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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.26 by root, Tue Aug 4 22:05:43 2009 UTC vs.
Revision 1.74 by root, Mon Aug 31 11:11:27 2009 UTC

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

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.26 by root, Tue Aug 4 22:05:43 2009 UTC vs. Revision 1.74 by root, Mon Aug 31 11:11:27 2009 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.26 by root, Tue Aug 4 22:05:43 2009 UTC vs.
Revision 1.74 by root, Mon Aug 31 11:11:27 2009 UTC