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

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use AnyEvent::MP;	7	use AnyEvent::MP;
8		8
9	$NODE # contains this node's noderef	9	$NODE # contains this node's node ID
10	NODE # returns this node's noderef	10	NODE # returns this node's node ID
11	NODE $port # returns the noderef of the port
12		11
		12	$SELF # receiving/own port id in rcv callbacks
		13
		14	# initialise the node so it can send/receive messages
		15	configure;
		16
		17	# ports are message destinations
		18
		19	# sending messages
13	snd $port, type => data...;	20	snd $port, type => data...;
		21	snd $port, @msg;
		22	snd @msg_with_first_element_being_a_port;
14		23
15	$SELF # receiving/own port id in rcv callbacks	24	# creating/using ports, the simple way
		25	my $simple_port = port { my @msg = @_ };
16		26
17	rcv $port, smartmatch => $cb->($port, @msg);	27	# creating/using ports, tagged message matching
18		28	my $port = port;
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	29	rcv $port, ping => sub { snd $_[0], "pong" };
21	rcv $port1, pong => sub { warn "pong received\n" };	30	rcv $port, pong => sub { warn "pong received\n" };
22	snd $port2, ping => $port1;
23		31
24	# more, smarter, matches (_any_ is exported by this module)	32	# create a port on another node
25	rcv $port, [child_died => $pid] => sub { ...	33	my $port = spawn $node, $initfunc, @initdata;
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	34
		35	# monitoring
		36	mon $port, $cb->(@msg) # callback is invoked on death
		37	mon $port, $otherport # kill otherport on abnormal death
		38	mon $port, $otherport, @msg # send message on death
		39
		40	=head1 CURRENT STATUS
		41
		42	bin/aemp - stable.
		43	AnyEvent::MP - stable API, should work.
		44	AnyEvent::MP::Intro - uptodate, but incomplete.
		45	AnyEvent::MP::Kernel - mostly stable.
		46	AnyEvent::MP::Global - stable API, protocol not yet final.
		47
		48	stay tuned.
27		49
28	=head1 DESCRIPTION	50	=head1 DESCRIPTION
29		51
30	This module (-family) implements a simple message passing framework.	52	This module (-family) implements a simple message passing framework.
31		53
32	Despite its simplicity, you can securely message other processes running	54	Despite its simplicity, you can securely message other processes running
33	on the same or other hosts.	55	on the same or other hosts, and you can supervise entities remotely.
34		56
35	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	57	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
36	manual page.	58	manual page and the examples under F<eg/>.
37		59
38	At the moment, this module family is severly broken and underdocumented,	60	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		61
42	=head1 CONCEPTS	62	=head1 CONCEPTS
43		63
44	=over 4	64	=over 4
45		65
46	=item port	66	=item port
47		67
48	A port is something you can send messages to (with the C<snd> function).	68	A port is something you can send messages to (with the C<snd> function).
49		69
50	Some ports allow you to register C<rcv> handlers that can match specific	70	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	71	some messages. Messages send to ports will not be queued, regardless of
52	will not be queued.	72	anything was listening for them or not.
53		73
54	=item port id - C<noderef#portname>	74	=item port ID - C<nodeid#portname>
55		75
56	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	76	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	77	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		78
61	=item node	79	=item node
62		80
63	A node is a single process containing at least one port - the node	81	A node is a single process containing at least one port - the node port,
64	port. You can send messages to node ports to find existing ports or to	82	which enables nodes to manage each other remotely, and to create new
65	create new ports, among other things.	83	ports.
66		84
67	Nodes are either private (single-process only), slaves (connected to a	85	Nodes are either public (have one or more listening ports) or private
68	master node only) or public nodes (connectable from unrelated nodes).	86	(no listening ports). Private nodes cannot talk to other private nodes
		87	currently.
69		88
70	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	89	=item node ID - C<[a-za-Z0-9_\-.:]+>
71		90
72	A node reference is a string that either simply identifies the node (for	91	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	92	network. Depending on the configuration used, node IDs can look like a
74	node (for public nodes).	93	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
		94	doesn't interpret node IDs in any way.
75		95
76	This recipe is simply a comma-separated list of C<address:port> pairs (for	96	=item binds - C<ip:port>
77	TCP/IP, other protocols might look different).
78		97
79	Node references come in two flavours: resolved (containing only numerical	98	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).	99	each other. To do this, nodes should listen on one or more local transport
		100	endpoints - binds. Currently, only standard C<ip:port> specifications can
		101	be used, which specify TCP ports to listen on.
81		102
82	Before using an unresolved node reference in a message you first have to	103	=item seeds - C<host:port>
83	resolve it.	104
		105	When a node starts, it knows nothing about the network. To teach the node
		106	about the network it first has to contact some other node within the
		107	network. This node is called a seed.
		108
		109	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes
		110	are expected to be long-running, and at least one of those should always
		111	be available. When nodes run out of connections (e.g. due to a network
		112	error), they try to re-establish connections to some seednodes again to
		113	join the network.
		114
		115	Apart from being sued for seeding, seednodes are not special in any way -
		116	every public node can be a seednode.
84		117
85	=back	118	=back
86		119
87	=head1 VARIABLES/FUNCTIONS	120	=head1 VARIABLES/FUNCTIONS
88		121
…		…
90		123
91	=cut	124	=cut
92		125
93	package AnyEvent::MP;	126	package AnyEvent::MP;
94		127
95	use AnyEvent::MP::Base;	128	use AnyEvent::MP::Kernel;
96		129
97	use common::sense;	130	use common::sense;
98		131
99	use Carp ();	132	use Carp ();
100		133
101	use AE ();	134	use AE ();
102		135
103	use base "Exporter";	136	use base "Exporter";
104		137
105	our $VERSION = '0.1';	138	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		139
106	our @EXPORT = qw(	140	our @EXPORT = qw(
107	NODE $NODE *SELF node_of _any_	141	NODE $NODE *SELF node_of after
108	resolve_node	142	configure
109	become_slave become_public
110	snd rcv mon kil reg psub	143	snd rcv mon mon_guard kil reg psub spawn
111	port	144	port
112	);	145	);
113		146
114	our $SELF;	147	our $SELF;
115		148
…		…
119	kil $SELF, die => $msg;	152	kil $SELF, die => $msg;
120	}	153	}
121		154
122	=item $thisnode = NODE / $NODE	155	=item $thisnode = NODE / $NODE
123		156
124	The C<NODE> function returns, and the C<$NODE> variable contains	157	The C<NODE> function returns, and the C<$NODE> variable contains, the node
125	the noderef of the local node. The value is initialised by a call	158	ID of the node running in the current process. This value is initialised by
126	to C<become_public> or C<become_slave>, after which all local port	159	a call to C<configure>.
127	identifiers become invalid.
128		160
129	=item $noderef = node_of $portid	161	=item $nodeid = node_of $port
130		162
131	Extracts and returns the noderef from a portid or a noderef.	163	Extracts and returns the node ID from a port ID or a node ID.
132		164
133	=item $cv = resolve_node $noderef	165	=item configure key => value...
134		166
135	Takes an unresolved node reference that may contain hostnames and	167	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	168	"distributed mode") it has to configure itself - the minimum a node needs
137	reference.	169	to know is its own name, and optionally it should know the addresses of
		170	some other nodes in the network to discover other nodes.
138		171
139	In addition to C<address:port> pairs allowed in resolved noderefs, the	172	This function configures a node - it must be called exactly once (or
140	following forms are supported:	173	never) before calling other AnyEvent::MP functions.
141		174
142	=over 4	175	=over 4
143		176
144	=item the empty string	177	=item step 1, gathering configuration from profiles
145		178
146	An empty-string component gets resolved as if the default port (4040) was	179	The function first looks up a profile in the aemp configuration (see the
147	specified.	180	L<aemp> commandline utility). The profile name can be specified via the
		181	named C<profile> parameter. If it is missing, then the nodename (F<uname
		182	-n>) will be used as profile name.
148		183
149	=item naked port numbers (e.g. C<1234>)	184	The profile data is then gathered as follows:
150		185
151	These are resolved by prepending the local nodename and a colon, to be	186	First, all remaining key => value pairs (all of which are conviniently
152	further resolved.	187	undocumented at the moment) will be interpreted as configuration
		188	data. Then they will be overwritten by any values specified in the global
		189	default configuration (see the F<aemp> utility), then the chain of
		190	profiles chosen by the profile name (and any C<parent> attributes).
153		191
154	=item hostnames (e.g. C<localhost:1234>, C<localhost>)	192	That means that the values specified in the profile have highest priority
		193	and the values specified directly via C<configure> have lowest priority,
		194	and can only be used to specify defaults.
155		195
156	These are resolved by using AnyEvent::DNS to resolve them, optionally	196	If the profile specifies a node ID, then this will become the node ID of
157	looking up SRV records for the C<aemp=4040> port, if no port was	197	this process. If not, then the profile name will be used as node ID. The
158	specified.	198	special node ID of C<anon/> will be replaced by a random node ID.
		199
		200	=item step 2, bind listener sockets
		201
		202	The next step is to look up the binds in the profile, followed by binding
		203	aemp protocol listeners on all binds specified (it is possible and valid
		204	to have no binds, meaning that the node cannot be contacted form the
		205	outside. This means the node cannot talk to other nodes that also have no
		206	binds, but it can still talk to all "normal" nodes).
		207
		208	If the profile does not specify a binds list, then a default of C<*> is
		209	used, meaning the node will bind on a dynamically-assigned port on every
		210	local IP address it finds.
		211
		212	=item step 3, connect to seed nodes
		213
		214	As the last step, the seeds list from the profile is passed to the
		215	L<AnyEvent::MP::Global> module, which will then use it to keep
		216	connectivity with at least one node at any point in time.
159		217
160	=back	218	=back
		219
		220	Example: become a distributed node using the locla node name as profile.
		221	This should be the most common form of invocation for "daemon"-type nodes.
		222
		223	configure
		224
		225	Example: become an anonymous node. This form is often used for commandline
		226	clients.
		227
		228	configure nodeid => "anon/";
		229
		230	Example: configure a node using a profile called seed, which si suitable
		231	for a seed node as it binds on all local addresses on a fixed port (4040,
		232	customary for aemp).
		233
		234	# use the aemp commandline utility
		235	# aemp profile seed nodeid anon/ binds '*:4040'
		236
		237	# then use it
		238	configure profile => "seed";
		239
		240	# or simply use aemp from the shell again:
		241	# aemp run profile seed
		242
		243	# or provide a nicer-to-remember nodeid
		244	# aemp run profile seed nodeid "$(hostname)"
161		245
162	=item $SELF	246	=item $SELF
163		247
164	Contains the current port id while executing C<rcv> callbacks or C<psub>	248	Contains the current port id while executing C<rcv> callbacks or C<psub>
165	blocks.	249	blocks.
166		250
167	=item SELF, %SELF, @SELF...	251	=item *SELF, SELF, %SELF, @SELF...
168		252
169	Due to some quirks in how perl exports variables, it is impossible to	253	Due to some quirks in how perl exports variables, it is impossible to
170	just export C<$SELF>, all the symbols called C<SELF> are exported by this	254	just export C<$SELF>, all the symbols named C<SELF> are exported by this
171	module, but only C<$SELF> is currently used.	255	module, but only C<$SELF> is currently used.
172		256
173	=item snd $portid, type => @data	257	=item snd $port, type => @data
174		258
175	=item snd $portid, @msg	259	=item snd $port, @msg
176		260
177	Send the given message to the given port ID, which can identify either	261	Send the given message to the given port, which can identify either a
178	a local or a remote port, and can be either a string or soemthignt hat	262	local or a remote port, and must be a port ID.
179	stringifies a sa port ID (such as a port object :).
180		263
181	While the message can be about anything, it is highly recommended to use a	264	While the message can be almost anything, it is highly recommended to
182	string as first element (a portid, or some word that indicates a request	265	use a string as first element (a port ID, or some word that indicates a
183	type etc.).	266	request type etc.) and to consist if only simple perl values (scalars,
		267	arrays, hashes) - if you think you need to pass an object, think again.
184		268
185	The message data effectively becomes read-only after a call to this	269	The message data logically becomes read-only after a call to this
186	function: modifying any argument is not allowed and can cause many	270	function: modifying any argument (or values referenced by them) is
187	problems.	271	forbidden, as there can be considerable time between the call to C<snd>
		272	and the time the message is actually being serialised - in fact, it might
		273	never be copied as within the same process it is simply handed to the
		274	receiving port.
188		275
189	The type of data you can transfer depends on the transport protocol: when	276	The type of data you can transfer depends on the transport protocol: when
190	JSON is used, then only strings, numbers and arrays and hashes consisting	277	JSON is used, then only strings, numbers and arrays and hashes consisting
191	of those are allowed (no objects). When Storable is used, then anything	278	of those are allowed (no objects). When Storable is used, then anything
192	that Storable can serialise and deserialise is allowed, and for the local	279	that Storable can serialise and deserialise is allowed, and for the local
193	node, anything can be passed.	280	node, anything can be passed. Best rely only on the common denominator of
		281	these.
194		282
195	=item kil $portid[, @reason]	283	=item $local_port = port
196		284
197	Kill the specified port with the given C<@reason>.	285	Create a new local port object and returns its port ID. Initially it has
		286	no callbacks set and will throw an error when it receives messages.
198		287
199	If no C<@reason> is specified, then the port is killed "normally" (linked	288	=item $local_port = port { my @msg = @_ }
200	ports will not be kileld, or even notified).
201		289
202	Otherwise, linked ports get killed with the same reason (second form of	290	Creates a new local port, and returns its ID. Semantically the same as
203	C<mon>, see below).	291	creating a port and calling C<rcv $port, $callback> on it.
204		292
205	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	293	The block will be called for every message received on the port, with the
206	will be reported as reason C<< die => $@ >>.	294	global variable C<$SELF> set to the port ID. Runtime errors will cause the
		295	port to be C<kil>ed. The message will be passed as-is, no extra argument
		296	(i.e. no port ID) will be passed to the callback.
207		297
208	Transport/communication errors are reported as C<< transport_error =>	298	If you want to stop/destroy the port, simply C<kil> it:
209	$message >>.
210		299
211	=item $guard = mon $portid, $cb->(@reason)	300	my $port = port {
		301	my @msg = @_;
		302	...
		303	kil $SELF;
		304	};
212		305
213	=item $guard = mon $portid, $otherport	306	=cut
214		307
215	=item $guard = mon $portid, $otherport, @msg	308	sub rcv($@);
216		309
		310	sub _kilme {
		311	die "received message on port without callback";
		312	}
		313
		314	sub port(;&) {
		315	my $id = "$UNIQ." . $ID++;
		316	my $port = "$NODE#$id";
		317
		318	rcv $port, shift \|\| \&_kilme;
		319
		320	$port
		321	}
		322
		323	=item rcv $local_port, $callback->(@msg)
		324
		325	Replaces the default callback on the specified port. There is no way to
		326	remove the default callback: use C<sub { }> to disable it, or better
		327	C<kil> the port when it is no longer needed.
		328
		329	The global C<$SELF> (exported by this module) contains C<$port> while
		330	executing the callback. Runtime errors during callback execution will
		331	result in the port being C<kil>ed.
		332
		333	The default callback received all messages not matched by a more specific
		334	C<tag> match.
		335
		336	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
		337
		338	Register (or replace) callbacks to be called on messages starting with the
		339	given tag on the given port (and return the port), or unregister it (when
		340	C<$callback> is C<$undef> or missing). There can only be one callback
		341	registered for each tag.
		342
		343	The original message will be passed to the callback, after the first
		344	element (the tag) has been removed. The callback will use the same
		345	environment as the default callback (see above).
		346
		347	Example: create a port and bind receivers on it in one go.
		348
		349	my $port = rcv port,
		350	msg1 => sub { ... },
		351	msg2 => sub { ... },
		352	;
		353
		354	Example: create a port, bind receivers and send it in a message elsewhere
		355	in one go:
		356
		357	snd $otherport, reply =>
		358	rcv port,
		359	msg1 => sub { ... },
		360	...
		361	;
		362
		363	Example: temporarily register a rcv callback for a tag matching some port
		364	(e.g. for a rpc reply) and unregister it after a message was received.
		365
		366	rcv $port, $otherport => sub {
		367	my @reply = @_;
		368
		369	rcv $SELF, $otherport;
		370	};
		371
		372	=cut
		373
		374	sub rcv($@) {
		375	my $port = shift;
		376	my ($nodeid, $portid) = split /#/, $port, 2;
		377
		378	$NODE{$nodeid} == $NODE{""}
		379	or Carp::croak "$port: rcv can only be called on local ports, caught";
		380
		381	while (@_) {
		382	if (ref $_[0]) {
		383	if (my $self = $PORT_DATA{$portid}) {
		384	"AnyEvent::MP::Port" eq ref $self
		385	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		386
		387	$self->[2] = shift;
		388	} else {
		389	my $cb = shift;
		390	$PORT{$portid} = sub {
		391	local $SELF = $port;
		392	eval { &$cb }; _self_die if $@;
		393	};
		394	}
		395	} elsif (defined $_[0]) {
		396	my $self = $PORT_DATA{$portid} \|\|= do {
		397	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
		398
		399	$PORT{$portid} = sub {
		400	local $SELF = $port;
		401
		402	if (my $cb = $self->[1]{$_[0]}) {
		403	shift;
		404	eval { &$cb }; _self_die if $@;
		405	} else {
		406	&{ $self->[0] };
		407	}
		408	};
		409
		410	$self
		411	};
		412
		413	"AnyEvent::MP::Port" eq ref $self
		414	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		415
		416	my ($tag, $cb) = splice @_, 0, 2;
		417
		418	if (defined $cb) {
		419	$self->[1]{$tag} = $cb;
		420	} else {
		421	delete $self->[1]{$tag};
		422	}
		423	}
		424	}
		425
		426	$port
		427	}
		428
		429	=item $closure = psub { BLOCK }
		430
		431	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
		432	closure is executed, sets up the environment in the same way as in C<rcv>
		433	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		434
		435	This is useful when you register callbacks from C<rcv> callbacks:
		436
		437	rcv delayed_reply => sub {
		438	my ($delay, @reply) = @_;
		439	my $timer = AE::timer $delay, 0, psub {
		440	snd @reply, $SELF;
		441	};
		442	};
		443
		444	=cut
		445
		446	sub psub(&) {
		447	my $cb = shift;
		448
		449	my $port = $SELF
		450	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
		451
		452	sub {
		453	local $SELF = $port;
		454
		455	if (wantarray) {
		456	my @res = eval { &$cb };
		457	_self_die if $@;
		458	@res
		459	} else {
		460	my $res = eval { &$cb };
		461	_self_die if $@;
		462	$res
		463	}
		464	}
		465	}
		466
		467	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
		468
		469	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
		470
		471	=item $guard = mon $port # kill $SELF when $port dies
		472
		473	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
		474
217	Monitor the given port and do something when the port is killed.	475	Monitor the given port and do something when the port is killed or
		476	messages to it were lost, and optionally return a guard that can be used
		477	to stop monitoring again.
218		478
		479	C<mon> effectively guarantees that, in the absence of hardware failures,
		480	after starting the monitor, either all messages sent to the port will
		481	arrive, or the monitoring action will be invoked after possible message
		482	loss has been detected. No messages will be lost "in between" (after
		483	the first lost message no further messages will be received by the
		484	port). After the monitoring action was invoked, further messages might get
		485	delivered again.
		486
		487	Note that monitoring-actions are one-shot: once messages are lost (and a
		488	monitoring alert was raised), they are removed and will not trigger again.
		489
219	In the first form, the callback is simply called with any number	490	In the first form (callback), the callback is simply called with any
220	of C<@reason> elements (no @reason means that the port was deleted	491	number of C<@reason> elements (no @reason means that the port was deleted
221	"normally"). Note also that I<< the callback B<must> never die >>, so use	492	"normally"). Note also that I<< the callback B<must> never die >>, so use
222	C<eval> if unsure.	493	C<eval> if unsure.
223		494
224	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	495	In the second form (another port given), the other port (C<$rcvport>)
225	a @reason was specified, i.e. on "normal" kils nothing happens, while	496	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
226	under all other conditions, the other port is killed with the same reason.	497	"normal" kils nothing happens, while under all other conditions, the other
		498	port is killed with the same reason.
227		499
		500	The third form (kill self) is the same as the second form, except that
		501	C<$rvport> defaults to C<$SELF>.
		502
228	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	503	In the last form (message), a message of the form C<@msg, @reason> will be
		504	C<snd>.
		505
		506	As a rule of thumb, monitoring requests should always monitor a port from
		507	a local port (or callback). The reason is that kill messages might get
		508	lost, just like any other message. Another less obvious reason is that
		509	even monitoring requests can get lost (for exmaple, when the connection
		510	to the other node goes down permanently). When monitoring a port locally
		511	these problems do not exist.
229		512
230	Example: call a given callback when C<$port> is killed.	513	Example: call a given callback when C<$port> is killed.
231		514
232	mon $port, sub { warn "port died because of <@_>\n" };	515	mon $port, sub { warn "port died because of <@_>\n" };
233		516
234	Example: kill ourselves when C<$port> is killed abnormally.	517	Example: kill ourselves when C<$port> is killed abnormally.
235		518
236	mon $port, $self;	519	mon $port;
237		520
238	Example: send us a restart message another C<$port> is killed.	521	Example: send us a restart message when another C<$port> is killed.
239		522
240	mon $port, $self => "restart";	523	mon $port, $self => "restart";
241		524
242	=cut	525	=cut
243		526
244	sub mon {	527	sub mon {
245	my ($noderef, $port, $cb) = ((split /#/, shift, 2), shift);	528	my ($nodeid, $port) = split /#/, shift, 2;
246		529
247	my $node = $NODE{$noderef} \|\| add_node $noderef;	530	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
248		531
249	#TODO: ports must not be references	532	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) {	533
		534	unless (ref $cb) {
251	if (@_) {	535	if (@_) {
252	# send a kill info message	536	# send a kill info message
253	my (@msg) = ($cb, @_);	537	my (@msg) = ($cb, @_);
254	$cb = sub { snd @msg, @_ };	538	$cb = sub { snd @msg, @_ };
255	} else {	539	} else {
…		…
271	is killed, the references will be freed.	555	is killed, the references will be freed.
272		556
273	Optionally returns a guard that will stop the monitoring.	557	Optionally returns a guard that will stop the monitoring.
274		558
275	This function is useful when you create e.g. timers or other watchers and	559	This function is useful when you create e.g. timers or other watchers and
276	want to free them when the port gets killed:	560	want to free them when the port gets killed (note the use of C<psub>):
277		561
278	$port->rcv (start => sub {	562	$port->rcv (start => sub {
279	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	563	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
280	undef $timer if 0.9 < rand;	564	undef $timer if 0.9 < rand;
281	});	565	});
282	});	566	});
283		567
284	=cut	568	=cut
285		569
286	sub mon_guard {	570	sub mon_guard {
287	my ($port, @refs) = @_;	571	my ($port, @refs) = @_;
288		572
		573	#TODO: mon-less form?
		574
289	mon $port, sub { 0 && @refs }	575	mon $port, sub { 0 && @refs }
290	}	576	}
291		577
292	=item lnk $port1, $port2	578	=item kil $port[, @reason]
293		579
294	Link two ports. This is simply a shorthand for:	580	Kill the specified port with the given C<@reason>.
295		581
296	mon $port1, $port2;	582	If no C<@reason> is specified, then the port is killed "normally" (ports
297	mon $port2, $port1;	583	monitoring other ports will not necessarily die because a port dies
		584	"normally").
298		585
299	It means that if either one is killed abnormally, the other one gets	586	Otherwise, linked ports get killed with the same reason (second form of
300	killed as well.	587	C<mon>, see above).
301		588
302	=item $local_port = port	589	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		590	will be reported as reason C<< die => $@ >>.
303		591
304	Create a new local port object that supports message matching.	592	Transport/communication errors are reported as C<< transport_error =>
		593	$message >>.
305		594
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	595	=cut
325		596
326	sub port(;&) {	597	=item $port = spawn $node, $initfunc[, @initdata]
327	my $id = "$UNIQ." . $ID++;
328	my $port = "$NODE#$id";
329		598
330	if (@_) {	599	Creates a port on the node C<$node> (which can also be a port ID, in which
331	my $cb = shift;	600	case it's the node where that port resides).
332	$PORT{$id} = sub {	601
333	local $SELF = $port;	602	The port ID of the newly created port is returned immediately, and it is
334	eval {	603	possible to immediately start sending messages or to monitor the port.
335	&$cb	604
336	and kil $id;	605	After the port has been created, the init function is called on the remote
		606	node, in the same context as a C<rcv> callback. This function must be a
		607	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
		608	specify a function in the main program, use C<::name>.
		609
		610	If the function doesn't exist, then the node tries to C<require>
		611	the package, then the package above the package and so on (e.g.
		612	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		613	exists or it runs out of package names.
		614
		615	The init function is then called with the newly-created port as context
		616	object (C<$SELF>) and the C<@initdata> values as arguments.
		617
		618	A common idiom is to pass a local port, immediately monitor the spawned
		619	port, and in the remote init function, immediately monitor the passed
		620	local port. This two-way monitoring ensures that both ports get cleaned up
		621	when there is a problem.
		622
		623	Example: spawn a chat server port on C<$othernode>.
		624
		625	# this node, executed from within a port context:
		626	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		627	mon $server;
		628
		629	# init function on C<$othernode>
		630	sub connect {
		631	my ($srcport) = @_;
		632
		633	mon $srcport;
		634
		635	rcv $SELF, sub {
337	};	636	...
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	};	637	};
369	}	638	}
370		639
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	640	=cut
384		641
385	sub reg(@) {	642	sub _spawn {
386	my ($portid, $name) = @_;	643	my $port = shift;
		644	my $init = shift;
387		645
388	$REG{$name} = $portid;	646	local $SELF = "$NODE#$port";
389	}	647	eval {
390		648	&{ 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	};	649	};
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 $@;	650	_self_die if $@;
479	@res	651	}
480	} else {	652
481	my $res = eval { &$cb };	653	sub spawn(@) {
482	_self_die if $@;	654	my ($nodeid, undef) = split /#/, shift, 2;
483	$res	655
484	}	656	my $id = "$RUNIQ." . $ID++;
		657
		658	$_[0] =~ /::/
		659	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		660
		661	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
		662
		663	"$nodeid#$id"
		664	}
		665
		666	=item after $timeout, @msg
		667
		668	=item after $timeout, $callback
		669
		670	Either sends the given message, or call the given callback, after the
		671	specified number of seconds.
		672
		673	This is simply a utility function that comes in handy at times - the
		674	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		675	so it may go away in the future.
		676
		677	=cut
		678
		679	sub after($@) {
		680	my ($timeout, @action) = @_;
		681
		682	my $t; $t = AE::timer $timeout, 0, sub {
		683	undef $t;
		684	ref $action[0]
		685	? $action[0]()
		686	: snd @action;
485	}	687	};
486	}	688	}
487		689
488	=back	690	=back
489		691
490	=head1 FUNCTIONS FOR NODES	692	=head1 AnyEvent::MP vs. Distributed Erlang
		693
		694	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
		695	== aemp node, Erlang process == aemp port), so many of the documents and
		696	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		697	sample:
		698
		699	http://www.Erlang.se/doc/programming_rules.shtml
		700	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		701	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		702	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		703
		704	Despite the similarities, there are also some important differences:
491		705
492	=over 4	706	=over 4
493		707
494	=item become_public $noderef	708	=item * Node IDs are arbitrary strings in AEMP.
495		709
496	Tells the node to become a public node, i.e. reachable from other nodes.
497
498	The first argument is the (unresolved) node reference of the local node
499	(if missing then the empty string is used).
500
501	It is quite common to not specify anything, in which case the local node
502	tries to listen on the default port, or to only specify a port number, in
503	which case AnyEvent::MP tries to guess the local addresses.
504
505	=cut
506
507	=back
508
509	=head1 NODE MESSAGES
510
511	Nodes understand the following messages sent to them. Many of them take
512	arguments called C<@reply>, which will simply be used to compose a reply
513	message - C<$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	710	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	711	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
575	convenience functionality.	712	configuraiton or DNS), but will otherwise discover other odes itself.
576		713
577	This means that AEMP requires a less tightly controlled environment at the	714	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
578	cost of longer node references and a slightly higher management overhead.	715	uses "local ports are like remote ports".
		716
		717	The failure modes for local ports are quite different (runtime errors
		718	only) then for remote ports - when a local port dies, you I<know> it dies,
		719	when a connection to another node dies, you know nothing about the other
		720	port.
		721
		722	Erlang pretends remote ports are as reliable as local ports, even when
		723	they are not.
		724
		725	AEMP encourages a "treat remote ports differently" philosophy, with local
		726	ports being the special case/exception, where transport errors cannot
		727	occur.
579		728
580	=item * Erlang uses processes and a mailbox, AEMP does not queue.	729	=item * Erlang uses processes and a mailbox, AEMP does not queue.
581		730
582	Erlang uses processes that selctively receive messages, and therefore	731	Erlang uses processes that selectively receive messages, and therefore
583	needs a queue. AEMP is event based, queuing messages would serve no useful	732	needs a queue. AEMP is event based, queuing messages would serve no
584	purpose.	733	useful purpose. For the same reason the pattern-matching abilities of
		734	AnyEvent::MP are more limited, as there is little need to be able to
		735	filter messages without dequeing them.
585		736
586	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	737	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
587		738
588	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	739	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
589		740
590	Sending messages in erlang is synchronous and blocks the process. AEMP	741	Sending messages in Erlang is synchronous and blocks the process (and
591	sends are immediate, connection establishment is handled in the	742	so does not need a queue that can overflow). AEMP sends are immediate,
592	background.	743	connection establishment is handled in the background.
593		744
594	=item * Erlang can silently lose messages, AEMP cannot.	745	=item * Erlang suffers from silent message loss, AEMP does not.
595		746
596	Erlang makes few guarantees on messages delivery - messages can get lost	747	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,	748	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).	749	and c, and the other side only receives messages a and c).
599		750
600	AEMP guarantees correct ordering, and the guarantee that there are no	751	AEMP guarantees correct ordering, and the guarantee that after one message
601	holes in the message sequence.	752	is lost, all following ones sent to the same port are lost as well, until
602		753	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	754	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		755
614	=item * Erlang can send messages to the wrong port, AEMP does not.	756	=item * Erlang can send messages to the wrong port, AEMP does not.
615		757
616	In erlang it is quite possible that a node that restarts reuses a process	758	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	759	known to other nodes for a completely different process, causing messages
618	messages destined for that process to end up in an unrelated process.	760	destined for that process to end up in an unrelated process.
619		761
620	AEMP never reuses port IDs, so old messages or old port IDs floating	762	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.	763	around in the network will not be sent to an unrelated port.
622		764
623	=item * Erlang uses unprotected connections, AEMP uses secure	765	=item * Erlang uses unprotected connections, AEMP uses secure
624	authentication and can use TLS.	766	authentication and can use TLS.
625		767
626	AEMP can use a proven protocol - SSL/TLS - to protect connections and	768	AEMP can use a proven protocol - TLS - to protect connections and
627	securely authenticate nodes.	769	securely authenticate nodes.
628		770
629	=item * The AEMP protocol is optimised for both text-based and binary	771	=item * The AEMP protocol is optimised for both text-based and binary
630	communications.	772	communications.
631		773
632	The AEMP protocol, unlike the erlang protocol, supports both	774	The AEMP protocol, unlike the Erlang protocol, supports both programming
633	language-independent text-only protocols (good for debugging) and binary,	775	language independent text-only protocols (good for debugging) and binary,
634	language-specific serialisers (e.g. Storable).	776	language-specific serialisers (e.g. Storable). By default, unless TLS is
		777	used, the protocol is actually completely text-based.
635		778
636	It has also been carefully designed to be implementable in other languages	779	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	780	with a minimum of work while gracefully degrading functionality to make the
638	protocol simple.	781	protocol simple.
639		782
		783	=item * AEMP has more flexible monitoring options than Erlang.
		784
		785	In Erlang, you can chose to receive I<all> exit signals as messages
		786	or I<none>, there is no in-between, so monitoring single processes is
		787	difficult to implement. Monitoring in AEMP is more flexible than in
		788	Erlang, as one can choose between automatic kill, exit message or callback
		789	on a per-process basis.
		790
		791	=item * Erlang tries to hide remote/local connections, AEMP does not.
		792
		793	Monitoring in Erlang is not an indicator of process death/crashes, in the
		794	same way as linking is (except linking is unreliable in Erlang).
		795
		796	In AEMP, you don't "look up" registered port names or send to named ports
		797	that might or might not be persistent. Instead, you normally spawn a port
		798	on the remote node. The init function monitors you, and you monitor the
		799	remote port. Since both monitors are local to the node, they are much more
		800	reliable (no need for C<spawn_link>).
		801
		802	This also saves round-trips and avoids sending messages to the wrong port
		803	(hard to do in Erlang).
		804
640	=back	805	=back
641		806
		807	=head1 RATIONALE
		808
		809	=over 4
		810
		811	=item Why strings for port and node IDs, why not objects?
		812
		813	We considered "objects", but found that the actual number of methods
		814	that can be called are quite low. Since port and node IDs travel over
		815	the network frequently, the serialising/deserialising would add lots of
		816	overhead, as well as having to keep a proxy object everywhere.
		817
		818	Strings can easily be printed, easily serialised etc. and need no special
		819	procedures to be "valid".
		820
		821	And as a result, a miniport consists of a single closure stored in a
		822	global hash - it can't become much cheaper.
		823
		824	=item Why favour JSON, why not a real serialising format such as Storable?
		825
		826	In fact, any AnyEvent::MP node will happily accept Storable as framing
		827	format, but currently there is no way to make a node use Storable by
		828	default (although all nodes will accept it).
		829
		830	The default framing protocol is JSON because a) JSON::XS is many times
		831	faster for small messages and b) most importantly, after years of
		832	experience we found that object serialisation is causing more problems
		833	than it solves: Just like function calls, objects simply do not travel
		834	easily over the network, mostly because they will always be a copy, so you
		835	always have to re-think your design.
		836
		837	Keeping your messages simple, concentrating on data structures rather than
		838	objects, will keep your messages clean, tidy and efficient.
		839
		840	=back
		841
642	=head1 SEE ALSO	842	=head1 SEE ALSO
		843
		844	L<AnyEvent::MP::Intro> - a gentle introduction.
		845
		846	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		847
		848	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		849	your applications.
643		850
644	L<AnyEvent>.	851	L<AnyEvent>.
645		852
646	=head1 AUTHOR	853	=head1 AUTHOR
647		854

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