[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 1.69 by root, Sun Aug 30 18:51:49 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		44	AnyEvent::MP::Intro - outdated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 will be used. Then they will be
147	specified.	184	overwritten by any values specified in the global default configuration
		185	(see the F<aemp> utility), then the chain of profiles selected, if
		186	any. That means that the values specified in the profile have highest
		187	priority and the values specified via C<initialise_node> have lowest
		188	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 the node ID will be
		201	treated as if it were of the form C<host:port>, which will be resolved and
		202	used as binds list.
155		203
156	These are resolved by using AnyEvent::DNS to resolve them, optionally	204	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	205	L<AnyEvent::MP::Global> module, which will then use it to keep
158	specified.	206	connectivity with at least on of those seed nodes at any point in time.
159		207
160	=back	208	Example: become a distributed node listening on the guessed noderef, or
		209	the one specified via C<aemp> for the current node. This should be the
		210	most common form of invocation for "daemon"-type nodes.
		211
		212	initialise_node;
		213
		214	Example: become an anonymous node. This form is often used for commandline
		215	clients.
		216
		217	initialise_node "anon/";
		218
		219	Example: become a distributed node. If there is no profile of the given
		220	name, or no binds list was specified, resolve C<localhost:4044> and bind
		221	on the resulting addresses.
		222
		223	initialise_node "localhost:4044";
161		224
162	=item $SELF	225	=item $SELF
163		226
164	Contains the current port id while executing C<rcv> callbacks or C<psub>	227	Contains the current port id while executing C<rcv> callbacks or C<psub>
165	blocks.	228	blocks.
166		229
167	=item SELF, %SELF, @SELF...	230	=item *SELF, SELF, %SELF, @SELF...
168		231
169	Due to some quirks in how perl exports variables, it is impossible to	232	Due to some quirks in how perl exports variables, it is impossible to
170	just export C<$SELF>, all the symbols called C<SELF> are exported by this	233	just export C<$SELF>, all the symbols named C<SELF> are exported by this
171	module, but only C<$SELF> is currently used.	234	module, but only C<$SELF> is currently used.
172		235
173	=item snd $portid, type => @data	236	=item snd $port, type => @data
174		237
175	=item snd $portid, @msg	238	=item snd $port, @msg
176		239
177	Send the given message to the given port ID, which can identify either	240	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	241	local or a remote port, and must be a port ID.
179	stringifies a sa port ID (such as a port object :).
180		242
181	While the message can be about anything, it is highly recommended to use a	243	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	244	use a string as first element (a port ID, or some word that indicates a
183	type etc.).	245	request type etc.) and to consist if only simple perl values (scalars,
		246	arrays, hashes) - if you think you need to pass an object, think again.
184		247
185	The message data effectively becomes read-only after a call to this	248	The message data logically becomes read-only after a call to this
186	function: modifying any argument is not allowed and can cause many	249	function: modifying any argument (or values referenced by them) is
187	problems.	250	forbidden, as there can be considerable time between the call to C<snd>
		251	and the time the message is actually being serialised - in fact, it might
		252	never be copied as within the same process it is simply handed to the
		253	receiving port.
188		254
189	The type of data you can transfer depends on the transport protocol: when	255	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	256	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	257	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	258	that Storable can serialise and deserialise is allowed, and for the local
193	node, anything can be passed.	259	node, anything can be passed. Best rely only on the common denominator of
		260	these.
194		261
195	=item kil $portid[, @reason]	262	=item $local_port = port
196		263
197	Kill the specified port with the given C<@reason>.	264	Create a new local port object and returns its port ID. Initially it has
		265	no callbacks set and will throw an error when it receives messages.
198		266
199	If no C<@reason> is specified, then the port is killed "normally" (linked	267	=item $local_port = port { my @msg = @_ }
200	ports will not be kileld, or even notified).
201		268
202	Otherwise, linked ports get killed with the same reason (second form of	269	Creates a new local port, and returns its ID. Semantically the same as
203	C<mon>, see below).	270	creating a port and calling C<rcv $port, $callback> on it.
204		271
205	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	272	The block will be called for every message received on the port, with the
206	will be reported as reason C<< die => $@ >>.	273	global variable C<$SELF> set to the port ID. Runtime errors will cause the
		274	port to be C<kil>ed. The message will be passed as-is, no extra argument
		275	(i.e. no port ID) will be passed to the callback.
207		276
208	Transport/communication errors are reported as C<< transport_error =>	277	If you want to stop/destroy the port, simply C<kil> it:
209	$message >>.
210		278
211	=item $guard = mon $portid, $cb->(@reason)	279	my $port = port {
		280	my @msg = @_;
		281	...
		282	kil $SELF;
		283	};
212		284
213	=item $guard = mon $portid, $otherport	285	=cut
214		286
215	=item $guard = mon $portid, $otherport, @msg	287	sub rcv($@);
216		288
		289	sub _kilme {
		290	die "received message on port without callback";
		291	}
		292
		293	sub port(;&) {
		294	my $id = "$UNIQ." . $ID++;
		295	my $port = "$NODE#$id";
		296
		297	rcv $port, shift \|\| \&_kilme;
		298
		299	$port
		300	}
		301
		302	=item rcv $local_port, $callback->(@msg)
		303
		304	Replaces the default callback on the specified port. There is no way to
		305	remove the default callback: use C<sub { }> to disable it, or better
		306	C<kil> the port when it is no longer needed.
		307
		308	The global C<$SELF> (exported by this module) contains C<$port> while
		309	executing the callback. Runtime errors during callback execution will
		310	result in the port being C<kil>ed.
		311
		312	The default callback received all messages not matched by a more specific
		313	C<tag> match.
		314
		315	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
		316
		317	Register (or replace) callbacks to be called on messages starting with the
		318	given tag on the given port (and return the port), or unregister it (when
		319	C<$callback> is C<$undef> or missing). There can only be one callback
		320	registered for each tag.
		321
		322	The original message will be passed to the callback, after the first
		323	element (the tag) has been removed. The callback will use the same
		324	environment as the default callback (see above).
		325
		326	Example: create a port and bind receivers on it in one go.
		327
		328	my $port = rcv port,
		329	msg1 => sub { ... },
		330	msg2 => sub { ... },
		331	;
		332
		333	Example: create a port, bind receivers and send it in a message elsewhere
		334	in one go:
		335
		336	snd $otherport, reply =>
		337	rcv port,
		338	msg1 => sub { ... },
		339	...
		340	;
		341
		342	Example: temporarily register a rcv callback for a tag matching some port
		343	(e.g. for a rpc reply) and unregister it after a message was received.
		344
		345	rcv $port, $otherport => sub {
		346	my @reply = @_;
		347
		348	rcv $SELF, $otherport;
		349	};
		350
		351	=cut
		352
		353	sub rcv($@) {
		354	my $port = shift;
		355	my ($noderef, $portid) = split /#/, $port, 2;
		356
		357	$NODE{$noderef} == $NODE{""}
		358	or Carp::croak "$port: rcv can only be called on local ports, caught";
		359
		360	while (@_) {
		361	if (ref $_[0]) {
		362	if (my $self = $PORT_DATA{$portid}) {
		363	"AnyEvent::MP::Port" eq ref $self
		364	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		365
		366	$self->[2] = shift;
		367	} else {
		368	my $cb = shift;
		369	$PORT{$portid} = sub {
		370	local $SELF = $port;
		371	eval { &$cb }; _self_die if $@;
		372	};
		373	}
		374	} elsif (defined $_[0]) {
		375	my $self = $PORT_DATA{$portid} \|\|= do {
		376	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
		377
		378	$PORT{$portid} = sub {
		379	local $SELF = $port;
		380
		381	if (my $cb = $self->[1]{$_[0]}) {
		382	shift;
		383	eval { &$cb }; _self_die if $@;
		384	} else {
		385	&{ $self->[0] };
		386	}
		387	};
		388
		389	$self
		390	};
		391
		392	"AnyEvent::MP::Port" eq ref $self
		393	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		394
		395	my ($tag, $cb) = splice @_, 0, 2;
		396
		397	if (defined $cb) {
		398	$self->[1]{$tag} = $cb;
		399	} else {
		400	delete $self->[1]{$tag};
		401	}
		402	}
		403	}
		404
		405	$port
		406	}
		407
		408	=item $closure = psub { BLOCK }
		409
		410	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
		411	closure is executed, sets up the environment in the same way as in C<rcv>
		412	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		413
		414	This is useful when you register callbacks from C<rcv> callbacks:
		415
		416	rcv delayed_reply => sub {
		417	my ($delay, @reply) = @_;
		418	my $timer = AE::timer $delay, 0, psub {
		419	snd @reply, $SELF;
		420	};
		421	};
		422
		423	=cut
		424
		425	sub psub(&) {
		426	my $cb = shift;
		427
		428	my $port = $SELF
		429	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
		430
		431	sub {
		432	local $SELF = $port;
		433
		434	if (wantarray) {
		435	my @res = eval { &$cb };
		436	_self_die if $@;
		437	@res
		438	} else {
		439	my $res = eval { &$cb };
		440	_self_die if $@;
		441	$res
		442	}
		443	}
		444	}
		445
		446	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
		447
		448	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
		449
		450	=item $guard = mon $port # kill $SELF when $port dies
		451
		452	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
		453
217	Monitor the given port and do something when the port is killed.	454	Monitor the given port and do something when the port is killed or
		455	messages to it were lost, and optionally return a guard that can be used
		456	to stop monitoring again.
218		457
		458	C<mon> effectively guarantees that, in the absence of hardware failures,
		459	after starting the monitor, either all messages sent to the port will
		460	arrive, or the monitoring action will be invoked after possible message
		461	loss has been detected. No messages will be lost "in between" (after
		462	the first lost message no further messages will be received by the
		463	port). After the monitoring action was invoked, further messages might get
		464	delivered again.
		465
		466	Note that monitoring-actions are one-shot: once messages are lost (and a
		467	monitoring alert was raised), they are removed and will not trigger again.
		468
219	In the first form, the callback is simply called with any number	469	In the first form (callback), the callback is simply called with any
220	of C<@reason> elements (no @reason means that the port was deleted	470	number of C<@reason> elements (no @reason means that the port was deleted
221	"normally"). Note also that I<< the callback B<must> never die >>, so use	471	"normally"). Note also that I<< the callback B<must> never die >>, so use
222	C<eval> if unsure.	472	C<eval> if unsure.
223		473
224	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	474	In the second form (another port given), the other port (C<$rcvport>)
225	a @reason was specified, i.e. on "normal" kils nothing happens, while	475	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.	476	"normal" kils nothing happens, while under all other conditions, the other
		477	port is killed with the same reason.
227		478
		479	The third form (kill self) is the same as the second form, except that
		480	C<$rvport> defaults to C<$SELF>.
		481
228	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	482	In the last form (message), a message of the form C<@msg, @reason> will be
		483	C<snd>.
		484
		485	As a rule of thumb, monitoring requests should always monitor a port from
		486	a local port (or callback). The reason is that kill messages might get
		487	lost, just like any other message. Another less obvious reason is that
		488	even monitoring requests can get lost (for exmaple, when the connection
		489	to the other node goes down permanently). When monitoring a port locally
		490	these problems do not exist.
229		491
230	Example: call a given callback when C<$port> is killed.	492	Example: call a given callback when C<$port> is killed.
231		493
232	mon $port, sub { warn "port died because of <@_>\n" };	494	mon $port, sub { warn "port died because of <@_>\n" };
233		495
234	Example: kill ourselves when C<$port> is killed abnormally.	496	Example: kill ourselves when C<$port> is killed abnormally.
235		497
236	mon $port, $self;	498	mon $port;
237		499
238	Example: send us a restart message another C<$port> is killed.	500	Example: send us a restart message when another C<$port> is killed.
239		501
240	mon $port, $self => "restart";	502	mon $port, $self => "restart";
241		503
242	=cut	504	=cut
243		505
244	sub mon {	506	sub mon {
245	my ($noderef, $port, $cb) = ((split /#/, shift, 2), shift);	507	my ($noderef, $port) = split /#/, shift, 2;
246		508
247	my $node = $NODE{$noderef} \|\| add_node $noderef;	509	my $node = $NODE{$noderef} \|\| add_node $noderef;
248		510
249	#TODO: ports must not be references	511	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) {	512
		513	unless (ref $cb) {
251	if (@_) {	514	if (@_) {
252	# send a kill info message	515	# send a kill info message
253	my (@msg) = ($cb, @_);	516	my (@msg) = ($cb, @_);
254	$cb = sub { snd @msg, @_ };	517	$cb = sub { snd @msg, @_ };
255	} else {	518	} else {
…		…
271	is killed, the references will be freed.	534	is killed, the references will be freed.
272		535
273	Optionally returns a guard that will stop the monitoring.	536	Optionally returns a guard that will stop the monitoring.
274		537
275	This function is useful when you create e.g. timers or other watchers and	538	This function is useful when you create e.g. timers or other watchers and
276	want to free them when the port gets killed:	539	want to free them when the port gets killed (note the use of C<psub>):
277		540
278	$port->rcv (start => sub {	541	$port->rcv (start => sub {
279	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	542	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
280	undef $timer if 0.9 < rand;	543	undef $timer if 0.9 < rand;
281	});	544	});
282	});	545	});
283		546
284	=cut	547	=cut
285		548
286	sub mon_guard {	549	sub mon_guard {
287	my ($port, @refs) = @_;	550	my ($port, @refs) = @_;
288		551
		552	#TODO: mon-less form?
		553
289	mon $port, sub { 0 && @refs }	554	mon $port, sub { 0 && @refs }
290	}	555	}
291		556
292	=item lnk $port1, $port2	557	=item kil $port[, @reason]
293		558
294	Link two ports. This is simply a shorthand for:	559	Kill the specified port with the given C<@reason>.
295		560
296	mon $port1, $port2;	561	If no C<@reason> is specified, then the port is killed "normally" (ports
297	mon $port2, $port1;	562	monitoring other ports will not necessarily die because a port dies
		563	"normally").
298		564
299	It means that if either one is killed abnormally, the other one gets	565	Otherwise, linked ports get killed with the same reason (second form of
300	killed as well.	566	C<mon>, see above).
301		567
302	=item $local_port = port	568	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		569	will be reported as reason C<< die => $@ >>.
303		570
304	Create a new local port object that supports message matching.	571	Transport/communication errors are reported as C<< transport_error =>
		572	$message >>.
305		573
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	574	=cut
325		575
326	sub port(;&) {	576	=item $port = spawn $node, $initfunc[, @initdata]
327	my $id = "$UNIQ." . $ID++;
328	my $port = "$NODE#$id";
329		577
330	if (@_) {	578	Creates a port on the node C<$node> (which can also be a port ID, in which
331	my $cb = shift;	579	case it's the node where that port resides).
332	$PORT{$id} = sub {	580
333	local $SELF = $port;	581	The port ID of the newly created port is returned immediately, and it is
334	eval {	582	possible to immediately start sending messages or to monitor the port.
335	&$cb	583
336	and kil $id;	584	After the port has been created, the init function is called on the remote
		585	node, in the same context as a C<rcv> callback. This function must be a
		586	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
		587	specify a function in the main program, use C<::name>.
		588
		589	If the function doesn't exist, then the node tries to C<require>
		590	the package, then the package above the package and so on (e.g.
		591	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		592	exists or it runs out of package names.
		593
		594	The init function is then called with the newly-created port as context
		595	object (C<$SELF>) and the C<@initdata> values as arguments.
		596
		597	A common idiom is to pass a local port, immediately monitor the spawned
		598	port, and in the remote init function, immediately monitor the passed
		599	local port. This two-way monitoring ensures that both ports get cleaned up
		600	when there is a problem.
		601
		602	Example: spawn a chat server port on C<$othernode>.
		603
		604	# this node, executed from within a port context:
		605	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		606	mon $server;
		607
		608	# init function on C<$othernode>
		609	sub connect {
		610	my ($srcport) = @_;
		611
		612	mon $srcport;
		613
		614	rcv $SELF, sub {
337	};	615	...
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	};	616	};
369	}	617	}
370		618
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	619	=cut
384		620
385	sub reg(@) {	621	sub _spawn {
386	my ($portid, $name) = @_;	622	my $port = shift;
		623	my $init = shift;
387		624
388	$REG{$name} = $portid;	625	local $SELF = "$NODE#$port";
389	}	626	eval {
390		627	&{ 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	};	628	};
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 $@;	629	_self_die if $@;
479	@res	630	}
480	} else {	631
481	my $res = eval { &$cb };	632	sub spawn(@) {
482	_self_die if $@;	633	my ($noderef, undef) = split /#/, shift, 2;
483	$res	634
484	}	635	my $id = "$RUNIQ." . $ID++;
		636
		637	$_[0] =~ /::/
		638	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		639
		640	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
		641
		642	"$noderef#$id"
		643	}
		644
		645	=item after $timeout, @msg
		646
		647	=item after $timeout, $callback
		648
		649	Either sends the given message, or call the given callback, after the
		650	specified number of seconds.
		651
		652	This is simply a utility function that comes in handy at times - the
		653	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		654	so it may go away in the future.
		655
		656	=cut
		657
		658	sub after($@) {
		659	my ($timeout, @action) = @_;
		660
		661	my $t; $t = AE::timer $timeout, 0, sub {
		662	undef $t;
		663	ref $action[0]
		664	? $action[0]()
		665	: snd @action;
485	}	666	};
486	}	667	}
487		668
488	=back	669	=back
489		670
490	=head1 FUNCTIONS FOR NODES	671	=head1 AnyEvent::MP vs. Distributed Erlang
		672
		673	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
		674	== aemp node, Erlang process == aemp port), so many of the documents and
		675	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		676	sample:
		677
		678	http://www.Erlang.se/doc/programming_rules.shtml
		679	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		680	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		681	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		682
		683	Despite the similarities, there are also some important differences:
491		684
492	=over 4	685	=over 4
493		686
494	=item become_public $noderef	687	=item * Node IDs are arbitrary strings in AEMP.
495		688
496	Tells the node to become a public node, i.e. reachable from other nodes.
497
498	The first argument is the (unresolved) node reference of the local node
499	(if missing then the empty string is used).
500
501	It is quite common to not specify anything, in which case the local node
502	tries to listen on the default port, or to only specify a port number, in
503	which case AnyEvent::MP tries to guess the local addresses.
504
505	=cut
506
507	=back
508
509	=head1 NODE MESSAGES
510
511	Nodes understand the following messages sent to them. Many of them take
512	arguments called C<@reply>, which will simply be used to compose a reply
513	message - C<$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	689	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	690	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
575	convenience functionality.	691	configuraiton or DNS), but will otherwise discover other odes itself.
576		692
577	This means that AEMP requires a less tightly controlled environment at the	693	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
578	cost of longer node references and a slightly higher management overhead.	694	uses "local ports are like remote ports".
		695
		696	The failure modes for local ports are quite different (runtime errors
		697	only) then for remote ports - when a local port dies, you I<know> it dies,
		698	when a connection to another node dies, you know nothing about the other
		699	port.
		700
		701	Erlang pretends remote ports are as reliable as local ports, even when
		702	they are not.
		703
		704	AEMP encourages a "treat remote ports differently" philosophy, with local
		705	ports being the special case/exception, where transport errors cannot
		706	occur.
579		707
580	=item * Erlang uses processes and a mailbox, AEMP does not queue.	708	=item * Erlang uses processes and a mailbox, AEMP does not queue.
581		709
582	Erlang uses processes that selctively receive messages, and therefore	710	Erlang uses processes that selectively receive messages, and therefore
583	needs a queue. AEMP is event based, queuing messages would serve no useful	711	needs a queue. AEMP is event based, queuing messages would serve no
584	purpose.	712	useful purpose. For the same reason the pattern-matching abilities of
		713	AnyEvent::MP are more limited, as there is little need to be able to
		714	filter messages without dequeing them.
585		715
586	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	716	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
587		717
588	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	718	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
589		719
590	Sending messages in erlang is synchronous and blocks the process. AEMP	720	Sending messages in Erlang is synchronous and blocks the process (and
591	sends are immediate, connection establishment is handled in the	721	so does not need a queue that can overflow). AEMP sends are immediate,
592	background.	722	connection establishment is handled in the background.
593		723
594	=item * Erlang can silently lose messages, AEMP cannot.	724	=item * Erlang suffers from silent message loss, AEMP does not.
595		725
596	Erlang makes few guarantees on messages delivery - messages can get lost	726	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,	727	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).	728	and c, and the other side only receives messages a and c).
599		729
600	AEMP guarantees correct ordering, and the guarantee that there are no	730	AEMP guarantees correct ordering, and the guarantee that after one message
601	holes in the message sequence.	731	is lost, all following ones sent to the same port are lost as well, until
602		732	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	733	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		734
614	=item * Erlang can send messages to the wrong port, AEMP does not.	735	=item * Erlang can send messages to the wrong port, AEMP does not.
615		736
616	In erlang it is quite possible that a node that restarts reuses a process	737	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	738	known to other nodes for a completely different process, causing messages
618	messages destined for that process to end up in an unrelated process.	739	destined for that process to end up in an unrelated process.
619		740
620	AEMP never reuses port IDs, so old messages or old port IDs floating	741	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.	742	around in the network will not be sent to an unrelated port.
622		743
623	=item * Erlang uses unprotected connections, AEMP uses secure	744	=item * Erlang uses unprotected connections, AEMP uses secure
624	authentication and can use TLS.	745	authentication and can use TLS.
625		746
626	AEMP can use a proven protocol - SSL/TLS - to protect connections and	747	AEMP can use a proven protocol - TLS - to protect connections and
627	securely authenticate nodes.	748	securely authenticate nodes.
628		749
629	=item * The AEMP protocol is optimised for both text-based and binary	750	=item * The AEMP protocol is optimised for both text-based and binary
630	communications.	751	communications.
631		752
632	The AEMP protocol, unlike the erlang protocol, supports both	753	The AEMP protocol, unlike the Erlang protocol, supports both programming
633	language-independent text-only protocols (good for debugging) and binary,	754	language independent text-only protocols (good for debugging) and binary,
634	language-specific serialisers (e.g. Storable).	755	language-specific serialisers (e.g. Storable). By default, unless TLS is
		756	used, the protocol is actually completely text-based.
635		757
636	It has also been carefully designed to be implementable in other languages	758	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	759	with a minimum of work while gracefully degrading functionality to make the
638	protocol simple.	760	protocol simple.
639		761
		762	=item * AEMP has more flexible monitoring options than Erlang.
		763
		764	In Erlang, you can chose to receive I<all> exit signals as messages
		765	or I<none>, there is no in-between, so monitoring single processes is
		766	difficult to implement. Monitoring in AEMP is more flexible than in
		767	Erlang, as one can choose between automatic kill, exit message or callback
		768	on a per-process basis.
		769
		770	=item * Erlang tries to hide remote/local connections, AEMP does not.
		771
		772	Monitoring in Erlang is not an indicator of process death/crashes, in the
		773	same way as linking is (except linking is unreliable in Erlang).
		774
		775	In AEMP, you don't "look up" registered port names or send to named ports
		776	that might or might not be persistent. Instead, you normally spawn a port
		777	on the remote node. The init function monitors you, and you monitor the
		778	remote port. Since both monitors are local to the node, they are much more
		779	reliable (no need for C<spawn_link>).
		780
		781	This also saves round-trips and avoids sending messages to the wrong port
		782	(hard to do in Erlang).
		783
640	=back	784	=back
641		785
		786	=head1 RATIONALE
		787
		788	=over 4
		789
		790	=item Why strings for port and node IDs, why not objects?
		791
		792	We considered "objects", but found that the actual number of methods
		793	that can be called are quite low. Since port and node IDs travel over
		794	the network frequently, the serialising/deserialising would add lots of
		795	overhead, as well as having to keep a proxy object everywhere.
		796
		797	Strings can easily be printed, easily serialised etc. and need no special
		798	procedures to be "valid".
		799
		800	And as a result, a miniport consists of a single closure stored in a
		801	global hash - it can't become much cheaper.
		802
		803	=item Why favour JSON, why not a real serialising format such as Storable?
		804
		805	In fact, any AnyEvent::MP node will happily accept Storable as framing
		806	format, but currently there is no way to make a node use Storable by
		807	default (although all nodes will accept it).
		808
		809	The default framing protocol is JSON because a) JSON::XS is many times
		810	faster for small messages and b) most importantly, after years of
		811	experience we found that object serialisation is causing more problems
		812	than it solves: Just like function calls, objects simply do not travel
		813	easily over the network, mostly because they will always be a copy, so you
		814	always have to re-think your design.
		815
		816	Keeping your messages simple, concentrating on data structures rather than
		817	objects, will keep your messages clean, tidy and efficient.
		818
		819	=back
		820
642	=head1 SEE ALSO	821	=head1 SEE ALSO
		822
		823	L<AnyEvent::MP::Intro> - a gentle introduction.
		824
		825	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		826
		827	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		828	your applications.
643		829
644	L<AnyEvent>.	830	L<AnyEvent>.
645		831
646	=head1 AUTHOR	832	=head1 AUTHOR
647		833

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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 1.69 by root, Sun Aug 30 18:51:49 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 1.69 by root, Sun Aug 30 18:51:49 2009 UTC