[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 1.70 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		44	AnyEvent::MP::Intro - outdated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 its 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 initialise_node	144	initialise_node
109	snd rcv mon kil reg psub	145	snd rcv mon mon_guard kil reg psub spawn
110	port	146	port
111	);	147	);
112		148
113	our $SELF;	149	our $SELF;
114		150
…		…
118	kil $SELF, die => $msg;	154	kil $SELF, die => $msg;
119	}	155	}
120		156
121	=item $thisnode = NODE / $NODE	157	=item $thisnode = NODE / $NODE
122		158
123	The C<NODE> function returns, and the C<$NODE> variable contains	159	The C<NODE> function returns, and the C<$NODE> variable contains, the node
124	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
125	to C<become_public> or C<become_slave>, after which all local port	161	a call to C<initialise_node>.
126	identifiers become invalid.
127		162
128	=item $noderef = node_of $portid	163	=item $nodeid = node_of $port
129		164
130	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.
131		166
132	=item $cv = resolve_node $noderef	167	=item initialise_node $profile_name, key => value...
133		168
134	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
135	abbreviated IDs, resolves all of them and returns a resolved node	170	"distributed mode") it has to initialise itself - the minimum a node needs
136	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.
137		173
138	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
139	following forms are supported:	175	never) before calling other AnyEvent::MP functions.
140		176
141	=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>).
142		179
143	=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:
144		182
145	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
146	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.
147		189
148	=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.
149		193
150	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
151	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).
152		199
153	=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.
154		202
155	These are resolved by using AnyEvent::DNS to resolve them, optionally	203	Lastly, the seeds list from the profile is passed to the
156	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
157	specified.	205	connectivity with at least on of those seed nodes at any point in time.
158		206
159	=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";
160		223
161	=item $SELF	224	=item $SELF
162		225
163	Contains the current port id while executing C<rcv> callbacks or C<psub>	226	Contains the current port id while executing C<rcv> callbacks or C<psub>
164	blocks.	227	blocks.
165		228
166	=item SELF, %SELF, @SELF...	229	=item *SELF, SELF, %SELF, @SELF...
167		230
168	Due to some quirks in how perl exports variables, it is impossible to	231	Due to some quirks in how perl exports variables, it is impossible to
169	just export C<$SELF>, all the symbols called C<SELF> are exported by this	232	just export C<$SELF>, all the symbols named C<SELF> are exported by this
170	module, but only C<$SELF> is currently used.	233	module, but only C<$SELF> is currently used.
171		234
172	=item snd $portid, type => @data	235	=item snd $port, type => @data
173		236
174	=item snd $portid, @msg	237	=item snd $port, @msg
175		238
176	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
177	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.
178	stringifies a sa port ID (such as a port object :).
179		241
180	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
181	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
182	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.
183		246
184	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
185	function: modifying any argument is not allowed and can cause many	248	function: modifying any argument (or values referenced by them) is
186	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.
187		253
188	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
189	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
190	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
191	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
192	node, anything can be passed.	258	node, anything can be passed. Best rely only on the common denominator of
		259	these.
193		260
194	=item kil $portid[, @reason]	261	=item $local_port = port
195		262
196	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.
197		265
198	If no C<@reason> is specified, then the port is killed "normally" (linked	266	=item $local_port = port { my @msg = @_ }
199	ports will not be kileld, or even notified).
200		267
201	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
202	C<mon>, see below).	269	creating a port and calling C<rcv $port, $callback> on it.
203		270
204	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
205	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.
206		275
207	Transport/communication errors are reported as C<< transport_error =>	276	If you want to stop/destroy the port, simply C<kil> it:
208	$message >>.
209		277
210	=item $guard = mon $portid, $cb->(@reason)	278	my $port = port {
		279	my @msg = @_;
		280	...
		281	kil $SELF;
		282	};
211		283
212	=item $guard = mon $portid, $otherport	284	=cut
213		285
214	=item $guard = mon $portid, $otherport, @msg	286	sub rcv($@);
215		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 $port dies
		452
216	Monitor the given port and do something when the port is killed.	453	Monitor the given port and do something when the port is killed or
		454	messages to it were lost, and optionally return a guard that can be used
		455	to stop monitoring again.
217		456
		457	C<mon> effectively guarantees that, in the absence of hardware failures,
		458	after starting the monitor, either all messages sent to the port will
		459	arrive, or the monitoring action will be invoked after possible message
		460	loss has been detected. No messages will be lost "in between" (after
		461	the first lost message no further messages will be received by the
		462	port). After the monitoring action was invoked, further messages might get
		463	delivered again.
		464
		465	Note that monitoring-actions are one-shot: once messages are lost (and a
		466	monitoring alert was raised), they are removed and will not trigger again.
		467
218	In the first form, the callback is simply called with any number	468	In the first form (callback), the callback is simply called with any
219	of C<@reason> elements (no @reason means that the port was deleted	469	number of C<@reason> elements (no @reason means that the port was deleted
220	"normally"). Note also that I<< the callback B<must> never die >>, so use	470	"normally"). Note also that I<< the callback B<must> never die >>, so use
221	C<eval> if unsure.	471	C<eval> if unsure.
222		472
223	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	473	In the second form (another port given), the other port (C<$rcvport>)
224	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
225	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.
226		477
		478	The third form (kill self) is the same as the second form, except that
		479	C<$rvport> defaults to C<$SELF>.
		480
227	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.
228		490
229	Example: call a given callback when C<$port> is killed.	491	Example: call a given callback when C<$port> is killed.
230		492
231	mon $port, sub { warn "port died because of <@_>\n" };	493	mon $port, sub { warn "port died because of <@_>\n" };
232		494
233	Example: kill ourselves when C<$port> is killed abnormally.	495	Example: kill ourselves when C<$port> is killed abnormally.
234		496
235	mon $port, $self;	497	mon $port;
236		498
237	Example: send us a restart message another C<$port> is killed.	499	Example: send us a restart message when another C<$port> is killed.
238		500
239	mon $port, $self => "restart";	501	mon $port, $self => "restart";
240		502
241	=cut	503	=cut
242		504
243	sub mon {	505	sub mon {
244	my ($noderef, $port) = split /#/, shift, 2;	506	my ($noderef, $port) = split /#/, shift, 2;
245		507
246	my $node = $NODE{$noderef} \|\| add_node $noderef;	508	my $node = $NODE{$noderef} \|\| add_node $noderef;
247		509
248	my $cb = shift;	510	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
249		511
250	unless (ref $cb) {	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, @_);
…		…
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 can be used either as a pattern	570	Transport/communication errors are reported as C<< transport_error =>
305	matching port ("full port") or a single-callback port ("miniport"),	571	$message >>.
306	depending on how C<rcv> callbacks are bound to the object.
307		572
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	573	=cut
327		574
328	sub port(;&) {	575	=item $port = spawn $node, $initfunc[, @initdata]
329	my $id = "$UNIQ." . $ID++;
330	my $port = "$NODE#$id";
331		576
332	if (@_) {	577	Creates a port on the node C<$node> (which can also be a port ID, in which
333	my $cb = shift;	578	case it's the node where that port resides).
334	$PORT{$id} = sub {	579
335	local $SELF = $port;	580	The port ID of the newly created port is returned immediately, and it is
336	eval {	581	possible to immediately start sending messages or to monitor the port.
337	&$cb	582
338	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 {
339	};	614	...
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	};	615	};
371	}	616	}
372		617
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	618	=cut
386		619
387	sub reg(@) {	620	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;	621	my $port = shift;
431	my ($noderef, $port) = split /#/, $port, 2;	622	my $init = shift;
432		623
433	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	624	local $SELF = "$NODE#$port";
434	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";	625	eval {
435		626	&{ 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	};	627	};
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 $@;	628	_self_die if $@;
489	@res	629	}
490	} else {	630
491	my $res = eval { &$cb };	631	sub spawn(@) {
492	_self_die if $@;	632	my ($noderef, undef) = split /#/, shift, 2;
493	$res	633
494	}	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;
495	}	665	};
496	}	666	}
497		667
498	=back	668	=back
499		669
500	=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:
501		683
502	=over 4	684	=over 4
503		685
504	=item become_public $noderef	686	=item * Node IDs are arbitrary strings in AEMP.
505		687
506	Tells the node to become a public node, i.e. reachable from other nodes.
507
508	The first argument is the (unresolved) node reference of the local node
509	(if missing then the empty string is used).
510
511	It is quite common to not specify anything, in which case the local node
512	tries to listen on the default port, or to only specify a port number, in
513	which case AnyEvent::MP tries to guess the local addresses.
514
515	=cut
516
517	=back
518
519	=head1 NODE MESSAGES
520
521	Nodes understand the following messages sent to them. Many of them take
522	arguments called C<@reply>, which will simply be used to compose a reply
523	message - C<$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	688	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	689	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
585	convenience functionality.	690	configuraiton or DNS), but will otherwise discover other odes itself.
586		691
587	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
588	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.
589		706
590	=item * Erlang uses processes and a mailbox, AEMP does not queue.	707	=item * Erlang uses processes and a mailbox, AEMP does not queue.
591		708
592	Erlang uses processes that selctively receive messages, and therefore	709	Erlang uses processes that selectively receive messages, and therefore
593	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
594	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.
595		714
596	(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).
597		716
598	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	717	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
599		718
600	Sending messages in erlang is synchronous and blocks the process. AEMP	719	Sending messages in Erlang is synchronous and blocks the process (and
601	sends are immediate, connection establishment is handled in the	720	so does not need a queue that can overflow). AEMP sends are immediate,
602	background.	721	connection establishment is handled in the background.
603		722
604	=item * Erlang can silently lose messages, AEMP cannot.	723	=item * Erlang suffers from silent message loss, AEMP does not.
605		724
606	Erlang makes few guarantees on messages delivery - messages can get lost	725	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,	726	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).	727	and c, and the other side only receives messages a and c).
609		728
610	AEMP guarantees correct ordering, and the guarantee that there are no	729	AEMP guarantees correct ordering, and the guarantee that after one message
611	holes in the message sequence.	730	is lost, all following ones sent to the same port are lost as well, until
612		731	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	732	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		733
624	=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.
625		735
626	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
627	ID known to other nodes for a completely different process, causing	737	known to other nodes for a completely different process, causing messages
628	messages destined for that process to end up in an unrelated process.	738	destined for that process to end up in an unrelated process.
629		739
630	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
631	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.
632		742
633	=item * Erlang uses unprotected connections, AEMP uses secure	743	=item * Erlang uses unprotected connections, AEMP uses secure
634	authentication and can use TLS.	744	authentication and can use TLS.
635		745
636	AEMP can use a proven protocol - SSL/TLS - to protect connections and	746	AEMP can use a proven protocol - TLS - to protect connections and
637	securely authenticate nodes.	747	securely authenticate nodes.
638		748
639	=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
640	communications.	750	communications.
641		751
642	The AEMP protocol, unlike the erlang protocol, supports both	752	The AEMP protocol, unlike the Erlang protocol, supports both programming
643	language-independent text-only protocols (good for debugging) and binary,	753	language independent text-only protocols (good for debugging) and binary,
644	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.
645		756
646	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
647	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
648	protocol simple.	759	protocol simple.
649		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
650	=back	783	=back
651		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
652	=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.
653		828
654	L<AnyEvent>.	829	L<AnyEvent>.
655		830
656	=head1 AUTHOR	831	=head1 AUTHOR
657		832

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.31 by root, Wed Aug 5 19:55:58 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 1.31 by root, Wed Aug 5 19:55:58 2009 UTC vs.
Revision 1.70 by root, Sun Aug 30 19:49:47 2009 UTC