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

Comparing cvsroot/AnyEvent-MP/MP.pm (file contents):
Revision 1.33 by root, Wed Aug 5 22:40:51 2009 UTC vs.
Revision 1.77 by elmex, Thu Sep 3 07:57:30 2009 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use AnyEvent::MP;	7	use AnyEvent::MP;
8		8
9	$NODE # contains this node's noderef	9	$NODE # contains this node's node ID
10	NODE # returns this node's noderef	10	NODE # returns this node's node ID
11	NODE $port # returns the noderef of the port
12		11
		12	$SELF # receiving/own port id in rcv callbacks
		13
		14	# initialise the node so it can send/receive messages
		15	configure;
		16
		17	# ports are message destinations
		18
		19	# sending messages
13	snd $port, type => data...;	20	snd $port, type => data...;
		21	snd $port, @msg;
		22	snd @msg_with_first_element_being_a_port;
14		23
15	$SELF # receiving/own port id in rcv callbacks	24	# creating/using ports, the simple way
		25	my $simple_port = port { my @msg = @_ };
16		26
17	rcv $port, smartmatch => $cb->($port, @msg);	27	# creating/using ports, tagged message matching
18		28	my $port = port;
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	29	rcv $port, ping => sub { snd $_[0], "pong" };
21	rcv $port1, pong => sub { warn "pong received\n" };	30	rcv $port, pong => sub { warn "pong received\n" };
22	snd $port2, ping => $port1;
23		31
24	# more, smarter, matches (_any_ is exported by this module)	32	# create a port on another node
25	rcv $port, [child_died => $pid] => sub { ...	33	my $port = spawn $node, $initfunc, @initdata;
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	34
		35	# monitoring
		36	mon $port, $cb->(@msg) # callback is invoked on death
		37	mon $port, $otherport # kill otherport on abnormal death
		38	mon $port, $otherport, @msg # send message on death
		39
		40	=head1 CURRENT STATUS
		41
		42	bin/aemp - stable.
		43	AnyEvent::MP - stable API, should work.
		44	AnyEvent::MP::Intro - explains most concepts.
		45	AnyEvent::MP::Kernel - mostly stable.
		46	AnyEvent::MP::Global - stable API, protocol not yet final.
		47
		48	stay tuned.
27		49
28	=head1 DESCRIPTION	50	=head1 DESCRIPTION
29		51
30	This module (-family) implements a simple message passing framework.	52	This module (-family) implements a simple message passing framework.
31		53
32	Despite its simplicity, you can securely message other processes running	54	Despite its simplicity, you can securely message other processes running
33	on the same or other hosts.	55	on the same or other hosts, and you can supervise entities remotely.
34		56
35	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	57	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
36	manual page.	58	manual page and the examples under F<eg/>.
37
38	At the moment, this module family is severly broken and underdocumented,
39	so do not use. This was uploaded mainly to reserve the CPAN namespace -
40	stay tuned! The basic API should be finished, however.
41		59
42	=head1 CONCEPTS	60	=head1 CONCEPTS
43		61
44	=over 4	62	=over 4
45		63
46	=item port	64	=item port
47		65
48	A port is something you can send messages to (with the C<snd> function).	66	A port is something you can send messages to (with the C<snd> function).
49		67
50	Some ports allow you to register C<rcv> handlers that can match specific	68	Ports allow you to register C<rcv> handlers that can match all or just
51	messages. All C<rcv> handlers will receive messages they match, messages	69	some messages. Messages send to ports will not be queued, regardless of
52	will not be queued.	70	anything was listening for them or not.
53		71
54	=item port id - C<noderef#portname>	72	=item port ID - C<nodeid#portname>
55		73
56	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	74	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as
57	separator, and a port name (a printable string of unspecified format). An	75	separator, and a port name (a printable string of unspecified format).
58	exception is the the node port, whose ID is identical to its node
59	reference.
60		76
61	=item node	77	=item node
62		78
63	A node is a single process containing at least one port - the node	79	A node is a single process containing at least one port - the node port,
64	port. You can send messages to node ports to find existing ports or to	80	which enables nodes to manage each other remotely, and to create new
65	create new ports, among other things.	81	ports.
66		82
67	Nodes are either private (single-process only), slaves (connected to a	83	Nodes are either public (have one or more listening ports) or private
68	master node only) or public nodes (connectable from unrelated nodes).	84	(no listening ports). Private nodes cannot talk to other private nodes
		85	currently.
69		86
70	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	87	=item node ID - C<[a-za-Z0-9_\-.:]+>
71		88
72	A node reference is a string that either simply identifies the node (for	89	A node ID is a string that uniquely identifies the node within a
73	private and slave nodes), or contains a recipe on how to reach a given	90	network. Depending on the configuration used, node IDs can look like a
74	node (for public nodes).	91	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
		92	doesn't interpret node IDs in any way.
75		93
76	This recipe is simply a comma-separated list of C<address:port> pairs (for	94	=item binds - C<ip:port>
77	TCP/IP, other protocols might look different).
78		95
79	Node references come in two flavours: resolved (containing only numerical	96	Nodes can only talk to each other by creating some kind of connection to
80	addresses) or unresolved (where hostnames are used instead of addresses).	97	each other. To do this, nodes should listen on one or more local transport
		98	endpoints - binds. Currently, only standard C<ip:port> specifications can
		99	be used, which specify TCP ports to listen on.
81		100
82	Before using an unresolved node reference in a message you first have to	101	=item seeds - C<host:port>
83	resolve it.	102
		103	When a node starts, it knows nothing about the network. To teach the node
		104	about the network it first has to contact some other node within the
		105	network. This node is called a seed.
		106
		107	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes
		108	are expected to be long-running, and at least one of those should always
		109	be available. When nodes run out of connections (e.g. due to a network
		110	error), they try to re-establish connections to some seednodes again to
		111	join the network.
		112
		113	Apart from being sued for seeding, seednodes are not special in any way -
		114	every public node can be a seednode.
84		115
85	=back	116	=back
86		117
87	=head1 VARIABLES/FUNCTIONS	118	=head1 VARIABLES/FUNCTIONS
88		119
…		…
90		121
91	=cut	122	=cut
92		123
93	package AnyEvent::MP;	124	package AnyEvent::MP;
94		125
95	use AnyEvent::MP::Base;	126	use AnyEvent::MP::Kernel;
96		127
97	use common::sense;	128	use common::sense;
98		129
99	use Carp ();	130	use Carp ();
100		131
101	use AE ();	132	use AE ();
102		133
103	use base "Exporter";	134	use base "Exporter";
104		135
105	our $VERSION = '0.1';	136	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		137
106	our @EXPORT = qw(	138	our @EXPORT = qw(
107	NODE $NODE *SELF node_of _any_	139	NODE $NODE *SELF node_of after
108	resolve_node initialise_node	140	configure
109	snd rcv mon kil reg psub	141	snd rcv mon mon_guard kil reg psub spawn
110	port	142	port
111	);	143	);
112		144
113	our $SELF;	145	our $SELF;
114		146
…		…
118	kil $SELF, die => $msg;	150	kil $SELF, die => $msg;
119	}	151	}
120		152
121	=item $thisnode = NODE / $NODE	153	=item $thisnode = NODE / $NODE
122		154
123	The C<NODE> function returns, and the C<$NODE> variable contains	155	The C<NODE> function returns, and the C<$NODE> variable contains, the node
124	the noderef of the local node. The value is initialised by a call	156	ID of the node running in the current process. This value is initialised by
125	to C<become_public> or C<become_slave>, after which all local port	157	a call to C<configure>.
126	identifiers become invalid.
127		158
128	=item $noderef = node_of $port	159	=item $nodeid = node_of $port
129		160
130	Extracts and returns the noderef from a portid or a noderef.	161	Extracts and returns the node ID from a port ID or a node ID.
131		162
132	=item $cv = resolve_node $noderef	163	=item configure key => value...
133		164
134	Takes an unresolved node reference that may contain hostnames and	165	Before a node can talk to other nodes on the network (i.e. enter
135	abbreviated IDs, resolves all of them and returns a resolved node	166	"distributed mode") it has to configure itself - the minimum a node needs
136	reference.	167	to know is its own name, and optionally it should know the addresses of
		168	some other nodes in the network to discover other nodes.
137		169
138	In addition to C<address:port> pairs allowed in resolved noderefs, the	170	This function configures a node - it must be called exactly once (or
139	following forms are supported:	171	never) before calling other AnyEvent::MP functions.
140		172
141	=over 4	173	=over 4
142		174
143	=item the empty string	175	=item step 1, gathering configuration from profiles
144		176
145	An empty-string component gets resolved as if the default port (4040) was	177	The function first looks up a profile in the aemp configuration (see the
146	specified.	178	L<aemp> commandline utility). The profile name can be specified via the
		179	named C<profile> parameter. If it is missing, then the nodename (F<uname
		180	-n>) will be used as profile name.
147		181
148	=item naked port numbers (e.g. C<1234>)	182	The profile data is then gathered as follows:
149		183
150	These are resolved by prepending the local nodename and a colon, to be	184	First, all remaining key => value pairs (all of which are conveniently
151	further resolved.	185	undocumented at the moment) will be interpreted as configuration
		186	data. Then they will be overwritten by any values specified in the global
		187	default configuration (see the F<aemp> utility), then the chain of
		188	profiles chosen by the profile name (and any C<parent> attributes).
152		189
153	=item hostnames (e.g. C<localhost:1234>, C<localhost>)	190	That means that the values specified in the profile have highest priority
		191	and the values specified directly via C<configure> have lowest priority,
		192	and can only be used to specify defaults.
154		193
155	These are resolved by using AnyEvent::DNS to resolve them, optionally	194	If the profile specifies a node ID, then this will become the node ID of
156	looking up SRV records for the C<aemp=4040> port, if no port was	195	this process. If not, then the profile name will be used as node ID. The
157	specified.	196	special node ID of C<anon/> will be replaced by a random node ID.
		197
		198	=item step 2, bind listener sockets
		199
		200	The next step is to look up the binds in the profile, followed by binding
		201	aemp protocol listeners on all binds specified (it is possible and valid
		202	to have no binds, meaning that the node cannot be contacted form the
		203	outside. This means the node cannot talk to other nodes that also have no
		204	binds, but it can still talk to all "normal" nodes).
		205
		206	If the profile does not specify a binds list, then a default of C<*> is
		207	used, meaning the node will bind on a dynamically-assigned port on every
		208	local IP address it finds.
		209
		210	=item step 3, connect to seed nodes
		211
		212	As the last step, the seeds list from the profile is passed to the
		213	L<AnyEvent::MP::Global> module, which will then use it to keep
		214	connectivity with at least one node at any point in time.
158		215
159	=back	216	=back
		217
		218	Example: become a distributed node using the locla node name as profile.
		219	This should be the most common form of invocation for "daemon"-type nodes.
		220
		221	configure
		222
		223	Example: become an anonymous node. This form is often used for commandline
		224	clients.
		225
		226	configure nodeid => "anon/";
		227
		228	Example: configure a node using a profile called seed, which si suitable
		229	for a seed node as it binds on all local addresses on a fixed port (4040,
		230	customary for aemp).
		231
		232	# use the aemp commandline utility
		233	# aemp profile seed nodeid anon/ binds '*:4040'
		234
		235	# then use it
		236	configure profile => "seed";
		237
		238	# or simply use aemp from the shell again:
		239	# aemp run profile seed
		240
		241	# or provide a nicer-to-remember nodeid
		242	# aemp run profile seed nodeid "$(hostname)"
160		243
161	=item $SELF	244	=item $SELF
162		245
163	Contains the current port id while executing C<rcv> callbacks or C<psub>	246	Contains the current port id while executing C<rcv> callbacks or C<psub>
164	blocks.	247	blocks.
165		248
166	=item SELF, %SELF, @SELF...	249	=item *SELF, SELF, %SELF, @SELF...
167		250
168	Due to some quirks in how perl exports variables, it is impossible to	251	Due to some quirks in how perl exports variables, it is impossible to
169	just export C<$SELF>, all the symbols called C<SELF> are exported by this	252	just export C<$SELF>, all the symbols named C<SELF> are exported by this
170	module, but only C<$SELF> is currently used.	253	module, but only C<$SELF> is currently used.
171		254
172	=item snd $port, type => @data	255	=item snd $port, type => @data
173		256
174	=item snd $port, @msg	257	=item snd $port, @msg
175		258
176	Send the given message to the given port ID, which can identify either	259	Send the given message to the given port, which can identify either a
177	a local or a remote port, and can be either a string or soemthignt hat	260	local or a remote port, and must be a port ID.
178	stringifies a sa port ID (such as a port object :).
179		261
180	While the message can be about anything, it is highly recommended to use a	262	While the message can be almost anything, it is highly recommended to
181	string as first element (a portid, or some word that indicates a request	263	use a string as first element (a port ID, or some word that indicates a
182	type etc.).	264	request type etc.) and to consist if only simple perl values (scalars,
		265	arrays, hashes) - if you think you need to pass an object, think again.
183		266
184	The message data effectively becomes read-only after a call to this	267	The message data logically becomes read-only after a call to this
185	function: modifying any argument is not allowed and can cause many	268	function: modifying any argument (or values referenced by them) is
186	problems.	269	forbidden, as there can be considerable time between the call to C<snd>
		270	and the time the message is actually being serialised - in fact, it might
		271	never be copied as within the same process it is simply handed to the
		272	receiving port.
187		273
188	The type of data you can transfer depends on the transport protocol: when	274	The type of data you can transfer depends on the transport protocol: when
189	JSON is used, then only strings, numbers and arrays and hashes consisting	275	JSON is used, then only strings, numbers and arrays and hashes consisting
190	of those are allowed (no objects). When Storable is used, then anything	276	of those are allowed (no objects). When Storable is used, then anything
191	that Storable can serialise and deserialise is allowed, and for the local	277	that Storable can serialise and deserialise is allowed, and for the local
192	node, anything can be passed.	278	node, anything can be passed. Best rely only on the common denominator of
		279	these.
193		280
194	=item $local_port = port	281	=item $local_port = port
195		282
196	Create a new local port object that can be used either as a pattern	283	Create a new local port object and returns its port ID. Initially it has
197	matching port ("full port") or a single-callback port ("miniport"),	284	no callbacks set and will throw an error when it receives messages.
198	depending on how C<rcv> callbacks are bound to the object.
199		285
200	=item $port = port { my @msg = @_; $finished }	286	=item $local_port = port { my @msg = @_ }
201		287
202	Creates a "miniport", that is, a very lightweight port without any pattern	288	Creates a new local port, and returns its ID. Semantically the same as
203	matching behind it, and returns its ID. Semantically the same as creating
204	a port and calling C<rcv $port, $callback> on it.	289	creating a port and calling C<rcv $port, $callback> on it.
205		290
206	The block will be called for every message received on the port. When the	291	The block will be called for every message received on the port, with the
207	callback returns a true value its job is considered "done" and the port	292	global variable C<$SELF> set to the port ID. Runtime errors will cause the
208	will be destroyed. Otherwise it will stay alive.	293	port to be C<kil>ed. The message will be passed as-is, no extra argument
		294	(i.e. no port ID) will be passed to the callback.
209		295
210	The message will be passed as-is, no extra argument (i.e. no port id) will	296	If you want to stop/destroy the port, simply C<kil> it:
211	be passed to the callback.
212		297
213	If you need the local port id in the callback, this works nicely:	298	my $port = port {
214		299	my @msg = @_;
215	my $port; $port = port {	300	...
216	snd $otherport, reply => $port;	301	kil $SELF;
217	};	302	};
218		303
219	=cut	304	=cut
220		305
221	sub rcv($@);	306	sub rcv($@);
		307
		308	sub _kilme {
		309	die "received message on port without callback";
		310	}
222		311
223	sub port(;&) {	312	sub port(;&) {
224	my $id = "$UNIQ." . $ID++;	313	my $id = "$UNIQ." . $ID++;
225	my $port = "$NODE#$id";	314	my $port = "$NODE#$id";
226		315
227	if (@_) {	316	rcv $port, shift \|\| \&_kilme;
228	rcv $port, shift;
229	} else {
230	$PORT{$id} = sub { }; # nop
231	}
232		317
233	$port	318	$port
234	}	319	}
235		320
236	=item reg $port, $name
237
238	Registers the given port under the name C<$name>. If the name already
239	exists it is replaced.
240
241	A port can only be registered under one well known name.
242
243	A port automatically becomes unregistered when it is killed.
244
245	=cut
246
247	sub reg(@) {
248	my ($port, $name) = @_;
249
250	$REG{$name} = $port;
251	}
252
253	=item rcv $port, $callback->(@msg)	321	=item rcv $local_port, $callback->(@msg)
254		322
255	Replaces the callback on the specified miniport (after converting it to	323	Replaces the default callback on the specified port. There is no way to
256	one if required).	324	remove the default callback: use C<sub { }> to disable it, or better
257		325	C<kil> the port when it is no longer needed.
258	=item rcv $port, tagstring => $callback->(@msg), ...
259
260	=item rcv $port, $smartmatch => $callback->(@msg), ...
261
262	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
263
264	Register callbacks to be called on matching messages on the given full
265	port (after converting it to one if required).
266
267	The callback has to return a true value when its work is done, after
268	which is will be removed, or a false value in which case it will stay
269	registered.
270		326
271	The global C<$SELF> (exported by this module) contains C<$port> while	327	The global C<$SELF> (exported by this module) contains C<$port> while
272	executing the callback.	328	executing the callback. Runtime errors during callback execution will
		329	result in the port being C<kil>ed.
273		330
274	Runtime errors wdurign callback execution will result in the port being	331	The default callback received all messages not matched by a more specific
275	C<kil>ed.	332	C<tag> match.
276		333
277	If the match is an array reference, then it will be matched against the	334	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
278	first elements of the message, otherwise only the first element is being
279	matched.
280		335
281	Any element in the match that is specified as C<_any_> (a function	336	Register (or replace) callbacks to be called on messages starting with the
282	exported by this module) matches any single element of the message.	337	given tag on the given port (and return the port), or unregister it (when
		338	C<$callback> is C<$undef> or missing). There can only be one callback
		339	registered for each tag.
283		340
284	While not required, it is highly recommended that the first matching	341	The original message will be passed to the callback, after the first
285	element is a string identifying the message. The one-string-only match is	342	element (the tag) has been removed. The callback will use the same
286	also the most efficient match (by far).	343	environment as the default callback (see above).
		344
		345	Example: create a port and bind receivers on it in one go.
		346
		347	my $port = rcv port,
		348	msg1 => sub { ... },
		349	msg2 => sub { ... },
		350	;
		351
		352	Example: create a port, bind receivers and send it in a message elsewhere
		353	in one go:
		354
		355	snd $otherport, reply =>
		356	rcv port,
		357	msg1 => sub { ... },
		358	...
		359	;
		360
		361	Example: temporarily register a rcv callback for a tag matching some port
		362	(e.g. for a rpc reply) and unregister it after a message was received.
		363
		364	rcv $port, $otherport => sub {
		365	my @reply = @_;
		366
		367	rcv $SELF, $otherport;
		368	};
287		369
288	=cut	370	=cut
289		371
290	sub rcv($@) {	372	sub rcv($@) {
291	my $port = shift;	373	my $port = shift;
292	my ($noderef, $portid) = split /#/, $port, 2;	374	my ($nodeid, $portid) = split /#/, $port, 2;
293		375
294	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	376	$NODE{$nodeid} == $NODE{""}
295	or Carp::croak "$port: rcv can only be called on local ports, caught";	377	or Carp::croak "$port: rcv can only be called on local ports, caught";
296		378
297	if (@_ == 1) {	379	while (@_) {
		380	if (ref $_[0]) {
		381	if (my $self = $PORT_DATA{$portid}) {
		382	"AnyEvent::MP::Port" eq ref $self
		383	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		384
		385	$self->[2] = shift;
		386	} else {
298	my $cb = shift;	387	my $cb = shift;
299	delete $PORT_DATA{$portid};
300	$PORT{$portid} = sub {	388	$PORT{$portid} = sub {
301	local $SELF = $port;	389	local $SELF = $port;
302	eval {	390	eval { &$cb }; _self_die if $@;
303	&$cb	391	};
304	and kil $port;
305	};	392	}
306	_self_die if $@;	393	} elsif (defined $_[0]) {
307	};
308	} else {
309	my $self = $PORT_DATA{$portid} \|\|= do {	394	my $self = $PORT_DATA{$portid} \|\|= do {
310	my $self = bless {	395	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
311	id => $port,
312	}, "AnyEvent::MP::Port";
313		396
314	$PORT{$portid} = sub {	397	$PORT{$portid} = sub {
315	local $SELF = $port;	398	local $SELF = $port;
316		399
317	eval {
318	for (@{ $self->{rc0}{$_[0]} }) {	400	if (my $cb = $self->[1]{$_[0]}) {
319	$_ && &{$_->[0]}	401	shift;
320	&& undef $_;	402	eval { &$cb }; _self_die if $@;
321	}	403	} else {
322
323	for (@{ $self->{rcv}{$_[0]} }) {
324	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
325	&& &{$_->[0]}	404	&{ $self->[0] };
326	&& undef $_;
327	}
328
329	for (@{ $self->{any} }) {
330	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
331	&& &{$_->[0]}
332	&& undef $_;
333	}	405	}
334	};	406	};
335	_self_die if $@;	407
		408	$self
336	};	409	};
337		410
338	$self
339	};
340
341	"AnyEvent::MP::Port" eq ref $self	411	"AnyEvent::MP::Port" eq ref $self
342	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	412	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
343		413
344	while (@_) {
345	my ($match, $cb) = splice @_, 0, 2;	414	my ($tag, $cb) = splice @_, 0, 2;
346		415
347	if (!ref $match) {	416	if (defined $cb) {
348	push @{ $self->{rc0}{$match} }, [$cb];	417	$self->[1]{$tag} = $cb;
349	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
350	my ($type, @match) = @$match;
351	@match
352	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
353	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
354	} else {	418	} else {
355	push @{ $self->{any} }, [$cb, $match];	419	delete $self->[1]{$tag};
356	}	420	}
357	}	421	}
358	}	422	}
359		423
360	$port	424	$port
…		…
396	$res	460	$res
397	}	461	}
398	}	462	}
399	}	463	}
400		464
401	=item $guard = mon $port, $cb->(@reason)	465	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
402		466
403	=item $guard = mon $port, $otherport	467	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
404		468
405	=item $guard = mon $port, $otherport, @msg	469	=item $guard = mon $port # kill $SELF when $port dies
406		470
		471	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
		472
407	Monitor the given port and do something when the port is killed.	473	Monitor the given port and do something when the port is killed or
		474	messages to it were lost, and optionally return a guard that can be used
		475	to stop monitoring again.
408		476
		477	C<mon> effectively guarantees that, in the absence of hardware failures,
		478	after starting the monitor, either all messages sent to the port will
		479	arrive, or the monitoring action will be invoked after possible message
		480	loss has been detected. No messages will be lost "in between" (after
		481	the first lost message no further messages will be received by the
		482	port). After the monitoring action was invoked, further messages might get
		483	delivered again.
		484
		485	Note that monitoring-actions are one-shot: once messages are lost (and a
		486	monitoring alert was raised), they are removed and will not trigger again.
		487
409	In the first form, the callback is simply called with any number	488	In the first form (callback), the callback is simply called with any
410	of C<@reason> elements (no @reason means that the port was deleted	489	number of C<@reason> elements (no @reason means that the port was deleted
411	"normally"). Note also that I<< the callback B<must> never die >>, so use	490	"normally"). Note also that I<< the callback B<must> never die >>, so use
412	C<eval> if unsure.	491	C<eval> if unsure.
413		492
414	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	493	In the second form (another port given), the other port (C<$rcvport>)
415	a @reason was specified, i.e. on "normal" kils nothing happens, while	494	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
416	under all other conditions, the other port is killed with the same reason.	495	"normal" kils nothing happens, while under all other conditions, the other
		496	port is killed with the same reason.
417		497
		498	The third form (kill self) is the same as the second form, except that
		499	C<$rvport> defaults to C<$SELF>.
		500
418	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	501	In the last form (message), a message of the form C<@msg, @reason> will be
		502	C<snd>.
		503
		504	As a rule of thumb, monitoring requests should always monitor a port from
		505	a local port (or callback). The reason is that kill messages might get
		506	lost, just like any other message. Another less obvious reason is that
		507	even monitoring requests can get lost (for example, when the connection
		508	to the other node goes down permanently). When monitoring a port locally
		509	these problems do not exist.
419		510
420	Example: call a given callback when C<$port> is killed.	511	Example: call a given callback when C<$port> is killed.
421		512
422	mon $port, sub { warn "port died because of <@_>\n" };	513	mon $port, sub { warn "port died because of <@_>\n" };
423		514
424	Example: kill ourselves when C<$port> is killed abnormally.	515	Example: kill ourselves when C<$port> is killed abnormally.
425		516
426	mon $port, $self;	517	mon $port;
427		518
428	Example: send us a restart message another C<$port> is killed.	519	Example: send us a restart message when another C<$port> is killed.
429		520
430	mon $port, $self => "restart";	521	mon $port, $self => "restart";
431		522
432	=cut	523	=cut
433		524
434	sub mon {	525	sub mon {
435	my ($noderef, $port) = split /#/, shift, 2;	526	my ($nodeid, $port) = split /#/, shift, 2;
436		527
437	my $node = $NODE{$noderef} \|\| add_node $noderef;	528	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
438		529
439	my $cb = shift;	530	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
440		531
441	unless (ref $cb) {	532	unless (ref $cb) {
442	if (@_) {	533	if (@_) {
443	# send a kill info message	534	# send a kill info message
444	my (@msg) = ($cb, @_);	535	my (@msg) = ($cb, @_);
…		…
462	is killed, the references will be freed.	553	is killed, the references will be freed.
463		554
464	Optionally returns a guard that will stop the monitoring.	555	Optionally returns a guard that will stop the monitoring.
465		556
466	This function is useful when you create e.g. timers or other watchers and	557	This function is useful when you create e.g. timers or other watchers and
467	want to free them when the port gets killed:	558	want to free them when the port gets killed (note the use of C<psub>):
468		559
469	$port->rcv (start => sub {	560	$port->rcv (start => sub {
470	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	561	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
471	undef $timer if 0.9 < rand;	562	undef $timer if 0.9 < rand;
472	});	563	});
473	});	564	});
474		565
475	=cut	566	=cut
476		567
477	sub mon_guard {	568	sub mon_guard {
478	my ($port, @refs) = @_;	569	my ($port, @refs) = @_;
479		570
		571	#TODO: mon-less form?
		572
480	mon $port, sub { 0 && @refs }	573	mon $port, sub { 0 && @refs }
481	}	574	}
482		575
483	=item lnk $port1, $port2
484
485	Link two ports. This is simply a shorthand for:
486
487	mon $port1, $port2;
488	mon $port2, $port1;
489
490	It means that if either one is killed abnormally, the other one gets
491	killed as well.
492
493	=item kil $port[, @reason]	576	=item kil $port[, @reason]
494		577
495	Kill the specified port with the given C<@reason>.	578	Kill the specified port with the given C<@reason>.
496		579
497	If no C<@reason> is specified, then the port is killed "normally" (linked	580	If no C<@reason> is specified, then the port is killed "normally" (ports
498	ports will not be kileld, or even notified).	581	monitoring other ports will not necessarily die because a port dies
		582	"normally").
499		583
500	Otherwise, linked ports get killed with the same reason (second form of	584	Otherwise, linked ports get killed with the same reason (second form of
501	C<mon>, see below).	585	C<mon>, see above).
502		586
503	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	587	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
504	will be reported as reason C<< die => $@ >>.	588	will be reported as reason C<< die => $@ >>.
505		589
506	Transport/communication errors are reported as C<< transport_error =>	590	Transport/communication errors are reported as C<< transport_error =>
507	$message >>.	591	$message >>.
508		592
		593	=cut
		594
		595	=item $port = spawn $node, $initfunc[, @initdata]
		596
		597	Creates a port on the node C<$node> (which can also be a port ID, in which
		598	case it's the node where that port resides).
		599
		600	The port ID of the newly created port is returned immediately, and it is
		601	possible to immediately start sending messages or to monitor the port.
		602
		603	After the port has been created, the init function is called on the remote
		604	node, in the same context as a C<rcv> callback. This function must be a
		605	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
		606	specify a function in the main program, use C<::name>.
		607
		608	If the function doesn't exist, then the node tries to C<require>
		609	the package, then the package above the package and so on (e.g.
		610	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		611	exists or it runs out of package names.
		612
		613	The init function is then called with the newly-created port as context
		614	object (C<$SELF>) and the C<@initdata> values as arguments.
		615
		616	A common idiom is to pass a local port, immediately monitor the spawned
		617	port, and in the remote init function, immediately monitor the passed
		618	local port. This two-way monitoring ensures that both ports get cleaned up
		619	when there is a problem.
		620
		621	Example: spawn a chat server port on C<$othernode>.
		622
		623	# this node, executed from within a port context:
		624	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		625	mon $server;
		626
		627	# init function on C<$othernode>
		628	sub connect {
		629	my ($srcport) = @_;
		630
		631	mon $srcport;
		632
		633	rcv $SELF, sub {
		634	...
		635	};
		636	}
		637
		638	=cut
		639
		640	sub _spawn {
		641	my $port = shift;
		642	my $init = shift;
		643
		644	local $SELF = "$NODE#$port";
		645	eval {
		646	&{ load_func $init }
		647	};
		648	_self_die if $@;
		649	}
		650
		651	sub spawn(@) {
		652	my ($nodeid, undef) = split /#/, shift, 2;
		653
		654	my $id = "$RUNIQ." . $ID++;
		655
		656	$_[0] =~ /::/
		657	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		658
		659	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
		660
		661	"$nodeid#$id"
		662	}
		663
		664	=item after $timeout, @msg
		665
		666	=item after $timeout, $callback
		667
		668	Either sends the given message, or call the given callback, after the
		669	specified number of seconds.
		670
		671	This is simply a utility function that comes in handy at times - the
		672	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		673	so it may go away in the future.
		674
		675	=cut
		676
		677	sub after($@) {
		678	my ($timeout, @action) = @_;
		679
		680	my $t; $t = AE::timer $timeout, 0, sub {
		681	undef $t;
		682	ref $action[0]
		683	? $action[0]()
		684	: snd @action;
		685	};
		686	}
		687
509	=back	688	=back
510		689
511	=head1 FUNCTIONS FOR NODES	690	=head1 AnyEvent::MP vs. Distributed Erlang
		691
		692	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
		693	== aemp node, Erlang process == aemp port), so many of the documents and
		694	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		695	sample:
		696
		697	http://www.Erlang.se/doc/programming_rules.shtml
		698	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		699	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		700	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		701
		702	Despite the similarities, there are also some important differences:
512		703
513	=over 4	704	=over 4
514		705
515	=item initialise_node $noderef, $seednode, $seednode...	706	=item * Node IDs are arbitrary strings in AEMP.
516		707
517	=item initialise_node "slave/", $master, $master...
518
519	Initialises a node - must be called exactly once before calling other
520	AnyEvent::MP functions when talking to other nodes is required.
521
522	All arguments are noderefs, which can be either resolved or unresolved.
523
524	There are two types of networked nodes, public nodes and slave nodes:
525
526	=over 4
527
528	=item public nodes
529
530	For public nodes, C<$noderef> must either be a (possibly unresolved)
531	noderef, in which case it will be resolved, or C<undef> (or missing), in
532	which case the noderef will be guessed.
533
534	Afterwards, the node will bind itself on all endpoints and try to connect
535	to all additional C<$seednodes> that are specified. Seednodes are optional
536	and can be used to quickly bootstrap the node into an existing network.
537
538	=item slave nodes
539
540	When the C<$noderef> is the special string C<slave/>, then the node will
541	become a slave node. Slave nodes cannot be contacted from outside and will
542	route most of their traffic to the master node that they attach to.
543
544	At least one additional noderef is required: The node will try to connect
545	to all of them and will become a slave attached to the first node it can
546	successfully connect to.
547
548	=back
549
550	This function will block until all nodes have been resolved and, for slave
551	nodes, until it has successfully established a connection to a master
552	server.
553
554	Example: become a public node listening on the default node.
555
556	initialise_node;
557
558	Example: become a public node, and try to contact some well-known master
559	servers to become part of the network.
560
561	initialise_node undef, "master1", "master2";
562
563	Example: become a public node listening on port C<4041>.
564
565	initialise_node 4041;
566
567	Example: become a public node, only visible on localhost port 4044.
568
569	initialise_node "locahost:4044";
570
571	Example: become a slave node to any of the specified master servers.
572
573	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
574
575	=cut
576
577	=back
578
579	=head1 NODE MESSAGES
580
581	Nodes understand the following messages sent to them. Many of them take
582	arguments called C<@reply>, which will simply be used to compose a reply
583	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
584	the remaining arguments are simply the message data.
585
586	While other messages exist, they are not public and subject to change.
587
588	=over 4
589
590	=cut
591
592	=item lookup => $name, @reply
593
594	Replies with the port ID of the specified well-known port, or C<undef>.
595
596	=item devnull => ...
597
598	Generic data sink/CPU heat conversion.
599
600	=item relay => $port, @msg
601
602	Simply forwards the message to the given port.
603
604	=item eval => $string[ @reply]
605
606	Evaluates the given string. If C<@reply> is given, then a message of the
607	form C<@reply, $@, @evalres> is sent.
608
609	Example: crash another node.
610
611	snd $othernode, eval => "exit";
612
613	=item time => @reply
614
615	Replies the the current node time to C<@reply>.
616
617	Example: tell the current node to send the current time to C<$myport> in a
618	C<timereply> message.
619
620	snd $NODE, time => $myport, timereply => 1, 2;
621	# => snd $myport, timereply => 1, 2, <time>
622
623	=back
624
625	=head1 AnyEvent::MP vs. Distributed Erlang
626
627	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node
628	== aemp node, erlang process == aemp port), so many of the documents and
629	programming techniques employed by erlang apply to AnyEvent::MP. Here is a
630	sample:
631
632	http://www.erlang.se/doc/programming_rules.shtml
633	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
634	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6
635	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
636
637	Despite the similarities, there are also some important differences:
638
639	=over 4
640
641	=item * Node references contain the recipe on how to contact them.
642
643	Erlang relies on special naming and DNS to work everywhere in the	708	Erlang relies on special naming and DNS to work everywhere in the same
644	same way. AEMP relies on each node knowing it's own address(es), with	709	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
645	convenience functionality.	710	configuration or DNS), but will otherwise discover other odes itself.
646		711
647	This means that AEMP requires a less tightly controlled environment at the	712	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
648	cost of longer node references and a slightly higher management overhead.	713	uses "local ports are like remote ports".
		714
		715	The failure modes for local ports are quite different (runtime errors
		716	only) then for remote ports - when a local port dies, you I<know> it dies,
		717	when a connection to another node dies, you know nothing about the other
		718	port.
		719
		720	Erlang pretends remote ports are as reliable as local ports, even when
		721	they are not.
		722
		723	AEMP encourages a "treat remote ports differently" philosophy, with local
		724	ports being the special case/exception, where transport errors cannot
		725	occur.
649		726
650	=item * Erlang uses processes and a mailbox, AEMP does not queue.	727	=item * Erlang uses processes and a mailbox, AEMP does not queue.
651		728
652	Erlang uses processes that selctively receive messages, and therefore	729	Erlang uses processes that selectively receive messages, and therefore
653	needs a queue. AEMP is event based, queuing messages would serve no useful	730	needs a queue. AEMP is event based, queuing messages would serve no
654	purpose.	731	useful purpose. For the same reason the pattern-matching abilities of
		732	AnyEvent::MP are more limited, as there is little need to be able to
		733	filter messages without dequeuing them.
655		734
656	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	735	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
657		736
658	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	737	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
659		738
660	Sending messages in erlang is synchronous and blocks the process. AEMP	739	Sending messages in Erlang is synchronous and blocks the process (and
661	sends are immediate, connection establishment is handled in the	740	so does not need a queue that can overflow). AEMP sends are immediate,
662	background.	741	connection establishment is handled in the background.
663		742
664	=item * Erlang can silently lose messages, AEMP cannot.	743	=item * Erlang suffers from silent message loss, AEMP does not.
665		744
666	Erlang makes few guarantees on messages delivery - messages can get lost	745	Erlang makes few guarantees on messages delivery - messages can get lost
667	without any of the processes realising it (i.e. you send messages a, b,	746	without any of the processes realising it (i.e. you send messages a, b,
668	and c, and the other side only receives messages a and c).	747	and c, and the other side only receives messages a and c).
669		748
670	AEMP guarantees correct ordering, and the guarantee that there are no	749	AEMP guarantees correct ordering, and the guarantee that after one message
671	holes in the message sequence.	750	is lost, all following ones sent to the same port are lost as well, until
672		751	monitoring raises an error, so there are no silent "holes" in the message
673	=item * In erlang, processes can be declared dead and later be found to be	752	sequence.
674	alive.
675
676	In erlang it can happen that a monitored process is declared dead and
677	linked processes get killed, but later it turns out that the process is
678	still alive - and can receive messages.
679
680	In AEMP, when port monitoring detects a port as dead, then that port will
681	eventually be killed - it cannot happen that a node detects a port as dead
682	and then later sends messages to it, finding it is still alive.
683		753
684	=item * Erlang can send messages to the wrong port, AEMP does not.	754	=item * Erlang can send messages to the wrong port, AEMP does not.
685		755
686	In erlang it is quite possible that a node that restarts reuses a process	756	In Erlang it is quite likely that a node that restarts reuses a process ID
687	ID known to other nodes for a completely different process, causing	757	known to other nodes for a completely different process, causing messages
688	messages destined for that process to end up in an unrelated process.	758	destined for that process to end up in an unrelated process.
689		759
690	AEMP never reuses port IDs, so old messages or old port IDs floating	760	AEMP never reuses port IDs, so old messages or old port IDs floating
691	around in the network will not be sent to an unrelated port.	761	around in the network will not be sent to an unrelated port.
692		762
693	=item * Erlang uses unprotected connections, AEMP uses secure	763	=item * Erlang uses unprotected connections, AEMP uses secure
694	authentication and can use TLS.	764	authentication and can use TLS.
695		765
696	AEMP can use a proven protocol - SSL/TLS - to protect connections and	766	AEMP can use a proven protocol - TLS - to protect connections and
697	securely authenticate nodes.	767	securely authenticate nodes.
698		768
699	=item * The AEMP protocol is optimised for both text-based and binary	769	=item * The AEMP protocol is optimised for both text-based and binary
700	communications.	770	communications.
701		771
702	The AEMP protocol, unlike the erlang protocol, supports both	772	The AEMP protocol, unlike the Erlang protocol, supports both programming
703	language-independent text-only protocols (good for debugging) and binary,	773	language independent text-only protocols (good for debugging) and binary,
704	language-specific serialisers (e.g. Storable).	774	language-specific serialisers (e.g. Storable). By default, unless TLS is
		775	used, the protocol is actually completely text-based.
705		776
706	It has also been carefully designed to be implementable in other languages	777	It has also been carefully designed to be implementable in other languages
707	with a minimum of work while gracefully degrading fucntionality to make the	778	with a minimum of work while gracefully degrading functionality to make the
708	protocol simple.	779	protocol simple.
709		780
		781	=item * AEMP has more flexible monitoring options than Erlang.
		782
		783	In Erlang, you can chose to receive I<all> exit signals as messages
		784	or I<none>, there is no in-between, so monitoring single processes is
		785	difficult to implement. Monitoring in AEMP is more flexible than in
		786	Erlang, as one can choose between automatic kill, exit message or callback
		787	on a per-process basis.
		788
		789	=item * Erlang tries to hide remote/local connections, AEMP does not.
		790
		791	Monitoring in Erlang is not an indicator of process death/crashes, in the
		792	same way as linking is (except linking is unreliable in Erlang).
		793
		794	In AEMP, you don't "look up" registered port names or send to named ports
		795	that might or might not be persistent. Instead, you normally spawn a port
		796	on the remote node. The init function monitors you, and you monitor the
		797	remote port. Since both monitors are local to the node, they are much more
		798	reliable (no need for C<spawn_link>).
		799
		800	This also saves round-trips and avoids sending messages to the wrong port
		801	(hard to do in Erlang).
		802
710	=back	803	=back
711		804
		805	=head1 RATIONALE
		806
		807	=over 4
		808
		809	=item Why strings for port and node IDs, why not objects?
		810
		811	We considered "objects", but found that the actual number of methods
		812	that can be called are quite low. Since port and node IDs travel over
		813	the network frequently, the serialising/deserialising would add lots of
		814	overhead, as well as having to keep a proxy object everywhere.
		815
		816	Strings can easily be printed, easily serialised etc. and need no special
		817	procedures to be "valid".
		818
		819	And as a result, a miniport consists of a single closure stored in a
		820	global hash - it can't become much cheaper.
		821
		822	=item Why favour JSON, why not a real serialising format such as Storable?
		823
		824	In fact, any AnyEvent::MP node will happily accept Storable as framing
		825	format, but currently there is no way to make a node use Storable by
		826	default (although all nodes will accept it).
		827
		828	The default framing protocol is JSON because a) JSON::XS is many times
		829	faster for small messages and b) most importantly, after years of
		830	experience we found that object serialisation is causing more problems
		831	than it solves: Just like function calls, objects simply do not travel
		832	easily over the network, mostly because they will always be a copy, so you
		833	always have to re-think your design.
		834
		835	Keeping your messages simple, concentrating on data structures rather than
		836	objects, will keep your messages clean, tidy and efficient.
		837
		838	=back
		839
712	=head1 SEE ALSO	840	=head1 SEE ALSO
		841
		842	L<AnyEvent::MP::Intro> - a gentle introduction.
		843
		844	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		845
		846	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		847	your applications.
713		848
714	L<AnyEvent>.	849	L<AnyEvent>.
715		850
716	=head1 AUTHOR	851	=head1 AUTHOR
717		852

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Comparing cvsroot/AnyEvent-MP/MP.pm (file contents): Revision 1.33 by root, Wed Aug 5 22:40:51 2009 UTC vs. Revision 1.77 by elmex, Thu Sep 3 07:57:30 2009 UTC

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Comparing cvsroot/AnyEvent-MP/MP.pm (file contents):
Revision 1.33 by root, Wed Aug 5 22:40:51 2009 UTC vs.
Revision 1.77 by elmex, Thu Sep 3 07:57:30 2009 UTC