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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.27 by root, Tue Aug 4 22:13:45 2009 UTC vs.
Revision 1.70 by root, Sun Aug 30 19:49:47 2009 UTC

…		…
8		8
9	$NODE # contains this node's noderef	9	$NODE # contains this node's noderef
10	NODE # returns this node's noderef	10	NODE # returns this node's noderef
11	NODE $port # returns the noderef of the port	11	NODE $port # returns the noderef of the port
12		12
		13	$SELF # receiving/own port id in rcv callbacks
		14
		15	# initialise the node so it can send/receive messages
		16	initialise_node;
		17
		18	# ports are message endpoints
		19
		20	# sending messages
13	snd $port, type => data...;	21	snd $port, type => data...;
		22	snd $port, @msg;
		23	snd @msg_with_first_element_being_a_port;
14		24
15	$SELF # receiving/own port id in rcv callbacks	25	# creating/using ports, the simple way
		26	my $simple_port = port { my @msg = @_; 0 };
16		27
17	rcv $port, smartmatch => $cb->($port, @msg);	28	# creating/using ports, tagged message matching
18		29	my $port = port;
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	30	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
21	rcv $port1, pong => sub { warn "pong received\n" };	31	rcv $port, pong => sub { warn "pong received\n"; 0 };
22	snd $port2, ping => $port1;
23		32
24	# more, smarter, matches (_any_ is exported by this module)	33	# create a port on another node
25	rcv $port, [child_died => $pid] => sub { ...	34	my $port = spawn $node, $initfunc, @initdata;
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	35
		36	# monitoring
		37	mon $port, $cb->(@msg) # callback is invoked on death
		38	mon $port, $otherport # kill otherport on abnormal death
		39	mon $port, $otherport, @msg # send message on death
		40
		41	=head1 CURRENT STATUS
		42
		43	AnyEvent::MP - stable API, should work
		44	AnyEvent::MP::Intro - outdated
		45	AnyEvent::MP::Kernel - mostly stable
		46	AnyEvent::MP::Global - mostly stable
		47	AnyEvent::MP::Node - mostly stable, but internal anyways
		48	AnyEvent::MP::Transport - mostly stable, but internal anyways
		49
		50	stay tuned.
27		51
28	=head1 DESCRIPTION	52	=head1 DESCRIPTION
29		53
30	This module (-family) implements a simple message passing framework.	54	This module (-family) implements a simple message passing framework.
31		55
32	Despite its simplicity, you can securely message other processes running	56	Despite its simplicity, you can securely message other processes running
33	on the same or other hosts.	57	on the same or other hosts, and you can supervise entities remotely.
34		58
35	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	59	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
36	manual page.	60	manual page and the examples under F<eg/>.
37		61
38	At the moment, this module family is severly broken and underdocumented,	62	At the moment, this module family is a bit underdocumented.
39	so do not use. This was uploaded mainly to reserve the CPAN namespace -
40	stay tuned! The basic API should be finished, however.
41		63
42	=head1 CONCEPTS	64	=head1 CONCEPTS
43		65
44	=over 4	66	=over 4
45		67
46	=item port	68	=item port
47		69
48	A port is something you can send messages to with the C<snd> function, and	70	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		71
		72	Ports allow you to register C<rcv> handlers that can match all or just
		73	some messages. Messages send to ports will not be queued, regardless of
		74	anything was listening for them or not.
		75
52	=item port id - C<noderef#portname>	76	=item port ID - C<nodeid#portname>
53		77
54	A port id is always the noderef, a hash-mark (C<#>) as separator, followed	78	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).	79	separator, and a port name (a printable string of unspecified format).
56		80
57	=item node	81	=item node
58		82
59	A node is a single process containing at least one port - the node	83	A node is a single process containing at least one port - the node port,
60	port. You can send messages to node ports to let them create new ports,	84	which enables nodes to manage each other remotely, and to create new
61	among other things.	85	ports.
62		86
63	Initially, nodes are either private (single-process only) or hidden	87	Nodes are either public (have one or more listening ports) or private
64	(connected to a master node only). Only when they epxlicitly "become	88	(no listening ports). Private nodes cannot talk to other private nodes
65	public" can you send them messages from unrelated other nodes.	89	currently.
66		90
67	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	91	=item node ID - C<[a-za-Z0-9_\-.:]+>
68		92
69	A noderef is a string that either uniquely identifies a given node (for	93	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	94	network. Depending on the configuration used, node IDs can look like a
71	node (for public nodes).	95	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
		96	doesn't interpret node IDs in any way.
		97
		98	=item binds - C<ip:port>
		99
		100	Nodes can only talk to each other by creating some kind of connection to
		101	each other. To do this, nodes should listen on one or more local transport
		102	endpoints - binds. Currently, only standard C<ip:port> specifications can
		103	be used, which specify TCP ports to listen on.
		104
		105	=item seeds - C<host:port>
		106
		107	When a node starts, it knows nothing about the network. To teach the node
		108	about the network it first has to contact some other node within the
		109	network. This node is called a seed.
		110
		111	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes
		112	are expected to be long-running, and at least one of those should always
		113	be available. When nodes run out of connections (e.g. due to a network
		114	error), they try to re-establish connections to some seednodes again to
		115	join the network.
		116
		117	Apart from being sued for seeding, seednodes are not special in any way -
		118	every public node can be a seednode.
72		119
73	=back	120	=back
74		121
75	=head1 VARIABLES/FUNCTIONS	122	=head1 VARIABLES/FUNCTIONS
76		123
…		…
78		125
79	=cut	126	=cut
80		127
81	package AnyEvent::MP;	128	package AnyEvent::MP;
82		129
83	use AnyEvent::MP::Base;	130	use AnyEvent::MP::Kernel;
84		131
85	use common::sense;	132	use common::sense;
86		133
87	use Carp ();	134	use Carp ();
88		135
89	use AE ();	136	use AE ();
90		137
91	use base "Exporter";	138	use base "Exporter";
92		139
93	our $VERSION = '0.1';	140	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		141
94	our @EXPORT = qw(	142	our @EXPORT = qw(
95	NODE $NODE *SELF node_of _any_	143	NODE $NODE *SELF node_of after
96	become_slave become_public	144	initialise_node
97	snd rcv mon kil reg psub	145	snd rcv mon mon_guard kil reg psub spawn
98	port	146	port
99	);	147	);
100		148
101	our $SELF;	149	our $SELF;
102		150
…		…
106	kil $SELF, die => $msg;	154	kil $SELF, die => $msg;
107	}	155	}
108		156
109	=item $thisnode = NODE / $NODE	157	=item $thisnode = NODE / $NODE
110		158
111	The C<NODE> function returns, and the C<$NODE> variable contains	159	The C<NODE> function returns, and the C<$NODE> variable contains, the node
112	the noderef of the local node. The value is initialised by a call	160	ID of the node running in the current process. This value is initialised by
113	to C<become_public> or C<become_slave>, after which all local port	161	a call to C<initialise_node>.
114	identifiers become invalid.
115		162
116	=item $noderef = node_of $portid	163	=item $nodeid = node_of $port
117		164
118	Extracts and returns the noderef from a portid or a noderef.	165	Extracts and returns the node ID from a port ID or a node ID.
		166
		167	=item initialise_node $profile_name, key => value...
		168
		169	Before a node can talk to other nodes on the network (i.e. enter
		170	"distributed mode") it has to initialise itself - the minimum a node needs
		171	to know is its own name, and optionally it should know the addresses of
		172	some other nodes in the network to discover other nodes.
		173
		174	This function initialises a node - it must be called exactly once (or
		175	never) before calling other AnyEvent::MP functions.
		176
		177	The first argument is a profile name. If it is C<undef> or missing, then
		178	the current nodename will be used instead (i.e. F<uname -n>).
		179
		180	The function first looks up the profile in the aemp configuration (see the
		181	L<aemp> commandline utility). the profile is calculated as follows:
		182
		183	First, all remaining key => value pairs (all of which are conviniently
		184	undocumented at the moment) will be used. Then they will be overwritten by
		185	any values specified in the global default configuration (see the F<aemp>
		186	utility), then the chain of profiles selected, if any. That means that
		187	the values specified in the profile have highest priority and the values
		188	specified via C<initialise_node> have lowest priority.
		189
		190	If the profile specifies a node ID, then this will become the node ID of
		191	this process. If not, then the profile name will be used as node ID. The
		192	special node ID of C<anon/> will be replaced by a random node ID.
		193
		194	The next step is to look up the binds in the profile, followed by binding
		195	aemp protocol listeners on all binds specified (it is possible and valid
		196	to have no binds, meaning that the node cannot be contacted form the
		197	outside. This means the node cannot talk to other nodes that also have no
		198	binds, but it can still talk to all "normal" nodes).
		199
		200	If the profile does not specify a binds list, then a default of C<*> is
		201	used.
		202
		203	Lastly, the seeds list from the profile is passed to the
		204	L<AnyEvent::MP::Global> module, which will then use it to keep
		205	connectivity with at least on of those seed nodes at any point in time.
		206
		207	Example: become a distributed node listening on the guessed noderef, or
		208	the one specified via C<aemp> for the current node. This should be the
		209	most common form of invocation for "daemon"-type nodes.
		210
		211	initialise_node;
		212
		213	Example: become an anonymous node. This form is often used for commandline
		214	clients.
		215
		216	initialise_node "anon/";
		217
		218	Example: become a distributed node. If there is no profile of the given
		219	name, or no binds list was specified, resolve C<localhost:4044> and bind
		220	on the resulting addresses.
		221
		222	initialise_node "localhost:4044";
119		223
120	=item $SELF	224	=item $SELF
121		225
122	Contains the current port id while executing C<rcv> callbacks or C<psub>	226	Contains the current port id while executing C<rcv> callbacks or C<psub>
123	blocks.	227	blocks.
124		228
125	=item SELF, %SELF, @SELF...	229	=item *SELF, SELF, %SELF, @SELF...
126		230
127	Due to some quirks in how perl exports variables, it is impossible to	231	Due to some quirks in how perl exports variables, it is impossible to
128	just export C<$SELF>, all the symbols called C<SELF> are exported by this	232	just export C<$SELF>, all the symbols named C<SELF> are exported by this
129	module, but only C<$SELF> is currently used.	233	module, but only C<$SELF> is currently used.
130		234
131	=item snd $portid, type => @data	235	=item snd $port, type => @data
132		236
133	=item snd $portid, @msg	237	=item snd $port, @msg
134		238
135	Send the given message to the given port ID, which can identify either	239	Send the given message to the given port, which can identify either a
136	a local or a remote port, and can be either a string or soemthignt hat	240	local or a remote port, and must be a port ID.
137	stringifies a sa port ID (such as a port object :).
138		241
139	While the message can be about anything, it is highly recommended to use a	242	While the message can be almost anything, it is highly recommended to
140	string as first element (a portid, or some word that indicates a request	243	use a string as first element (a port ID, or some word that indicates a
141	type etc.).	244	request type etc.) and to consist if only simple perl values (scalars,
		245	arrays, hashes) - if you think you need to pass an object, think again.
142		246
143	The message data effectively becomes read-only after a call to this	247	The message data logically becomes read-only after a call to this
144	function: modifying any argument is not allowed and can cause many	248	function: modifying any argument (or values referenced by them) is
145	problems.	249	forbidden, as there can be considerable time between the call to C<snd>
		250	and the time the message is actually being serialised - in fact, it might
		251	never be copied as within the same process it is simply handed to the
		252	receiving port.
146		253
147	The type of data you can transfer depends on the transport protocol: when	254	The type of data you can transfer depends on the transport protocol: when
148	JSON is used, then only strings, numbers and arrays and hashes consisting	255	JSON is used, then only strings, numbers and arrays and hashes consisting
149	of those are allowed (no objects). When Storable is used, then anything	256	of those are allowed (no objects). When Storable is used, then anything
150	that Storable can serialise and deserialise is allowed, and for the local	257	that Storable can serialise and deserialise is allowed, and for the local
151	node, anything can be passed.	258	node, anything can be passed. Best rely only on the common denominator of
		259	these.
152		260
153	=item kil $portid[, @reason]	261	=item $local_port = port
154		262
155	Kill the specified port with the given C<@reason>.	263	Create a new local port object and returns its port ID. Initially it has
		264	no callbacks set and will throw an error when it receives messages.
156		265
157	If no C<@reason> is specified, then the port is killed "normally" (linked	266	=item $local_port = port { my @msg = @_ }
158	ports will not be kileld, or even notified).
159		267
160	Otherwise, linked ports get killed with the same reason (second form of	268	Creates a new local port, and returns its ID. Semantically the same as
161	C<mon>, see below).	269	creating a port and calling C<rcv $port, $callback> on it.
162		270
163	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	271	The block will be called for every message received on the port, with the
164	will be reported as reason C<< die => $@ >>.	272	global variable C<$SELF> set to the port ID. Runtime errors will cause the
		273	port to be C<kil>ed. The message will be passed as-is, no extra argument
		274	(i.e. no port ID) will be passed to the callback.
165		275
166	Transport/communication errors are reported as C<< transport_error =>	276	If you want to stop/destroy the port, simply C<kil> it:
167	$message >>.
168		277
169	=item $guard = mon $portid, $cb->(@reason)	278	my $port = port {
		279	my @msg = @_;
		280	...
		281	kil $SELF;
		282	};
170		283
171	=item $guard = mon $portid, $otherport	284	=cut
172		285
173	=item $guard = mon $portid, $otherport, @msg	286	sub rcv($@);
174		287
		288	sub _kilme {
		289	die "received message on port without callback";
		290	}
		291
		292	sub port(;&) {
		293	my $id = "$UNIQ." . $ID++;
		294	my $port = "$NODE#$id";
		295
		296	rcv $port, shift \|\| \&_kilme;
		297
		298	$port
		299	}
		300
		301	=item rcv $local_port, $callback->(@msg)
		302
		303	Replaces the default callback on the specified port. There is no way to
		304	remove the default callback: use C<sub { }> to disable it, or better
		305	C<kil> the port when it is no longer needed.
		306
		307	The global C<$SELF> (exported by this module) contains C<$port> while
		308	executing the callback. Runtime errors during callback execution will
		309	result in the port being C<kil>ed.
		310
		311	The default callback received all messages not matched by a more specific
		312	C<tag> match.
		313
		314	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
		315
		316	Register (or replace) callbacks to be called on messages starting with the
		317	given tag on the given port (and return the port), or unregister it (when
		318	C<$callback> is C<$undef> or missing). There can only be one callback
		319	registered for each tag.
		320
		321	The original message will be passed to the callback, after the first
		322	element (the tag) has been removed. The callback will use the same
		323	environment as the default callback (see above).
		324
		325	Example: create a port and bind receivers on it in one go.
		326
		327	my $port = rcv port,
		328	msg1 => sub { ... },
		329	msg2 => sub { ... },
		330	;
		331
		332	Example: create a port, bind receivers and send it in a message elsewhere
		333	in one go:
		334
		335	snd $otherport, reply =>
		336	rcv port,
		337	msg1 => sub { ... },
		338	...
		339	;
		340
		341	Example: temporarily register a rcv callback for a tag matching some port
		342	(e.g. for a rpc reply) and unregister it after a message was received.
		343
		344	rcv $port, $otherport => sub {
		345	my @reply = @_;
		346
		347	rcv $SELF, $otherport;
		348	};
		349
		350	=cut
		351
		352	sub rcv($@) {
		353	my $port = shift;
		354	my ($noderef, $portid) = split /#/, $port, 2;
		355
		356	$NODE{$noderef} == $NODE{""}
		357	or Carp::croak "$port: rcv can only be called on local ports, caught";
		358
		359	while (@_) {
		360	if (ref $_[0]) {
		361	if (my $self = $PORT_DATA{$portid}) {
		362	"AnyEvent::MP::Port" eq ref $self
		363	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		364
		365	$self->[2] = shift;
		366	} else {
		367	my $cb = shift;
		368	$PORT{$portid} = sub {
		369	local $SELF = $port;
		370	eval { &$cb }; _self_die if $@;
		371	};
		372	}
		373	} elsif (defined $_[0]) {
		374	my $self = $PORT_DATA{$portid} \|\|= do {
		375	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
		376
		377	$PORT{$portid} = sub {
		378	local $SELF = $port;
		379
		380	if (my $cb = $self->[1]{$_[0]}) {
		381	shift;
		382	eval { &$cb }; _self_die if $@;
		383	} else {
		384	&{ $self->[0] };
		385	}
		386	};
		387
		388	$self
		389	};
		390
		391	"AnyEvent::MP::Port" eq ref $self
		392	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		393
		394	my ($tag, $cb) = splice @_, 0, 2;
		395
		396	if (defined $cb) {
		397	$self->[1]{$tag} = $cb;
		398	} else {
		399	delete $self->[1]{$tag};
		400	}
		401	}
		402	}
		403
		404	$port
		405	}
		406
		407	=item $closure = psub { BLOCK }
		408
		409	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
		410	closure is executed, sets up the environment in the same way as in C<rcv>
		411	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		412
		413	This is useful when you register callbacks from C<rcv> callbacks:
		414
		415	rcv delayed_reply => sub {
		416	my ($delay, @reply) = @_;
		417	my $timer = AE::timer $delay, 0, psub {
		418	snd @reply, $SELF;
		419	};
		420	};
		421
		422	=cut
		423
		424	sub psub(&) {
		425	my $cb = shift;
		426
		427	my $port = $SELF
		428	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
		429
		430	sub {
		431	local $SELF = $port;
		432
		433	if (wantarray) {
		434	my @res = eval { &$cb };
		435	_self_die if $@;
		436	@res
		437	} else {
		438	my $res = eval { &$cb };
		439	_self_die if $@;
		440	$res
		441	}
		442	}
		443	}
		444
		445	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
		446
		447	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
		448
		449	=item $guard = mon $port # kill $SELF when $port dies
		450
		451	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
		452
175	Monitor the given port and do something when the port is killed.	453	Monitor the given port and do something when the port is killed or
		454	messages to it were lost, and optionally return a guard that can be used
		455	to stop monitoring again.
176		456
		457	C<mon> effectively guarantees that, in the absence of hardware failures,
		458	after starting the monitor, either all messages sent to the port will
		459	arrive, or the monitoring action will be invoked after possible message
		460	loss has been detected. No messages will be lost "in between" (after
		461	the first lost message no further messages will be received by the
		462	port). After the monitoring action was invoked, further messages might get
		463	delivered again.
		464
		465	Note that monitoring-actions are one-shot: once messages are lost (and a
		466	monitoring alert was raised), they are removed and will not trigger again.
		467
177	In the first form, the callback is simply called with any number	468	In the first form (callback), the callback is simply called with any
178	of C<@reason> elements (no @reason means that the port was deleted	469	number of C<@reason> elements (no @reason means that the port was deleted
179	"normally"). Note also that I<< the callback B<must> never die >>, so use	470	"normally"). Note also that I<< the callback B<must> never die >>, so use
180	C<eval> if unsure.	471	C<eval> if unsure.
181		472
182	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	473	In the second form (another port given), the other port (C<$rcvport>)
183	a @reason was specified, i.e. on "normal" kils nothing happens, while	474	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
184	under all other conditions, the other port is killed with the same reason.	475	"normal" kils nothing happens, while under all other conditions, the other
		476	port is killed with the same reason.
185		477
		478	The third form (kill self) is the same as the second form, except that
		479	C<$rvport> defaults to C<$SELF>.
		480
186	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	481	In the last form (message), a message of the form C<@msg, @reason> will be
		482	C<snd>.
		483
		484	As a rule of thumb, monitoring requests should always monitor a port from
		485	a local port (or callback). The reason is that kill messages might get
		486	lost, just like any other message. Another less obvious reason is that
		487	even monitoring requests can get lost (for exmaple, when the connection
		488	to the other node goes down permanently). When monitoring a port locally
		489	these problems do not exist.
187		490
188	Example: call a given callback when C<$port> is killed.	491	Example: call a given callback when C<$port> is killed.
189		492
190	mon $port, sub { warn "port died because of <@_>\n" };	493	mon $port, sub { warn "port died because of <@_>\n" };
191		494
192	Example: kill ourselves when C<$port> is killed abnormally.	495	Example: kill ourselves when C<$port> is killed abnormally.
193		496
194	mon $port, $self;	497	mon $port;
195		498
196	Example: send us a restart message another C<$port> is killed.	499	Example: send us a restart message when another C<$port> is killed.
197		500
198	mon $port, $self => "restart";	501	mon $port, $self => "restart";
199		502
200	=cut	503	=cut
201		504
202	sub mon {	505	sub mon {
203	my ($noderef, $port, $cb) = ((split /#/, shift, 2), shift);	506	my ($noderef, $port) = split /#/, shift, 2;
204		507
205	my $node = $NODE{$noderef} \|\| add_node $noderef;	508	my $node = $NODE{$noderef} \|\| add_node $noderef;
206		509
207	#TODO: ports must not be references	510	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) {	511
		512	unless (ref $cb) {
209	if (@_) {	513	if (@_) {
210	# send a kill info message	514	# send a kill info message
211	my (@msg) = ($cb, @_);	515	my (@msg) = ($cb, @_);
212	$cb = sub { snd @msg, @_ };	516	$cb = sub { snd @msg, @_ };
213	} else {	517	} else {
…		…
229	is killed, the references will be freed.	533	is killed, the references will be freed.
230		534
231	Optionally returns a guard that will stop the monitoring.	535	Optionally returns a guard that will stop the monitoring.
232		536
233	This function is useful when you create e.g. timers or other watchers and	537	This function is useful when you create e.g. timers or other watchers and
234	want to free them when the port gets killed:	538	want to free them when the port gets killed (note the use of C<psub>):
235		539
236	$port->rcv (start => sub {	540	$port->rcv (start => sub {
237	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	541	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
238	undef $timer if 0.9 < rand;	542	undef $timer if 0.9 < rand;
239	});	543	});
240	});	544	});
241		545
242	=cut	546	=cut
243		547
244	sub mon_guard {	548	sub mon_guard {
245	my ($port, @refs) = @_;	549	my ($port, @refs) = @_;
246		550
		551	#TODO: mon-less form?
		552
247	mon $port, sub { 0 && @refs }	553	mon $port, sub { 0 && @refs }
248	}	554	}
249		555
250	=item lnk $port1, $port2	556	=item kil $port[, @reason]
251		557
252	Link two ports. This is simply a shorthand for:	558	Kill the specified port with the given C<@reason>.
253		559
254	mon $port1, $port2;	560	If no C<@reason> is specified, then the port is killed "normally" (ports
255	mon $port2, $port1;	561	monitoring other ports will not necessarily die because a port dies
		562	"normally").
256		563
257	It means that if either one is killed abnormally, the other one gets	564	Otherwise, linked ports get killed with the same reason (second form of
258	killed as well.	565	C<mon>, see above).
259		566
260	=item $local_port = port	567	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		568	will be reported as reason C<< die => $@ >>.
261		569
262	Create a new local port object that supports message matching.	570	Transport/communication errors are reported as C<< transport_error =>
		571	$message >>.
263		572
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	573	=cut
283		574
284	sub port(;&) {	575	=item $port = spawn $node, $initfunc[, @initdata]
285	my $id = "$UNIQ." . $ID++;
286	my $port = "$NODE#$id";
287		576
288	if (@_) {	577	Creates a port on the node C<$node> (which can also be a port ID, in which
289	my $cb = shift;	578	case it's the node where that port resides).
290	$PORT{$id} = sub {	579
291	local $SELF = $port;	580	The port ID of the newly created port is returned immediately, and it is
292	eval {	581	possible to immediately start sending messages or to monitor the port.
293	&$cb	582
294	and kil $id;	583	After the port has been created, the init function is called on the remote
		584	node, in the same context as a C<rcv> callback. This function must be a
		585	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
		586	specify a function in the main program, use C<::name>.
		587
		588	If the function doesn't exist, then the node tries to C<require>
		589	the package, then the package above the package and so on (e.g.
		590	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		591	exists or it runs out of package names.
		592
		593	The init function is then called with the newly-created port as context
		594	object (C<$SELF>) and the C<@initdata> values as arguments.
		595
		596	A common idiom is to pass a local port, immediately monitor the spawned
		597	port, and in the remote init function, immediately monitor the passed
		598	local port. This two-way monitoring ensures that both ports get cleaned up
		599	when there is a problem.
		600
		601	Example: spawn a chat server port on C<$othernode>.
		602
		603	# this node, executed from within a port context:
		604	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		605	mon $server;
		606
		607	# init function on C<$othernode>
		608	sub connect {
		609	my ($srcport) = @_;
		610
		611	mon $srcport;
		612
		613	rcv $SELF, sub {
295	};	614	...
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	};	615	};
327	}	616	}
328		617
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	618	=cut
342		619
343	sub reg(@) {	620	sub _spawn {
344	my ($portid, $name) = @_;	621	my $port = shift;
		622	my $init = shift;
345		623
346	$REG{$name} = $portid;	624	local $SELF = "$NODE#$port";
347	}	625	eval {
348		626	&{ 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	};	627	};
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 $@;	628	_self_die if $@;
437	@res	629	}
438	} else {	630
439	my $res = eval { &$cb };	631	sub spawn(@) {
440	_self_die if $@;	632	my ($noderef, undef) = split /#/, shift, 2;
441	$res	633
442	}	634	my $id = "$RUNIQ." . $ID++;
		635
		636	$_[0] =~ /::/
		637	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		638
		639	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
		640
		641	"$noderef#$id"
		642	}
		643
		644	=item after $timeout, @msg
		645
		646	=item after $timeout, $callback
		647
		648	Either sends the given message, or call the given callback, after the
		649	specified number of seconds.
		650
		651	This is simply a utility function that comes in handy at times - the
		652	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		653	so it may go away in the future.
		654
		655	=cut
		656
		657	sub after($@) {
		658	my ($timeout, @action) = @_;
		659
		660	my $t; $t = AE::timer $timeout, 0, sub {
		661	undef $t;
		662	ref $action[0]
		663	? $action[0]()
		664	: snd @action;
443	}	665	};
444	}	666	}
445		667
446	=back	668	=back
447		669
448	=head1 FUNCTIONS FOR NODES	670	=head1 AnyEvent::MP vs. Distributed Erlang
		671
		672	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
		673	== aemp node, Erlang process == aemp port), so many of the documents and
		674	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		675	sample:
		676
		677	http://www.Erlang.se/doc/programming_rules.shtml
		678	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		679	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		680	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		681
		682	Despite the similarities, there are also some important differences:
449		683
450	=over 4	684	=over 4
451		685
452	=item become_public endpoint...	686	=item * Node IDs are arbitrary strings in AEMP.
453		687
454	Tells the node to become a public node, i.e. reachable from other nodes.
455
456	If no arguments are given, or the first argument is C<undef>, then
457	AnyEvent::MP tries to bind on port C<4040> on all IP addresses that the
458	local nodename resolves to.
459
460	Otherwise the first argument must be an array-reference with transport
461	endpoints ("ip:port", "hostname:port") or port numbers (in which case the
462	local nodename is used as hostname). The endpoints are all resolved and
463	will become the node reference.
464
465	=cut
466
467	=back
468
469	=head1 NODE MESSAGES
470
471	Nodes understand the following messages sent to them. Many of them take
472	arguments called C<@reply>, which will simply be used to compose a reply
473	message - C<$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 (erlang node
516	== aemp node, erlang process == aemp port), so many of the documents and
517	programming techniques employed by erlang apply to AnyEvent::MP. Here is a
518	sample:
519
520	http://www.erlang.se/doc/programming_rules.shtml
521	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
522	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6
523	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
524
525	Despite the similarities, there are also some important differences:
526
527	=over 4
528
529	=item * Node references contain the recipe on how to contact them.
530
531	Erlang relies on special naming and DNS to work everywhere in the	688	Erlang relies on special naming and DNS to work everywhere in the same
532	same way. AEMP relies on each node knowing it's own address(es), with	689	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
533	convenience functionality.	690	configuraiton or DNS), but will otherwise discover other odes itself.
534		691
535	This means that AEMP requires a less tightly controlled environment at the	692	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
536	cost of longer node references and a slightly higher management overhead.	693	uses "local ports are like remote ports".
		694
		695	The failure modes for local ports are quite different (runtime errors
		696	only) then for remote ports - when a local port dies, you I<know> it dies,
		697	when a connection to another node dies, you know nothing about the other
		698	port.
		699
		700	Erlang pretends remote ports are as reliable as local ports, even when
		701	they are not.
		702
		703	AEMP encourages a "treat remote ports differently" philosophy, with local
		704	ports being the special case/exception, where transport errors cannot
		705	occur.
537		706
538	=item * Erlang uses processes and a mailbox, AEMP does not queue.	707	=item * Erlang uses processes and a mailbox, AEMP does not queue.
539		708
540	Erlang uses processes that selctively receive messages, and therefore	709	Erlang uses processes that selectively receive messages, and therefore
541	needs a queue. AEMP is event based, queuing messages would serve no useful	710	needs a queue. AEMP is event based, queuing messages would serve no
542	purpose.	711	useful purpose. For the same reason the pattern-matching abilities of
		712	AnyEvent::MP are more limited, as there is little need to be able to
		713	filter messages without dequeing them.
543		714
544	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	715	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
545		716
546	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	717	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
547		718
548	Sending messages in erlang is synchronous and blocks the process. AEMP	719	Sending messages in Erlang is synchronous and blocks the process (and
549	sends are immediate, connection establishment is handled in the	720	so does not need a queue that can overflow). AEMP sends are immediate,
550	background.	721	connection establishment is handled in the background.
551		722
552	=item * Erlang can silently lose messages, AEMP cannot.	723	=item * Erlang suffers from silent message loss, AEMP does not.
553		724
554	Erlang makes few guarantees on messages delivery - messages can get lost	725	Erlang makes few guarantees on messages delivery - messages can get lost
555	without any of the processes realising it (i.e. you send messages a, b,	726	without any of the processes realising it (i.e. you send messages a, b,
556	and c, and the other side only receives messages a and c).	727	and c, and the other side only receives messages a and c).
557		728
558	AEMP guarantees correct ordering, and the guarantee that there are no	729	AEMP guarantees correct ordering, and the guarantee that after one message
559	holes in the message sequence.	730	is lost, all following ones sent to the same port are lost as well, until
560		731	monitoring raises an error, so there are no silent "holes" in the message
561	=item * In erlang, processes can be declared dead and later be found to be	732	sequence.
562	alive.
563
564	In erlang it can happen that a monitored process is declared dead and
565	linked processes get killed, but later it turns out that the process is
566	still alive - and can receive messages.
567
568	In AEMP, when port monitoring detects a port as dead, then that port will
569	eventually be killed - it cannot happen that a node detects a port as dead
570	and then later sends messages to it, finding it is still alive.
571		733
572	=item * Erlang can send messages to the wrong port, AEMP does not.	734	=item * Erlang can send messages to the wrong port, AEMP does not.
573		735
574	In erlang it is quite possible that a node that restarts reuses a process	736	In Erlang it is quite likely that a node that restarts reuses a process ID
575	ID known to other nodes for a completely different process, causing	737	known to other nodes for a completely different process, causing messages
576	messages destined for that process to end up in an unrelated process.	738	destined for that process to end up in an unrelated process.
577		739
578	AEMP never reuses port IDs, so old messages or old port IDs floating	740	AEMP never reuses port IDs, so old messages or old port IDs floating
579	around in the network will not be sent to an unrelated port.	741	around in the network will not be sent to an unrelated port.
580		742
581	=item * Erlang uses unprotected connections, AEMP uses secure	743	=item * Erlang uses unprotected connections, AEMP uses secure
582	authentication and can use TLS.	744	authentication and can use TLS.
583		745
584	AEMP can use a proven protocol - SSL/TLS - to protect connections and	746	AEMP can use a proven protocol - TLS - to protect connections and
585	securely authenticate nodes.	747	securely authenticate nodes.
586		748
		749	=item * The AEMP protocol is optimised for both text-based and binary
		750	communications.
		751
		752	The AEMP protocol, unlike the Erlang protocol, supports both programming
		753	language independent text-only protocols (good for debugging) and binary,
		754	language-specific serialisers (e.g. Storable). By default, unless TLS is
		755	used, the protocol is actually completely text-based.
		756
		757	It has also been carefully designed to be implementable in other languages
		758	with a minimum of work while gracefully degrading functionality to make the
		759	protocol simple.
		760
		761	=item * AEMP has more flexible monitoring options than Erlang.
		762
		763	In Erlang, you can chose to receive I<all> exit signals as messages
		764	or I<none>, there is no in-between, so monitoring single processes is
		765	difficult to implement. Monitoring in AEMP is more flexible than in
		766	Erlang, as one can choose between automatic kill, exit message or callback
		767	on a per-process basis.
		768
		769	=item * Erlang tries to hide remote/local connections, AEMP does not.
		770
		771	Monitoring in Erlang is not an indicator of process death/crashes, in the
		772	same way as linking is (except linking is unreliable in Erlang).
		773
		774	In AEMP, you don't "look up" registered port names or send to named ports
		775	that might or might not be persistent. Instead, you normally spawn a port
		776	on the remote node. The init function monitors you, and you monitor the
		777	remote port. Since both monitors are local to the node, they are much more
		778	reliable (no need for C<spawn_link>).
		779
		780	This also saves round-trips and avoids sending messages to the wrong port
		781	(hard to do in Erlang).
		782
587	=back	783	=back
588		784
		785	=head1 RATIONALE
		786
		787	=over 4
		788
		789	=item Why strings for port and node IDs, why not objects?
		790
		791	We considered "objects", but found that the actual number of methods
		792	that can be called are quite low. Since port and node IDs travel over
		793	the network frequently, the serialising/deserialising would add lots of
		794	overhead, as well as having to keep a proxy object everywhere.
		795
		796	Strings can easily be printed, easily serialised etc. and need no special
		797	procedures to be "valid".
		798
		799	And as a result, a miniport consists of a single closure stored in a
		800	global hash - it can't become much cheaper.
		801
		802	=item Why favour JSON, why not a real serialising format such as Storable?
		803
		804	In fact, any AnyEvent::MP node will happily accept Storable as framing
		805	format, but currently there is no way to make a node use Storable by
		806	default (although all nodes will accept it).
		807
		808	The default framing protocol is JSON because a) JSON::XS is many times
		809	faster for small messages and b) most importantly, after years of
		810	experience we found that object serialisation is causing more problems
		811	than it solves: Just like function calls, objects simply do not travel
		812	easily over the network, mostly because they will always be a copy, so you
		813	always have to re-think your design.
		814
		815	Keeping your messages simple, concentrating on data structures rather than
		816	objects, will keep your messages clean, tidy and efficient.
		817
		818	=back
		819
589	=head1 SEE ALSO	820	=head1 SEE ALSO
		821
		822	L<AnyEvent::MP::Intro> - a gentle introduction.
		823
		824	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		825
		826	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		827	your applications.
590		828
591	L<AnyEvent>.	829	L<AnyEvent>.
592		830
593	=head1 AUTHOR	831	=head1 AUTHOR
594		832

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.27 by root, Tue Aug 4 22:13:45 2009 UTC vs. Revision 1.70 by root, Sun Aug 30 19:49:47 2009 UTC

Diff Legend

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.27 by root, Tue Aug 4 22:13:45 2009 UTC vs.
Revision 1.70 by root, Sun Aug 30 19:49:47 2009 UTC