SELF	244	=item $SELF
118		245
119	Contains the current port id while executing C<rcv> callbacks or C<psub>	246	Contains the current port id while executing C<rcv> callbacks or C<psub>
120	blocks.	247	blocks.
121		248
122	=item SELF, %SELF, @SELF...	249	=item *SELF, SELF, %SELF, @SELF...
123		250
124	Due to some quirks in how perl exports variables, it is impossible to	251	Due to some quirks in how perl exports variables, it is impossible to
125	just export C<$SELF>, all the symbols called C<SELF> are exported by this	252	just export C<$SELF>, all the symbols named C<SELF> are exported by this
126	module, but only C<$SELF> is currently used.	253	module, but only C<$SELF> is currently used.
127		254
128	=item snd $portid, type => @data	255	=item snd $port, type => @data
129		256
130	=item snd $portid, @msg	257	=item snd $port, @msg
131		258
132	Send the given message to the given port ID, which can identify either	259	Send the given message to the given port, which can identify either a
133	a local or a remote port, and can be either a string or soemthignt hat	260	local or a remote port, and must be a port ID.
134	stringifies a sa port ID (such as a port object :).
135		261
136	While the message can be about anything, it is highly recommended to use a	262	While the message can be almost anything, it is highly recommended to
137	string as first element (a portid, or some word that indicates a request	263	use a string as first element (a port ID, or some word that indicates a
138	type etc.).	264	request type etc.) and to consist if only simple perl values (scalars,
		265	arrays, hashes) - if you think you need to pass an object, think again.
139		266
140	The message data effectively becomes read-only after a call to this	267	The message data logically becomes read-only after a call to this
141	function: modifying any argument is not allowed and can cause many	268	function: modifying any argument (or values referenced by them) is
142	problems.	269	forbidden, as there can be considerable time between the call to C<snd>
		270	and the time the message is actually being serialised - in fact, it might
		271	never be copied as within the same process it is simply handed to the
		272	receiving port.
143		273
144	The type of data you can transfer depends on the transport protocol: when	274	The type of data you can transfer depends on the transport protocol: when
145	JSON is used, then only strings, numbers and arrays and hashes consisting	275	JSON is used, then only strings, numbers and arrays and hashes consisting
146	of those are allowed (no objects). When Storable is used, then anything	276	of those are allowed (no objects). When Storable is used, then anything
147	that Storable can serialise and deserialise is allowed, and for the local	277	that Storable can serialise and deserialise is allowed, and for the local
148	node, anything can be passed.	278	node, anything can be passed. Best rely only on the common denominator of
		279	these.
149		280
150	=item kil $portid[, @reason]	281	=item $local_port = port
151		282
152	Kill the specified port with the given C<@reason>.	283	Create a new local port object and returns its port ID. Initially it has
		284	no callbacks set and will throw an error when it receives messages.
153		285
154	If no C<@reason> is specified, then the port is killed "normally" (linked	286	=item $local_port = port { my @msg = @_ }
155	ports will not be kileld, or even notified).
156		287
157	Otherwise, linked ports get killed with the same reason (second form of	288	Creates a new local port, and returns its ID. Semantically the same as
158	C<mon>, see below).	289	creating a port and calling C<rcv $port, $callback> on it.
159		290
160	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	291	The block will be called for every message received on the port, with the
161	will be reported as reason C<< die => $@ >>.	292	global variable C<$SELF> set to the port ID. Runtime errors will cause the
		293	port to be C<kil>ed. The message will be passed as-is, no extra argument
		294	(i.e. no port ID) will be passed to the callback.
162		295
163	Transport/communication errors are reported as C<< transport_error =>	296	If you want to stop/destroy the port, simply C<kil> it:
164	$message >>.
165		297
166	=item $guard = mon $portid, $cb->(@reason)	298	my $port = port {
		299	my @msg = @_;
		300	...
		301	kil $SELF;
		302	};
167		303
168	=item $guard = mon $portid, $otherport	304	=cut
169		305
170	=item $guard = mon $portid, $otherport, @msg	306	sub rcv($@);
171		307
		308	sub _kilme {
		309	die "received message on port without callback";
		310	}
		311
		312	sub port(;&) {
		313	my $id = "$UNIQ." . $ID++;
		314	my $port = "$NODE#$id";
		315
		316	rcv $port, shift \|\| \&_kilme;
		317
		318	$port
		319	}
		320
		321	=item rcv $local_port, $callback->(@msg)
		322
		323	Replaces the default callback on the specified port. There is no way to
		324	remove the default callback: use C<sub { }> to disable it, or better
		325	C<kil> the port when it is no longer needed.
		326
		327	The global C<$SELF> (exported by this module) contains C<$port> while
		328	executing the callback. Runtime errors during callback execution will
		329	result in the port being C<kil>ed.
		330
		331	The default callback received all messages not matched by a more specific
		332	C<tag> match.
		333
		334	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
		335
		336	Register (or replace) callbacks to be called on messages starting with the
		337	given tag on the given port (and return the port), or unregister it (when
		338	C<$callback> is C<$undef> or missing). There can only be one callback
		339	registered for each tag.
		340
		341	The original message will be passed to the callback, after the first
		342	element (the tag) has been removed. The callback will use the same
		343	environment as the default callback (see above).
		344
		345	Example: create a port and bind receivers on it in one go.
		346
		347	my $port = rcv port,
		348	msg1 => sub { ... },
		349	msg2 => sub { ... },
		350	;
		351
		352	Example: create a port, bind receivers and send it in a message elsewhere
		353	in one go:
		354
		355	snd $otherport, reply =>
		356	rcv port,
		357	msg1 => sub { ... },
		358	...
		359	;
		360
		361	Example: temporarily register a rcv callback for a tag matching some port
		362	(e.g. for a rpc reply) and unregister it after a message was received.
		363
		364	rcv $port, $otherport => sub {
		365	my @reply = @_;
		366
		367	rcv $SELF, $otherport;
		368	};
		369
		370	=cut
		371
		372	sub rcv($@) {
		373	my $port = shift;
		374	my ($nodeid, $portid) = split /#/, $port, 2;
		375
		376	$NODE{$nodeid} == $NODE{""}
		377	or Carp::croak "$port: rcv can only be called on local ports, caught";
		378
		379	while (@_) {
		380	if (ref $_[0]) {
		381	if (my $self = $PORT_DATA{$portid}) {
		382	"AnyEvent::MP::Port" eq ref $self
		383	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		384
		385	$self->[2] = shift;
		386	} else {
		387	my $cb = shift;
		388	$PORT{$portid} = sub {
		389	local $SELF = $port;
		390	eval { &$cb }; _self_die if $@;
		391	};
		392	}
		393	} elsif (defined $_[0]) {
		394	my $self = $PORT_DATA{$portid} \|\|= do {
		395	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
		396
		397	$PORT{$portid} = sub {
		398	local $SELF = $port;
		399
		400	if (my $cb = $self->[1]{$_[0]}) {
		401	shift;
		402	eval { &$cb }; _self_die if $@;
		403	} else {
		404	&{ $self->[0] };
		405	}
		406	};
		407
		408	$self
		409	};
		410
		411	"AnyEvent::MP::Port" eq ref $self
		412	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		413
		414	my ($tag, $cb) = splice @_, 0, 2;
		415
		416	if (defined $cb) {
		417	$self->[1]{$tag} = $cb;
		418	} else {
		419	delete $self->[1]{$tag};
		420	}
		421	}
		422	}
		423
		424	$port
		425	}
		426
		427	=item $closure = psub { BLOCK }
		428
		429	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
		430	closure is executed, sets up the environment in the same way as in C<rcv>
		431	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		432
		433	This is useful when you register callbacks from C<rcv> callbacks:
		434
		435	rcv delayed_reply => sub {
		436	my ($delay, @reply) = @_;
		437	my $timer = AE::timer $delay, 0, psub {
		438	snd @reply, $SELF;
		439	};
		440	};
		441
		442	=cut
		443
		444	sub psub(&) {
		445	my $cb = shift;
		446
		447	my $port = $SELF
		448	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
		449
		450	sub {
		451	local $SELF = $port;
		452
		453	if (wantarray) {
		454	my @res = eval { &$cb };
		455	_self_die if $@;
		456	@res
		457	} else {
		458	my $res = eval { &$cb };
		459	_self_die if $@;
		460	$res
		461	}
		462	}
		463	}
		464
		465	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
		466
		467	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
		468
		469	=item $guard = mon $port # kill $SELF when $port dies
		470
		471	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
		472
172	Monitor the given port and do something when the port is killed.	473	Monitor the given port and do something when the port is killed or
		474	messages to it were lost, and optionally return a guard that can be used
		475	to stop monitoring again.
173		476
		477	C<mon> effectively guarantees that, in the absence of hardware failures,
		478	after starting the monitor, either all messages sent to the port will
		479	arrive, or the monitoring action will be invoked after possible message
		480	loss has been detected. No messages will be lost "in between" (after
		481	the first lost message no further messages will be received by the
		482	port). After the monitoring action was invoked, further messages might get
		483	delivered again.
		484
		485	Note that monitoring-actions are one-shot: once messages are lost (and a
		486	monitoring alert was raised), they are removed and will not trigger again.
		487
174	In the first form, the callback is simply called with any number	488	In the first form (callback), the callback is simply called with any
175	of C<@reason> elements (no @reason means that the port was deleted	489	number of C<@reason> elements (no @reason means that the port was deleted
176	"normally"). Note also that I<< the callback B<must> never die >>, so use	490	"normally"). Note also that I<< the callback B<must> never die >>, so use
177	C<eval> if unsure.	491	C<eval> if unsure.
178		492
179	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	493	In the second form (another port given), the other port (C<$rcvport>)
180	a @reason was specified, i.e. on "normal" kils nothing happens, while	494	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
181	under all other conditions, the other port is killed with the same reason.	495	"normal" kils nothing happens, while under all other conditions, the other
		496	port is killed with the same reason.
182		497
		498	The third form (kill self) is the same as the second form, except that
		499	C<$rvport> defaults to C<$SELF>.
		500
183	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	501	In the last form (message), a message of the form C<@msg, @reason> will be
		502	C<snd>.
		503
		504	As a rule of thumb, monitoring requests should always monitor a port from
		505	a local port (or callback). The reason is that kill messages might get
		506	lost, just like any other message. Another less obvious reason is that
		507	even monitoring requests can get lost (for example, when the connection
		508	to the other node goes down permanently). When monitoring a port locally
		509	these problems do not exist.
184		510
185	Example: call a given callback when C<$port> is killed.	511	Example: call a given callback when C<$port> is killed.
186		512
187	mon $port, sub { warn "port died because of <@_>\n" };	513	mon $port, sub { warn "port died because of <@_>\n" };
188		514
189	Example: kill ourselves when C<$port> is killed abnormally.	515	Example: kill ourselves when C<$port> is killed abnormally.
190		516
191	mon $port, $self;	517	mon $port;
192		518
193	Example: send us a restart message another C<$port> is killed.	519	Example: send us a restart message when another C<$port> is killed.
194		520
195	mon $port, $self => "restart";	521	mon $port, $self => "restart";
196		522
197	=cut	523	=cut
198		524
199	sub mon {	525	sub mon {
200	my ($noderef, $port, $cb) = ((split /#/, shift, 2), shift);	526	my ($nodeid, $port) = split /#/, shift, 2;
201		527
202	my $node = $NODE{$noderef} \|\| add_node $noderef;	528	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
203		529
204	#TODO: ports must not be references	530	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
205	if (!ref $cb or "AnyEvent::MP::Port" eq ref $cb) {	531
		532	unless (ref $cb) {
206	if (@_) {	533	if (@_) {
207	# send a kill info message	534	# send a kill info message
208	my (@msg) = ($cb, @_);	535	my (@msg) = ($cb, @_);
209	$cb = sub { snd @msg, @_ };	536	$cb = sub { snd @msg, @_ };
210	} else {	537	} else {
…		…
226	is killed, the references will be freed.	553	is killed, the references will be freed.
227		554
228	Optionally returns a guard that will stop the monitoring.	555	Optionally returns a guard that will stop the monitoring.
229		556
230	This function is useful when you create e.g. timers or other watchers and	557	This function is useful when you create e.g. timers or other watchers and
231	want to free them when the port gets killed:	558	want to free them when the port gets killed (note the use of C<psub>):
232		559
233	$port->rcv (start => sub {	560	$port->rcv (start => sub {
234	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	561	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
235	undef $timer if 0.9 < rand;	562	undef $timer if 0.9 < rand;
236	});	563	});
237	});	564	});
238		565
239	=cut	566	=cut
240		567
241	sub mon_guard {	568	sub mon_guard {
242	my ($port, @refs) = @_;	569	my ($port, @refs) = @_;
243		570
		571	#TODO: mon-less form?
		572
244	mon $port, sub { 0 && @refs }	573	mon $port, sub { 0 && @refs }
245	}	574	}
246		575
247	=item $local_port = port	576	=item kil $port[, @reason]
248		577
249	Create a new local port object that supports message matching.	578	Kill the specified port with the given C<@reason>.
250		579
251	=item $portid = port { my @msg = @_; $finished }	580	If no C<@reason> is specified, then the port is killed "normally" (ports
		581	monitoring other ports will not necessarily die because a port dies
		582	"normally").
252		583
253	Creates a "mini port", that is, a very lightweight port without any	584	Otherwise, linked ports get killed with the same reason (second form of
254	pattern matching behind it, and returns its ID.	585	C<mon>, see above).
255		586
256	The block will be called for every message received on the port. When the	587	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
257	callback returns a true value its job is considered "done" and the port	588	will be reported as reason C<< die => $@ >>.
258	will be destroyed. Otherwise it will stay alive.
259		589
260	The message will be passed as-is, no extra argument (i.e. no port id) will	590	Transport/communication errors are reported as C<< transport_error =>
261	be passed to the callback.	591	$message >>.
262		592
263	If you need the local port id in the callback, this works nicely:
264
265	my $port; $port = miniport {
266	snd $otherport, reply => $port;
267	};
268
269	=cut	593	=cut
270		594
271	sub port(;&) {	595	=item $port = spawn $node, $initfunc[, @initdata]
272	my $id = "$UNIQ." . $ID++;
273	my $port = "$NODE#$id";
274		596
275	if (@_) {	597	Creates a port on the node C<$node> (which can also be a port ID, in which
276	my $cb = shift;	598	case it's the node where that port resides).
277	$PORT{$id} = sub {	599
278	local $SELF = $port;	600	The port ID of the newly created port is returned immediately, and it is
279	eval {	601	possible to immediately start sending messages or to monitor the port.
280	&$cb	602
281	and kil $id;	603	After the port has been created, the init function is called on the remote
		604	node, in the same context as a C<rcv> callback. This function must be a
		605	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
		606	specify a function in the main program, use C<::name>.
		607
		608	If the function doesn't exist, then the node tries to C<require>
		609	the package, then the package above the package and so on (e.g.
		610	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		611	exists or it runs out of package names.
		612
		613	The init function is then called with the newly-created port as context
		614	object (C<$SELF>) and the C<@initdata> values as arguments.
		615
		616	A common idiom is to pass a local port, immediately monitor the spawned
		617	port, and in the remote init function, immediately monitor the passed
		618	local port. This two-way monitoring ensures that both ports get cleaned up
		619	when there is a problem.
		620
		621	Example: spawn a chat server port on C<$othernode>.
		622
		623	# this node, executed from within a port context:
		624	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		625	mon $server;
		626
		627	# init function on C<$othernode>
		628	sub connect {
		629	my ($srcport) = @_;
		630
		631	mon $srcport;
		632
		633	rcv $SELF, sub {
282	};	634	...
283	_self_die if $@;
284	};
285	} else {
286	my $self = bless {
287	id => "$NODE#$id",
288	}, "AnyEvent::MP::Port";
289
290	$PORT_DATA{$id} = $self;
291	$PORT{$id} = sub {
292	local $SELF = $port;
293
294	eval {
295	for (@{ $self->{rc0}{$_[0]} }) {
296	$_ && &{$_->[0]}
297	&& undef $_;
298	}
299
300	for (@{ $self->{rcv}{$_[0]} }) {
301	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
302	&& &{$_->[0]}
303	&& undef $_;
304	}
305
306	for (@{ $self->{any} }) {
307	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
308	&& &{$_->[0]}
309	&& undef $_;
310	}
311	};
312	_self_die if $@;
313	};	635	};
314	}	636	}
315		637
316	$port
317	}
318
319	=item reg $portid, $name
320
321	Registers the given port under the name C<$name>. If the name already
322	exists it is replaced.
323
324	A port can only be registered under one well known name.
325
326	A port automatically becomes unregistered when it is killed.
327
328	=cut	638	=cut
329		639
330	sub reg(@) {	640	sub _spawn {
331	my ($portid, $name) = @_;	641	my $port = shift;
		642	my $init = shift;
332		643
333	$REG{$name} = $portid;	644	local $SELF = "$NODE#$port";
334	}	645	eval {
335		646	&{ load_func $init }
336	=item rcv $portid, tagstring => $callback->(@msg), ...
337
338	=item rcv $portid, $smartmatch => $callback->(@msg), ...
339
340	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
341
342	Register callbacks to be called on matching messages on the given port.
343
344	The callback has to return a true value when its work is done, after
345	which is will be removed, or a false value in which case it will stay
346	registered.
347
348	The global C<$SELF> (exported by this module) contains C<$portid> while
349	executing the callback.
350
351	Runtime errors wdurign callback execution will result in the port being
352	C<kil>ed.
353
354	If the match is an array reference, then it will be matched against the
355	first elements of the message, otherwise only the first element is being
356	matched.
357
358	Any element in the match that is specified as C<_any_> (a function
359	exported by this module) matches any single element of the message.
360
361	While not required, it is highly recommended that the first matching
362	element is a string identifying the message. The one-string-only match is
363	also the most efficient match (by far).
364
365	=cut
366
367	sub rcv($@) {
368	my ($noderef, $port) = split /#/, shift, 2;
369
370	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
371	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";
372
373	my $self = $PORT_DATA{$port}
374	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
375
376	"AnyEvent::MP::Port" eq ref $self
377	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
378
379	while (@_) {
380	my ($match, $cb) = splice @_, 0, 2;
381
382	if (!ref $match) {
383	push @{ $self->{rc0}{$match} }, [$cb];
384	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
385	my ($type, @match) = @$match;
386	@match
387	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
388	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
389	} else {
390	push @{ $self->{any} }, [$cb, $match];
391	}
392	}
393	}
394
395	=item $closure = psub { BLOCK }
396
397	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
398	closure is executed, sets up the environment in the same way as in C<rcv>
399	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
400
401	This is useful when you register callbacks from C<rcv> callbacks:
402
403	rcv delayed_reply => sub {
404	my ($delay, @reply) = @_;
405	my $timer = AE::timer $delay, 0, psub {
406	snd @reply, $SELF;
407	};
408	};	647	};
409
410	=cut
411
412	sub psub(&) {
413	my $cb = shift;
414
415	my $port = $SELF
416	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
417
418	sub {
419	local $SELF = $port;
420
421	if (wantarray) {
422	my @res = eval { &$cb };
423	_self_die if $@;	648	_self_die if $@;
424	@res	649	}
425	} else {	650
426	my $res = eval { &$cb };	651	sub spawn(@) {
427	_self_die if $@;	652	my ($nodeid, undef) = split /#/, shift, 2;
428	$res	653
429	}	654	my $id = "$RUNIQ." . $ID++;
		655
		656	$_[0] =~ /::/
		657	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		658
		659	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
		660
		661	"$nodeid#$id"
		662	}
		663
		664	=item after $timeout, @msg
		665
		666	=item after $timeout, $callback
		667
		668	Either sends the given message, or call the given callback, after the
		669	specified number of seconds.
		670
		671	This is simply a utility function that comes in handy at times - the
		672	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		673	so it may go away in the future.
		674
		675	=cut
		676
		677	sub after($@) {
		678	my ($timeout, @action) = @_;
		679
		680	my $t; $t = AE::timer $timeout, 0, sub {
		681	undef $t;
		682	ref $action[0]
		683	? $action[0]()
		684	: snd @action;
430	}	685	};
431	}	686	}
432		687
433	=back	688	=back
434		689
435	=head1 FUNCTIONS FOR NODES	690	=head1 AnyEvent::MP vs. Distributed Erlang
		691
		692	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
		693	== aemp node, Erlang process == aemp port), so many of the documents and
		694	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		695	sample:
		696
		697	http://www.Erlang.se/doc/programming_rules.shtml
		698	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		699	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		700	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		701
		702	Despite the similarities, there are also some important differences:
436		703
437	=over 4	704	=over 4
438		705
439	=item become_public endpoint...	706	=item * Node IDs are arbitrary strings in AEMP.
440		707
441	Tells the node to become a public node, i.e. reachable from other nodes.	708	Erlang relies on special naming and DNS to work everywhere in the same
		709	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
		710	configuration or DNS), but will otherwise discover other odes itself.
442		711
443	If no arguments are given, or the first argument is C<undef>, then	712	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
444	AnyEvent::MP tries to bind on port C<4040> on all IP addresses that the	713	uses "local ports are like remote ports".
445	local nodename resolves to.
446		714
447	Otherwise the first argument must be an array-reference with transport	715	The failure modes for local ports are quite different (runtime errors
448	endpoints ("ip:port", "hostname:port") or port numbers (in which case the	716	only) then for remote ports - when a local port dies, you I<know> it dies,
449	local nodename is used as hostname). The endpoints are all resolved and	717	when a connection to another node dies, you know nothing about the other
450	will become the node reference.	718	port.
451		719
452	=cut	720	Erlang pretends remote ports are as reliable as local ports, even when
		721	they are not.
		722
		723	AEMP encourages a "treat remote ports differently" philosophy, with local
		724	ports being the special case/exception, where transport errors cannot
		725	occur.
		726
		727	=item * Erlang uses processes and a mailbox, AEMP does not queue.
		728
		729	Erlang uses processes that selectively receive messages, and therefore
		730	needs a queue. AEMP is event based, queuing messages would serve no
		731	useful purpose. For the same reason the pattern-matching abilities of
		732	AnyEvent::MP are more limited, as there is little need to be able to
		733	filter messages without dequeuing them.
		734
		735	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
		736
		737	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
		738
		739	Sending messages in Erlang is synchronous and blocks the process (and
		740	so does not need a queue that can overflow). AEMP sends are immediate,
		741	connection establishment is handled in the background.
		742
		743	=item * Erlang suffers from silent message loss, AEMP does not.
		744
		745	Erlang makes few guarantees on messages delivery - messages can get lost
		746	without any of the processes realising it (i.e. you send messages a, b,
		747	and c, and the other side only receives messages a and c).
		748
		749	AEMP guarantees correct ordering, and the guarantee that after one message
		750	is lost, all following ones sent to the same port are lost as well, until
		751	monitoring raises an error, so there are no silent "holes" in the message
		752	sequence.
		753
		754	=item * Erlang can send messages to the wrong port, AEMP does not.
		755
		756	In Erlang it is quite likely that a node that restarts reuses a process ID
		757	known to other nodes for a completely different process, causing messages
		758	destined for that process to end up in an unrelated process.
		759
		760	AEMP never reuses port IDs, so old messages or old port IDs floating
		761	around in the network will not be sent to an unrelated port.
		762
		763	=item * Erlang uses unprotected connections, AEMP uses secure
		764	authentication and can use TLS.
		765
		766	AEMP can use a proven protocol - TLS - to protect connections and
		767	securely authenticate nodes.
		768
		769	=item * The AEMP protocol is optimised for both text-based and binary
		770	communications.
		771
		772	The AEMP protocol, unlike the Erlang protocol, supports both programming
		773	language independent text-only protocols (good for debugging) and binary,
		774	language-specific serialisers (e.g. Storable). By default, unless TLS is
		775	used, the protocol is actually completely text-based.
		776
		777	It has also been carefully designed to be implementable in other languages
		778	with a minimum of work while gracefully degrading functionality to make the
		779	protocol simple.
		780
		781	=item * AEMP has more flexible monitoring options than Erlang.
		782
		783	In Erlang, you can chose to receive I<all> exit signals as messages
		784	or I<none>, there is no in-between, so monitoring single processes is
		785	difficult to implement. Monitoring in AEMP is more flexible than in
		786	Erlang, as one can choose between automatic kill, exit message or callback
		787	on a per-process basis.
		788
		789	=item * Erlang tries to hide remote/local connections, AEMP does not.
		790
		791	Monitoring in Erlang is not an indicator of process death/crashes, in the
		792	same way as linking is (except linking is unreliable in Erlang).
		793
		794	In AEMP, you don't "look up" registered port names or send to named ports
		795	that might or might not be persistent. Instead, you normally spawn a port
		796	on the remote node. The init function monitors you, and you monitor the
		797	remote port. Since both monitors are local to the node, they are much more
		798	reliable (no need for C<spawn_link>).
		799
		800	This also saves round-trips and avoids sending messages to the wrong port
		801	(hard to do in Erlang).
453		802
454	=back	803	=back
455		804
456	=head1 NODE MESSAGES	805	=head1 RATIONALE
457
458	Nodes understand the following messages sent to them. Many of them take
459	arguments called C<@reply>, which will simply be used to compose a reply
460	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
461	the remaining arguments are simply the message data.
462		806
463	=over 4	807	=over 4
464		808
465	=cut	809	=item Why strings for port and node IDs, why not objects?
466		810
467	=item lookup => $name, @reply	811	We considered "objects", but found that the actual number of methods
		812	that can be called are quite low. Since port and node IDs travel over
		813	the network frequently, the serialising/deserialising would add lots of
		814	overhead, as well as having to keep a proxy object everywhere.
468		815
469	Replies with the port ID of the specified well-known port, or C<undef>.	816	Strings can easily be printed, easily serialised etc. and need no special
		817	procedures to be "valid".
470		818
471	=item devnull => ...	819	And as a result, a miniport consists of a single closure stored in a
		820	global hash - it can't become much cheaper.
472		821
473	Generic data sink/CPU heat conversion.	822	=item Why favour JSON, why not a real serialising format such as Storable?
474		823
475	=item relay => $port, @msg	824	In fact, any AnyEvent::MP node will happily accept Storable as framing
		825	format, but currently there is no way to make a node use Storable by
		826	default (although all nodes will accept it).
476		827
477	Simply forwards the message to the given port.	828	The default framing protocol is JSON because a) JSON::XS is many times
		829	faster for small messages and b) most importantly, after years of
		830	experience we found that object serialisation is causing more problems
		831	than it solves: Just like function calls, objects simply do not travel
		832	easily over the network, mostly because they will always be a copy, so you
		833	always have to re-think your design.
478		834
479	=item eval => $string[ @reply]	835	Keeping your messages simple, concentrating on data structures rather than
480		836	objects, will keep your messages clean, tidy and efficient.
481	Evaluates the given string. If C<@reply> is given, then a message of the
482	form C<@reply, $@, @evalres> is sent.
483
484	Example: crash another node.
485
486	snd $othernode, eval => "exit";
487
488	=item time => @reply
489
490	Replies the the current node time to C<@reply>.
491
492	Example: tell the current node to send the current time to C<$myport> in a
493	C<timereply> message.
494
495	snd $NODE, time => $myport, timereply => 1, 2;
496	# => snd $myport, timereply => 1, 2, <time>
497		837
498	=back	838	=back
499		839
500	=head1 SEE ALSO	840	=head1 SEE ALSO
		841
		842	L<AnyEvent::MP::Intro> - a gentle introduction.
		843
		844	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		845
		846	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		847	your applications.
501		848
502	L<AnyEvent>.	849	L<AnyEvent>.
503		850
504	=head1 AUTHOR	851	=head1 AUTHOR
505		852

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Revision 1.77 by elmex, Thu Sep 3 07:57:30 2009 UTC