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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.31 by root, Wed Aug 5 19:55:58 2009 UTC vs.
Revision 1.83 by root, Tue Sep 8 01:38:16 2009 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use AnyEvent::MP;	7	use AnyEvent::MP;
8		8
9	$NODE # contains this node's noderef	9	$NODE # contains this node's node ID
10	NODE # returns this node's noderef	10	NODE # returns this node's node ID
11	NODE $port # returns the noderef of the port
12		11
		12	$SELF # receiving/own port id in rcv callbacks
		13
		14	# initialise the node so it can send/receive messages
		15	configure;
		16
		17	# ports are message destinations
		18
		19	# sending messages
13	snd $port, type => data...;	20	snd $port, type => data...;
		21	snd $port, @msg;
		22	snd @msg_with_first_element_being_a_port;
14		23
15	$SELF # receiving/own port id in rcv callbacks	24	# creating/using ports, the simple way
		25	my $simple_port = port { my @msg = @_ };
16		26
17	rcv $port, smartmatch => $cb->($port, @msg);	27	# creating/using ports, tagged message matching
18		28	my $port = port;
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	29	rcv $port, ping => sub { snd $_[0], "pong" };
21	rcv $port1, pong => sub { warn "pong received\n" };	30	rcv $port, pong => sub { warn "pong received\n" };
22	snd $port2, ping => $port1;
23		31
24	# more, smarter, matches (_any_ is exported by this module)	32	# create a port on another node
25	rcv $port, [child_died => $pid] => sub { ...	33	my $port = spawn $node, $initfunc, @initdata;
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	34
		35	# monitoring
		36	mon $port, $cb->(@msg) # callback is invoked on death
		37	mon $port, $otherport # kill otherport on abnormal death
		38	mon $port, $otherport, @msg # send message on death
		39
		40	=head1 CURRENT STATUS
		41
		42	bin/aemp - stable.
		43	AnyEvent::MP - stable API, should work.
		44	AnyEvent::MP::Intro - explains most concepts.
		45	AnyEvent::MP::Kernel - mostly stable.
		46	AnyEvent::MP::Global - stable but incomplete, protocol not yet final.
		47
		48	stay tuned.
27		49
28	=head1 DESCRIPTION	50	=head1 DESCRIPTION
29		51
30	This module (-family) implements a simple message passing framework.	52	This module (-family) implements a simple message passing framework.
31		53
32	Despite its simplicity, you can securely message other processes running	54	Despite its simplicity, you can securely message other processes running
33	on the same or other hosts.	55	on the same or other hosts, and you can supervise entities remotely.
34		56
35	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	57	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
36	manual page.	58	manual page and the examples under F<eg/>.
37
38	At the moment, this module family is severly broken and underdocumented,
39	so do not use. This was uploaded mainly to reserve the CPAN namespace -
40	stay tuned! The basic API should be finished, however.
41		59
42	=head1 CONCEPTS	60	=head1 CONCEPTS
43		61
44	=over 4	62	=over 4
45		63
46	=item port	64	=item port
47		65
48	A port is something you can send messages to (with the C<snd> function).	66	Not to be confused with a TCP port, a "port" is something you can send
		67	messages to (with the C<snd> function).
49		68
50	Some ports allow you to register C<rcv> handlers that can match specific	69	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	70	some messages. Messages send to ports will not be queued, regardless of
52	will not be queued.	71	anything was listening for them or not.
53		72
54	=item port id - C<noderef#portname>	73	=item port ID - C<nodeid#portname>
55		74
56	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	75	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	76	separator, and a port name (a printable string of unspecified format).
58	exception is the the node port, whose ID is identical to its node
59	reference.
60		77
61	=item node	78	=item node
62		79
63	A node is a single process containing at least one port - the node	80	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	81	which enables nodes to manage each other remotely, and to create new
65	create new ports, among other things.	82	ports.
66		83
67	Nodes are either private (single-process only), slaves (connected to a	84	Nodes are either public (have one or more listening ports) or private
68	master node only) or public nodes (connectable from unrelated nodes).	85	(no listening ports). Private nodes cannot talk to other private nodes
		86	currently.
69		87
70	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	88	=item node ID - C<[a-za-Z0-9_\-.:]+>
71		89
72	A node reference is a string that either simply identifies the node (for	90	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	91	network. Depending on the configuration used, node IDs can look like a
74	node (for public nodes).	92	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
		93	doesn't interpret node IDs in any way.
75		94
76	This recipe is simply a comma-separated list of C<address:port> pairs (for	95	=item binds - C<ip:port>
77	TCP/IP, other protocols might look different).
78		96
79	Node references come in two flavours: resolved (containing only numerical	97	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).	98	each other. To do this, nodes should listen on one or more local transport
		99	endpoints - binds. Currently, only standard C<ip:port> specifications can
		100	be used, which specify TCP ports to listen on.
81		101
82	Before using an unresolved node reference in a message you first have to	102	=item seed nodes
83	resolve it.	103
		104	When a node starts, it knows nothing about the network. To teach the node
		105	about the network it first has to contact some other node within the
		106	network. This node is called a seed.
		107
		108	Apart from the fact that other nodes know them as seed nodes and they have
		109	to have fixed listening addresses, seed nodes are perfectly normal nodes -
		110	any node can function as a seed node for others.
		111
		112	In addition to discovering the network, seed nodes are also used to
		113	maintain the network and to connect nodes that otherwise would have
		114	trouble connecting. They form the backbone of the AnyEvent::MP network.
		115
		116	Seed nodes are expected to be long-running, and at least one seed node
		117	should always be available.
		118
		119	=item seeds - C<host:port>
		120
		121	Seeds are transport endpoint(s) (usually a hostname/IP address and a
		122	TCP port) of nodes thta should be used as seed nodes.
		123
		124	The nodes listening on those endpoints are expected to be long-running,
		125	and at least one of those should always be available. When nodes run out
		126	of connections (e.g. due to a network error), they try to re-establish
		127	connections to some seednodes again to join the network.
84		128
85	=back	129	=back
86		130
87	=head1 VARIABLES/FUNCTIONS	131	=head1 VARIABLES/FUNCTIONS
88		132
…		…
90		134
91	=cut	135	=cut
92		136
93	package AnyEvent::MP;	137	package AnyEvent::MP;
94		138
95	use AnyEvent::MP::Base;	139	use AnyEvent::MP::Kernel;
96		140
97	use common::sense;	141	use common::sense;
98		142
99	use Carp ();	143	use Carp ();
100		144
101	use AE ();	145	use AE ();
102		146
103	use base "Exporter";	147	use base "Exporter";
104		148
105	our $VERSION = '0.1';	149	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		150
106	our @EXPORT = qw(	151	our @EXPORT = qw(
107	NODE $NODE *SELF node_of _any_	152	NODE $NODE *SELF node_of after
108	resolve_node initialise_node	153	configure
109	snd rcv mon kil reg psub	154	snd rcv mon mon_guard kil reg psub spawn
110	port	155	port
111	);	156	);
112		157
113	our $SELF;	158	our $SELF;
114		159
…		…
118	kil $SELF, die => $msg;	163	kil $SELF, die => $msg;
119	}	164	}
120		165
121	=item $thisnode = NODE / $NODE	166	=item $thisnode = NODE / $NODE
122		167
123	The C<NODE> function returns, and the C<$NODE> variable contains	168	The C<NODE> function returns, and the C<$NODE> variable contains, the node
124	the noderef of the local node. The value is initialised by a call	169	ID of the node running in the current process. This value is initialised by
125	to C<become_public> or C<become_slave>, after which all local port	170	a call to C<configure>.
126	identifiers become invalid.
127		171
128	=item $noderef = node_of $portid	172	=item $nodeid = node_of $port
129		173
130	Extracts and returns the noderef from a portid or a noderef.	174	Extracts and returns the node ID from a port ID or a node ID.
131		175
132	=item $cv = resolve_node $noderef	176	=item configure $profile, key => value...
133		177
134	Takes an unresolved node reference that may contain hostnames and	178	=item configure key => value...
135	abbreviated IDs, resolves all of them and returns a resolved node
136	reference.
137		179
138	In addition to C<address:port> pairs allowed in resolved noderefs, the	180	Before a node can talk to other nodes on the network (i.e. enter
139	following forms are supported:	181	"distributed mode") it has to configure itself - the minimum a node needs
		182	to know is its own name, and optionally it should know the addresses of
		183	some other nodes in the network to discover other nodes.
		184
		185	This function configures a node - it must be called exactly once (or
		186	never) before calling other AnyEvent::MP functions.
140		187
141	=over 4	188	=over 4
142		189
143	=item the empty string	190	=item step 1, gathering configuration from profiles
144		191
145	An empty-string component gets resolved as if the default port (4040) was	192	The function first looks up a profile in the aemp configuration (see the
146	specified.	193	L<aemp> commandline utility). The profile name can be specified via the
		194	named C<profile> parameter or can simply be the first parameter). If it is
		195	missing, then the nodename (F<uname -n>) will be used as profile name.
147		196
148	=item naked port numbers (e.g. C<1234>)	197	The profile data is then gathered as follows:
149		198
150	These are resolved by prepending the local nodename and a colon, to be	199	First, all remaining key => value pairs (all of which are conveniently
151	further resolved.	200	undocumented at the moment) will be interpreted as configuration
		201	data. Then they will be overwritten by any values specified in the global
		202	default configuration (see the F<aemp> utility), then the chain of
		203	profiles chosen by the profile name (and any C<parent> attributes).
152		204
153	=item hostnames (e.g. C<localhost:1234>, C<localhost>)	205	That means that the values specified in the profile have highest priority
		206	and the values specified directly via C<configure> have lowest priority,
		207	and can only be used to specify defaults.
154		208
155	These are resolved by using AnyEvent::DNS to resolve them, optionally	209	If the profile specifies a node ID, then this will become the node ID of
156	looking up SRV records for the C<aemp=4040> port, if no port was	210	this process. If not, then the profile name will be used as node ID. The
157	specified.	211	special node ID of C<anon/> will be replaced by a random node ID.
		212
		213	=item step 2, bind listener sockets
		214
		215	The next step is to look up the binds in the profile, followed by binding
		216	aemp protocol listeners on all binds specified (it is possible and valid
		217	to have no binds, meaning that the node cannot be contacted form the
		218	outside. This means the node cannot talk to other nodes that also have no
		219	binds, but it can still talk to all "normal" nodes).
		220
		221	If the profile does not specify a binds list, then a default of C<*> is
		222	used, meaning the node will bind on a dynamically-assigned port on every
		223	local IP address it finds.
		224
		225	=item step 3, connect to seed nodes
		226
		227	As the last step, the seeds list from the profile is passed to the
		228	L<AnyEvent::MP::Global> module, which will then use it to keep
		229	connectivity with at least one node at any point in time.
158		230
159	=back	231	=back
		232
		233	Example: become a distributed node using the locla node name as profile.
		234	This should be the most common form of invocation for "daemon"-type nodes.
		235
		236	configure
		237
		238	Example: become an anonymous node. This form is often used for commandline
		239	clients.
		240
		241	configure nodeid => "anon/";
		242
		243	Example: configure a node using a profile called seed, which si suitable
		244	for a seed node as it binds on all local addresses on a fixed port (4040,
		245	customary for aemp).
		246
		247	# use the aemp commandline utility
		248	# aemp profile seed nodeid anon/ binds '*:4040'
		249
		250	# then use it
		251	configure profile => "seed";
		252
		253	# or simply use aemp from the shell again:
		254	# aemp run profile seed
		255
		256	# or provide a nicer-to-remember nodeid
		257	# aemp run profile seed nodeid "$(hostname)"
160		258
161	=item $SELF	259	=item $SELF
162		260
163	Contains the current port id while executing C<rcv> callbacks or C<psub>	261	Contains the current port id while executing C<rcv> callbacks or C<psub>
164	blocks.	262	blocks.
165		263
166	=item SELF, %SELF, @SELF...	264	=item *SELF, SELF, %SELF, @SELF...
167		265
168	Due to some quirks in how perl exports variables, it is impossible to	266	Due to some quirks in how perl exports variables, it is impossible to
169	just export C<$SELF>, all the symbols called C<SELF> are exported by this	267	just export C<$SELF>, all the symbols named C<SELF> are exported by this
170	module, but only C<$SELF> is currently used.	268	module, but only C<$SELF> is currently used.
171		269
172	=item snd $portid, type => @data	270	=item snd $port, type => @data
173		271
174	=item snd $portid, @msg	272	=item snd $port, @msg
175		273
176	Send the given message to the given port ID, which can identify either	274	Send the given message to the given port, which can identify either a
177	a local or a remote port, and can be either a string or soemthignt hat	275	local or a remote port, and must be a port ID.
178	stringifies a sa port ID (such as a port object :).
179		276
180	While the message can be about anything, it is highly recommended to use a	277	While the message can be almost anything, it is highly recommended to
181	string as first element (a portid, or some word that indicates a request	278	use a string as first element (a port ID, or some word that indicates a
182	type etc.).	279	request type etc.) and to consist if only simple perl values (scalars,
		280	arrays, hashes) - if you think you need to pass an object, think again.
183		281
184	The message data effectively becomes read-only after a call to this	282	The message data logically becomes read-only after a call to this
185	function: modifying any argument is not allowed and can cause many	283	function: modifying any argument (or values referenced by them) is
186	problems.	284	forbidden, as there can be considerable time between the call to C<snd>
		285	and the time the message is actually being serialised - in fact, it might
		286	never be copied as within the same process it is simply handed to the
		287	receiving port.
187		288
188	The type of data you can transfer depends on the transport protocol: when	289	The type of data you can transfer depends on the transport protocol: when
189	JSON is used, then only strings, numbers and arrays and hashes consisting	290	JSON is used, then only strings, numbers and arrays and hashes consisting
190	of those are allowed (no objects). When Storable is used, then anything	291	of those are allowed (no objects). When Storable is used, then anything
191	that Storable can serialise and deserialise is allowed, and for the local	292	that Storable can serialise and deserialise is allowed, and for the local
192	node, anything can be passed.	293	node, anything can be passed. Best rely only on the common denominator of
		294	these.
193		295
194	=item kil $portid[, @reason]	296	=item $local_port = port
195		297
196	Kill the specified port with the given C<@reason>.	298	Create a new local port object and returns its port ID. Initially it has
		299	no callbacks set and will throw an error when it receives messages.
197		300
198	If no C<@reason> is specified, then the port is killed "normally" (linked	301	=item $local_port = port { my @msg = @_ }
199	ports will not be kileld, or even notified).
200		302
201	Otherwise, linked ports get killed with the same reason (second form of	303	Creates a new local port, and returns its ID. Semantically the same as
202	C<mon>, see below).	304	creating a port and calling C<rcv $port, $callback> on it.
203		305
204	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	306	The block will be called for every message received on the port, with the
205	will be reported as reason C<< die => $@ >>.	307	global variable C<$SELF> set to the port ID. Runtime errors will cause the
		308	port to be C<kil>ed. The message will be passed as-is, no extra argument
		309	(i.e. no port ID) will be passed to the callback.
206		310
207	Transport/communication errors are reported as C<< transport_error =>	311	If you want to stop/destroy the port, simply C<kil> it:
208	$message >>.
209		312
210	=item $guard = mon $portid, $cb->(@reason)	313	my $port = port {
		314	my @msg = @_;
		315	...
		316	kil $SELF;
		317	};
211		318
212	=item $guard = mon $portid, $otherport	319	=cut
213		320
214	=item $guard = mon $portid, $otherport, @msg	321	sub rcv($@);
215		322
		323	sub _kilme {
		324	die "received message on port without callback";
		325	}
		326
		327	sub port(;&) {
		328	my $id = "$UNIQ." . $ID++;
		329	my $port = "$NODE#$id";
		330
		331	rcv $port, shift \|\| \&_kilme;
		332
		333	$port
		334	}
		335
		336	=item rcv $local_port, $callback->(@msg)
		337
		338	Replaces the default callback on the specified port. There is no way to
		339	remove the default callback: use C<sub { }> to disable it, or better
		340	C<kil> the port when it is no longer needed.
		341
		342	The global C<$SELF> (exported by this module) contains C<$port> while
		343	executing the callback. Runtime errors during callback execution will
		344	result in the port being C<kil>ed.
		345
		346	The default callback received all messages not matched by a more specific
		347	C<tag> match.
		348
		349	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
		350
		351	Register (or replace) callbacks to be called on messages starting with the
		352	given tag on the given port (and return the port), or unregister it (when
		353	C<$callback> is C<$undef> or missing). There can only be one callback
		354	registered for each tag.
		355
		356	The original message will be passed to the callback, after the first
		357	element (the tag) has been removed. The callback will use the same
		358	environment as the default callback (see above).
		359
		360	Example: create a port and bind receivers on it in one go.
		361
		362	my $port = rcv port,
		363	msg1 => sub { ... },
		364	msg2 => sub { ... },
		365	;
		366
		367	Example: create a port, bind receivers and send it in a message elsewhere
		368	in one go:
		369
		370	snd $otherport, reply =>
		371	rcv port,
		372	msg1 => sub { ... },
		373	...
		374	;
		375
		376	Example: temporarily register a rcv callback for a tag matching some port
		377	(e.g. for a rpc reply) and unregister it after a message was received.
		378
		379	rcv $port, $otherport => sub {
		380	my @reply = @_;
		381
		382	rcv $SELF, $otherport;
		383	};
		384
		385	=cut
		386
		387	sub rcv($@) {
		388	my $port = shift;
		389	my ($nodeid, $portid) = split /#/, $port, 2;
		390
		391	$NODE{$nodeid} == $NODE{""}
		392	or Carp::croak "$port: rcv can only be called on local ports, caught";
		393
		394	while (@_) {
		395	if (ref $_[0]) {
		396	if (my $self = $PORT_DATA{$portid}) {
		397	"AnyEvent::MP::Port" eq ref $self
		398	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		399
		400	$self->[2] = shift;
		401	} else {
		402	my $cb = shift;
		403	$PORT{$portid} = sub {
		404	local $SELF = $port;
		405	eval { &$cb }; _self_die if $@;
		406	};
		407	}
		408	} elsif (defined $_[0]) {
		409	my $self = $PORT_DATA{$portid} \|\|= do {
		410	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
		411
		412	$PORT{$portid} = sub {
		413	local $SELF = $port;
		414
		415	if (my $cb = $self->[1]{$_[0]}) {
		416	shift;
		417	eval { &$cb }; _self_die if $@;
		418	} else {
		419	&{ $self->[0] };
		420	}
		421	};
		422
		423	$self
		424	};
		425
		426	"AnyEvent::MP::Port" eq ref $self
		427	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		428
		429	my ($tag, $cb) = splice @_, 0, 2;
		430
		431	if (defined $cb) {
		432	$self->[1]{$tag} = $cb;
		433	} else {
		434	delete $self->[1]{$tag};
		435	}
		436	}
		437	}
		438
		439	$port
		440	}
		441
		442	=item $closure = psub { BLOCK }
		443
		444	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
		445	closure is executed, sets up the environment in the same way as in C<rcv>
		446	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		447
		448	This is useful when you register callbacks from C<rcv> callbacks:
		449
		450	rcv delayed_reply => sub {
		451	my ($delay, @reply) = @_;
		452	my $timer = AE::timer $delay, 0, psub {
		453	snd @reply, $SELF;
		454	};
		455	};
		456
		457	=cut
		458
		459	sub psub(&) {
		460	my $cb = shift;
		461
		462	my $port = $SELF
		463	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
		464
		465	sub {
		466	local $SELF = $port;
		467
		468	if (wantarray) {
		469	my @res = eval { &$cb };
		470	_self_die if $@;
		471	@res
		472	} else {
		473	my $res = eval { &$cb };
		474	_self_die if $@;
		475	$res
		476	}
		477	}
		478	}
		479
		480	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
		481
		482	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
		483
		484	=item $guard = mon $port # kill $SELF when $port dies
		485
		486	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
		487
216	Monitor the given port and do something when the port is killed.	488	Monitor the given port and do something when the port is killed or
		489	messages to it were lost, and optionally return a guard that can be used
		490	to stop monitoring again.
217		491
218	In the first form, the callback is simply called with any number	492	In the first form (callback), the callback is simply called with any
219	of C<@reason> elements (no @reason means that the port was deleted	493	number of C<@reason> elements (no @reason means that the port was deleted
220	"normally"). Note also that I<< the callback B<must> never die >>, so use	494	"normally"). Note also that I<< the callback B<must> never die >>, so use
221	C<eval> if unsure.	495	C<eval> if unsure.
222		496
223	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	497	In the second form (another port given), the other port (C<$rcvport>)
224	a @reason was specified, i.e. on "normal" kils nothing happens, while	498	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
225	under all other conditions, the other port is killed with the same reason.	499	"normal" kils nothing happens, while under all other conditions, the other
		500	port is killed with the same reason.
226		501
		502	The third form (kill self) is the same as the second form, except that
		503	C<$rvport> defaults to C<$SELF>.
		504
227	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	505	In the last form (message), a message of the form C<@msg, @reason> will be
		506	C<snd>.
		507
		508	Monitoring-actions are one-shot: once messages are lost (and a monitoring
		509	alert was raised), they are removed and will not trigger again.
		510
		511	As a rule of thumb, monitoring requests should always monitor a port from
		512	a local port (or callback). The reason is that kill messages might get
		513	lost, just like any other message. Another less obvious reason is that
		514	even monitoring requests can get lost (for example, when the connection
		515	to the other node goes down permanently). When monitoring a port locally
		516	these problems do not exist.
		517
		518	C<mon> effectively guarantees that, in the absence of hardware failures,
		519	after starting the monitor, either all messages sent to the port will
		520	arrive, or the monitoring action will be invoked after possible message
		521	loss has been detected. No messages will be lost "in between" (after
		522	the first lost message no further messages will be received by the
		523	port). After the monitoring action was invoked, further messages might get
		524	delivered again.
		525
		526	Inter-host-connection timeouts and monitoring depend on the transport
		527	used. The only transport currently implemented is TCP, and AnyEvent::MP
		528	relies on TCP to detect node-downs (this can take 10-15 minutes on a
		529	non-idle connection, and usually around two hours for idle conenctions).
		530
		531	This means that monitoring is good for program errors and cleaning up
		532	stuff eventually, but they are no replacement for a timeout when you need
		533	to ensure some maximum latency.
228		534
229	Example: call a given callback when C<$port> is killed.	535	Example: call a given callback when C<$port> is killed.
230		536
231	mon $port, sub { warn "port died because of <@_>\n" };	537	mon $port, sub { warn "port died because of <@_>\n" };
232		538
233	Example: kill ourselves when C<$port> is killed abnormally.	539	Example: kill ourselves when C<$port> is killed abnormally.
234		540
235	mon $port, $self;	541	mon $port;
236		542
237	Example: send us a restart message another C<$port> is killed.	543	Example: send us a restart message when another C<$port> is killed.
238		544
239	mon $port, $self => "restart";	545	mon $port, $self => "restart";
240		546
241	=cut	547	=cut
242		548
243	sub mon {	549	sub mon {
244	my ($noderef, $port) = split /#/, shift, 2;	550	my ($nodeid, $port) = split /#/, shift, 2;
245		551
246	my $node = $NODE{$noderef} \|\| add_node $noderef;	552	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
247		553
248	my $cb = shift;	554	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
249		555
250	unless (ref $cb) {	556	unless (ref $cb) {
251	if (@_) {	557	if (@_) {
252	# send a kill info message	558	# send a kill info message
253	my (@msg) = ($cb, @_);	559	my (@msg) = ($cb, @_);
…		…
271	is killed, the references will be freed.	577	is killed, the references will be freed.
272		578
273	Optionally returns a guard that will stop the monitoring.	579	Optionally returns a guard that will stop the monitoring.
274		580
275	This function is useful when you create e.g. timers or other watchers and	581	This function is useful when you create e.g. timers or other watchers and
276	want to free them when the port gets killed:	582	want to free them when the port gets killed (note the use of C<psub>):
277		583
278	$port->rcv (start => sub {	584	$port->rcv (start => sub {
279	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	585	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
280	undef $timer if 0.9 < rand;	586	undef $timer if 0.9 < rand;
281	});	587	});
282	});	588	});
283		589
284	=cut	590	=cut
285		591
286	sub mon_guard {	592	sub mon_guard {
287	my ($port, @refs) = @_;	593	my ($port, @refs) = @_;
288		594
		595	#TODO: mon-less form?
		596
289	mon $port, sub { 0 && @refs }	597	mon $port, sub { 0 && @refs }
290	}	598	}
291		599
292	=item lnk $port1, $port2	600	=item kil $port[, @reason]
293		601
294	Link two ports. This is simply a shorthand for:	602	Kill the specified port with the given C<@reason>.
295		603
296	mon $port1, $port2;	604	If no C<@reason> is specified, then the port is killed "normally" (ports
297	mon $port2, $port1;	605	monitoring other ports will not necessarily die because a port dies
		606	"normally").
298		607
299	It means that if either one is killed abnormally, the other one gets	608	Otherwise, linked ports get killed with the same reason (second form of
300	killed as well.	609	C<mon>, see above).
301		610
302	=item $local_port = port	611	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		612	will be reported as reason C<< die => $@ >>.
303		613
304	Create a new local port object that can be used either as a pattern	614	Transport/communication errors are reported as C<< transport_error =>
305	matching port ("full port") or a single-callback port ("miniport"),	615	$message >>.
306	depending on how C<rcv> callbacks are bound to the object.
307		616
308	=item $portid = port { my @msg = @_; $finished }
309
310	Creates a "mini port", that is, a very lightweight port without any
311	pattern matching behind it, and returns its ID.
312
313	The block will be called for every message received on the port. When the
314	callback returns a true value its job is considered "done" and the port
315	will be destroyed. Otherwise it will stay alive.
316
317	The message will be passed as-is, no extra argument (i.e. no port id) will
318	be passed to the callback.
319
320	If you need the local port id in the callback, this works nicely:
321
322	my $port; $port = port {
323	snd $otherport, reply => $port;
324	};
325
326	=cut	617	=cut
327		618
328	sub port(;&) {	619	=item $port = spawn $node, $initfunc[, @initdata]
329	my $id = "$UNIQ." . $ID++;
330	my $port = "$NODE#$id";
331		620
332	if (@_) {	621	Creates a port on the node C<$node> (which can also be a port ID, in which
333	my $cb = shift;	622	case it's the node where that port resides).
334	$PORT{$id} = sub {	623
335	local $SELF = $port;	624	The port ID of the newly created port is returned immediately, and it is
336	eval {	625	possible to immediately start sending messages or to monitor the port.
337	&$cb	626
338	and kil $id;	627	After the port has been created, the init function is called on the remote
		628	node, in the same context as a C<rcv> callback. This function must be a
		629	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
		630	specify a function in the main program, use C<::name>.
		631
		632	If the function doesn't exist, then the node tries to C<require>
		633	the package, then the package above the package and so on (e.g.
		634	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		635	exists or it runs out of package names.
		636
		637	The init function is then called with the newly-created port as context
		638	object (C<$SELF>) and the C<@initdata> values as arguments. It I<must>
		639	call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise
		640	the port might not get created.
		641
		642	A common idiom is to pass a local port, immediately monitor the spawned
		643	port, and in the remote init function, immediately monitor the passed
		644	local port. This two-way monitoring ensures that both ports get cleaned up
		645	when there is a problem.
		646
		647	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
		648	caller before C<spawn> returns (by delaying invocation when spawn is
		649	called for the local node).
		650
		651	Example: spawn a chat server port on C<$othernode>.
		652
		653	# this node, executed from within a port context:
		654	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		655	mon $server;
		656
		657	# init function on C<$othernode>
		658	sub connect {
		659	my ($srcport) = @_;
		660
		661	mon $srcport;
		662
		663	rcv $SELF, sub {
339	};	664	...
340	_self_die if $@;
341	};
342	} else {
343	my $self = bless {
344	id => "$NODE#$id",
345	}, "AnyEvent::MP::Port";
346
347	$PORT_DATA{$id} = $self;
348	$PORT{$id} = sub {
349	local $SELF = $port;
350
351	eval {
352	for (@{ $self->{rc0}{$_[0]} }) {
353	$_ && &{$_->[0]}
354	&& undef $_;
355	}
356
357	for (@{ $self->{rcv}{$_[0]} }) {
358	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
359	&& &{$_->[0]}
360	&& undef $_;
361	}
362
363	for (@{ $self->{any} }) {
364	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
365	&& &{$_->[0]}
366	&& undef $_;
367	}
368	};
369	_self_die if $@;
370	};	665	};
371	}	666	}
372		667
373	$port
374	}
375
376	=item reg $portid, $name
377
378	Registers the given port under the name C<$name>. If the name already
379	exists it is replaced.
380
381	A port can only be registered under one well known name.
382
383	A port automatically becomes unregistered when it is killed.
384
385	=cut	668	=cut
386		669
387	sub reg(@) {	670	sub _spawn {
388	my ($portid, $name) = @_;
389
390	$REG{$name} = $portid;
391	}
392
393	=item rcv $portid, $callback->(@msg)
394
395	Replaces the callback on the specified miniport (or newly created port
396	object, see C<port>). Full ports are configured with the following calls:
397
398	=item rcv $portid, tagstring => $callback->(@msg), ...
399
400	=item rcv $portid, $smartmatch => $callback->(@msg), ...
401
402	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
403
404	Register callbacks to be called on matching messages on the given port.
405
406	The callback has to return a true value when its work is done, after
407	which is will be removed, or a false value in which case it will stay
408	registered.
409
410	The global C<$SELF> (exported by this module) contains C<$portid> while
411	executing the callback.
412
413	Runtime errors wdurign callback execution will result in the port being
414	C<kil>ed.
415
416	If the match is an array reference, then it will be matched against the
417	first elements of the message, otherwise only the first element is being
418	matched.
419
420	Any element in the match that is specified as C<_any_> (a function
421	exported by this module) matches any single element of the message.
422
423	While not required, it is highly recommended that the first matching
424	element is a string identifying the message. The one-string-only match is
425	also the most efficient match (by far).
426
427	=cut
428
429	sub rcv($@) {
430	my $portid = shift;	671	my $port = shift;
431	my ($noderef, $port) = split /#/, $port, 2;	672	my $init = shift;
432		673
433	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	674	# rcv will create the actual port
434	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";	675	local $SELF = "$NODE#$port";
435		676	eval {
436	my $self = $PORT_DATA{$port}	677	&{ load_func $init }
437	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
438
439	"AnyEvent::MP::Port" eq ref $self
440	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
441
442	while (@_) {
443	my ($match, $cb) = splice @_, 0, 2;
444
445	if (!ref $match) {
446	push @{ $self->{rc0}{$match} }, [$cb];
447	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
448	my ($type, @match) = @$match;
449	@match
450	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
451	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
452	} else {
453	push @{ $self->{any} }, [$cb, $match];
454	}
455	}
456
457	$portid
458	}
459
460	=item $closure = psub { BLOCK }
461
462	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
463	closure is executed, sets up the environment in the same way as in C<rcv>
464	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
465
466	This is useful when you register callbacks from C<rcv> callbacks:
467
468	rcv delayed_reply => sub {
469	my ($delay, @reply) = @_;
470	my $timer = AE::timer $delay, 0, psub {
471	snd @reply, $SELF;
472	};
473	};	678	};
474
475	=cut
476
477	sub psub(&) {
478	my $cb = shift;
479
480	my $port = $SELF
481	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
482
483	sub {
484	local $SELF = $port;
485
486	if (wantarray) {
487	my @res = eval { &$cb };
488	_self_die if $@;	679	_self_die if $@;
489	@res	680	}
490	} else {	681
491	my $res = eval { &$cb };	682	sub spawn(@) {
492	_self_die if $@;	683	my ($nodeid, undef) = split /#/, shift, 2;
493	$res	684
494	}	685	my $id = "$RUNIQ." . $ID++;
		686
		687	$_[0] =~ /::/
		688	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		689
		690	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
		691
		692	"$nodeid#$id"
		693	}
		694
		695	=item after $timeout, @msg
		696
		697	=item after $timeout, $callback
		698
		699	Either sends the given message, or call the given callback, after the
		700	specified number of seconds.
		701
		702	This is simply a utility function that comes in handy at times - the
		703	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		704	so it may go away in the future.
		705
		706	=cut
		707
		708	sub after($@) {
		709	my ($timeout, @action) = @_;
		710
		711	my $t; $t = AE::timer $timeout, 0, sub {
		712	undef $t;
		713	ref $action[0]
		714	? $action[0]()
		715	: snd @action;
495	}	716	};
496	}	717	}
497		718
498	=back	719	=back
499		720
500	=head1 FUNCTIONS FOR NODES	721	=head1 AnyEvent::MP vs. Distributed Erlang
		722
		723	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
		724	== aemp node, Erlang process == aemp port), so many of the documents and
		725	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		726	sample:
		727
		728	http://www.Erlang.se/doc/programming_rules.shtml
		729	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		730	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		731	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		732
		733	Despite the similarities, there are also some important differences:
501		734
502	=over 4	735	=over 4
503		736
504	=item become_public $noderef	737	=item * Node IDs are arbitrary strings in AEMP.
505		738
506	Tells the node to become a public node, i.e. reachable from other nodes.
507
508	The first argument is the (unresolved) node reference of the local node
509	(if missing then the empty string is used).
510
511	It is quite common to not specify anything, in which case the local node
512	tries to listen on the default port, or to only specify a port number, in
513	which case AnyEvent::MP tries to guess the local addresses.
514
515	=cut
516
517	=back
518
519	=head1 NODE MESSAGES
520
521	Nodes understand the following messages sent to them. Many of them take
522	arguments called C<@reply>, which will simply be used to compose a reply
523	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
524	the remaining arguments are simply the message data.
525
526	While other messages exist, they are not public and subject to change.
527
528	=over 4
529
530	=cut
531
532	=item lookup => $name, @reply
533
534	Replies with the port ID of the specified well-known port, or C<undef>.
535
536	=item devnull => ...
537
538	Generic data sink/CPU heat conversion.
539
540	=item relay => $port, @msg
541
542	Simply forwards the message to the given port.
543
544	=item eval => $string[ @reply]
545
546	Evaluates the given string. If C<@reply> is given, then a message of the
547	form C<@reply, $@, @evalres> is sent.
548
549	Example: crash another node.
550
551	snd $othernode, eval => "exit";
552
553	=item time => @reply
554
555	Replies the the current node time to C<@reply>.
556
557	Example: tell the current node to send the current time to C<$myport> in a
558	C<timereply> message.
559
560	snd $NODE, time => $myport, timereply => 1, 2;
561	# => snd $myport, timereply => 1, 2, <time>
562
563	=back
564
565	=head1 AnyEvent::MP vs. Distributed Erlang
566
567	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node
568	== aemp node, erlang process == aemp port), so many of the documents and
569	programming techniques employed by erlang apply to AnyEvent::MP. Here is a
570	sample:
571
572	http://www.erlang.se/doc/programming_rules.shtml
573	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
574	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6
575	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
576
577	Despite the similarities, there are also some important differences:
578
579	=over 4
580
581	=item * Node references contain the recipe on how to contact them.
582
583	Erlang relies on special naming and DNS to work everywhere in the	739	Erlang relies on special naming and DNS to work everywhere in the same
584	same way. AEMP relies on each node knowing it's own address(es), with	740	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
585	convenience functionality.	741	configuration or DNS), but will otherwise discover other odes itself.
586		742
587	This means that AEMP requires a less tightly controlled environment at the	743	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
588	cost of longer node references and a slightly higher management overhead.	744	uses "local ports are like remote ports".
		745
		746	The failure modes for local ports are quite different (runtime errors
		747	only) then for remote ports - when a local port dies, you I<know> it dies,
		748	when a connection to another node dies, you know nothing about the other
		749	port.
		750
		751	Erlang pretends remote ports are as reliable as local ports, even when
		752	they are not.
		753
		754	AEMP encourages a "treat remote ports differently" philosophy, with local
		755	ports being the special case/exception, where transport errors cannot
		756	occur.
589		757
590	=item * Erlang uses processes and a mailbox, AEMP does not queue.	758	=item * Erlang uses processes and a mailbox, AEMP does not queue.
591		759
592	Erlang uses processes that selctively receive messages, and therefore	760	Erlang uses processes that selectively receive messages, and therefore
593	needs a queue. AEMP is event based, queuing messages would serve no useful	761	needs a queue. AEMP is event based, queuing messages would serve no
594	purpose.	762	useful purpose. For the same reason the pattern-matching abilities of
		763	AnyEvent::MP are more limited, as there is little need to be able to
		764	filter messages without dequeuing them.
595		765
596	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	766	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
597		767
598	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	768	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
599		769
600	Sending messages in erlang is synchronous and blocks the process. AEMP	770	Sending messages in Erlang is synchronous and blocks the process (and
601	sends are immediate, connection establishment is handled in the	771	so does not need a queue that can overflow). AEMP sends are immediate,
602	background.	772	connection establishment is handled in the background.
603		773
604	=item * Erlang can silently lose messages, AEMP cannot.	774	=item * Erlang suffers from silent message loss, AEMP does not.
605		775
606	Erlang makes few guarantees on messages delivery - messages can get lost	776	Erlang makes few guarantees on messages delivery - messages can get lost
607	without any of the processes realising it (i.e. you send messages a, b,	777	without any of the processes realising it (i.e. you send messages a, b,
608	and c, and the other side only receives messages a and c).	778	and c, and the other side only receives messages a and c).
609		779
610	AEMP guarantees correct ordering, and the guarantee that there are no	780	AEMP guarantees correct ordering, and the guarantee that after one message
611	holes in the message sequence.	781	is lost, all following ones sent to the same port are lost as well, until
612		782	monitoring raises an error, so there are no silent "holes" in the message
613	=item * In erlang, processes can be declared dead and later be found to be	783	sequence.
614	alive.
615
616	In erlang it can happen that a monitored process is declared dead and
617	linked processes get killed, but later it turns out that the process is
618	still alive - and can receive messages.
619
620	In AEMP, when port monitoring detects a port as dead, then that port will
621	eventually be killed - it cannot happen that a node detects a port as dead
622	and then later sends messages to it, finding it is still alive.
623		784
624	=item * Erlang can send messages to the wrong port, AEMP does not.	785	=item * Erlang can send messages to the wrong port, AEMP does not.
625		786
626	In erlang it is quite possible that a node that restarts reuses a process	787	In Erlang it is quite likely that a node that restarts reuses a process ID
627	ID known to other nodes for a completely different process, causing	788	known to other nodes for a completely different process, causing messages
628	messages destined for that process to end up in an unrelated process.	789	destined for that process to end up in an unrelated process.
629		790
630	AEMP never reuses port IDs, so old messages or old port IDs floating	791	AEMP never reuses port IDs, so old messages or old port IDs floating
631	around in the network will not be sent to an unrelated port.	792	around in the network will not be sent to an unrelated port.
632		793
633	=item * Erlang uses unprotected connections, AEMP uses secure	794	=item * Erlang uses unprotected connections, AEMP uses secure
634	authentication and can use TLS.	795	authentication and can use TLS.
635		796
636	AEMP can use a proven protocol - SSL/TLS - to protect connections and	797	AEMP can use a proven protocol - TLS - to protect connections and
637	securely authenticate nodes.	798	securely authenticate nodes.
638		799
639	=item * The AEMP protocol is optimised for both text-based and binary	800	=item * The AEMP protocol is optimised for both text-based and binary
640	communications.	801	communications.
641		802
642	The AEMP protocol, unlike the erlang protocol, supports both	803	The AEMP protocol, unlike the Erlang protocol, supports both programming
643	language-independent text-only protocols (good for debugging) and binary,	804	language independent text-only protocols (good for debugging) and binary,
644	language-specific serialisers (e.g. Storable).	805	language-specific serialisers (e.g. Storable). By default, unless TLS is
		806	used, the protocol is actually completely text-based.
645		807
646	It has also been carefully designed to be implementable in other languages	808	It has also been carefully designed to be implementable in other languages
647	with a minimum of work while gracefully degrading fucntionality to make the	809	with a minimum of work while gracefully degrading functionality to make the
648	protocol simple.	810	protocol simple.
649		811
		812	=item * AEMP has more flexible monitoring options than Erlang.
		813
		814	In Erlang, you can chose to receive I<all> exit signals as messages
		815	or I<none>, there is no in-between, so monitoring single processes is
		816	difficult to implement. Monitoring in AEMP is more flexible than in
		817	Erlang, as one can choose between automatic kill, exit message or callback
		818	on a per-process basis.
		819
		820	=item * Erlang tries to hide remote/local connections, AEMP does not.
		821
		822	Monitoring in Erlang is not an indicator of process death/crashes, in the
		823	same way as linking is (except linking is unreliable in Erlang).
		824
		825	In AEMP, you don't "look up" registered port names or send to named ports
		826	that might or might not be persistent. Instead, you normally spawn a port
		827	on the remote node. The init function monitors you, and you monitor the
		828	remote port. Since both monitors are local to the node, they are much more
		829	reliable (no need for C<spawn_link>).
		830
		831	This also saves round-trips and avoids sending messages to the wrong port
		832	(hard to do in Erlang).
		833
650	=back	834	=back
651		835
		836	=head1 RATIONALE
		837
		838	=over 4
		839
		840	=item Why strings for port and node IDs, why not objects?
		841
		842	We considered "objects", but found that the actual number of methods
		843	that can be called are quite low. Since port and node IDs travel over
		844	the network frequently, the serialising/deserialising would add lots of
		845	overhead, as well as having to keep a proxy object everywhere.
		846
		847	Strings can easily be printed, easily serialised etc. and need no special
		848	procedures to be "valid".
		849
		850	And as a result, a miniport consists of a single closure stored in a
		851	global hash - it can't become much cheaper.
		852
		853	=item Why favour JSON, why not a real serialising format such as Storable?
		854
		855	In fact, any AnyEvent::MP node will happily accept Storable as framing
		856	format, but currently there is no way to make a node use Storable by
		857	default (although all nodes will accept it).
		858
		859	The default framing protocol is JSON because a) JSON::XS is many times
		860	faster for small messages and b) most importantly, after years of
		861	experience we found that object serialisation is causing more problems
		862	than it solves: Just like function calls, objects simply do not travel
		863	easily over the network, mostly because they will always be a copy, so you
		864	always have to re-think your design.
		865
		866	Keeping your messages simple, concentrating on data structures rather than
		867	objects, will keep your messages clean, tidy and efficient.
		868
		869	=back
		870
652	=head1 SEE ALSO	871	=head1 SEE ALSO
		872
		873	L<AnyEvent::MP::Intro> - a gentle introduction.
		874
		875	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		876
		877	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		878	your applications.
		879
		880	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
		881	all nodes.
653		882
654	L<AnyEvent>.	883	L<AnyEvent>.
655		884
656	=head1 AUTHOR	885	=head1 AUTHOR
657		886

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Revision 1.31 by root, Wed Aug 5 19:55:58 2009 UTC vs.
Revision 1.83 by root, Tue Sep 8 01:38:16 2009 UTC