[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 1.75 by root, Mon Aug 31 13:18:06 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 - uptodate, but incomplete.
		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
		57	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
		58	manual page and the examples under F<eg/>.
		59
35	At the moment, this module family is severly brokena nd underdocumented,	60	At the moment, this module family is a bit underdocumented.
36	so do not use. This was uploaded mainly to reserve the CPAN namespace -
37	stay tuned!
38		61
39	=head1 CONCEPTS	62	=head1 CONCEPTS
40		63
41	=over 4	64	=over 4
42		65
43	=item port	66	=item port
44		67
45	A port is something you can send messages to with the C<snd> function, and	68	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		69
		70	Ports allow you to register C<rcv> handlers that can match all or just
		71	some messages. Messages send to ports will not be queued, regardless of
		72	anything was listening for them or not.
		73
49	=item port id - C<noderef#portname>	74	=item port ID - C<nodeid#portname>
50		75
51	A port id is always the noderef, a hash-mark (C<#>) as separator, followed	76	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).	77	separator, and a port name (a printable string of unspecified format).
53		78
54	=item node	79	=item node
55		80
56	A node is a single process containing at least one port - the node	81	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,	82	which enables nodes to manage each other remotely, and to create new
58	among other things.	83	ports.
59		84
60	Initially, nodes are either private (single-process only) or hidden	85	Nodes are either public (have one or more listening ports) or private
61	(connected to a master node only). Only when they epxlicitly "become	86	(no listening ports). Private nodes cannot talk to other private nodes
62	public" can you send them messages from unrelated other nodes.	87	currently.
63		88
64	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	89	=item node ID - C<[a-za-Z0-9_\-.:]+>
65		90
66	A noderef is a string that either uniquely identifies a given node (for	91	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	92	network. Depending on the configuration used, node IDs can look like a
68	node (for public nodes).	93	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
		94	doesn't interpret node IDs in any way.
		95
		96	=item binds - C<ip:port>
		97
		98	Nodes can only talk to each other by creating some kind of connection to
		99	each other. To do this, nodes should listen on one or more local transport
		100	endpoints - binds. Currently, only standard C<ip:port> specifications can
		101	be used, which specify TCP ports to listen on.
		102
		103	=item seeds - C<host:port>
		104
		105	When a node starts, it knows nothing about the network. To teach the node
		106	about the network it first has to contact some other node within the
		107	network. This node is called a seed.
		108
		109	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes
		110	are expected to be long-running, and at least one of those should always
		111	be available. When nodes run out of connections (e.g. due to a network
		112	error), they try to re-establish connections to some seednodes again to
		113	join the network.
		114
		115	Apart from being sued for seeding, seednodes are not special in any way -
		116	every public node can be a seednode.
69		117
70	=back	118	=back
71		119
72	=head1 VARIABLES/FUNCTIONS	120	=head1 VARIABLES/FUNCTIONS
73		121
…		…
75		123
76	=cut	124	=cut
77		125
78	package AnyEvent::MP;	126	package AnyEvent::MP;
79		127
80	use AnyEvent::MP::Base;	128	use AnyEvent::MP::Kernel;
81		129
82	use common::sense;	130	use common::sense;
83		131
84	use Carp ();	132	use Carp ();
85		133
86	use AE ();	134	use AE ();
87		135
88	use base "Exporter";	136	use base "Exporter";
89		137
90	our $VERSION = '0.02';	138	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		139
91	our @EXPORT = qw(	140	our @EXPORT = qw(
92	NODE $NODE *SELF node_of _any_	141	NODE $NODE *SELF node_of after
93	become_slave become_public	142	configure
94	snd rcv mon kil reg psub	143	snd rcv mon mon_guard kil reg psub spawn
95	port	144	port
96	);	145	);
97		146
98	our $SELF;	147	our $SELF;
99		148
…		…
103	kil $SELF, die => $msg;	152	kil $SELF, die => $msg;
104	}	153	}
105		154
106	=item $thisnode = NODE / $NODE	155	=item $thisnode = NODE / $NODE
107		156
108	The C<NODE> function returns, and the C<$NODE> variable contains	157	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	158	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	159	a call to C<configure>.
111	identifiers become invalid.
112		160
113	=item $noderef = node_of $portid	161	=item $nodeid = node_of $port
114		162
115	Extracts and returns the noderef from a portid or a noderef.	163	Extracts and returns the node ID from a port ID or a node ID.
		164
		165	=item configure key => value...
		166
		167	Before a node can talk to other nodes on the network (i.e. enter
		168	"distributed mode") it has to configure itself - the minimum a node needs
		169	to know is its own name, and optionally it should know the addresses of
		170	some other nodes in the network to discover other nodes.
		171
		172	This function configures a node - it must be called exactly once (or
		173	never) before calling other AnyEvent::MP functions.
		174
		175	=over 4
		176
		177	=item step 1, gathering configuration from profiles
		178
		179	The function first looks up a profile in the aemp configuration (see the
		180	L<aemp> commandline utility). The profile name can be specified via the
		181	named C<profile> parameter. If it is missing, then the nodename (F<uname
		182	-n>) will be used as profile name.
		183
		184	The profile data is then gathered as follows:
		185
		186	First, all remaining key => value pairs (all of which are conviniently
		187	undocumented at the moment) will be interpreted as configuration
		188	data. Then they will be overwritten by any values specified in the global
		189	default configuration (see the F<aemp> utility), then the chain of
		190	profiles chosen by the profile name (and any C<parent> attributes).
		191
		192	That means that the values specified in the profile have highest priority
		193	and the values specified directly via C<configure> have lowest priority,
		194	and can only be used to specify defaults.
		195
		196	If the profile specifies a node ID, then this will become the node ID of
		197	this process. If not, then the profile name will be used as node ID. The
		198	special node ID of C<anon/> will be replaced by a random node ID.
		199
		200	=item step 2, bind listener sockets
		201
		202	The next step is to look up the binds in the profile, followed by binding
		203	aemp protocol listeners on all binds specified (it is possible and valid
		204	to have no binds, meaning that the node cannot be contacted form the
		205	outside. This means the node cannot talk to other nodes that also have no
		206	binds, but it can still talk to all "normal" nodes).
		207
		208	If the profile does not specify a binds list, then a default of C<*> is
		209	used, meaning the node will bind on a dynamically-assigned port on every
		210	local IP address it finds.
		211
		212	=item step 3, connect to seed nodes
		213
		214	As the last step, the seeds list from the profile is passed to the
		215	L<AnyEvent::MP::Global> module, which will then use it to keep
		216	connectivity with at least one node at any point in time.
		217
		218	=back
		219
		220	Example: become a distributed node using the locla node name as profile.
		221	This should be the most common form of invocation for "daemon"-type nodes.
		222
		223	configure
		224
		225	Example: become an anonymous node. This form is often used for commandline
		226	clients.
		227
		228	configure nodeid => "anon/";
		229
		230	Example: configure a node using a profile called seed, which si suitable
		231	for a seed node as it binds on all local addresses on a fixed port (4040,
		232	customary for aemp).
		233
		234	# use the aemp commandline utility
		235	# aemp profile seed nodeid anon/ binds '*:4040'
		236
		237	# then use it
		238	configure profile => "seed";
		239
		240	# or simply use aemp from the shell again:
		241	# aemp run profile seed
		242
		243	# or provide a nicer-to-remember nodeid
		244	# aemp run profile seed nodeid "$(hostname)"
116		245
117	=item $SELF	246	=item $SELF
118		247
119	Contains the current port id while executing C<rcv> callbacks or C<psub>	248	Contains the current port id while executing C<rcv> callbacks or C<psub>
120	blocks.	249	blocks.
121		250
122	=item SELF, %SELF, @SELF...	251	=item *SELF, SELF, %SELF, @SELF...
123		252
124	Due to some quirks in how perl exports variables, it is impossible to	253	Due to some quirks in how perl exports variables, it is impossible to
125	just export C<$SELF>, all the symbols called C<SELF> are exported by this	254	just export C<$SELF>, all the symbols named C<SELF> are exported by this
126	module, but only C<$SELF> is currently used.	255	module, but only C<$SELF> is currently used.
127		256
128	=item snd $portid, type => @data	257	=item snd $port, type => @data
129		258
130	=item snd $portid, @msg	259	=item snd $port, @msg
131		260
132	Send the given message to the given port ID, which can identify either	261	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	262	local or a remote port, and must be a port ID.
134	stringifies a sa port ID (such as a port object :).
135		263
136	While the message can be about anything, it is highly recommended to use a	264	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	265	use a string as first element (a port ID, or some word that indicates a
138	type etc.).	266	request type etc.) and to consist if only simple perl values (scalars,
		267	arrays, hashes) - if you think you need to pass an object, think again.
139		268
140	The message data effectively becomes read-only after a call to this	269	The message data logically becomes read-only after a call to this
141	function: modifying any argument is not allowed and can cause many	270	function: modifying any argument (or values referenced by them) is
142	problems.	271	forbidden, as there can be considerable time between the call to C<snd>
		272	and the time the message is actually being serialised - in fact, it might
		273	never be copied as within the same process it is simply handed to the
		274	receiving port.
143		275
144	The type of data you can transfer depends on the transport protocol: when	276	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	277	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	278	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	279	that Storable can serialise and deserialise is allowed, and for the local
148	node, anything can be passed.	280	node, anything can be passed. Best rely only on the common denominator of
		281	these.
149		282
150	=item kil $portid[, @reason]	283	=item $local_port = port
151		284
152	Kill the specified port with the given C<@reason>.	285	Create a new local port object and returns its port ID. Initially it has
		286	no callbacks set and will throw an error when it receives messages.
153		287
154	If no C<@reason> is specified, then the port is killed "normally" (linked	288	=item $local_port = port { my @msg = @_ }
155	ports will not be kileld, or even notified).
156		289
157	Otherwise, linked ports get killed with the same reason (second form of	290	Creates a new local port, and returns its ID. Semantically the same as
158	C<mon>, see below).	291	creating a port and calling C<rcv $port, $callback> on it.
159		292
160	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	293	The block will be called for every message received on the port, with the
161	will be reported as reason C<< die => $@ >>.	294	global variable C<$SELF> set to the port ID. Runtime errors will cause the
		295	port to be C<kil>ed. The message will be passed as-is, no extra argument
		296	(i.e. no port ID) will be passed to the callback.
162		297
163	Transport/communication errors are reported as C<< transport_error =>	298	If you want to stop/destroy the port, simply C<kil> it:
164	$message >>.
165		299
166	=item $guard = mon $portid, $cb->(@reason)	300	my $port = port {
		301	my @msg = @_;
		302	...
		303	kil $SELF;
		304	};
167		305
168	=item $guard = mon $portid, $otherport	306	=cut
169		307
170	=item $guard = mon $portid, $otherport, @msg	308	sub rcv($@);
171		309
		310	sub _kilme {
		311	die "received message on port without callback";
		312	}
		313
		314	sub port(;&) {
		315	my $id = "$UNIQ." . $ID++;
		316	my $port = "$NODE#$id";
		317
		318	rcv $port, shift \|\| \&_kilme;
		319
		320	$port
		321	}
		322
		323	=item rcv $local_port, $callback->(@msg)
		324
		325	Replaces the default callback on the specified port. There is no way to
		326	remove the default callback: use C<sub { }> to disable it, or better
		327	C<kil> the port when it is no longer needed.
		328
		329	The global C<$SELF> (exported by this module) contains C<$port> while
		330	executing the callback. Runtime errors during callback execution will
		331	result in the port being C<kil>ed.
		332
		333	The default callback received all messages not matched by a more specific
		334	C<tag> match.
		335
		336	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
		337
		338	Register (or replace) callbacks to be called on messages starting with the
		339	given tag on the given port (and return the port), or unregister it (when
		340	C<$callback> is C<$undef> or missing). There can only be one callback
		341	registered for each tag.
		342
		343	The original message will be passed to the callback, after the first
		344	element (the tag) has been removed. The callback will use the same
		345	environment as the default callback (see above).
		346
		347	Example: create a port and bind receivers on it in one go.
		348
		349	my $port = rcv port,
		350	msg1 => sub { ... },
		351	msg2 => sub { ... },
		352	;
		353
		354	Example: create a port, bind receivers and send it in a message elsewhere
		355	in one go:
		356
		357	snd $otherport, reply =>
		358	rcv port,
		359	msg1 => sub { ... },
		360	...
		361	;
		362
		363	Example: temporarily register a rcv callback for a tag matching some port
		364	(e.g. for a rpc reply) and unregister it after a message was received.
		365
		366	rcv $port, $otherport => sub {
		367	my @reply = @_;
		368
		369	rcv $SELF, $otherport;
		370	};
		371
		372	=cut
		373
		374	sub rcv($@) {
		375	my $port = shift;
		376	my ($nodeid, $portid) = split /#/, $port, 2;
		377
		378	$NODE{$nodeid} == $NODE{""}
		379	or Carp::croak "$port: rcv can only be called on local ports, caught";
		380
		381	while (@_) {
		382	if (ref $_[0]) {
		383	if (my $self = $PORT_DATA{$portid}) {
		384	"AnyEvent::MP::Port" eq ref $self
		385	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		386
		387	$self->[2] = shift;
		388	} else {
		389	my $cb = shift;
		390	$PORT{$portid} = sub {
		391	local $SELF = $port;
		392	eval { &$cb }; _self_die if $@;
		393	};
		394	}
		395	} elsif (defined $_[0]) {
		396	my $self = $PORT_DATA{$portid} \|\|= do {
		397	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
		398
		399	$PORT{$portid} = sub {
		400	local $SELF = $port;
		401
		402	if (my $cb = $self->[1]{$_[0]}) {
		403	shift;
		404	eval { &$cb }; _self_die if $@;
		405	} else {
		406	&{ $self->[0] };
		407	}
		408	};
		409
		410	$self
		411	};
		412
		413	"AnyEvent::MP::Port" eq ref $self
		414	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		415
		416	my ($tag, $cb) = splice @_, 0, 2;
		417
		418	if (defined $cb) {
		419	$self->[1]{$tag} = $cb;
		420	} else {
		421	delete $self->[1]{$tag};
		422	}
		423	}
		424	}
		425
		426	$port
		427	}
		428
		429	=item $closure = psub { BLOCK }
		430
		431	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
		432	closure is executed, sets up the environment in the same way as in C<rcv>
		433	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		434
		435	This is useful when you register callbacks from C<rcv> callbacks:
		436
		437	rcv delayed_reply => sub {
		438	my ($delay, @reply) = @_;
		439	my $timer = AE::timer $delay, 0, psub {
		440	snd @reply, $SELF;
		441	};
		442	};
		443
		444	=cut
		445
		446	sub psub(&) {
		447	my $cb = shift;
		448
		449	my $port = $SELF
		450	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
		451
		452	sub {
		453	local $SELF = $port;
		454
		455	if (wantarray) {
		456	my @res = eval { &$cb };
		457	_self_die if $@;
		458	@res
		459	} else {
		460	my $res = eval { &$cb };
		461	_self_die if $@;
		462	$res
		463	}
		464	}
		465	}
		466
		467	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
		468
		469	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
		470
		471	=item $guard = mon $port # kill $SELF when $port dies
		472
		473	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
		474
172	Monitor the given port and do something when the port is killed.	475	Monitor the given port and do something when the port is killed or
		476	messages to it were lost, and optionally return a guard that can be used
		477	to stop monitoring again.
173		478
		479	C<mon> effectively guarantees that, in the absence of hardware failures,
		480	after starting the monitor, either all messages sent to the port will
		481	arrive, or the monitoring action will be invoked after possible message
		482	loss has been detected. No messages will be lost "in between" (after
		483	the first lost message no further messages will be received by the
		484	port). After the monitoring action was invoked, further messages might get
		485	delivered again.
		486
		487	Note that monitoring-actions are one-shot: once messages are lost (and a
		488	monitoring alert was raised), they are removed and will not trigger again.
		489
174	In the first form, the callback is simply called with any number	490	In the first form (callback), the callback is simply called with any
175	of C<@reason> elements (no @reason means that the port was deleted	491	number of C<@reason> elements (no @reason means that the port was deleted
176	"normally"). Note also that I<< the callback B<must> never die >>, so use	492	"normally"). Note also that I<< the callback B<must> never die >>, so use
177	C<eval> if unsure.	493	C<eval> if unsure.
178		494
179	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	495	In the second form (another port given), the other port (C<$rcvport>)
180	a @reason was specified, i.e. on "normal" kils nothing happens, while	496	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
181	under all other conditions, the other port is killed with the same reason.	497	"normal" kils nothing happens, while under all other conditions, the other
		498	port is killed with the same reason.
182		499
		500	The third form (kill self) is the same as the second form, except that
		501	C<$rvport> defaults to C<$SELF>.
		502
183	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	503	In the last form (message), a message of the form C<@msg, @reason> will be
		504	C<snd>.
		505
		506	As a rule of thumb, monitoring requests should always monitor a port from
		507	a local port (or callback). The reason is that kill messages might get
		508	lost, just like any other message. Another less obvious reason is that
		509	even monitoring requests can get lost (for exmaple, when the connection
		510	to the other node goes down permanently). When monitoring a port locally
		511	these problems do not exist.
184		512
185	Example: call a given callback when C<$port> is killed.	513	Example: call a given callback when C<$port> is killed.
186		514
187	mon $port, sub { warn "port died because of <@_>\n" };	515	mon $port, sub { warn "port died because of <@_>\n" };
188		516
189	Example: kill ourselves when C<$port> is killed abnormally.	517	Example: kill ourselves when C<$port> is killed abnormally.
190		518
191	mon $port, $self;	519	mon $port;
192		520
193	Example: send us a restart message another C<$port> is killed.	521	Example: send us a restart message when another C<$port> is killed.
194		522
195	mon $port, $self => "restart";	523	mon $port, $self => "restart";
196		524
197	=cut	525	=cut
198		526
199	sub mon {	527	sub mon {
200	my ($noderef, $port, $cb) = ((split /#/, shift, 2), shift);	528	my ($nodeid, $port) = split /#/, shift, 2;
201		529
202	my $node = $NODE{$noderef} \|\| add_node $noderef;	530	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
203		531
204	#TODO: ports must not be references	532	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) {	533
		534	unless (ref $cb) {
206	if (@_) {	535	if (@_) {
207	# send a kill info message	536	# send a kill info message
208	my (@msg) = ($cb, @_);	537	my (@msg) = ($cb, @_);
209	$cb = sub { snd @msg, @_ };	538	$cb = sub { snd @msg, @_ };
210	} else {	539	} else {
…		…
226	is killed, the references will be freed.	555	is killed, the references will be freed.
227		556
228	Optionally returns a guard that will stop the monitoring.	557	Optionally returns a guard that will stop the monitoring.
229		558
230	This function is useful when you create e.g. timers or other watchers and	559	This function is useful when you create e.g. timers or other watchers and
231	want to free them when the port gets killed:	560	want to free them when the port gets killed (note the use of C<psub>):
232		561
233	$port->rcv (start => sub {	562	$port->rcv (start => sub {
234	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	563	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
235	undef $timer if 0.9 < rand;	564	undef $timer if 0.9 < rand;
236	});	565	});
237	});	566	});
238		567
239	=cut	568	=cut
240		569
241	sub mon_guard {	570	sub mon_guard {
242	my ($port, @refs) = @_;	571	my ($port, @refs) = @_;
243		572
		573	#TODO: mon-less form?
		574
244	mon $port, sub { 0 && @refs }	575	mon $port, sub { 0 && @refs }
245	}	576	}
246		577
247	=item $local_port = port	578	=item kil $port[, @reason]
248		579
249	Create a new local port object that supports message matching.	580	Kill the specified port with the given C<@reason>.
250		581
251	=item $portid = port { my @msg = @_; $finished }	582	If no C<@reason> is specified, then the port is killed "normally" (ports
		583	monitoring other ports will not necessarily die because a port dies
		584	"normally").
252		585
253	Creates a "mini port", that is, a very lightweight port without any	586	Otherwise, linked ports get killed with the same reason (second form of
254	pattern matching behind it, and returns its ID.	587	C<mon>, see above).
255		588
256	The block will be called for every message received on the port. When the	589	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	590	will be reported as reason C<< die => $@ >>.
258	will be destroyed. Otherwise it will stay alive.
259		591
260	The message will be passed as-is, no extra argument (i.e. no port id) will	592	Transport/communication errors are reported as C<< transport_error =>
261	be passed to the callback.	593	$message >>.
262		594
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	595	=cut
270		596
271	sub port(;&) {	597	=item $port = spawn $node, $initfunc[, @initdata]
272	my $id = "$UNIQ." . $ID++;
273	my $port = "$NODE#$id";
274		598
275	if (@_) {	599	Creates a port on the node C<$node> (which can also be a port ID, in which
276	my $cb = shift;	600	case it's the node where that port resides).
277	$PORT{$id} = sub {	601
278	local $SELF = $port;	602	The port ID of the newly created port is returned immediately, and it is
279	eval {	603	possible to immediately start sending messages or to monitor the port.
280	&$cb	604
281	and kil $id;	605	After the port has been created, the init function is called on the remote
		606	node, in the same context as a C<rcv> callback. This function must be a
		607	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
		608	specify a function in the main program, use C<::name>.
		609
		610	If the function doesn't exist, then the node tries to C<require>
		611	the package, then the package above the package and so on (e.g.
		612	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		613	exists or it runs out of package names.
		614
		615	The init function is then called with the newly-created port as context
		616	object (C<$SELF>) and the C<@initdata> values as arguments.
		617
		618	A common idiom is to pass a local port, immediately monitor the spawned
		619	port, and in the remote init function, immediately monitor the passed
		620	local port. This two-way monitoring ensures that both ports get cleaned up
		621	when there is a problem.
		622
		623	Example: spawn a chat server port on C<$othernode>.
		624
		625	# this node, executed from within a port context:
		626	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		627	mon $server;
		628
		629	# init function on C<$othernode>
		630	sub connect {
		631	my ($srcport) = @_;
		632
		633	mon $srcport;
		634
		635	rcv $SELF, sub {
282	};	636	...
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	};	637	};
314	}	638	}
315		639
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	640	=cut
329		641
330	sub reg(@) {	642	sub _spawn {
331	my ($portid, $name) = @_;	643	my $port = shift;
		644	my $init = shift;
332		645
333	$REG{$name} = $portid;	646	local $SELF = "$NODE#$port";
334	}	647	eval {
335		648	&{ 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	};	649	};
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 $@;	650	_self_die if $@;
424	@res	651	}
425	} else {	652
426	my $res = eval { &$cb };	653	sub spawn(@) {
427	_self_die if $@;	654	my ($nodeid, undef) = split /#/, shift, 2;
428	$res	655
429	}	656	my $id = "$RUNIQ." . $ID++;
		657
		658	$_[0] =~ /::/
		659	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		660
		661	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
		662
		663	"$nodeid#$id"
		664	}
		665
		666	=item after $timeout, @msg
		667
		668	=item after $timeout, $callback
		669
		670	Either sends the given message, or call the given callback, after the
		671	specified number of seconds.
		672
		673	This is simply a utility function that comes in handy at times - the
		674	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		675	so it may go away in the future.
		676
		677	=cut
		678
		679	sub after($@) {
		680	my ($timeout, @action) = @_;
		681
		682	my $t; $t = AE::timer $timeout, 0, sub {
		683	undef $t;
		684	ref $action[0]
		685	? $action[0]()
		686	: snd @action;
430	}	687	};
431	}	688	}
432		689
433	=back	690	=back
434		691
435	=head1 FUNCTIONS FOR NODES	692	=head1 AnyEvent::MP vs. Distributed Erlang
		693
		694	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
		695	== aemp node, Erlang process == aemp port), so many of the documents and
		696	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		697	sample:
		698
		699	http://www.Erlang.se/doc/programming_rules.shtml
		700	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		701	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		702	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		703
		704	Despite the similarities, there are also some important differences:
436		705
437	=over 4	706	=over 4
438		707
439	=item become_public endpoint...	708	=item * Node IDs are arbitrary strings in AEMP.
440		709
441	Tells the node to become a public node, i.e. reachable from other nodes.	710	Erlang relies on special naming and DNS to work everywhere in the same
		711	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
		712	configuraiton or DNS), but will otherwise discover other odes itself.
442		713
443	If no arguments are given, or the first argument is C<undef>, then	714	=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	715	uses "local ports are like remote ports".
445	local nodename resolves to.
446		716
447	Otherwise the first argument must be an array-reference with transport	717	The failure modes for local ports are quite different (runtime errors
448	endpoints ("ip:port", "hostname:port") or port numbers (in which case the	718	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	719	when a connection to another node dies, you know nothing about the other
450	will become the node reference.	720	port.
451		721
452	=cut	722	Erlang pretends remote ports are as reliable as local ports, even when
		723	they are not.
		724
		725	AEMP encourages a "treat remote ports differently" philosophy, with local
		726	ports being the special case/exception, where transport errors cannot
		727	occur.
		728
		729	=item * Erlang uses processes and a mailbox, AEMP does not queue.
		730
		731	Erlang uses processes that selectively receive messages, and therefore
		732	needs a queue. AEMP is event based, queuing messages would serve no
		733	useful purpose. For the same reason the pattern-matching abilities of
		734	AnyEvent::MP are more limited, as there is little need to be able to
		735	filter messages without dequeing them.
		736
		737	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
		738
		739	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
		740
		741	Sending messages in Erlang is synchronous and blocks the process (and
		742	so does not need a queue that can overflow). AEMP sends are immediate,
		743	connection establishment is handled in the background.
		744
		745	=item * Erlang suffers from silent message loss, AEMP does not.
		746
		747	Erlang makes few guarantees on messages delivery - messages can get lost
		748	without any of the processes realising it (i.e. you send messages a, b,
		749	and c, and the other side only receives messages a and c).
		750
		751	AEMP guarantees correct ordering, and the guarantee that after one message
		752	is lost, all following ones sent to the same port are lost as well, until
		753	monitoring raises an error, so there are no silent "holes" in the message
		754	sequence.
		755
		756	=item * Erlang can send messages to the wrong port, AEMP does not.
		757
		758	In Erlang it is quite likely that a node that restarts reuses a process ID
		759	known to other nodes for a completely different process, causing messages
		760	destined for that process to end up in an unrelated process.
		761
		762	AEMP never reuses port IDs, so old messages or old port IDs floating
		763	around in the network will not be sent to an unrelated port.
		764
		765	=item * Erlang uses unprotected connections, AEMP uses secure
		766	authentication and can use TLS.
		767
		768	AEMP can use a proven protocol - TLS - to protect connections and
		769	securely authenticate nodes.
		770
		771	=item * The AEMP protocol is optimised for both text-based and binary
		772	communications.
		773
		774	The AEMP protocol, unlike the Erlang protocol, supports both programming
		775	language independent text-only protocols (good for debugging) and binary,
		776	language-specific serialisers (e.g. Storable). By default, unless TLS is
		777	used, the protocol is actually completely text-based.
		778
		779	It has also been carefully designed to be implementable in other languages
		780	with a minimum of work while gracefully degrading functionality to make the
		781	protocol simple.
		782
		783	=item * AEMP has more flexible monitoring options than Erlang.
		784
		785	In Erlang, you can chose to receive I<all> exit signals as messages
		786	or I<none>, there is no in-between, so monitoring single processes is
		787	difficult to implement. Monitoring in AEMP is more flexible than in
		788	Erlang, as one can choose between automatic kill, exit message or callback
		789	on a per-process basis.
		790
		791	=item * Erlang tries to hide remote/local connections, AEMP does not.
		792
		793	Monitoring in Erlang is not an indicator of process death/crashes, in the
		794	same way as linking is (except linking is unreliable in Erlang).
		795
		796	In AEMP, you don't "look up" registered port names or send to named ports
		797	that might or might not be persistent. Instead, you normally spawn a port
		798	on the remote node. The init function monitors you, and you monitor the
		799	remote port. Since both monitors are local to the node, they are much more
		800	reliable (no need for C<spawn_link>).
		801
		802	This also saves round-trips and avoids sending messages to the wrong port
		803	(hard to do in Erlang).
453		804
454	=back	805	=back
455		806
456	=head1 NODE MESSAGES	807	=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		808
463	=over 4	809	=over 4
464		810
465	=cut	811	=item Why strings for port and node IDs, why not objects?
466		812
467	=item lookup => $name, @reply	813	We considered "objects", but found that the actual number of methods
		814	that can be called are quite low. Since port and node IDs travel over
		815	the network frequently, the serialising/deserialising would add lots of
		816	overhead, as well as having to keep a proxy object everywhere.
468		817
469	Replies with the port ID of the specified well-known port, or C<undef>.	818	Strings can easily be printed, easily serialised etc. and need no special
		819	procedures to be "valid".
470		820
471	=item devnull => ...	821	And as a result, a miniport consists of a single closure stored in a
		822	global hash - it can't become much cheaper.
472		823
473	Generic data sink/CPU heat conversion.	824	=item Why favour JSON, why not a real serialising format such as Storable?
474		825
475	=item relay => $port, @msg	826	In fact, any AnyEvent::MP node will happily accept Storable as framing
		827	format, but currently there is no way to make a node use Storable by
		828	default (although all nodes will accept it).
476		829
477	Simply forwards the message to the given port.	830	The default framing protocol is JSON because a) JSON::XS is many times
		831	faster for small messages and b) most importantly, after years of
		832	experience we found that object serialisation is causing more problems
		833	than it solves: Just like function calls, objects simply do not travel
		834	easily over the network, mostly because they will always be a copy, so you
		835	always have to re-think your design.
478		836
479	=item eval => $string[ @reply]	837	Keeping your messages simple, concentrating on data structures rather than
480		838	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		839
498	=back	840	=back
499		841
500	=head1 SEE ALSO	842	=head1 SEE ALSO
		843
		844	L<AnyEvent::MP::Intro> - a gentle introduction.
		845
		846	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		847
		848	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		849	your applications.
501		850
502	L<AnyEvent>.	851	L<AnyEvent>.
503		852
504	=head1 AUTHOR	853	=head1 AUTHOR
505		854

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Revision 1.75 by root, Mon Aug 31 13:18:06 2009 UTC