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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.29 by root, Tue Aug 4 23:16:57 2009 UTC vs.
Revision 1.70 by root, Sun Aug 30 19:49:47 2009 UTC

…		…
8		8
9	$NODE # contains this node's noderef	9	$NODE # contains this node's noderef
10	NODE # returns this node's noderef	10	NODE # returns this node's noderef
11	NODE $port # returns the noderef of the port	11	NODE $port # returns the noderef of the port
12		12
		13	$SELF # receiving/own port id in rcv callbacks
		14
		15	# initialise the node so it can send/receive messages
		16	initialise_node;
		17
		18	# ports are message endpoints
		19
		20	# sending messages
13	snd $port, type => data...;	21	snd $port, type => data...;
		22	snd $port, @msg;
		23	snd @msg_with_first_element_being_a_port;
14		24
15	$SELF # receiving/own port id in rcv callbacks	25	# creating/using ports, the simple way
		26	my $simple_port = port { my @msg = @_; 0 };
16		27
17	rcv $port, smartmatch => $cb->($port, @msg);	28	# creating/using ports, tagged message matching
18		29	my $port = port;
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	30	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
21	rcv $port1, pong => sub { warn "pong received\n" };	31	rcv $port, pong => sub { warn "pong received\n"; 0 };
22	snd $port2, ping => $port1;
23		32
24	# more, smarter, matches (_any_ is exported by this module)	33	# create a port on another node
25	rcv $port, [child_died => $pid] => sub { ...	34	my $port = spawn $node, $initfunc, @initdata;
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	35
		36	# monitoring
		37	mon $port, $cb->(@msg) # callback is invoked on death
		38	mon $port, $otherport # kill otherport on abnormal death
		39	mon $port, $otherport, @msg # send message on death
		40
		41	=head1 CURRENT STATUS
		42
		43	AnyEvent::MP - stable API, should work
		44	AnyEvent::MP::Intro - outdated
		45	AnyEvent::MP::Kernel - mostly stable
		46	AnyEvent::MP::Global - mostly stable
		47	AnyEvent::MP::Node - mostly stable, but internal anyways
		48	AnyEvent::MP::Transport - mostly stable, but internal anyways
		49
		50	stay tuned.
27		51
28	=head1 DESCRIPTION	52	=head1 DESCRIPTION
29		53
30	This module (-family) implements a simple message passing framework.	54	This module (-family) implements a simple message passing framework.
31		55
32	Despite its simplicity, you can securely message other processes running	56	Despite its simplicity, you can securely message other processes running
33	on the same or other hosts.	57	on the same or other hosts, and you can supervise entities remotely.
34		58
35	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	59	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
36	manual page.	60	manual page and the examples under F<eg/>.
37		61
38	At the moment, this module family is severly broken and underdocumented,	62	At the moment, this module family is a bit underdocumented.
39	so do not use. This was uploaded mainly to reserve the CPAN namespace -
40	stay tuned! The basic API should be finished, however.
41		63
42	=head1 CONCEPTS	64	=head1 CONCEPTS
43		65
44	=over 4	66	=over 4
45		67
46	=item port	68	=item port
47		69
48	A port is something you can send messages to (with the C<snd> function).	70	A port is something you can send messages to (with the C<snd> function).
49		71
50	Some ports allow you to register C<rcv> handlers that can match specific	72	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	73	some messages. Messages send to ports will not be queued, regardless of
52	will not be queued.	74	anything was listening for them or not.
53		75
54	=item port id - C<noderef#portname>	76	=item port ID - C<nodeid#portname>
55		77
56	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	78	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	79	separator, and a port name (a printable string of unspecified format).
58	exception is the the node port, whose ID is identical to it's node
59	reference.
60		80
61	=item node	81	=item node
62		82
63	A node is a single process containing at least one port - the node	83	A node is a single process containing at least one port - the node port,
64	port. You can send messages to node ports to find existing ports or to	84	which enables nodes to manage each other remotely, and to create new
65	create new ports, among other things.	85	ports.
66		86
67	Nodes are either private (single-process only), slaves (connected to a	87	Nodes are either public (have one or more listening ports) or private
68	master node only) or public nodes (connectable from unrelated nodes).	88	(no listening ports). Private nodes cannot talk to other private nodes
		89	currently.
69		90
70	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	91	=item node ID - C<[a-za-Z0-9_\-.:]+>
71		92
72	A node reference is a string that either simply identifies the node (for	93	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	94	network. Depending on the configuration used, node IDs can look like a
74	node (for public nodes).	95	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
		96	doesn't interpret node IDs in any way.
75		97
76	This recipe is simply a comma-separated list of C<address:port> pairs (for	98	=item binds - C<ip:port>
77	TCP/IP, other protocols might look different).
78		99
79	Node references come in two flavours: resolved (containing only numerical	100	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).	101	each other. To do this, nodes should listen on one or more local transport
		102	endpoints - binds. Currently, only standard C<ip:port> specifications can
		103	be used, which specify TCP ports to listen on.
81		104
82	Before using an unresolved node reference in a message you first have to	105	=item seeds - C<host:port>
83	resolve it.	106
		107	When a node starts, it knows nothing about the network. To teach the node
		108	about the network it first has to contact some other node within the
		109	network. This node is called a seed.
		110
		111	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes
		112	are expected to be long-running, and at least one of those should always
		113	be available. When nodes run out of connections (e.g. due to a network
		114	error), they try to re-establish connections to some seednodes again to
		115	join the network.
		116
		117	Apart from being sued for seeding, seednodes are not special in any way -
		118	every public node can be a seednode.
84		119
85	=back	120	=back
86		121
87	=head1 VARIABLES/FUNCTIONS	122	=head1 VARIABLES/FUNCTIONS
88		123
…		…
90		125
91	=cut	126	=cut
92		127
93	package AnyEvent::MP;	128	package AnyEvent::MP;
94		129
95	use AnyEvent::MP::Base;	130	use AnyEvent::MP::Kernel;
96		131
97	use common::sense;	132	use common::sense;
98		133
99	use Carp ();	134	use Carp ();
100		135
101	use AE ();	136	use AE ();
102		137
103	use base "Exporter";	138	use base "Exporter";
104		139
105	our $VERSION = '0.1';	140	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		141
106	our @EXPORT = qw(	142	our @EXPORT = qw(
107	NODE $NODE *SELF node_of _any_	143	NODE $NODE *SELF node_of after
108	resolve_node	144	initialise_node
109	become_slave become_public
110	snd rcv mon kil reg psub	145	snd rcv mon mon_guard kil reg psub spawn
111	port	146	port
112	);	147	);
113		148
114	our $SELF;	149	our $SELF;
115		150
…		…
119	kil $SELF, die => $msg;	154	kil $SELF, die => $msg;
120	}	155	}
121		156
122	=item $thisnode = NODE / $NODE	157	=item $thisnode = NODE / $NODE
123		158
124	The C<NODE> function returns, and the C<$NODE> variable contains	159	The C<NODE> function returns, and the C<$NODE> variable contains, the node
125	the noderef of the local node. The value is initialised by a call	160	ID of the node running in the current process. This value is initialised by
126	to C<become_public> or C<become_slave>, after which all local port	161	a call to C<initialise_node>.
127	identifiers become invalid.
128		162
129	=item $noderef = node_of $portid	163	=item $nodeid = node_of $port
130		164
131	Extracts and returns the noderef from a portid or a noderef.	165	Extracts and returns the node ID from a port ID or a node ID.
132		166
133	=item $cv = resolve_node $noderef	167	=item initialise_node $profile_name, key => value...
134		168
135	Takes an unresolved node reference that may contain hostnames and	169	Before a node can talk to other nodes on the network (i.e. enter
136	abbreviated IDs, resolves all of them and returns a resolved node	170	"distributed mode") it has to initialise itself - the minimum a node needs
137	reference.	171	to know is its own name, and optionally it should know the addresses of
		172	some other nodes in the network to discover other nodes.
138		173
139	In addition to C<address:port> pairs allowed in resolved noderefs, the	174	This function initialises a node - it must be called exactly once (or
140	following forms are supported:	175	never) before calling other AnyEvent::MP functions.
141		176
142	=over 4	177	The first argument is a profile name. If it is C<undef> or missing, then
		178	the current nodename will be used instead (i.e. F<uname -n>).
143		179
144	=item the empty string	180	The function first looks up the profile in the aemp configuration (see the
		181	L<aemp> commandline utility). the profile is calculated as follows:
145		182
146	An empty-string component gets resolved as if the default port (4040) was	183	First, all remaining key => value pairs (all of which are conviniently
147	specified.	184	undocumented at the moment) will be used. Then they will be overwritten by
		185	any values specified in the global default configuration (see the F<aemp>
		186	utility), then the chain of profiles selected, if any. That means that
		187	the values specified in the profile have highest priority and the values
		188	specified via C<initialise_node> have lowest priority.
148		189
149	=item naked port numbers (e.g. C<1234>)	190	If the profile specifies a node ID, then this will become the node ID of
		191	this process. If not, then the profile name will be used as node ID. The
		192	special node ID of C<anon/> will be replaced by a random node ID.
150		193
151	These are resolved by prepending the local nodename and a colon, to be	194	The next step is to look up the binds in the profile, followed by binding
152	further resolved.	195	aemp protocol listeners on all binds specified (it is possible and valid
		196	to have no binds, meaning that the node cannot be contacted form the
		197	outside. This means the node cannot talk to other nodes that also have no
		198	binds, but it can still talk to all "normal" nodes).
153		199
154	=item hostnames (e.g. C<localhost:1234>, C<localhost>)	200	If the profile does not specify a binds list, then a default of C<*> is
		201	used.
155		202
156	These are resolved by using AnyEvent::DNS to resolve them, optionally	203	Lastly, the seeds list from the profile is passed to the
157	looking up SRV records for the C<aemp=4040> port, if no port was	204	L<AnyEvent::MP::Global> module, which will then use it to keep
158	specified.	205	connectivity with at least on of those seed nodes at any point in time.
159		206
160	=back	207	Example: become a distributed node listening on the guessed noderef, or
		208	the one specified via C<aemp> for the current node. This should be the
		209	most common form of invocation for "daemon"-type nodes.
		210
		211	initialise_node;
		212
		213	Example: become an anonymous node. This form is often used for commandline
		214	clients.
		215
		216	initialise_node "anon/";
		217
		218	Example: become a distributed node. If there is no profile of the given
		219	name, or no binds list was specified, resolve C<localhost:4044> and bind
		220	on the resulting addresses.
		221
		222	initialise_node "localhost:4044";
161		223
162	=item $SELF	224	=item $SELF
163		225
164	Contains the current port id while executing C<rcv> callbacks or C<psub>	226	Contains the current port id while executing C<rcv> callbacks or C<psub>
165	blocks.	227	blocks.
166		228
167	=item SELF, %SELF, @SELF...	229	=item *SELF, SELF, %SELF, @SELF...
168		230
169	Due to some quirks in how perl exports variables, it is impossible to	231	Due to some quirks in how perl exports variables, it is impossible to
170	just export C<$SELF>, all the symbols called C<SELF> are exported by this	232	just export C<$SELF>, all the symbols named C<SELF> are exported by this
171	module, but only C<$SELF> is currently used.	233	module, but only C<$SELF> is currently used.
172		234
173	=item snd $portid, type => @data	235	=item snd $port, type => @data
174		236
175	=item snd $portid, @msg	237	=item snd $port, @msg
176		238
177	Send the given message to the given port ID, which can identify either	239	Send the given message to the given port, which can identify either a
178	a local or a remote port, and can be either a string or soemthignt hat	240	local or a remote port, and must be a port ID.
179	stringifies a sa port ID (such as a port object :).
180		241
181	While the message can be about anything, it is highly recommended to use a	242	While the message can be almost anything, it is highly recommended to
182	string as first element (a portid, or some word that indicates a request	243	use a string as first element (a port ID, or some word that indicates a
183	type etc.).	244	request type etc.) and to consist if only simple perl values (scalars,
		245	arrays, hashes) - if you think you need to pass an object, think again.
184		246
185	The message data effectively becomes read-only after a call to this	247	The message data logically becomes read-only after a call to this
186	function: modifying any argument is not allowed and can cause many	248	function: modifying any argument (or values referenced by them) is
187	problems.	249	forbidden, as there can be considerable time between the call to C<snd>
		250	and the time the message is actually being serialised - in fact, it might
		251	never be copied as within the same process it is simply handed to the
		252	receiving port.
188		253
189	The type of data you can transfer depends on the transport protocol: when	254	The type of data you can transfer depends on the transport protocol: when
190	JSON is used, then only strings, numbers and arrays and hashes consisting	255	JSON is used, then only strings, numbers and arrays and hashes consisting
191	of those are allowed (no objects). When Storable is used, then anything	256	of those are allowed (no objects). When Storable is used, then anything
192	that Storable can serialise and deserialise is allowed, and for the local	257	that Storable can serialise and deserialise is allowed, and for the local
193	node, anything can be passed.	258	node, anything can be passed. Best rely only on the common denominator of
		259	these.
194		260
195	=item kil $portid[, @reason]	261	=item $local_port = port
196		262
197	Kill the specified port with the given C<@reason>.	263	Create a new local port object and returns its port ID. Initially it has
		264	no callbacks set and will throw an error when it receives messages.
198		265
199	If no C<@reason> is specified, then the port is killed "normally" (linked	266	=item $local_port = port { my @msg = @_ }
200	ports will not be kileld, or even notified).
201		267
202	Otherwise, linked ports get killed with the same reason (second form of	268	Creates a new local port, and returns its ID. Semantically the same as
203	C<mon>, see below).	269	creating a port and calling C<rcv $port, $callback> on it.
204		270
205	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	271	The block will be called for every message received on the port, with the
206	will be reported as reason C<< die => $@ >>.	272	global variable C<$SELF> set to the port ID. Runtime errors will cause the
		273	port to be C<kil>ed. The message will be passed as-is, no extra argument
		274	(i.e. no port ID) will be passed to the callback.
207		275
208	Transport/communication errors are reported as C<< transport_error =>	276	If you want to stop/destroy the port, simply C<kil> it:
209	$message >>.
210		277
211	=item $guard = mon $portid, $cb->(@reason)	278	my $port = port {
		279	my @msg = @_;
		280	...
		281	kil $SELF;
		282	};
212		283
213	=item $guard = mon $portid, $otherport	284	=cut
214		285
215	=item $guard = mon $portid, $otherport, @msg	286	sub rcv($@);
216		287
		288	sub _kilme {
		289	die "received message on port without callback";
		290	}
		291
		292	sub port(;&) {
		293	my $id = "$UNIQ." . $ID++;
		294	my $port = "$NODE#$id";
		295
		296	rcv $port, shift \|\| \&_kilme;
		297
		298	$port
		299	}
		300
		301	=item rcv $local_port, $callback->(@msg)
		302
		303	Replaces the default callback on the specified port. There is no way to
		304	remove the default callback: use C<sub { }> to disable it, or better
		305	C<kil> the port when it is no longer needed.
		306
		307	The global C<$SELF> (exported by this module) contains C<$port> while
		308	executing the callback. Runtime errors during callback execution will
		309	result in the port being C<kil>ed.
		310
		311	The default callback received all messages not matched by a more specific
		312	C<tag> match.
		313
		314	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
		315
		316	Register (or replace) callbacks to be called on messages starting with the
		317	given tag on the given port (and return the port), or unregister it (when
		318	C<$callback> is C<$undef> or missing). There can only be one callback
		319	registered for each tag.
		320
		321	The original message will be passed to the callback, after the first
		322	element (the tag) has been removed. The callback will use the same
		323	environment as the default callback (see above).
		324
		325	Example: create a port and bind receivers on it in one go.
		326
		327	my $port = rcv port,
		328	msg1 => sub { ... },
		329	msg2 => sub { ... },
		330	;
		331
		332	Example: create a port, bind receivers and send it in a message elsewhere
		333	in one go:
		334
		335	snd $otherport, reply =>
		336	rcv port,
		337	msg1 => sub { ... },
		338	...
		339	;
		340
		341	Example: temporarily register a rcv callback for a tag matching some port
		342	(e.g. for a rpc reply) and unregister it after a message was received.
		343
		344	rcv $port, $otherport => sub {
		345	my @reply = @_;
		346
		347	rcv $SELF, $otherport;
		348	};
		349
		350	=cut
		351
		352	sub rcv($@) {
		353	my $port = shift;
		354	my ($noderef, $portid) = split /#/, $port, 2;
		355
		356	$NODE{$noderef} == $NODE{""}
		357	or Carp::croak "$port: rcv can only be called on local ports, caught";
		358
		359	while (@_) {
		360	if (ref $_[0]) {
		361	if (my $self = $PORT_DATA{$portid}) {
		362	"AnyEvent::MP::Port" eq ref $self
		363	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		364
		365	$self->[2] = shift;
		366	} else {
		367	my $cb = shift;
		368	$PORT{$portid} = sub {
		369	local $SELF = $port;
		370	eval { &$cb }; _self_die if $@;
		371	};
		372	}
		373	} elsif (defined $_[0]) {
		374	my $self = $PORT_DATA{$portid} \|\|= do {
		375	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
		376
		377	$PORT{$portid} = sub {
		378	local $SELF = $port;
		379
		380	if (my $cb = $self->[1]{$_[0]}) {
		381	shift;
		382	eval { &$cb }; _self_die if $@;
		383	} else {
		384	&{ $self->[0] };
		385	}
		386	};
		387
		388	$self
		389	};
		390
		391	"AnyEvent::MP::Port" eq ref $self
		392	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		393
		394	my ($tag, $cb) = splice @_, 0, 2;
		395
		396	if (defined $cb) {
		397	$self->[1]{$tag} = $cb;
		398	} else {
		399	delete $self->[1]{$tag};
		400	}
		401	}
		402	}
		403
		404	$port
		405	}
		406
		407	=item $closure = psub { BLOCK }
		408
		409	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
		410	closure is executed, sets up the environment in the same way as in C<rcv>
		411	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		412
		413	This is useful when you register callbacks from C<rcv> callbacks:
		414
		415	rcv delayed_reply => sub {
		416	my ($delay, @reply) = @_;
		417	my $timer = AE::timer $delay, 0, psub {
		418	snd @reply, $SELF;
		419	};
		420	};
		421
		422	=cut
		423
		424	sub psub(&) {
		425	my $cb = shift;
		426
		427	my $port = $SELF
		428	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
		429
		430	sub {
		431	local $SELF = $port;
		432
		433	if (wantarray) {
		434	my @res = eval { &$cb };
		435	_self_die if $@;
		436	@res
		437	} else {
		438	my $res = eval { &$cb };
		439	_self_die if $@;
		440	$res
		441	}
		442	}
		443	}
		444
		445	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
		446
		447	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
		448
		449	=item $guard = mon $port # kill $SELF when $port dies
		450
		451	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
		452
217	Monitor the given port and do something when the port is killed.	453	Monitor the given port and do something when the port is killed or
		454	messages to it were lost, and optionally return a guard that can be used
		455	to stop monitoring again.
218		456
		457	C<mon> effectively guarantees that, in the absence of hardware failures,
		458	after starting the monitor, either all messages sent to the port will
		459	arrive, or the monitoring action will be invoked after possible message
		460	loss has been detected. No messages will be lost "in between" (after
		461	the first lost message no further messages will be received by the
		462	port). After the monitoring action was invoked, further messages might get
		463	delivered again.
		464
		465	Note that monitoring-actions are one-shot: once messages are lost (and a
		466	monitoring alert was raised), they are removed and will not trigger again.
		467
219	In the first form, the callback is simply called with any number	468	In the first form (callback), the callback is simply called with any
220	of C<@reason> elements (no @reason means that the port was deleted	469	number of C<@reason> elements (no @reason means that the port was deleted
221	"normally"). Note also that I<< the callback B<must> never die >>, so use	470	"normally"). Note also that I<< the callback B<must> never die >>, so use
222	C<eval> if unsure.	471	C<eval> if unsure.
223		472
224	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	473	In the second form (another port given), the other port (C<$rcvport>)
225	a @reason was specified, i.e. on "normal" kils nothing happens, while	474	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
226	under all other conditions, the other port is killed with the same reason.	475	"normal" kils nothing happens, while under all other conditions, the other
		476	port is killed with the same reason.
227		477
		478	The third form (kill self) is the same as the second form, except that
		479	C<$rvport> defaults to C<$SELF>.
		480
228	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	481	In the last form (message), a message of the form C<@msg, @reason> will be
		482	C<snd>.
		483
		484	As a rule of thumb, monitoring requests should always monitor a port from
		485	a local port (or callback). The reason is that kill messages might get
		486	lost, just like any other message. Another less obvious reason is that
		487	even monitoring requests can get lost (for exmaple, when the connection
		488	to the other node goes down permanently). When monitoring a port locally
		489	these problems do not exist.
229		490
230	Example: call a given callback when C<$port> is killed.	491	Example: call a given callback when C<$port> is killed.
231		492
232	mon $port, sub { warn "port died because of <@_>\n" };	493	mon $port, sub { warn "port died because of <@_>\n" };
233		494
234	Example: kill ourselves when C<$port> is killed abnormally.	495	Example: kill ourselves when C<$port> is killed abnormally.
235		496
236	mon $port, $self;	497	mon $port;
237		498
238	Example: send us a restart message another C<$port> is killed.	499	Example: send us a restart message when another C<$port> is killed.
239		500
240	mon $port, $self => "restart";	501	mon $port, $self => "restart";
241		502
242	=cut	503	=cut
243		504
244	sub mon {	505	sub mon {
245	my ($noderef, $port, $cb) = ((split /#/, shift, 2), shift);	506	my ($noderef, $port) = split /#/, shift, 2;
246		507
247	my $node = $NODE{$noderef} \|\| add_node $noderef;	508	my $node = $NODE{$noderef} \|\| add_node $noderef;
248		509
249	#TODO: ports must not be references	510	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
250	if (!ref $cb or "AnyEvent::MP::Port" eq ref $cb) {	511
		512	unless (ref $cb) {
251	if (@_) {	513	if (@_) {
252	# send a kill info message	514	# send a kill info message
253	my (@msg) = ($cb, @_);	515	my (@msg) = ($cb, @_);
254	$cb = sub { snd @msg, @_ };	516	$cb = sub { snd @msg, @_ };
255	} else {	517	} else {
…		…
271	is killed, the references will be freed.	533	is killed, the references will be freed.
272		534
273	Optionally returns a guard that will stop the monitoring.	535	Optionally returns a guard that will stop the monitoring.
274		536
275	This function is useful when you create e.g. timers or other watchers and	537	This function is useful when you create e.g. timers or other watchers and
276	want to free them when the port gets killed:	538	want to free them when the port gets killed (note the use of C<psub>):
277		539
278	$port->rcv (start => sub {	540	$port->rcv (start => sub {
279	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	541	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
280	undef $timer if 0.9 < rand;	542	undef $timer if 0.9 < rand;
281	});	543	});
282	});	544	});
283		545
284	=cut	546	=cut
285		547
286	sub mon_guard {	548	sub mon_guard {
287	my ($port, @refs) = @_;	549	my ($port, @refs) = @_;
288		550
		551	#TODO: mon-less form?
		552
289	mon $port, sub { 0 && @refs }	553	mon $port, sub { 0 && @refs }
290	}	554	}
291		555
292	=item lnk $port1, $port2	556	=item kil $port[, @reason]
293		557
294	Link two ports. This is simply a shorthand for:	558	Kill the specified port with the given C<@reason>.
295		559
296	mon $port1, $port2;	560	If no C<@reason> is specified, then the port is killed "normally" (ports
297	mon $port2, $port1;	561	monitoring other ports will not necessarily die because a port dies
		562	"normally").
298		563
299	It means that if either one is killed abnormally, the other one gets	564	Otherwise, linked ports get killed with the same reason (second form of
300	killed as well.	565	C<mon>, see above).
301		566
302	=item $local_port = port	567	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		568	will be reported as reason C<< die => $@ >>.
303		569
304	Create a new local port object that supports message matching.	570	Transport/communication errors are reported as C<< transport_error =>
		571	$message >>.
305		572
306	=item $portid = port { my @msg = @_; $finished }
307
308	Creates a "mini port", that is, a very lightweight port without any
309	pattern matching behind it, and returns its ID.
310
311	The block will be called for every message received on the port. When the
312	callback returns a true value its job is considered "done" and the port
313	will be destroyed. Otherwise it will stay alive.
314
315	The message will be passed as-is, no extra argument (i.e. no port id) will
316	be passed to the callback.
317
318	If you need the local port id in the callback, this works nicely:
319
320	my $port; $port = miniport {
321	snd $otherport, reply => $port;
322	};
323
324	=cut	573	=cut
325		574
326	sub port(;&) {	575	=item $port = spawn $node, $initfunc[, @initdata]
327	my $id = "$UNIQ." . $ID++;
328	my $port = "$NODE#$id";
329		576
330	if (@_) {	577	Creates a port on the node C<$node> (which can also be a port ID, in which
331	my $cb = shift;	578	case it's the node where that port resides).
332	$PORT{$id} = sub {	579
333	local $SELF = $port;	580	The port ID of the newly created port is returned immediately, and it is
334	eval {	581	possible to immediately start sending messages or to monitor the port.
335	&$cb	582
336	and kil $id;	583	After the port has been created, the init function is called on the remote
		584	node, in the same context as a C<rcv> callback. This function must be a
		585	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
		586	specify a function in the main program, use C<::name>.
		587
		588	If the function doesn't exist, then the node tries to C<require>
		589	the package, then the package above the package and so on (e.g.
		590	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		591	exists or it runs out of package names.
		592
		593	The init function is then called with the newly-created port as context
		594	object (C<$SELF>) and the C<@initdata> values as arguments.
		595
		596	A common idiom is to pass a local port, immediately monitor the spawned
		597	port, and in the remote init function, immediately monitor the passed
		598	local port. This two-way monitoring ensures that both ports get cleaned up
		599	when there is a problem.
		600
		601	Example: spawn a chat server port on C<$othernode>.
		602
		603	# this node, executed from within a port context:
		604	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		605	mon $server;
		606
		607	# init function on C<$othernode>
		608	sub connect {
		609	my ($srcport) = @_;
		610
		611	mon $srcport;
		612
		613	rcv $SELF, sub {
337	};	614	...
338	_self_die if $@;
339	};
340	} else {
341	my $self = bless {
342	id => "$NODE#$id",
343	}, "AnyEvent::MP::Port";
344
345	$PORT_DATA{$id} = $self;
346	$PORT{$id} = sub {
347	local $SELF = $port;
348
349	eval {
350	for (@{ $self->{rc0}{$_[0]} }) {
351	$_ && &{$_->[0]}
352	&& undef $_;
353	}
354
355	for (@{ $self->{rcv}{$_[0]} }) {
356	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
357	&& &{$_->[0]}
358	&& undef $_;
359	}
360
361	for (@{ $self->{any} }) {
362	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
363	&& &{$_->[0]}
364	&& undef $_;
365	}
366	};
367	_self_die if $@;
368	};	615	};
369	}	616	}
370		617
371	$port
372	}
373
374	=item reg $portid, $name
375
376	Registers the given port under the name C<$name>. If the name already
377	exists it is replaced.
378
379	A port can only be registered under one well known name.
380
381	A port automatically becomes unregistered when it is killed.
382
383	=cut	618	=cut
384		619
385	sub reg(@) {	620	sub _spawn {
386	my ($portid, $name) = @_;	621	my $port = shift;
		622	my $init = shift;
387		623
388	$REG{$name} = $portid;	624	local $SELF = "$NODE#$port";
389	}	625	eval {
390		626	&{ load_func $init }
391	=item rcv $portid, tagstring => $callback->(@msg), ...
392
393	=item rcv $portid, $smartmatch => $callback->(@msg), ...
394
395	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
396
397	Register callbacks to be called on matching messages on the given port.
398
399	The callback has to return a true value when its work is done, after
400	which is will be removed, or a false value in which case it will stay
401	registered.
402
403	The global C<$SELF> (exported by this module) contains C<$portid> while
404	executing the callback.
405
406	Runtime errors wdurign callback execution will result in the port being
407	C<kil>ed.
408
409	If the match is an array reference, then it will be matched against the
410	first elements of the message, otherwise only the first element is being
411	matched.
412
413	Any element in the match that is specified as C<_any_> (a function
414	exported by this module) matches any single element of the message.
415
416	While not required, it is highly recommended that the first matching
417	element is a string identifying the message. The one-string-only match is
418	also the most efficient match (by far).
419
420	=cut
421
422	sub rcv($@) {
423	my ($noderef, $port) = split /#/, shift, 2;
424
425	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
426	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";
427
428	my $self = $PORT_DATA{$port}
429	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
430
431	"AnyEvent::MP::Port" eq ref $self
432	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
433
434	while (@_) {
435	my ($match, $cb) = splice @_, 0, 2;
436
437	if (!ref $match) {
438	push @{ $self->{rc0}{$match} }, [$cb];
439	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
440	my ($type, @match) = @$match;
441	@match
442	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
443	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
444	} else {
445	push @{ $self->{any} }, [$cb, $match];
446	}
447	}
448	}
449
450	=item $closure = psub { BLOCK }
451
452	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
453	closure is executed, sets up the environment in the same way as in C<rcv>
454	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
455
456	This is useful when you register callbacks from C<rcv> callbacks:
457
458	rcv delayed_reply => sub {
459	my ($delay, @reply) = @_;
460	my $timer = AE::timer $delay, 0, psub {
461	snd @reply, $SELF;
462	};
463	};	627	};
464
465	=cut
466
467	sub psub(&) {
468	my $cb = shift;
469
470	my $port = $SELF
471	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
472
473	sub {
474	local $SELF = $port;
475
476	if (wantarray) {
477	my @res = eval { &$cb };
478	_self_die if $@;	628	_self_die if $@;
479	@res	629	}
480	} else {	630
481	my $res = eval { &$cb };	631	sub spawn(@) {
482	_self_die if $@;	632	my ($noderef, undef) = split /#/, shift, 2;
483	$res	633
484	}	634	my $id = "$RUNIQ." . $ID++;
		635
		636	$_[0] =~ /::/
		637	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		638
		639	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
		640
		641	"$noderef#$id"
		642	}
		643
		644	=item after $timeout, @msg
		645
		646	=item after $timeout, $callback
		647
		648	Either sends the given message, or call the given callback, after the
		649	specified number of seconds.
		650
		651	This is simply a utility function that comes in handy at times - the
		652	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		653	so it may go away in the future.
		654
		655	=cut
		656
		657	sub after($@) {
		658	my ($timeout, @action) = @_;
		659
		660	my $t; $t = AE::timer $timeout, 0, sub {
		661	undef $t;
		662	ref $action[0]
		663	? $action[0]()
		664	: snd @action;
485	}	665	};
486	}	666	}
487		667
488	=back	668	=back
489		669
490	=head1 FUNCTIONS FOR NODES	670	=head1 AnyEvent::MP vs. Distributed Erlang
		671
		672	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
		673	== aemp node, Erlang process == aemp port), so many of the documents and
		674	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		675	sample:
		676
		677	http://www.Erlang.se/doc/programming_rules.shtml
		678	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		679	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		680	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		681
		682	Despite the similarities, there are also some important differences:
491		683
492	=over 4	684	=over 4
493		685
494	=item become_public $noderef	686	=item * Node IDs are arbitrary strings in AEMP.
495		687
496	Tells the node to become a public node, i.e. reachable from other nodes.
497
498	The first argument is the (unresolved) node reference of the local node
499	(if missing then the empty string is used).
500
501	It is quite common to not specify anything, in which case the local node
502	tries to listen on the default port, or to only specify a port number, in
503	which case AnyEvent::MP tries to guess the local addresses.
504
505	=cut
506
507	=back
508
509	=head1 NODE MESSAGES
510
511	Nodes understand the following messages sent to them. Many of them take
512	arguments called C<@reply>, which will simply be used to compose a reply
513	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
514	the remaining arguments are simply the message data.
515
516	While other messages exist, they are not public and subject to change.
517
518	=over 4
519
520	=cut
521
522	=item lookup => $name, @reply
523
524	Replies with the port ID of the specified well-known port, or C<undef>.
525
526	=item devnull => ...
527
528	Generic data sink/CPU heat conversion.
529
530	=item relay => $port, @msg
531
532	Simply forwards the message to the given port.
533
534	=item eval => $string[ @reply]
535
536	Evaluates the given string. If C<@reply> is given, then a message of the
537	form C<@reply, $@, @evalres> is sent.
538
539	Example: crash another node.
540
541	snd $othernode, eval => "exit";
542
543	=item time => @reply
544
545	Replies the the current node time to C<@reply>.
546
547	Example: tell the current node to send the current time to C<$myport> in a
548	C<timereply> message.
549
550	snd $NODE, time => $myport, timereply => 1, 2;
551	# => snd $myport, timereply => 1, 2, <time>
552
553	=back
554
555	=head1 AnyEvent::MP vs. Distributed Erlang
556
557	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node
558	== aemp node, erlang process == aemp port), so many of the documents and
559	programming techniques employed by erlang apply to AnyEvent::MP. Here is a
560	sample:
561
562	http://www.erlang.se/doc/programming_rules.shtml
563	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
564	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6
565	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
566
567	Despite the similarities, there are also some important differences:
568
569	=over 4
570
571	=item * Node references contain the recipe on how to contact them.
572
573	Erlang relies on special naming and DNS to work everywhere in the	688	Erlang relies on special naming and DNS to work everywhere in the same
574	same way. AEMP relies on each node knowing it's own address(es), with	689	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
575	convenience functionality.	690	configuraiton or DNS), but will otherwise discover other odes itself.
576		691
577	This means that AEMP requires a less tightly controlled environment at the	692	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
578	cost of longer node references and a slightly higher management overhead.	693	uses "local ports are like remote ports".
		694
		695	The failure modes for local ports are quite different (runtime errors
		696	only) then for remote ports - when a local port dies, you I<know> it dies,
		697	when a connection to another node dies, you know nothing about the other
		698	port.
		699
		700	Erlang pretends remote ports are as reliable as local ports, even when
		701	they are not.
		702
		703	AEMP encourages a "treat remote ports differently" philosophy, with local
		704	ports being the special case/exception, where transport errors cannot
		705	occur.
579		706
580	=item * Erlang uses processes and a mailbox, AEMP does not queue.	707	=item * Erlang uses processes and a mailbox, AEMP does not queue.
581		708
582	Erlang uses processes that selctively receive messages, and therefore	709	Erlang uses processes that selectively receive messages, and therefore
583	needs a queue. AEMP is event based, queuing messages would serve no useful	710	needs a queue. AEMP is event based, queuing messages would serve no
584	purpose.	711	useful purpose. For the same reason the pattern-matching abilities of
		712	AnyEvent::MP are more limited, as there is little need to be able to
		713	filter messages without dequeing them.
585		714
586	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	715	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
587		716
588	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	717	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
589		718
590	Sending messages in erlang is synchronous and blocks the process. AEMP	719	Sending messages in Erlang is synchronous and blocks the process (and
591	sends are immediate, connection establishment is handled in the	720	so does not need a queue that can overflow). AEMP sends are immediate,
592	background.	721	connection establishment is handled in the background.
593		722
594	=item * Erlang can silently lose messages, AEMP cannot.	723	=item * Erlang suffers from silent message loss, AEMP does not.
595		724
596	Erlang makes few guarantees on messages delivery - messages can get lost	725	Erlang makes few guarantees on messages delivery - messages can get lost
597	without any of the processes realising it (i.e. you send messages a, b,	726	without any of the processes realising it (i.e. you send messages a, b,
598	and c, and the other side only receives messages a and c).	727	and c, and the other side only receives messages a and c).
599		728
600	AEMP guarantees correct ordering, and the guarantee that there are no	729	AEMP guarantees correct ordering, and the guarantee that after one message
601	holes in the message sequence.	730	is lost, all following ones sent to the same port are lost as well, until
602		731	monitoring raises an error, so there are no silent "holes" in the message
603	=item * In erlang, processes can be declared dead and later be found to be	732	sequence.
604	alive.
605
606	In erlang it can happen that a monitored process is declared dead and
607	linked processes get killed, but later it turns out that the process is
608	still alive - and can receive messages.
609
610	In AEMP, when port monitoring detects a port as dead, then that port will
611	eventually be killed - it cannot happen that a node detects a port as dead
612	and then later sends messages to it, finding it is still alive.
613		733
614	=item * Erlang can send messages to the wrong port, AEMP does not.	734	=item * Erlang can send messages to the wrong port, AEMP does not.
615		735
616	In erlang it is quite possible that a node that restarts reuses a process	736	In Erlang it is quite likely that a node that restarts reuses a process ID
617	ID known to other nodes for a completely different process, causing	737	known to other nodes for a completely different process, causing messages
618	messages destined for that process to end up in an unrelated process.	738	destined for that process to end up in an unrelated process.
619		739
620	AEMP never reuses port IDs, so old messages or old port IDs floating	740	AEMP never reuses port IDs, so old messages or old port IDs floating
621	around in the network will not be sent to an unrelated port.	741	around in the network will not be sent to an unrelated port.
622		742
623	=item * Erlang uses unprotected connections, AEMP uses secure	743	=item * Erlang uses unprotected connections, AEMP uses secure
624	authentication and can use TLS.	744	authentication and can use TLS.
625		745
626	AEMP can use a proven protocol - SSL/TLS - to protect connections and	746	AEMP can use a proven protocol - TLS - to protect connections and
627	securely authenticate nodes.	747	securely authenticate nodes.
628		748
629	=item * The AEMP protocol is optimised for both text-based and binary	749	=item * The AEMP protocol is optimised for both text-based and binary
630	communications.	750	communications.
631		751
632	The AEMP protocol, unlike the erlang protocol, supports both	752	The AEMP protocol, unlike the Erlang protocol, supports both programming
633	language-independent text-only protocols (good for debugging) and binary,	753	language independent text-only protocols (good for debugging) and binary,
634	language-specific serialisers (e.g. Storable).	754	language-specific serialisers (e.g. Storable). By default, unless TLS is
		755	used, the protocol is actually completely text-based.
635		756
636	It has also been carefully designed to be implementable in other languages	757	It has also been carefully designed to be implementable in other languages
637	with a minimum of work while gracefully degrading fucntionality to make the	758	with a minimum of work while gracefully degrading functionality to make the
638	protocol simple.	759	protocol simple.
639		760
		761	=item * AEMP has more flexible monitoring options than Erlang.
		762
		763	In Erlang, you can chose to receive I<all> exit signals as messages
		764	or I<none>, there is no in-between, so monitoring single processes is
		765	difficult to implement. Monitoring in AEMP is more flexible than in
		766	Erlang, as one can choose between automatic kill, exit message or callback
		767	on a per-process basis.
		768
		769	=item * Erlang tries to hide remote/local connections, AEMP does not.
		770
		771	Monitoring in Erlang is not an indicator of process death/crashes, in the
		772	same way as linking is (except linking is unreliable in Erlang).
		773
		774	In AEMP, you don't "look up" registered port names or send to named ports
		775	that might or might not be persistent. Instead, you normally spawn a port
		776	on the remote node. The init function monitors you, and you monitor the
		777	remote port. Since both monitors are local to the node, they are much more
		778	reliable (no need for C<spawn_link>).
		779
		780	This also saves round-trips and avoids sending messages to the wrong port
		781	(hard to do in Erlang).
		782
640	=back	783	=back
641		784
		785	=head1 RATIONALE
		786
		787	=over 4
		788
		789	=item Why strings for port and node IDs, why not objects?
		790
		791	We considered "objects", but found that the actual number of methods
		792	that can be called are quite low. Since port and node IDs travel over
		793	the network frequently, the serialising/deserialising would add lots of
		794	overhead, as well as having to keep a proxy object everywhere.
		795
		796	Strings can easily be printed, easily serialised etc. and need no special
		797	procedures to be "valid".
		798
		799	And as a result, a miniport consists of a single closure stored in a
		800	global hash - it can't become much cheaper.
		801
		802	=item Why favour JSON, why not a real serialising format such as Storable?
		803
		804	In fact, any AnyEvent::MP node will happily accept Storable as framing
		805	format, but currently there is no way to make a node use Storable by
		806	default (although all nodes will accept it).
		807
		808	The default framing protocol is JSON because a) JSON::XS is many times
		809	faster for small messages and b) most importantly, after years of
		810	experience we found that object serialisation is causing more problems
		811	than it solves: Just like function calls, objects simply do not travel
		812	easily over the network, mostly because they will always be a copy, so you
		813	always have to re-think your design.
		814
		815	Keeping your messages simple, concentrating on data structures rather than
		816	objects, will keep your messages clean, tidy and efficient.
		817
		818	=back
		819
642	=head1 SEE ALSO	820	=head1 SEE ALSO
		821
		822	L<AnyEvent::MP::Intro> - a gentle introduction.
		823
		824	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		825
		826	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		827	your applications.
643		828
644	L<AnyEvent>.	829	L<AnyEvent>.
645		830
646	=head1 AUTHOR	831	=head1 AUTHOR
647		832

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.29 by root, Tue Aug 4 23:16:57 2009 UTC vs. Revision 1.70 by root, Sun Aug 30 19:49:47 2009 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.29 by root, Tue Aug 4 23:16:57 2009 UTC vs.
Revision 1.70 by root, Sun Aug 30 19:49:47 2009 UTC