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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.31 by root, Wed Aug 5 19:55:58 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).	66	A port is something you can send messages to (with the C<snd> function).
49		67
50	Some ports allow you to register C<rcv> handlers that can match specific	68	Ports allow you to register C<rcv> handlers that can match all or just
51	messages. All C<rcv> handlers will receive messages they match, messages	69	some messages. Messages send to ports will not be queued, regardless of
52	will not be queued.	70	anything was listening for them or not.
53		71
54	=item port id - C<noderef#portname>	72	=item port ID - C<nodeid#portname>
55		73
56	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	74	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as
57	separator, and a port name (a printable string of unspecified format). An	75	separator, and a port name (a printable string of unspecified format).
58	exception is the the node port, whose ID is identical to its node
59	reference.
60		76
61	=item node	77	=item node
62		78
63	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,
64	port. You can send messages to node ports to find existing ports or to	80	which enables nodes to manage each other remotely, and to create new
65	create new ports, among other things.	81	ports.
66		82
67	Nodes are either private (single-process only), slaves (connected to a	83	Nodes are either public (have one or more listening ports) or private
68	master node only) or public nodes (connectable from unrelated nodes).	84	(no listening ports). Private nodes cannot talk to other private nodes
		85	currently.
69		86
70	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	87	=item node ID - C<[a-za-Z0-9_\-.:]+>
71		88
72	A node reference is a string that either simply identifies the node (for	89	A node ID is a string that uniquely identifies the node within a
73	private and slave nodes), or contains a recipe on how to reach a given	90	network. Depending on the configuration used, node IDs can look like a
74	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.
75		93
76	This recipe is simply a comma-separated list of C<address:port> pairs (for	94	=item binds - C<ip:port>
77	TCP/IP, other protocols might look different).
78		95
79	Node references come in two flavours: resolved (containing only numerical	96	Nodes can only talk to each other by creating some kind of connection to
80	addresses) or unresolved (where hostnames are used instead of addresses).	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.
81		100
82	Before using an unresolved node reference in a message you first have to	101	=item seeds - C<host:port>
83	resolve it.	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.
84		115
85	=back	116	=back
86		117
87	=head1 VARIABLES/FUNCTIONS	118	=head1 VARIABLES/FUNCTIONS
88		119
…		…
90		121
91	=cut	122	=cut
92		123
93	package AnyEvent::MP;	124	package AnyEvent::MP;
94		125
95	use AnyEvent::MP::Base;	126	use AnyEvent::MP::Kernel;
96		127
97	use common::sense;	128	use common::sense;
98		129
99	use Carp ();	130	use Carp ();
100		131
101	use AE ();	132	use AE ();
102		133
103	use base "Exporter";	134	use base "Exporter";
104		135
105	our $VERSION = '0.1';	136	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		137
106	our @EXPORT = qw(	138	our @EXPORT = qw(
107	NODE $NODE *SELF node_of _any_	139	NODE $NODE *SELF node_of after
108	resolve_node initialise_node	140	configure
109	snd rcv mon kil reg psub	141	snd rcv mon mon_guard kil reg psub spawn
110	port	142	port
111	);	143	);
112		144
113	our $SELF;	145	our $SELF;
114		146
…		…
118	kil $SELF, die => $msg;	150	kil $SELF, die => $msg;
119	}	151	}
120		152
121	=item $thisnode = NODE / $NODE	153	=item $thisnode = NODE / $NODE
122		154
123	The C<NODE> function returns, and the C<$NODE> variable contains	155	The C<NODE> function returns, and the C<$NODE> variable contains, the node
124	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
125	to C<become_public> or C<become_slave>, after which all local port	157	a call to C<configure>.
126	identifiers become invalid.
127		158
128	=item $noderef = node_of $portid	159	=item $nodeid = node_of $port
129		160
130	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.
131		162
132	=item $cv = resolve_node $noderef	163	=item configure key => value...
133		164
134	Takes an unresolved node reference that may contain hostnames and	165	Before a node can talk to other nodes on the network (i.e. enter
135	abbreviated IDs, resolves all of them and returns a resolved node	166	"distributed mode") it has to configure itself - the minimum a node needs
136	reference.	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.
137		169
138	In addition to C<address:port> pairs allowed in resolved noderefs, the	170	This function configures a node - it must be called exactly once (or
139	following forms are supported:	171	never) before calling other AnyEvent::MP functions.
140		172
141	=over 4	173	=over 4
142		174
143	=item the empty string	175	=item step 1, gathering configuration from profiles
144		176
145	An empty-string component gets resolved as if the default port (4040) was	177	The function first looks up a profile in the aemp configuration (see the
146	specified.	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.
147		181
148	=item naked port numbers (e.g. C<1234>)	182	The profile data is then gathered as follows:
149		183
150	These are resolved by prepending the local nodename and a colon, to be	184	First, all remaining key => value pairs (all of which are conveniently
151	further resolved.	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).
152		189
153	=item hostnames (e.g. C<localhost:1234>, C<localhost>)	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.
154		193
155	These are resolved by using AnyEvent::DNS to resolve them, optionally	194	If the profile specifies a node ID, then this will become the node ID of
156	looking up SRV records for the C<aemp=4040> port, if no port was	195	this process. If not, then the profile name will be used as node ID. The
157	specified.	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.
158		215
159	=back	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)"
160		243
161	=item $SELF	244	=item $SELF
162		245
163	Contains the current port id while executing C<rcv> callbacks or C<psub>	246	Contains the current port id while executing C<rcv> callbacks or C<psub>
164	blocks.	247	blocks.
165		248
166	=item SELF, %SELF, @SELF...	249	=item *SELF, SELF, %SELF, @SELF...
167		250
168	Due to some quirks in how perl exports variables, it is impossible to	251	Due to some quirks in how perl exports variables, it is impossible to
169	just export C<$SELF>, all the symbols called C<SELF> are exported by this	252	just export C<$SELF>, all the symbols named C<SELF> are exported by this
170	module, but only C<$SELF> is currently used.	253	module, but only C<$SELF> is currently used.
171		254
172	=item snd $portid, type => @data	255	=item snd $port, type => @data
173		256
174	=item snd $portid, @msg	257	=item snd $port, @msg
175		258
176	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
177	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.
178	stringifies a sa port ID (such as a port object :).
179		261
180	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
181	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
182	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.
183		266
184	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
185	function: modifying any argument is not allowed and can cause many	268	function: modifying any argument (or values referenced by them) is
186	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.
187		273
188	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
189	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
190	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
191	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
192	node, anything can be passed.	278	node, anything can be passed. Best rely only on the common denominator of
		279	these.
193		280
194	=item kil $portid[, @reason]	281	=item $local_port = port
195		282
196	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.
197		285
198	If no C<@reason> is specified, then the port is killed "normally" (linked	286	=item $local_port = port { my @msg = @_ }
199	ports will not be kileld, or even notified).
200		287
201	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
202	C<mon>, see below).	289	creating a port and calling C<rcv $port, $callback> on it.
203		290
204	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
205	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.
206		295
207	Transport/communication errors are reported as C<< transport_error =>	296	If you want to stop/destroy the port, simply C<kil> it:
208	$message >>.
209		297
210	=item $guard = mon $portid, $cb->(@reason)	298	my $port = port {
		299	my @msg = @_;
		300	...
		301	kil $SELF;
		302	};
211		303
212	=item $guard = mon $portid, $otherport	304	=cut
213		305
214	=item $guard = mon $portid, $otherport, @msg	306	sub rcv($@);
215		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 $port dies
		472
216	Monitor the given port and do something when the port is killed.	473	Monitor the given port and do something when the port is killed or
		474	messages to it were lost, and optionally return a guard that can be used
		475	to stop monitoring again.
217		476
		477	C<mon> effectively guarantees that, in the absence of hardware failures,
		478	after starting the monitor, either all messages sent to the port will
		479	arrive, or the monitoring action will be invoked after possible message
		480	loss has been detected. No messages will be lost "in between" (after
		481	the first lost message no further messages will be received by the
		482	port). After the monitoring action was invoked, further messages might get
		483	delivered again.
		484
		485	Note that monitoring-actions are one-shot: once messages are lost (and a
		486	monitoring alert was raised), they are removed and will not trigger again.
		487
218	In the first form, the callback is simply called with any number	488	In the first form (callback), the callback is simply called with any
219	of C<@reason> elements (no @reason means that the port was deleted	489	number of C<@reason> elements (no @reason means that the port was deleted
220	"normally"). Note also that I<< the callback B<must> never die >>, so use	490	"normally"). Note also that I<< the callback B<must> never die >>, so use
221	C<eval> if unsure.	491	C<eval> if unsure.
222		492
223	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	493	In the second form (another port given), the other port (C<$rcvport>)
224	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
225	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.
226		497
		498	The third form (kill self) is the same as the second form, except that
		499	C<$rvport> defaults to C<$SELF>.
		500
227	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.
228		510
229	Example: call a given callback when C<$port> is killed.	511	Example: call a given callback when C<$port> is killed.
230		512
231	mon $port, sub { warn "port died because of <@_>\n" };	513	mon $port, sub { warn "port died because of <@_>\n" };
232		514
233	Example: kill ourselves when C<$port> is killed abnormally.	515	Example: kill ourselves when C<$port> is killed abnormally.
234		516
235	mon $port, $self;	517	mon $port;
236		518
237	Example: send us a restart message another C<$port> is killed.	519	Example: send us a restart message when another C<$port> is killed.
238		520
239	mon $port, $self => "restart";	521	mon $port, $self => "restart";
240		522
241	=cut	523	=cut
242		524
243	sub mon {	525	sub mon {
244	my ($noderef, $port) = split /#/, shift, 2;	526	my ($nodeid, $port) = split /#/, shift, 2;
245		527
246	my $node = $NODE{$noderef} \|\| add_node $noderef;	528	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
247		529
248	my $cb = shift;	530	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
249		531
250	unless (ref $cb) {	532	unless (ref $cb) {
251	if (@_) {	533	if (@_) {
252	# send a kill info message	534	# send a kill info message
253	my (@msg) = ($cb, @_);	535	my (@msg) = ($cb, @_);
…		…
271	is killed, the references will be freed.	553	is killed, the references will be freed.
272		554
273	Optionally returns a guard that will stop the monitoring.	555	Optionally returns a guard that will stop the monitoring.
274		556
275	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
276	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>):
277		559
278	$port->rcv (start => sub {	560	$port->rcv (start => sub {
279	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	561	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
280	undef $timer if 0.9 < rand;	562	undef $timer if 0.9 < rand;
281	});	563	});
282	});	564	});
283		565
284	=cut	566	=cut
285		567
286	sub mon_guard {	568	sub mon_guard {
287	my ($port, @refs) = @_;	569	my ($port, @refs) = @_;
288		570
		571	#TODO: mon-less form?
		572
289	mon $port, sub { 0 && @refs }	573	mon $port, sub { 0 && @refs }
290	}	574	}
291		575
292	=item lnk $port1, $port2	576	=item kil $port[, @reason]
293		577
294	Link two ports. This is simply a shorthand for:	578	Kill the specified port with the given C<@reason>.
295		579
296	mon $port1, $port2;	580	If no C<@reason> is specified, then the port is killed "normally" (ports
297	mon $port2, $port1;	581	monitoring other ports will not necessarily die because a port dies
		582	"normally").
298		583
299	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
300	killed as well.	585	C<mon>, see above).
301		586
302	=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 => $@ >>.
303		589
304	Create a new local port object that can be used either as a pattern	590	Transport/communication errors are reported as C<< transport_error =>
305	matching port ("full port") or a single-callback port ("miniport"),	591	$message >>.
306	depending on how C<rcv> callbacks are bound to the object.
307		592
308	=item $portid = port { my @msg = @_; $finished }
309
310	Creates a "mini port", that is, a very lightweight port without any
311	pattern matching behind it, and returns its ID.
312
313	The block will be called for every message received on the port. When the
314	callback returns a true value its job is considered "done" and the port
315	will be destroyed. Otherwise it will stay alive.
316
317	The message will be passed as-is, no extra argument (i.e. no port id) will
318	be passed to the callback.
319
320	If you need the local port id in the callback, this works nicely:
321
322	my $port; $port = port {
323	snd $otherport, reply => $port;
324	};
325
326	=cut	593	=cut
327		594
328	sub port(;&) {	595	=item $port = spawn $node, $initfunc[, @initdata]
329	my $id = "$UNIQ." . $ID++;
330	my $port = "$NODE#$id";
331		596
332	if (@_) {	597	Creates a port on the node C<$node> (which can also be a port ID, in which
333	my $cb = shift;	598	case it's the node where that port resides).
334	$PORT{$id} = sub {	599
335	local $SELF = $port;	600	The port ID of the newly created port is returned immediately, and it is
336	eval {	601	possible to immediately start sending messages or to monitor the port.
337	&$cb	602
338	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 {
339	};	634	...
340	_self_die if $@;
341	};
342	} else {
343	my $self = bless {
344	id => "$NODE#$id",
345	}, "AnyEvent::MP::Port";
346
347	$PORT_DATA{$id} = $self;
348	$PORT{$id} = sub {
349	local $SELF = $port;
350
351	eval {
352	for (@{ $self->{rc0}{$_[0]} }) {
353	$_ && &{$_->[0]}
354	&& undef $_;
355	}
356
357	for (@{ $self->{rcv}{$_[0]} }) {
358	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
359	&& &{$_->[0]}
360	&& undef $_;
361	}
362
363	for (@{ $self->{any} }) {
364	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
365	&& &{$_->[0]}
366	&& undef $_;
367	}
368	};
369	_self_die if $@;
370	};	635	};
371	}	636	}
372		637
373	$port
374	}
375
376	=item reg $portid, $name
377
378	Registers the given port under the name C<$name>. If the name already
379	exists it is replaced.
380
381	A port can only be registered under one well known name.
382
383	A port automatically becomes unregistered when it is killed.
384
385	=cut	638	=cut
386		639
387	sub reg(@) {	640	sub _spawn {
388	my ($portid, $name) = @_;
389
390	$REG{$name} = $portid;
391	}
392
393	=item rcv $portid, $callback->(@msg)
394
395	Replaces the callback on the specified miniport (or newly created port
396	object, see C<port>). Full ports are configured with the following calls:
397
398	=item rcv $portid, tagstring => $callback->(@msg), ...
399
400	=item rcv $portid, $smartmatch => $callback->(@msg), ...
401
402	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
403
404	Register callbacks to be called on matching messages on the given port.
405
406	The callback has to return a true value when its work is done, after
407	which is will be removed, or a false value in which case it will stay
408	registered.
409
410	The global C<$SELF> (exported by this module) contains C<$portid> while
411	executing the callback.
412
413	Runtime errors wdurign callback execution will result in the port being
414	C<kil>ed.
415
416	If the match is an array reference, then it will be matched against the
417	first elements of the message, otherwise only the first element is being
418	matched.
419
420	Any element in the match that is specified as C<_any_> (a function
421	exported by this module) matches any single element of the message.
422
423	While not required, it is highly recommended that the first matching
424	element is a string identifying the message. The one-string-only match is
425	also the most efficient match (by far).
426
427	=cut
428
429	sub rcv($@) {
430	my $portid = shift;	641	my $port = shift;
431	my ($noderef, $port) = split /#/, $port, 2;	642	my $init = shift;
432		643
433	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	644	local $SELF = "$NODE#$port";
434	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";	645	eval {
435		646	&{ load_func $init }
436	my $self = $PORT_DATA{$port}
437	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
438
439	"AnyEvent::MP::Port" eq ref $self
440	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
441
442	while (@_) {
443	my ($match, $cb) = splice @_, 0, 2;
444
445	if (!ref $match) {
446	push @{ $self->{rc0}{$match} }, [$cb];
447	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
448	my ($type, @match) = @$match;
449	@match
450	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
451	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
452	} else {
453	push @{ $self->{any} }, [$cb, $match];
454	}
455	}
456
457	$portid
458	}
459
460	=item $closure = psub { BLOCK }
461
462	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
463	closure is executed, sets up the environment in the same way as in C<rcv>
464	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
465
466	This is useful when you register callbacks from C<rcv> callbacks:
467
468	rcv delayed_reply => sub {
469	my ($delay, @reply) = @_;
470	my $timer = AE::timer $delay, 0, psub {
471	snd @reply, $SELF;
472	};
473	};	647	};
474
475	=cut
476
477	sub psub(&) {
478	my $cb = shift;
479
480	my $port = $SELF
481	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
482
483	sub {
484	local $SELF = $port;
485
486	if (wantarray) {
487	my @res = eval { &$cb };
488	_self_die if $@;	648	_self_die if $@;
489	@res	649	}
490	} else {	650
491	my $res = eval { &$cb };	651	sub spawn(@) {
492	_self_die if $@;	652	my ($nodeid, undef) = split /#/, shift, 2;
493	$res	653
494	}	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;
495	}	685	};
496	}	686	}
497		687
498	=back	688	=back
499		689
500	=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:
501		703
502	=over 4	704	=over 4
503		705
504	=item become_public $noderef	706	=item * Node IDs are arbitrary strings in AEMP.
505		707
506	Tells the node to become a public node, i.e. reachable from other nodes.
507
508	The first argument is the (unresolved) node reference of the local node
509	(if missing then the empty string is used).
510
511	It is quite common to not specify anything, in which case the local node
512	tries to listen on the default port, or to only specify a port number, in
513	which case AnyEvent::MP tries to guess the local addresses.
514
515	=cut
516
517	=back
518
519	=head1 NODE MESSAGES
520
521	Nodes understand the following messages sent to them. Many of them take
522	arguments called C<@reply>, which will simply be used to compose a reply
523	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
524	the remaining arguments are simply the message data.
525
526	While other messages exist, they are not public and subject to change.
527
528	=over 4
529
530	=cut
531
532	=item lookup => $name, @reply
533
534	Replies with the port ID of the specified well-known port, or C<undef>.
535
536	=item devnull => ...
537
538	Generic data sink/CPU heat conversion.
539
540	=item relay => $port, @msg
541
542	Simply forwards the message to the given port.
543
544	=item eval => $string[ @reply]
545
546	Evaluates the given string. If C<@reply> is given, then a message of the
547	form C<@reply, $@, @evalres> is sent.
548
549	Example: crash another node.
550
551	snd $othernode, eval => "exit";
552
553	=item time => @reply
554
555	Replies the the current node time to C<@reply>.
556
557	Example: tell the current node to send the current time to C<$myport> in a
558	C<timereply> message.
559
560	snd $NODE, time => $myport, timereply => 1, 2;
561	# => snd $myport, timereply => 1, 2, <time>
562
563	=back
564
565	=head1 AnyEvent::MP vs. Distributed Erlang
566
567	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node
568	== aemp node, erlang process == aemp port), so many of the documents and
569	programming techniques employed by erlang apply to AnyEvent::MP. Here is a
570	sample:
571
572	http://www.erlang.se/doc/programming_rules.shtml
573	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
574	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6
575	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
576
577	Despite the similarities, there are also some important differences:
578
579	=over 4
580
581	=item * Node references contain the recipe on how to contact them.
582
583	Erlang relies on special naming and DNS to work everywhere in the	708	Erlang relies on special naming and DNS to work everywhere in the same
584	same way. AEMP relies on each node knowing it's own address(es), with	709	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
585	convenience functionality.	710	configuration or DNS), but will otherwise discover other odes itself.
586		711
587	This means that AEMP requires a less tightly controlled environment at the	712	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
588	cost of longer node references and a slightly higher management overhead.	713	uses "local ports are like remote ports".
		714
		715	The failure modes for local ports are quite different (runtime errors
		716	only) then for remote ports - when a local port dies, you I<know> it dies,
		717	when a connection to another node dies, you know nothing about the other
		718	port.
		719
		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.
589		726
590	=item * Erlang uses processes and a mailbox, AEMP does not queue.	727	=item * Erlang uses processes and a mailbox, AEMP does not queue.
591		728
592	Erlang uses processes that selctively receive messages, and therefore	729	Erlang uses processes that selectively receive messages, and therefore
593	needs a queue. AEMP is event based, queuing messages would serve no useful	730	needs a queue. AEMP is event based, queuing messages would serve no
594	purpose.	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.
595		734
596	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	735	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
597		736
598	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	737	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
599		738
600	Sending messages in erlang is synchronous and blocks the process. AEMP	739	Sending messages in Erlang is synchronous and blocks the process (and
601	sends are immediate, connection establishment is handled in the	740	so does not need a queue that can overflow). AEMP sends are immediate,
602	background.	741	connection establishment is handled in the background.
603		742
604	=item * Erlang can silently lose messages, AEMP cannot.	743	=item * Erlang suffers from silent message loss, AEMP does not.
605		744
606	Erlang makes few guarantees on messages delivery - messages can get lost	745	Erlang makes few guarantees on messages delivery - messages can get lost
607	without any of the processes realising it (i.e. you send messages a, b,	746	without any of the processes realising it (i.e. you send messages a, b,
608	and c, and the other side only receives messages a and c).	747	and c, and the other side only receives messages a and c).
609		748
610	AEMP guarantees correct ordering, and the guarantee that there are no	749	AEMP guarantees correct ordering, and the guarantee that after one message
611	holes in the message sequence.	750	is lost, all following ones sent to the same port are lost as well, until
612		751	monitoring raises an error, so there are no silent "holes" in the message
613	=item * In erlang, processes can be declared dead and later be found to be	752	sequence.
614	alive.
615
616	In erlang it can happen that a monitored process is declared dead and
617	linked processes get killed, but later it turns out that the process is
618	still alive - and can receive messages.
619
620	In AEMP, when port monitoring detects a port as dead, then that port will
621	eventually be killed - it cannot happen that a node detects a port as dead
622	and then later sends messages to it, finding it is still alive.
623		753
624	=item * Erlang can send messages to the wrong port, AEMP does not.	754	=item * Erlang can send messages to the wrong port, AEMP does not.
625		755
626	In erlang it is quite possible that a node that restarts reuses a process	756	In Erlang it is quite likely that a node that restarts reuses a process ID
627	ID known to other nodes for a completely different process, causing	757	known to other nodes for a completely different process, causing messages
628	messages destined for that process to end up in an unrelated process.	758	destined for that process to end up in an unrelated process.
629		759
630	AEMP never reuses port IDs, so old messages or old port IDs floating	760	AEMP never reuses port IDs, so old messages or old port IDs floating
631	around in the network will not be sent to an unrelated port.	761	around in the network will not be sent to an unrelated port.
632		762
633	=item * Erlang uses unprotected connections, AEMP uses secure	763	=item * Erlang uses unprotected connections, AEMP uses secure
634	authentication and can use TLS.	764	authentication and can use TLS.
635		765
636	AEMP can use a proven protocol - SSL/TLS - to protect connections and	766	AEMP can use a proven protocol - TLS - to protect connections and
637	securely authenticate nodes.	767	securely authenticate nodes.
638		768
639	=item * The AEMP protocol is optimised for both text-based and binary	769	=item * The AEMP protocol is optimised for both text-based and binary
640	communications.	770	communications.
641		771
642	The AEMP protocol, unlike the erlang protocol, supports both	772	The AEMP protocol, unlike the Erlang protocol, supports both programming
643	language-independent text-only protocols (good for debugging) and binary,	773	language independent text-only protocols (good for debugging) and binary,
644	language-specific serialisers (e.g. Storable).	774	language-specific serialisers (e.g. Storable). By default, unless TLS is
		775	used, the protocol is actually completely text-based.
645		776
646	It has also been carefully designed to be implementable in other languages	777	It has also been carefully designed to be implementable in other languages
647	with a minimum of work while gracefully degrading fucntionality to make the	778	with a minimum of work while gracefully degrading functionality to make the
648	protocol simple.	779	protocol simple.
649		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).
		802
650	=back	803	=back
651		804
		805	=head1 RATIONALE
		806
		807	=over 4
		808
		809	=item Why strings for port and node IDs, why not objects?
		810
		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.
		815
		816	Strings can easily be printed, easily serialised etc. and need no special
		817	procedures to be "valid".
		818
		819	And as a result, a miniport consists of a single closure stored in a
		820	global hash - it can't become much cheaper.
		821
		822	=item Why favour JSON, why not a real serialising format such as Storable?
		823
		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).
		827
		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.
		834
		835	Keeping your messages simple, concentrating on data structures rather than
		836	objects, will keep your messages clean, tidy and efficient.
		837
		838	=back
		839
652	=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.
653		848
654	L<AnyEvent>.	849	L<AnyEvent>.
655		850
656	=head1 AUTHOR	851	=head1 AUTHOR
657		852

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.31 by root, Wed Aug 5 19:55:58 2009 UTC vs. Revision 1.77 by elmex, Thu Sep 3 07:57:30 2009 UTC

Diff Legend

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.31 by root, Wed Aug 5 19:55:58 2009 UTC vs.
Revision 1.77 by elmex, Thu Sep 3 07:57:30 2009 UTC