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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.34 by root, Wed Aug 5 23:50:46 2009 UTC vs.
Revision 1.82 by root, Mon Sep 7 18:42:09 2009 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use AnyEvent::MP;	7	use AnyEvent::MP;
8		8
9	$NODE # contains this node's noderef	9	$NODE # contains this node's node ID
10	NODE # returns this node's noderef	10	NODE # returns this node's node ID
11	NODE $port # returns the noderef of the port
12		11
		12	$SELF # receiving/own port id in rcv callbacks
		13
		14	# initialise the node so it can send/receive messages
		15	configure;
		16
		17	# ports are message destinations
		18
		19	# sending messages
13	snd $port, type => data...;	20	snd $port, type => data...;
		21	snd $port, @msg;
		22	snd @msg_with_first_element_being_a_port;
14		23
15	$SELF # receiving/own port id in rcv callbacks	24	# creating/using ports, the simple way
		25	my $simple_port = port { my @msg = @_ };
16		26
17	rcv $port, smartmatch => $cb->($port, @msg);	27	# creating/using ports, tagged message matching
18		28	my $port = port;
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	29	rcv $port, ping => sub { snd $_[0], "pong" };
21	rcv $port1, pong => sub { warn "pong received\n" };	30	rcv $port, pong => sub { warn "pong received\n" };
22	snd $port2, ping => $port1;
23		31
24	# more, smarter, matches (_any_ is exported by this module)	32	# create a port on another node
25	rcv $port, [child_died => $pid] => sub { ...	33	my $port = spawn $node, $initfunc, @initdata;
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	34
		35	# monitoring
		36	mon $port, $cb->(@msg) # callback is invoked on death
		37	mon $port, $otherport # kill otherport on abnormal death
		38	mon $port, $otherport, @msg # send message on death
		39
		40	=head1 CURRENT STATUS
		41
		42	bin/aemp - stable.
		43	AnyEvent::MP - stable API, should work.
		44	AnyEvent::MP::Intro - explains most concepts.
		45	AnyEvent::MP::Kernel - mostly stable.
		46	AnyEvent::MP::Global - stable but incomplete, protocol not yet final.
		47
		48	stay tuned.
27		49
28	=head1 DESCRIPTION	50	=head1 DESCRIPTION
29		51
30	This module (-family) implements a simple message passing framework.	52	This module (-family) implements a simple message passing framework.
31		53
32	Despite its simplicity, you can securely message other processes running	54	Despite its simplicity, you can securely message other processes running
33	on the same or other hosts.	55	on the same or other hosts, and you can supervise entities remotely.
34		56
35	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	57	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
36	manual page.	58	manual page and the examples under F<eg/>.
37
38	At the moment, this module family is severly broken and underdocumented,
39	so do not use. This was uploaded mainly to reserve the CPAN namespace -
40	stay tuned! The basic API should be finished, however.
41		59
42	=head1 CONCEPTS	60	=head1 CONCEPTS
43		61
44	=over 4	62	=over 4
45		63
46	=item port	64	=item port
47		65
48	A port is something you can send messages to (with the C<snd> function).	66	Not to be confused with a TCP port, a "port" is something you can send
		67	messages to (with the C<snd> function).
49		68
50	Some ports allow you to register C<rcv> handlers that can match specific	69	Ports allow you to register C<rcv> handlers that can match all or just
51	messages. All C<rcv> handlers will receive messages they match, messages	70	some messages. Messages send to ports will not be queued, regardless of
52	will not be queued.	71	anything was listening for them or not.
53		72
54	=item port id - C<noderef#portname>	73	=item port ID - C<nodeid#portname>
55		74
56	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	75	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as
57	separator, and a port name (a printable string of unspecified format). An	76	separator, and a port name (a printable string of unspecified format).
58	exception is the the node port, whose ID is identical to its node
59	reference.
60		77
61	=item node	78	=item node
62		79
63	A node is a single process containing at least one port - the node	80	A node is a single process containing at least one port - the node port,
64	port. You can send messages to node ports to find existing ports or to	81	which enables nodes to manage each other remotely, and to create new
65	create new ports, among other things.	82	ports.
66		83
67	Nodes are either private (single-process only), slaves (connected to a	84	Nodes are either public (have one or more listening ports) or private
68	master node only) or public nodes (connectable from unrelated nodes).	85	(no listening ports). Private nodes cannot talk to other private nodes
		86	currently.
69		87
70	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	88	=item node ID - C<[a-za-Z0-9_\-.:]+>
71		89
72	A node reference is a string that either simply identifies the node (for	90	A node ID is a string that uniquely identifies the node within a
73	private and slave nodes), or contains a recipe on how to reach a given	91	network. Depending on the configuration used, node IDs can look like a
74	node (for public nodes).	92	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
		93	doesn't interpret node IDs in any way.
75		94
76	This recipe is simply a comma-separated list of C<address:port> pairs (for	95	=item binds - C<ip:port>
77	TCP/IP, other protocols might look different).
78		96
79	Node references come in two flavours: resolved (containing only numerical	97	Nodes can only talk to each other by creating some kind of connection to
80	addresses) or unresolved (where hostnames are used instead of addresses).	98	each other. To do this, nodes should listen on one or more local transport
		99	endpoints - binds. Currently, only standard C<ip:port> specifications can
		100	be used, which specify TCP ports to listen on.
81		101
82	Before using an unresolved node reference in a message you first have to	102	=item seeds - C<host:port>
83	resolve it.	103
		104	When a node starts, it knows nothing about the network. To teach the node
		105	about the network it first has to contact some other node within the
		106	network. This node is called a seed.
		107
		108	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes
		109	are expected to be long-running, and at least one of those should always
		110	be available. When nodes run out of connections (e.g. due to a network
		111	error), they try to re-establish connections to some seednodes again to
		112	join the network.
		113
		114	Apart from being sued for seeding, seednodes are not special in any way -
		115	every public node can be a seednode.
84		116
85	=back	117	=back
86		118
87	=head1 VARIABLES/FUNCTIONS	119	=head1 VARIABLES/FUNCTIONS
88		120
…		…
90		122
91	=cut	123	=cut
92		124
93	package AnyEvent::MP;	125	package AnyEvent::MP;
94		126
95	use AnyEvent::MP::Base;	127	use AnyEvent::MP::Kernel;
96		128
97	use common::sense;	129	use common::sense;
98		130
99	use Carp ();	131	use Carp ();
100		132
101	use AE ();	133	use AE ();
102		134
103	use base "Exporter";	135	use base "Exporter";
104		136
105	our $VERSION = '0.1';	137	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		138
106	our @EXPORT = qw(	139	our @EXPORT = qw(
107	NODE $NODE *SELF node_of _any_	140	NODE $NODE *SELF node_of after
108	resolve_node initialise_node	141	configure
109	snd rcv mon kil reg psub	142	snd rcv mon mon_guard kil reg psub spawn
110	port	143	port
111	);	144	);
112		145
113	our $SELF;	146	our $SELF;
114		147
…		…
118	kil $SELF, die => $msg;	151	kil $SELF, die => $msg;
119	}	152	}
120		153
121	=item $thisnode = NODE / $NODE	154	=item $thisnode = NODE / $NODE
122		155
123	The C<NODE> function returns, and the C<$NODE> variable contains	156	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	157	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	158	a call to C<configure>.
126	identifiers become invalid.
127		159
128	=item $noderef = node_of $port	160	=item $nodeid = node_of $port
129		161
130	Extracts and returns the noderef from a portid or a noderef.	162	Extracts and returns the node ID from a port ID or a node ID.
131		163
132	=item initialise_node $noderef, $seednode, $seednode...	164	=item configure $profile, key => value...
133		165
134	=item initialise_node "slave/", $master, $master...	166	=item configure key => value...
135		167
136	Before a node can talk to other nodes on the network it has to initialise	168	Before a node can talk to other nodes on the network (i.e. enter
137	itself - the minimum a node needs to know is it's own name, and optionally	169	"distributed mode") it has to configure itself - the minimum a node needs
138	it should know the noderefs of some other nodes in the network.	170	to know is its own name, and optionally it should know the addresses of
		171	some other nodes in the network to discover other nodes.
139		172
140	This function initialises a node - it must be called exactly once (or	173	This function configures a node - it must be called exactly once (or
141	never) before calling other AnyEvent::MP functions.	174	never) before calling other AnyEvent::MP functions.
142		175
143	All arguments are noderefs, which can be either resolved or unresolved.
144
145	There are two types of networked nodes, public nodes and slave nodes:
146
147	=over 4	176	=over 4
148		177
149	=item public nodes	178	=item step 1, gathering configuration from profiles
150		179
151	For public nodes, C<$noderef> must either be a (possibly unresolved)	180	The function first looks up a profile in the aemp configuration (see the
152	noderef, in which case it will be resolved, or C<undef> (or missing), in	181	L<aemp> commandline utility). The profile name can be specified via the
153	which case the noderef will be guessed.	182	named C<profile> parameter or can simply be the first parameter). If it is
		183	missing, then the nodename (F<uname -n>) will be used as profile name.
154		184
155	Afterwards, the node will bind itself on all endpoints and try to connect	185	The profile data is then gathered as follows:
156	to all additional C<$seednodes> that are specified. Seednodes are optional
157	and can be used to quickly bootstrap the node into an existing network.
158		186
159	=item slave nodes	187	First, all remaining key => value pairs (all of which are conveniently
		188	undocumented at the moment) will be interpreted as configuration
		189	data. Then they will be overwritten by any values specified in the global
		190	default configuration (see the F<aemp> utility), then the chain of
		191	profiles chosen by the profile name (and any C<parent> attributes).
160		192
161	When the C<$noderef> is the special string C<slave/>, then the node will	193	That means that the values specified in the profile have highest priority
162	become a slave node. Slave nodes cannot be contacted from outside and will	194	and the values specified directly via C<configure> have lowest priority,
163	route most of their traffic to the master node that they attach to.	195	and can only be used to specify defaults.
164		196
165	At least one additional noderef is required: The node will try to connect	197	If the profile specifies a node ID, then this will become the node ID of
166	to all of them and will become a slave attached to the first node it can	198	this process. If not, then the profile name will be used as node ID. The
167	successfully connect to.	199	special node ID of C<anon/> will be replaced by a random node ID.
		200
		201	=item step 2, bind listener sockets
		202
		203	The next step is to look up the binds in the profile, followed by binding
		204	aemp protocol listeners on all binds specified (it is possible and valid
		205	to have no binds, meaning that the node cannot be contacted form the
		206	outside. This means the node cannot talk to other nodes that also have no
		207	binds, but it can still talk to all "normal" nodes).
		208
		209	If the profile does not specify a binds list, then a default of C<*> is
		210	used, meaning the node will bind on a dynamically-assigned port on every
		211	local IP address it finds.
		212
		213	=item step 3, connect to seed nodes
		214
		215	As the last step, the seeds list from the profile is passed to the
		216	L<AnyEvent::MP::Global> module, which will then use it to keep
		217	connectivity with at least one node at any point in time.
168		218
169	=back	219	=back
170		220
171	This function will block until all nodes have been resolved and, for slave	221	Example: become a distributed node using the locla node name as profile.
172	nodes, until it has successfully established a connection to a master	222	This should be the most common form of invocation for "daemon"-type nodes.
173	server.
174		223
175	Example: become a public node listening on the default node.	224	configure
176		225
177	initialise_node;	226	Example: become an anonymous node. This form is often used for commandline
		227	clients.
178		228
179	Example: become a public node, and try to contact some well-known master	229	configure nodeid => "anon/";
180	servers to become part of the network.
181		230
182	initialise_node undef, "master1", "master2";	231	Example: configure a node using a profile called seed, which si suitable
		232	for a seed node as it binds on all local addresses on a fixed port (4040,
		233	customary for aemp).
183		234
184	Example: become a public node listening on port C<4041>.	235	# use the aemp commandline utility
		236	# aemp profile seed nodeid anon/ binds '*:4040'
185		237
186	initialise_node 4041;	238	# then use it
		239	configure profile => "seed";
187		240
188	Example: become a public node, only visible on localhost port 4044.	241	# or simply use aemp from the shell again:
		242	# aemp run profile seed
189		243
190	initialise_node "locahost:4044";	244	# or provide a nicer-to-remember nodeid
191		245	# aemp run profile seed nodeid "$(hostname)"
192	Example: become a slave node to any of the specified master servers.
193
194	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
195
196	=item $cv = resolve_node $noderef
197
198	Takes an unresolved node reference that may contain hostnames and
199	abbreviated IDs, resolves all of them and returns a resolved node
200	reference.
201
202	In addition to C<address:port> pairs allowed in resolved noderefs, the
203	following forms are supported:
204
205	=over 4
206
207	=item the empty string
208
209	An empty-string component gets resolved as if the default port (4040) was
210	specified.
211
212	=item naked port numbers (e.g. C<1234>)
213
214	These are resolved by prepending the local nodename and a colon, to be
215	further resolved.
216
217	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
218
219	These are resolved by using AnyEvent::DNS to resolve them, optionally
220	looking up SRV records for the C<aemp=4040> port, if no port was
221	specified.
222
223	=back
224		246
225	=item $SELF	247	=item $SELF
226		248
227	Contains the current port id while executing C<rcv> callbacks or C<psub>	249	Contains the current port id while executing C<rcv> callbacks or C<psub>
228	blocks.	250	blocks.
229		251
230	=item SELF, %SELF, @SELF...	252	=item *SELF, SELF, %SELF, @SELF...
231		253
232	Due to some quirks in how perl exports variables, it is impossible to	254	Due to some quirks in how perl exports variables, it is impossible to
233	just export C<$SELF>, all the symbols called C<SELF> are exported by this	255	just export C<$SELF>, all the symbols named C<SELF> are exported by this
234	module, but only C<$SELF> is currently used.	256	module, but only C<$SELF> is currently used.
235		257
236	=item snd $port, type => @data	258	=item snd $port, type => @data
237		259
238	=item snd $port, @msg	260	=item snd $port, @msg
239		261
240	Send the given message to the given port ID, which can identify either	262	Send the given message to the given port, which can identify either a
241	a local or a remote port, and can be either a string or soemthignt hat	263	local or a remote port, and must be a port ID.
242	stringifies a sa port ID (such as a port object :).
243		264
244	While the message can be about anything, it is highly recommended to use a	265	While the message can be almost anything, it is highly recommended to
245	string as first element (a portid, or some word that indicates a request	266	use a string as first element (a port ID, or some word that indicates a
246	type etc.).	267	request type etc.) and to consist if only simple perl values (scalars,
		268	arrays, hashes) - if you think you need to pass an object, think again.
247		269
248	The message data effectively becomes read-only after a call to this	270	The message data logically becomes read-only after a call to this
249	function: modifying any argument is not allowed and can cause many	271	function: modifying any argument (or values referenced by them) is
250	problems.	272	forbidden, as there can be considerable time between the call to C<snd>
		273	and the time the message is actually being serialised - in fact, it might
		274	never be copied as within the same process it is simply handed to the
		275	receiving port.
251		276
252	The type of data you can transfer depends on the transport protocol: when	277	The type of data you can transfer depends on the transport protocol: when
253	JSON is used, then only strings, numbers and arrays and hashes consisting	278	JSON is used, then only strings, numbers and arrays and hashes consisting
254	of those are allowed (no objects). When Storable is used, then anything	279	of those are allowed (no objects). When Storable is used, then anything
255	that Storable can serialise and deserialise is allowed, and for the local	280	that Storable can serialise and deserialise is allowed, and for the local
256	node, anything can be passed.	281	node, anything can be passed. Best rely only on the common denominator of
		282	these.
257		283
258	=item $local_port = port	284	=item $local_port = port
259		285
260	Create a new local port object that can be used either as a pattern	286	Create a new local port object and returns its port ID. Initially it has
261	matching port ("full port") or a single-callback port ("miniport"),	287	no callbacks set and will throw an error when it receives messages.
262	depending on how C<rcv> callbacks are bound to the object.
263		288
264	=item $port = port { my @msg = @_; $finished }	289	=item $local_port = port { my @msg = @_ }
265		290
266	Creates a "miniport", that is, a very lightweight port without any pattern	291	Creates a new local port, and returns its ID. Semantically the same as
267	matching behind it, and returns its ID. Semantically the same as creating
268	a port and calling C<rcv $port, $callback> on it.	292	creating a port and calling C<rcv $port, $callback> on it.
269		293
270	The block will be called for every message received on the port. When the	294	The block will be called for every message received on the port, with the
271	callback returns a true value its job is considered "done" and the port	295	global variable C<$SELF> set to the port ID. Runtime errors will cause the
272	will be destroyed. Otherwise it will stay alive.	296	port to be C<kil>ed. The message will be passed as-is, no extra argument
		297	(i.e. no port ID) will be passed to the callback.
273		298
274	The message will be passed as-is, no extra argument (i.e. no port id) will	299	If you want to stop/destroy the port, simply C<kil> it:
275	be passed to the callback.
276		300
277	If you need the local port id in the callback, this works nicely:	301	my $port = port {
278		302	my @msg = @_;
279	my $port; $port = port {	303	...
280	snd $otherport, reply => $port;	304	kil $SELF;
281	};	305	};
282		306
283	=cut	307	=cut
284		308
285	sub rcv($@);	309	sub rcv($@);
		310
		311	sub _kilme {
		312	die "received message on port without callback";
		313	}
286		314
287	sub port(;&) {	315	sub port(;&) {
288	my $id = "$UNIQ." . $ID++;	316	my $id = "$UNIQ." . $ID++;
289	my $port = "$NODE#$id";	317	my $port = "$NODE#$id";
290		318
291	if (@_) {	319	rcv $port, shift \|\| \&_kilme;
292	rcv $port, shift;
293	} else {
294	$PORT{$id} = sub { }; # nop
295	}
296		320
297	$port	321	$port
298	}	322	}
299		323
300	=item reg $port, $name
301
302	Registers the given port under the name C<$name>. If the name already
303	exists it is replaced.
304
305	A port can only be registered under one well known name.
306
307	A port automatically becomes unregistered when it is killed.
308
309	=cut
310
311	sub reg(@) {
312	my ($port, $name) = @_;
313
314	$REG{$name} = $port;
315	}
316
317	=item rcv $port, $callback->(@msg)	324	=item rcv $local_port, $callback->(@msg)
318		325
319	Replaces the callback on the specified miniport (after converting it to	326	Replaces the default callback on the specified port. There is no way to
320	one if required).	327	remove the default callback: use C<sub { }> to disable it, or better
321		328	C<kil> the port when it is no longer needed.
322	=item rcv $port, tagstring => $callback->(@msg), ...
323
324	=item rcv $port, $smartmatch => $callback->(@msg), ...
325
326	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
327
328	Register callbacks to be called on matching messages on the given full
329	port (after converting it to one if required).
330
331	The callback has to return a true value when its work is done, after
332	which is will be removed, or a false value in which case it will stay
333	registered.
334		329
335	The global C<$SELF> (exported by this module) contains C<$port> while	330	The global C<$SELF> (exported by this module) contains C<$port> while
336	executing the callback.	331	executing the callback. Runtime errors during callback execution will
		332	result in the port being C<kil>ed.
337		333
338	Runtime errors wdurign callback execution will result in the port being	334	The default callback received all messages not matched by a more specific
339	C<kil>ed.	335	C<tag> match.
340		336
341	If the match is an array reference, then it will be matched against the	337	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
342	first elements of the message, otherwise only the first element is being
343	matched.
344		338
345	Any element in the match that is specified as C<_any_> (a function	339	Register (or replace) callbacks to be called on messages starting with the
346	exported by this module) matches any single element of the message.	340	given tag on the given port (and return the port), or unregister it (when
		341	C<$callback> is C<$undef> or missing). There can only be one callback
		342	registered for each tag.
347		343
348	While not required, it is highly recommended that the first matching	344	The original message will be passed to the callback, after the first
349	element is a string identifying the message. The one-string-only match is	345	element (the tag) has been removed. The callback will use the same
350	also the most efficient match (by far).	346	environment as the default callback (see above).
		347
		348	Example: create a port and bind receivers on it in one go.
		349
		350	my $port = rcv port,
		351	msg1 => sub { ... },
		352	msg2 => sub { ... },
		353	;
		354
		355	Example: create a port, bind receivers and send it in a message elsewhere
		356	in one go:
		357
		358	snd $otherport, reply =>
		359	rcv port,
		360	msg1 => sub { ... },
		361	...
		362	;
		363
		364	Example: temporarily register a rcv callback for a tag matching some port
		365	(e.g. for a rpc reply) and unregister it after a message was received.
		366
		367	rcv $port, $otherport => sub {
		368	my @reply = @_;
		369
		370	rcv $SELF, $otherport;
		371	};
351		372
352	=cut	373	=cut
353		374
354	sub rcv($@) {	375	sub rcv($@) {
355	my $port = shift;	376	my $port = shift;
356	my ($noderef, $portid) = split /#/, $port, 2;	377	my ($nodeid, $portid) = split /#/, $port, 2;
357		378
358	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	379	$NODE{$nodeid} == $NODE{""}
359	or Carp::croak "$port: rcv can only be called on local ports, caught";	380	or Carp::croak "$port: rcv can only be called on local ports, caught";
360		381
361	if (@_ == 1) {	382	while (@_) {
		383	if (ref $_[0]) {
		384	if (my $self = $PORT_DATA{$portid}) {
		385	"AnyEvent::MP::Port" eq ref $self
		386	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		387
		388	$self->[2] = shift;
		389	} else {
362	my $cb = shift;	390	my $cb = shift;
363	delete $PORT_DATA{$portid};
364	$PORT{$portid} = sub {	391	$PORT{$portid} = sub {
365	local $SELF = $port;	392	local $SELF = $port;
366	eval {	393	eval { &$cb }; _self_die if $@;
367	&$cb	394	};
368	and kil $port;
369	};	395	}
370	_self_die if $@;	396	} elsif (defined $_[0]) {
371	};
372	} else {
373	my $self = $PORT_DATA{$portid} \|\|= do {	397	my $self = $PORT_DATA{$portid} \|\|= do {
374	my $self = bless {	398	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
375	id => $port,
376	}, "AnyEvent::MP::Port";
377		399
378	$PORT{$portid} = sub {	400	$PORT{$portid} = sub {
379	local $SELF = $port;	401	local $SELF = $port;
380		402
381	eval {
382	for (@{ $self->{rc0}{$_[0]} }) {	403	if (my $cb = $self->[1]{$_[0]}) {
383	$_ && &{$_->[0]}	404	shift;
384	&& undef $_;	405	eval { &$cb }; _self_die if $@;
385	}	406	} else {
386
387	for (@{ $self->{rcv}{$_[0]} }) {
388	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
389	&& &{$_->[0]}	407	&{ $self->[0] };
390	&& undef $_;
391	}
392
393	for (@{ $self->{any} }) {
394	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
395	&& &{$_->[0]}
396	&& undef $_;
397	}	408	}
398	};	409	};
399	_self_die if $@;	410
		411	$self
400	};	412	};
401		413
402	$self
403	};
404
405	"AnyEvent::MP::Port" eq ref $self	414	"AnyEvent::MP::Port" eq ref $self
406	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	415	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
407		416
408	while (@_) {
409	my ($match, $cb) = splice @_, 0, 2;	417	my ($tag, $cb) = splice @_, 0, 2;
410		418
411	if (!ref $match) {	419	if (defined $cb) {
412	push @{ $self->{rc0}{$match} }, [$cb];	420	$self->[1]{$tag} = $cb;
413	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
414	my ($type, @match) = @$match;
415	@match
416	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
417	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
418	} else {	421	} else {
419	push @{ $self->{any} }, [$cb, $match];	422	delete $self->[1]{$tag};
420	}	423	}
421	}	424	}
422	}	425	}
423		426
424	$port	427	$port
…		…
460	$res	463	$res
461	}	464	}
462	}	465	}
463	}	466	}
464		467
465	=item $guard = mon $port, $cb->(@reason)	468	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
466		469
467	=item $guard = mon $port, $otherport	470	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
468		471
469	=item $guard = mon $port, $otherport, @msg	472	=item $guard = mon $port # kill $SELF when $port dies
470		473
		474	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
		475
471	Monitor the given port and do something when the port is killed.	476	Monitor the given port and do something when the port is killed or
		477	messages to it were lost, and optionally return a guard that can be used
		478	to stop monitoring again.
472		479
473	In the first form, the callback is simply called with any number	480	In the first form (callback), the callback is simply called with any
474	of C<@reason> elements (no @reason means that the port was deleted	481	number of C<@reason> elements (no @reason means that the port was deleted
475	"normally"). Note also that I<< the callback B<must> never die >>, so use	482	"normally"). Note also that I<< the callback B<must> never die >>, so use
476	C<eval> if unsure.	483	C<eval> if unsure.
477		484
478	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	485	In the second form (another port given), the other port (C<$rcvport>)
479	a @reason was specified, i.e. on "normal" kils nothing happens, while	486	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
480	under all other conditions, the other port is killed with the same reason.	487	"normal" kils nothing happens, while under all other conditions, the other
		488	port is killed with the same reason.
481		489
		490	The third form (kill self) is the same as the second form, except that
		491	C<$rvport> defaults to C<$SELF>.
		492
482	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	493	In the last form (message), a message of the form C<@msg, @reason> will be
		494	C<snd>.
		495
		496	Monitoring-actions are one-shot: once messages are lost (and a monitoring
		497	alert was raised), they are removed and will not trigger again.
		498
		499	As a rule of thumb, monitoring requests should always monitor a port from
		500	a local port (or callback). The reason is that kill messages might get
		501	lost, just like any other message. Another less obvious reason is that
		502	even monitoring requests can get lost (for example, when the connection
		503	to the other node goes down permanently). When monitoring a port locally
		504	these problems do not exist.
		505
		506	C<mon> effectively guarantees that, in the absence of hardware failures,
		507	after starting the monitor, either all messages sent to the port will
		508	arrive, or the monitoring action will be invoked after possible message
		509	loss has been detected. No messages will be lost "in between" (after
		510	the first lost message no further messages will be received by the
		511	port). After the monitoring action was invoked, further messages might get
		512	delivered again.
		513
		514	Inter-host-connection timeouts and monitoring depend on the transport
		515	used. The only transport currently implemented is TCP, and AnyEvent::MP
		516	relies on TCP to detect node-downs (this can take 10-15 minutes on a
		517	non-idle connection, and usually around two hours for idle conenctions).
		518
		519	This means that monitoring is good for program errors and cleaning up
		520	stuff eventually, but they are no replacement for a timeout when you need
		521	to ensure some maximum latency.
483		522
484	Example: call a given callback when C<$port> is killed.	523	Example: call a given callback when C<$port> is killed.
485		524
486	mon $port, sub { warn "port died because of <@_>\n" };	525	mon $port, sub { warn "port died because of <@_>\n" };
487		526
488	Example: kill ourselves when C<$port> is killed abnormally.	527	Example: kill ourselves when C<$port> is killed abnormally.
489		528
490	mon $port, $self;	529	mon $port;
491		530
492	Example: send us a restart message another C<$port> is killed.	531	Example: send us a restart message when another C<$port> is killed.
493		532
494	mon $port, $self => "restart";	533	mon $port, $self => "restart";
495		534
496	=cut	535	=cut
497		536
498	sub mon {	537	sub mon {
499	my ($noderef, $port) = split /#/, shift, 2;	538	my ($nodeid, $port) = split /#/, shift, 2;
500		539
501	my $node = $NODE{$noderef} \|\| add_node $noderef;	540	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
502		541
503	my $cb = shift;	542	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
504		543
505	unless (ref $cb) {	544	unless (ref $cb) {
506	if (@_) {	545	if (@_) {
507	# send a kill info message	546	# send a kill info message
508	my (@msg) = ($cb, @_);	547	my (@msg) = ($cb, @_);
…		…
526	is killed, the references will be freed.	565	is killed, the references will be freed.
527		566
528	Optionally returns a guard that will stop the monitoring.	567	Optionally returns a guard that will stop the monitoring.
529		568
530	This function is useful when you create e.g. timers or other watchers and	569	This function is useful when you create e.g. timers or other watchers and
531	want to free them when the port gets killed:	570	want to free them when the port gets killed (note the use of C<psub>):
532		571
533	$port->rcv (start => sub {	572	$port->rcv (start => sub {
534	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	573	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
535	undef $timer if 0.9 < rand;	574	undef $timer if 0.9 < rand;
536	});	575	});
537	});	576	});
538		577
539	=cut	578	=cut
540		579
541	sub mon_guard {	580	sub mon_guard {
542	my ($port, @refs) = @_;	581	my ($port, @refs) = @_;
543		582
		583	#TODO: mon-less form?
		584
544	mon $port, sub { 0 && @refs }	585	mon $port, sub { 0 && @refs }
545	}	586	}
546		587
547	=item lnk $port1, $port2
548
549	Link two ports. This is simply a shorthand for:
550
551	mon $port1, $port2;
552	mon $port2, $port1;
553
554	It means that if either one is killed abnormally, the other one gets
555	killed as well.
556
557	=item kil $port[, @reason]	588	=item kil $port[, @reason]
558		589
559	Kill the specified port with the given C<@reason>.	590	Kill the specified port with the given C<@reason>.
560		591
561	If no C<@reason> is specified, then the port is killed "normally" (linked	592	If no C<@reason> is specified, then the port is killed "normally" (ports
562	ports will not be kileld, or even notified).	593	monitoring other ports will not necessarily die because a port dies
		594	"normally").
563		595
564	Otherwise, linked ports get killed with the same reason (second form of	596	Otherwise, linked ports get killed with the same reason (second form of
565	C<mon>, see below).	597	C<mon>, see above).
566		598
567	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	599	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
568	will be reported as reason C<< die => $@ >>.	600	will be reported as reason C<< die => $@ >>.
569		601
570	Transport/communication errors are reported as C<< transport_error =>	602	Transport/communication errors are reported as C<< transport_error =>
571	$message >>.	603	$message >>.
572		604
		605	=cut
		606
		607	=item $port = spawn $node, $initfunc[, @initdata]
		608
		609	Creates a port on the node C<$node> (which can also be a port ID, in which
		610	case it's the node where that port resides).
		611
		612	The port ID of the newly created port is returned immediately, and it is
		613	possible to immediately start sending messages or to monitor the port.
		614
		615	After the port has been created, the init function is called on the remote
		616	node, in the same context as a C<rcv> callback. This function must be a
		617	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
		618	specify a function in the main program, use C<::name>.
		619
		620	If the function doesn't exist, then the node tries to C<require>
		621	the package, then the package above the package and so on (e.g.
		622	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		623	exists or it runs out of package names.
		624
		625	The init function is then called with the newly-created port as context
		626	object (C<$SELF>) and the C<@initdata> values as arguments. It I<must>
		627	call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise
		628	the port might not get created.
		629
		630	A common idiom is to pass a local port, immediately monitor the spawned
		631	port, and in the remote init function, immediately monitor the passed
		632	local port. This two-way monitoring ensures that both ports get cleaned up
		633	when there is a problem.
		634
		635	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
		636	caller before C<spawn> returns (by delaying invocation when spawn is
		637	called for the local node).
		638
		639	Example: spawn a chat server port on C<$othernode>.
		640
		641	# this node, executed from within a port context:
		642	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		643	mon $server;
		644
		645	# init function on C<$othernode>
		646	sub connect {
		647	my ($srcport) = @_;
		648
		649	mon $srcport;
		650
		651	rcv $SELF, sub {
		652	...
		653	};
		654	}
		655
		656	=cut
		657
		658	sub _spawn {
		659	my $port = shift;
		660	my $init = shift;
		661
		662	# rcv will create the actual port
		663	local $SELF = "$NODE#$port";
		664	eval {
		665	&{ load_func $init }
		666	};
		667	_self_die if $@;
		668	}
		669
		670	sub spawn(@) {
		671	my ($nodeid, undef) = split /#/, shift, 2;
		672
		673	my $id = "$RUNIQ." . $ID++;
		674
		675	$_[0] =~ /::/
		676	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		677
		678	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
		679
		680	"$nodeid#$id"
		681	}
		682
		683	=item after $timeout, @msg
		684
		685	=item after $timeout, $callback
		686
		687	Either sends the given message, or call the given callback, after the
		688	specified number of seconds.
		689
		690	This is simply a utility function that comes in handy at times - the
		691	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		692	so it may go away in the future.
		693
		694	=cut
		695
		696	sub after($@) {
		697	my ($timeout, @action) = @_;
		698
		699	my $t; $t = AE::timer $timeout, 0, sub {
		700	undef $t;
		701	ref $action[0]
		702	? $action[0]()
		703	: snd @action;
		704	};
		705	}
		706
573	=back	707	=back
574		708
575	=head1 NODE MESSAGES	709	=head1 AnyEvent::MP vs. Distributed Erlang
576		710
577	Nodes understand the following messages sent to them. Many of them take	711	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
578	arguments called C<@reply>, which will simply be used to compose a reply	712	== aemp node, Erlang process == aemp port), so many of the documents and
579	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and	713	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
580	the remaining arguments are simply the message data.	714	sample:
581		715
582	While other messages exist, they are not public and subject to change.	716	http://www.Erlang.se/doc/programming_rules.shtml
		717	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		718	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		719	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		720
		721	Despite the similarities, there are also some important differences:
583		722
584	=over 4	723	=over 4
585		724
586	=cut	725	=item * Node IDs are arbitrary strings in AEMP.
587		726
588	=item lookup => $name, @reply
589
590	Replies with the port ID of the specified well-known port, or C<undef>.
591
592	=item devnull => ...
593
594	Generic data sink/CPU heat conversion.
595
596	=item relay => $port, @msg
597
598	Simply forwards the message to the given port.
599
600	=item eval => $string[ @reply]
601
602	Evaluates the given string. If C<@reply> is given, then a message of the
603	form C<@reply, $@, @evalres> is sent.
604
605	Example: crash another node.
606
607	snd $othernode, eval => "exit";
608
609	=item time => @reply
610
611	Replies the the current node time to C<@reply>.
612
613	Example: tell the current node to send the current time to C<$myport> in a
614	C<timereply> message.
615
616	snd $NODE, time => $myport, timereply => 1, 2;
617	# => snd $myport, timereply => 1, 2, <time>
618
619	=back
620
621	=head1 AnyEvent::MP vs. Distributed Erlang
622
623	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node
624	== aemp node, erlang process == aemp port), so many of the documents and
625	programming techniques employed by erlang apply to AnyEvent::MP. Here is a
626	sample:
627
628	http://www.erlang.se/doc/programming_rules.shtml
629	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
630	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6
631	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
632
633	Despite the similarities, there are also some important differences:
634
635	=over 4
636
637	=item * Node references contain the recipe on how to contact them.
638
639	Erlang relies on special naming and DNS to work everywhere in the	727	Erlang relies on special naming and DNS to work everywhere in the same
640	same way. AEMP relies on each node knowing it's own address(es), with	728	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
641	convenience functionality.	729	configuration or DNS), but will otherwise discover other odes itself.
642		730
643	This means that AEMP requires a less tightly controlled environment at the	731	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
644	cost of longer node references and a slightly higher management overhead.	732	uses "local ports are like remote ports".
		733
		734	The failure modes for local ports are quite different (runtime errors
		735	only) then for remote ports - when a local port dies, you I<know> it dies,
		736	when a connection to another node dies, you know nothing about the other
		737	port.
		738
		739	Erlang pretends remote ports are as reliable as local ports, even when
		740	they are not.
		741
		742	AEMP encourages a "treat remote ports differently" philosophy, with local
		743	ports being the special case/exception, where transport errors cannot
		744	occur.
645		745
646	=item * Erlang uses processes and a mailbox, AEMP does not queue.	746	=item * Erlang uses processes and a mailbox, AEMP does not queue.
647		747
648	Erlang uses processes that selctively receive messages, and therefore	748	Erlang uses processes that selectively receive messages, and therefore
649	needs a queue. AEMP is event based, queuing messages would serve no useful	749	needs a queue. AEMP is event based, queuing messages would serve no
650	purpose.	750	useful purpose. For the same reason the pattern-matching abilities of
		751	AnyEvent::MP are more limited, as there is little need to be able to
		752	filter messages without dequeuing them.
651		753
652	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	754	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
653		755
654	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	756	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
655		757
656	Sending messages in erlang is synchronous and blocks the process. AEMP	758	Sending messages in Erlang is synchronous and blocks the process (and
657	sends are immediate, connection establishment is handled in the	759	so does not need a queue that can overflow). AEMP sends are immediate,
658	background.	760	connection establishment is handled in the background.
659		761
660	=item * Erlang can silently lose messages, AEMP cannot.	762	=item * Erlang suffers from silent message loss, AEMP does not.
661		763
662	Erlang makes few guarantees on messages delivery - messages can get lost	764	Erlang makes few guarantees on messages delivery - messages can get lost
663	without any of the processes realising it (i.e. you send messages a, b,	765	without any of the processes realising it (i.e. you send messages a, b,
664	and c, and the other side only receives messages a and c).	766	and c, and the other side only receives messages a and c).
665		767
666	AEMP guarantees correct ordering, and the guarantee that there are no	768	AEMP guarantees correct ordering, and the guarantee that after one message
667	holes in the message sequence.	769	is lost, all following ones sent to the same port are lost as well, until
668		770	monitoring raises an error, so there are no silent "holes" in the message
669	=item * In erlang, processes can be declared dead and later be found to be	771	sequence.
670	alive.
671
672	In erlang it can happen that a monitored process is declared dead and
673	linked processes get killed, but later it turns out that the process is
674	still alive - and can receive messages.
675
676	In AEMP, when port monitoring detects a port as dead, then that port will
677	eventually be killed - it cannot happen that a node detects a port as dead
678	and then later sends messages to it, finding it is still alive.
679		772
680	=item * Erlang can send messages to the wrong port, AEMP does not.	773	=item * Erlang can send messages to the wrong port, AEMP does not.
681		774
682	In erlang it is quite possible that a node that restarts reuses a process	775	In Erlang it is quite likely that a node that restarts reuses a process ID
683	ID known to other nodes for a completely different process, causing	776	known to other nodes for a completely different process, causing messages
684	messages destined for that process to end up in an unrelated process.	777	destined for that process to end up in an unrelated process.
685		778
686	AEMP never reuses port IDs, so old messages or old port IDs floating	779	AEMP never reuses port IDs, so old messages or old port IDs floating
687	around in the network will not be sent to an unrelated port.	780	around in the network will not be sent to an unrelated port.
688		781
689	=item * Erlang uses unprotected connections, AEMP uses secure	782	=item * Erlang uses unprotected connections, AEMP uses secure
690	authentication and can use TLS.	783	authentication and can use TLS.
691		784
692	AEMP can use a proven protocol - SSL/TLS - to protect connections and	785	AEMP can use a proven protocol - TLS - to protect connections and
693	securely authenticate nodes.	786	securely authenticate nodes.
694		787
695	=item * The AEMP protocol is optimised for both text-based and binary	788	=item * The AEMP protocol is optimised for both text-based and binary
696	communications.	789	communications.
697		790
698	The AEMP protocol, unlike the erlang protocol, supports both	791	The AEMP protocol, unlike the Erlang protocol, supports both programming
699	language-independent text-only protocols (good for debugging) and binary,	792	language independent text-only protocols (good for debugging) and binary,
700	language-specific serialisers (e.g. Storable).	793	language-specific serialisers (e.g. Storable). By default, unless TLS is
		794	used, the protocol is actually completely text-based.
701		795
702	It has also been carefully designed to be implementable in other languages	796	It has also been carefully designed to be implementable in other languages
703	with a minimum of work while gracefully degrading fucntionality to make the	797	with a minimum of work while gracefully degrading functionality to make the
704	protocol simple.	798	protocol simple.
705		799
		800	=item * AEMP has more flexible monitoring options than Erlang.
		801
		802	In Erlang, you can chose to receive I<all> exit signals as messages
		803	or I<none>, there is no in-between, so monitoring single processes is
		804	difficult to implement. Monitoring in AEMP is more flexible than in
		805	Erlang, as one can choose between automatic kill, exit message or callback
		806	on a per-process basis.
		807
		808	=item * Erlang tries to hide remote/local connections, AEMP does not.
		809
		810	Monitoring in Erlang is not an indicator of process death/crashes, in the
		811	same way as linking is (except linking is unreliable in Erlang).
		812
		813	In AEMP, you don't "look up" registered port names or send to named ports
		814	that might or might not be persistent. Instead, you normally spawn a port
		815	on the remote node. The init function monitors you, and you monitor the
		816	remote port. Since both monitors are local to the node, they are much more
		817	reliable (no need for C<spawn_link>).
		818
		819	This also saves round-trips and avoids sending messages to the wrong port
		820	(hard to do in Erlang).
		821
706	=back	822	=back
707		823
		824	=head1 RATIONALE
		825
		826	=over 4
		827
		828	=item Why strings for port and node IDs, why not objects?
		829
		830	We considered "objects", but found that the actual number of methods
		831	that can be called are quite low. Since port and node IDs travel over
		832	the network frequently, the serialising/deserialising would add lots of
		833	overhead, as well as having to keep a proxy object everywhere.
		834
		835	Strings can easily be printed, easily serialised etc. and need no special
		836	procedures to be "valid".
		837
		838	And as a result, a miniport consists of a single closure stored in a
		839	global hash - it can't become much cheaper.
		840
		841	=item Why favour JSON, why not a real serialising format such as Storable?
		842
		843	In fact, any AnyEvent::MP node will happily accept Storable as framing
		844	format, but currently there is no way to make a node use Storable by
		845	default (although all nodes will accept it).
		846
		847	The default framing protocol is JSON because a) JSON::XS is many times
		848	faster for small messages and b) most importantly, after years of
		849	experience we found that object serialisation is causing more problems
		850	than it solves: Just like function calls, objects simply do not travel
		851	easily over the network, mostly because they will always be a copy, so you
		852	always have to re-think your design.
		853
		854	Keeping your messages simple, concentrating on data structures rather than
		855	objects, will keep your messages clean, tidy and efficient.
		856
		857	=back
		858
708	=head1 SEE ALSO	859	=head1 SEE ALSO
		860
		861	L<AnyEvent::MP::Intro> - a gentle introduction.
		862
		863	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		864
		865	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		866	your applications.
		867
		868	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
		869	all nodes.
709		870
710	L<AnyEvent>.	871	L<AnyEvent>.
711		872
712	=head1 AUTHOR	873	=head1 AUTHOR
713		874

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.34 by root, Wed Aug 5 23:50:46 2009 UTC vs. Revision 1.82 by root, Mon Sep 7 18:42:09 2009 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.34 by root, Wed Aug 5 23:50:46 2009 UTC vs.
Revision 1.82 by root, Mon Sep 7 18:42:09 2009 UTC