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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.24 by root, Tue Aug 4 20:00:00 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	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	57	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
36	manual page.	58	manual page and the examples under F<eg/>.
37
38	At the moment, this module family is severly broken and 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		59
42	=head1 CONCEPTS	60	=head1 CONCEPTS
43		61
44	=over 4	62	=over 4
45		63
46	=item port	64	=item port
47		65
48	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).
49	you can register C<rcv> handlers with. All C<rcv> handlers will receive
50	messages they match, messages will not be queued.
51		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
52	=item port id - C<noderef#portname>	72	=item port ID - C<nodeid#portname>
53		73
54	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
55	by a port name (a printable string of unspecified format).	75	separator, and a port name (a printable string of unspecified format).
56		76
57	=item node	77	=item node
58		78
59	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,
60	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
61	among other things.	81	ports.
62		82
63	Initially, nodes are either private (single-process only) or hidden	83	Nodes are either public (have one or more listening ports) or private
64	(connected to a master node only). Only when they epxlicitly "become	84	(no listening ports). Private nodes cannot talk to other private nodes
65	public" can you send them messages from unrelated other nodes.	85	currently.
66		86
67	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	87	=item node ID - C<[a-za-Z0-9_\-.:]+>
68		88
69	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
70	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
71	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.
72		115
73	=back	116	=back
74		117
75	=head1 VARIABLES/FUNCTIONS	118	=head1 VARIABLES/FUNCTIONS
76		119
…		…
78		121
79	=cut	122	=cut
80		123
81	package AnyEvent::MP;	124	package AnyEvent::MP;
82		125
83	use AnyEvent::MP::Base;	126	use AnyEvent::MP::Kernel;
84		127
85	use common::sense;	128	use common::sense;
86		129
87	use Carp ();	130	use Carp ();
88		131
89	use AE ();	132	use AE ();
90		133
91	use base "Exporter";	134	use base "Exporter";
92		135
93	our $VERSION = '0.02';	136	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		137
94	our @EXPORT = qw(	138	our @EXPORT = qw(
95	NODE $NODE *SELF node_of _any_	139	NODE $NODE *SELF node_of after
96	become_slave become_public	140	configure
97	snd rcv mon kil reg psub	141	snd rcv mon mon_guard kil reg psub spawn
98	port	142	port
99	);	143	);
100		144
101	our $SELF;	145	our $SELF;
102		146
…		…
106	kil $SELF, die => $msg;	150	kil $SELF, die => $msg;
107	}	151	}
108		152
109	=item $thisnode = NODE / $NODE	153	=item $thisnode = NODE / $NODE
110		154
111	The C<NODE> function returns, and the C<$NODE> variable contains	155	The C<NODE> function returns, and the C<$NODE> variable contains, the node
112	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
113	to C<become_public> or C<become_slave>, after which all local port	157	a call to C<configure>.
114	identifiers become invalid.
115		158
116	=item $noderef = node_of $portid	159	=item $nodeid = node_of $port
117		160
118	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)"
119		243
120	=item $SELF	244	=item $SELF
121		245
122	Contains the current port id while executing C<rcv> callbacks or C<psub>	246	Contains the current port id while executing C<rcv> callbacks or C<psub>
123	blocks.	247	blocks.
124		248
125	=item SELF, %SELF, @SELF...	249	=item *SELF, SELF, %SELF, @SELF...
126		250
127	Due to some quirks in how perl exports variables, it is impossible to	251	Due to some quirks in how perl exports variables, it is impossible to
128	just export C<$SELF>, all the symbols called C<SELF> are exported by this	252	just export C<$SELF>, all the symbols named C<SELF> are exported by this
129	module, but only C<$SELF> is currently used.	253	module, but only C<$SELF> is currently used.
130		254
131	=item snd $portid, type => @data	255	=item snd $port, type => @data
132		256
133	=item snd $portid, @msg	257	=item snd $port, @msg
134		258
135	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
136	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.
137	stringifies a sa port ID (such as a port object :).
138		261
139	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
140	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
141	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.
142		266
143	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
144	function: modifying any argument is not allowed and can cause many	268	function: modifying any argument (or values referenced by them) is
145	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.
146		273
147	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
148	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
149	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
150	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
151	node, anything can be passed.	278	node, anything can be passed. Best rely only on the common denominator of
		279	these.
152		280
153	=item kil $portid[, @reason]	281	=item $local_port = port
154		282
155	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.
156		285
157	If no C<@reason> is specified, then the port is killed "normally" (linked	286	=item $local_port = port { my @msg = @_ }
158	ports will not be kileld, or even notified).
159		287
160	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
161	C<mon>, see below).	289	creating a port and calling C<rcv $port, $callback> on it.
162		290
163	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
164	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.
165		295
166	Transport/communication errors are reported as C<< transport_error =>	296	If you want to stop/destroy the port, simply C<kil> it:
167	$message >>.
168		297
169	=item $guard = mon $portid, $cb->(@reason)	298	my $port = port {
		299	my @msg = @_;
		300	...
		301	kil $SELF;
		302	};
170		303
171	=item $guard = mon $portid, $otherport	304	=cut
172		305
173	=item $guard = mon $portid, $otherport, @msg	306	sub rcv($@);
174		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 $port dies
		472
175	Monitor the given port and do something when the port is killed.	473	Monitor the given port and do something when the port is killed or
		474	messages to it were lost, and optionally return a guard that can be used
		475	to stop monitoring again.
176		476
		477	C<mon> effectively guarantees that, in the absence of hardware failures,
		478	after starting the monitor, either all messages sent to the port will
		479	arrive, or the monitoring action will be invoked after possible message
		480	loss has been detected. No messages will be lost "in between" (after
		481	the first lost message no further messages will be received by the
		482	port). After the monitoring action was invoked, further messages might get
		483	delivered again.
		484
		485	Note that monitoring-actions are one-shot: once messages are lost (and a
		486	monitoring alert was raised), they are removed and will not trigger again.
		487
177	In the first form, the callback is simply called with any number	488	In the first form (callback), the callback is simply called with any
178	of C<@reason> elements (no @reason means that the port was deleted	489	number of C<@reason> elements (no @reason means that the port was deleted
179	"normally"). Note also that I<< the callback B<must> never die >>, so use	490	"normally"). Note also that I<< the callback B<must> never die >>, so use
180	C<eval> if unsure.	491	C<eval> if unsure.
181		492
182	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	493	In the second form (another port given), the other port (C<$rcvport>)
183	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
184	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.
185		497
		498	The third form (kill self) is the same as the second form, except that
		499	C<$rvport> defaults to C<$SELF>.
		500
186	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.
187		510
188	Example: call a given callback when C<$port> is killed.	511	Example: call a given callback when C<$port> is killed.
189		512
190	mon $port, sub { warn "port died because of <@_>\n" };	513	mon $port, sub { warn "port died because of <@_>\n" };
191		514
192	Example: kill ourselves when C<$port> is killed abnormally.	515	Example: kill ourselves when C<$port> is killed abnormally.
193		516
194	mon $port, $self;	517	mon $port;
195		518
196	Example: send us a restart message another C<$port> is killed.	519	Example: send us a restart message when another C<$port> is killed.
197		520
198	mon $port, $self => "restart";	521	mon $port, $self => "restart";
199		522
200	=cut	523	=cut
201		524
202	sub mon {	525	sub mon {
203	my ($noderef, $port, $cb) = ((split /#/, shift, 2), shift);	526	my ($nodeid, $port) = split /#/, shift, 2;
204		527
205	my $node = $NODE{$noderef} \|\| add_node $noderef;	528	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
206		529
207	#TODO: ports must not be references	530	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) {	531
		532	unless (ref $cb) {
209	if (@_) {	533	if (@_) {
210	# send a kill info message	534	# send a kill info message
211	my (@msg) = ($cb, @_);	535	my (@msg) = ($cb, @_);
212	$cb = sub { snd @msg, @_ };	536	$cb = sub { snd @msg, @_ };
213	} else {	537	} else {
…		…
229	is killed, the references will be freed.	553	is killed, the references will be freed.
230		554
231	Optionally returns a guard that will stop the monitoring.	555	Optionally returns a guard that will stop the monitoring.
232		556
233	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
234	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>):
235		559
236	$port->rcv (start => sub {	560	$port->rcv (start => sub {
237	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	561	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
238	undef $timer if 0.9 < rand;	562	undef $timer if 0.9 < rand;
239	});	563	});
240	});	564	});
241		565
242	=cut	566	=cut
243		567
244	sub mon_guard {	568	sub mon_guard {
245	my ($port, @refs) = @_;	569	my ($port, @refs) = @_;
246		570
		571	#TODO: mon-less form?
		572
247	mon $port, sub { 0 && @refs }	573	mon $port, sub { 0 && @refs }
248	}	574	}
249		575
250	=item lnk $port1, $port2	576	=item kil $port[, @reason]
251		577
252	Link two ports. This is simply a shorthand for:	578	Kill the specified port with the given C<@reason>.
253		579
254	mon $port1, $port2;	580	If no C<@reason> is specified, then the port is killed "normally" (ports
255	mon $port2, $port1;	581	monitoring other ports will not necessarily die because a port dies
		582	"normally").
256		583
257	It means that if either one is killed abnormally, the other one gets	584	Otherwise, linked ports get killed with the same reason (second form of
258	killed as well.	585	C<mon>, see above).
259		586
260	=item $local_port = port	587	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		588	will be reported as reason C<< die => $@ >>.
261		589
262	Create a new local port object that supports message matching.	590	Transport/communication errors are reported as C<< transport_error =>
		591	$message >>.
263		592
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	593	=cut
283		594
284	sub port(;&) {	595	=item $port = spawn $node, $initfunc[, @initdata]
285	my $id = "$UNIQ." . $ID++;
286	my $port = "$NODE#$id";
287		596
288	if (@_) {	597	Creates a port on the node C<$node> (which can also be a port ID, in which
289	my $cb = shift;	598	case it's the node where that port resides).
290	$PORT{$id} = sub {	599
291	local $SELF = $port;	600	The port ID of the newly created port is returned immediately, and it is
292	eval {	601	possible to immediately start sending messages or to monitor the port.
293	&$cb	602
294	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 {
295	};	634	...
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	};	635	};
327	}	636	}
328		637
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	638	=cut
342		639
343	sub reg(@) {	640	sub _spawn {
344	my ($portid, $name) = @_;	641	my $port = shift;
		642	my $init = shift;
345		643
346	$REG{$name} = $portid;	644	local $SELF = "$NODE#$port";
347	}	645	eval {
348		646	&{ 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	};	647	};
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 $@;	648	_self_die if $@;
437	@res	649	}
438	} else {	650
439	my $res = eval { &$cb };	651	sub spawn(@) {
440	_self_die if $@;	652	my ($nodeid, undef) = split /#/, shift, 2;
441	$res	653
442	}	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;
443	}	685	};
444	}	686	}
445		687
446	=back	688	=back
447		689
448	=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:
449		703
450	=over 4	704	=over 4
451		705
452	=item become_public endpoint...	706	=item * Node IDs are arbitrary strings in AEMP.
453		707
454	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.
455		711
456	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
457	AnyEvent::MP tries to bind on port C<4040> on all IP addresses that the	713	uses "local ports are like remote ports".
458	local nodename resolves to.
459		714
460	Otherwise the first argument must be an array-reference with transport	715	The failure modes for local ports are quite different (runtime errors
461	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,
462	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
463	will become the node reference.	718	port.
464		719
465	=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).
466		802
467	=back	803	=back
468		804
469	=head1 NODE MESSAGES	805	=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		806
476	=over 4	807	=over 4
477		808
478	=cut	809	=item Why strings for port and node IDs, why not objects?
479		810
480	=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.
481		815
482	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".
483		818
484	=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.
485		821
486	Generic data sink/CPU heat conversion.	822	=item Why favour JSON, why not a real serialising format such as Storable?
487		823
488	=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).
489		827
490	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.
491		834
492	=item eval => $string[ @reply]	835	Keeping your messages simple, concentrating on data structures rather than
493		836	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		837
511	=back	838	=back
512		839
513	=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.
514		848
515	L<AnyEvent>.	849	L<AnyEvent>.
516		850
517	=head1 AUTHOR	851	=head1 AUTHOR
518		852

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