[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 1.75 by root, Mon Aug 31 13:18:06 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 - uptodate, but incomplete.
		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		59
38	At the moment, this module family is severly broken and underdocumented,	60	At the moment, this module family is a bit underdocumented.
39	so do not use. This was uploaded mainly to reserve the CPAN namespace -
40	stay tuned! The basic API should be finished, however.
41		61
42	=head1 CONCEPTS	62	=head1 CONCEPTS
43		63
44	=over 4	64	=over 4
45		65
46	=item port	66	=item port
47		67
48	A port is something you can send messages to (with the C<snd> function).	68	A port is something you can send messages to (with the C<snd> function).
49		69
50	Some ports allow you to register C<rcv> handlers that can match specific	70	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	71	some messages. Messages send to ports will not be queued, regardless of
52	will not be queued.	72	anything was listening for them or not.
53		73
54	=item port id - C<noderef#portname>	74	=item port ID - C<nodeid#portname>
55		75
56	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	76	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	77	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		78
61	=item node	79	=item node
62		80
63	A node is a single process containing at least one port - the node	81	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	82	which enables nodes to manage each other remotely, and to create new
65	create new ports, among other things.	83	ports.
66		84
67	Nodes are either private (single-process only), slaves (connected to a	85	Nodes are either public (have one or more listening ports) or private
68	master node only) or public nodes (connectable from unrelated nodes).	86	(no listening ports). Private nodes cannot talk to other private nodes
		87	currently.
69		88
70	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	89	=item node ID - C<[a-za-Z0-9_\-.:]+>
71		90
72	A node reference is a string that either simply identifies the node (for	91	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	92	network. Depending on the configuration used, node IDs can look like a
74	node (for public nodes).	93	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
		94	doesn't interpret node IDs in any way.
75		95
76	This recipe is simply a comma-separated list of C<address:port> pairs (for	96	=item binds - C<ip:port>
77	TCP/IP, other protocols might look different).
78		97
79	Node references come in two flavours: resolved (containing only numerical	98	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).	99	each other. To do this, nodes should listen on one or more local transport
		100	endpoints - binds. Currently, only standard C<ip:port> specifications can
		101	be used, which specify TCP ports to listen on.
81		102
82	Before using an unresolved node reference in a message you first have to	103	=item seeds - C<host:port>
83	resolve it.	104
		105	When a node starts, it knows nothing about the network. To teach the node
		106	about the network it first has to contact some other node within the
		107	network. This node is called a seed.
		108
		109	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes
		110	are expected to be long-running, and at least one of those should always
		111	be available. When nodes run out of connections (e.g. due to a network
		112	error), they try to re-establish connections to some seednodes again to
		113	join the network.
		114
		115	Apart from being sued for seeding, seednodes are not special in any way -
		116	every public node can be a seednode.
84		117
85	=back	118	=back
86		119
87	=head1 VARIABLES/FUNCTIONS	120	=head1 VARIABLES/FUNCTIONS
88		121
…		…
90		123
91	=cut	124	=cut
92		125
93	package AnyEvent::MP;	126	package AnyEvent::MP;
94		127
95	use AnyEvent::MP::Base;	128	use AnyEvent::MP::Kernel;
96		129
97	use common::sense;	130	use common::sense;
98		131
99	use Carp ();	132	use Carp ();
100		133
101	use AE ();	134	use AE ();
102		135
103	use base "Exporter";	136	use base "Exporter";
104		137
105	our $VERSION = '0.1';	138	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		139
106	our @EXPORT = qw(	140	our @EXPORT = qw(
107	NODE $NODE *SELF node_of _any_	141	NODE $NODE *SELF node_of after
108	resolve_node initialise_node	142	configure
109	snd rcv mon kil reg psub	143	snd rcv mon mon_guard kil reg psub spawn
110	port	144	port
111	);	145	);
112		146
113	our $SELF;	147	our $SELF;
114		148
…		…
118	kil $SELF, die => $msg;	152	kil $SELF, die => $msg;
119	}	153	}
120		154
121	=item $thisnode = NODE / $NODE	155	=item $thisnode = NODE / $NODE
122		156
123	The C<NODE> function returns, and the C<$NODE> variable contains	157	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	158	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	159	a call to C<configure>.
126	identifiers become invalid.
127		160
128	=item $noderef = node_of $port	161	=item $nodeid = node_of $port
129		162
130	Extracts and returns the noderef from a portid or a noderef.	163	Extracts and returns the node ID from a port ID or a node ID.
131		164
132	=item initialise_node $noderef, $seednode, $seednode...	165	=item configure key => value...
133		166
134	=item initialise_node "slave/", $master, $master...
135
136	Before a node can talk to other nodes on the network it has to initialise	167	Before a node can talk to other nodes on the network (i.e. enter
137	itself - the minimum a node needs to know is it's own name, and optionally	168	"distributed mode") it has to configure itself - the minimum a node needs
138	it should know the noderefs of some other nodes in the network.	169	to know is its own name, and optionally it should know the addresses of
		170	some other nodes in the network to discover other nodes.
139		171
140	This function initialises a node - it must be called exactly once (or	172	This function configures a node - it must be called exactly once (or
141	never) before calling other AnyEvent::MP functions.	173	never) before calling other AnyEvent::MP functions.
142		174
143	All arguments are noderefs, which can be either resolved or unresolved.
144
145	There are two types of networked nodes, public nodes and slave nodes:
146
147	=over 4	175	=over 4
148		176
149	=item public nodes	177	=item step 1, gathering configuration from profiles
150		178
151	For public nodes, C<$noderef> must either be a (possibly unresolved)	179	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	180	L<aemp> commandline utility). The profile name can be specified via the
153	which case the noderef will be guessed.	181	named C<profile> parameter. If it is missing, then the nodename (F<uname
		182	-n>) will be used as profile name.
154		183
155	Afterwards, the node will bind itself on all endpoints and try to connect	184	The profile data is then gathered as follows:
156	to all additional C<$seednodes> that are specified. Seednodes are optional
157	and can be used to quickly bootstrap the node into an existing network.
158		185
159	=item slave nodes	186	First, all remaining key => value pairs (all of which are conviniently
		187	undocumented at the moment) will be interpreted as configuration
		188	data. Then they will be overwritten by any values specified in the global
		189	default configuration (see the F<aemp> utility), then the chain of
		190	profiles chosen by the profile name (and any C<parent> attributes).
160		191
161	When the C<$noderef> is the special string C<slave/>, then the node will	192	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	193	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.	194	and can only be used to specify defaults.
164		195
165	At least one additional noderef is required: The node will try to connect	196	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	197	this process. If not, then the profile name will be used as node ID. The
167	successfully connect to.	198	special node ID of C<anon/> will be replaced by a random node ID.
		199
		200	=item step 2, bind listener sockets
		201
		202	The next step is to look up the binds in the profile, followed by binding
		203	aemp protocol listeners on all binds specified (it is possible and valid
		204	to have no binds, meaning that the node cannot be contacted form the
		205	outside. This means the node cannot talk to other nodes that also have no
		206	binds, but it can still talk to all "normal" nodes).
		207
		208	If the profile does not specify a binds list, then a default of C<*> is
		209	used, meaning the node will bind on a dynamically-assigned port on every
		210	local IP address it finds.
		211
		212	=item step 3, connect to seed nodes
		213
		214	As the last step, the seeds list from the profile is passed to the
		215	L<AnyEvent::MP::Global> module, which will then use it to keep
		216	connectivity with at least one node at any point in time.
168		217
169	=back	218	=back
170		219
171	This function will block until all nodes have been resolved and, for slave	220	Example: become a distributed node using the locla node name as profile.
172	nodes, until it has successfully established a connection to a master	221	This should be the most common form of invocation for "daemon"-type nodes.
173	server.
174		222
175	Example: become a public node listening on the default node.	223	configure
176		224
177	initialise_node;	225	Example: become an anonymous node. This form is often used for commandline
		226	clients.
178		227
179	Example: become a public node, and try to contact some well-known master	228	configure nodeid => "anon/";
180	servers to become part of the network.
181		229
182	initialise_node undef, "master1", "master2";	230	Example: configure a node using a profile called seed, which si suitable
		231	for a seed node as it binds on all local addresses on a fixed port (4040,
		232	customary for aemp).
183		233
184	Example: become a public node listening on port C<4041>.	234	# use the aemp commandline utility
		235	# aemp profile seed nodeid anon/ binds '*:4040'
185		236
186	initialise_node 4041;	237	# then use it
		238	configure profile => "seed";
187		239
188	Example: become a public node, only visible on localhost port 4044.	240	# or simply use aemp from the shell again:
		241	# aemp run profile seed
189		242
190	initialise_node "locahost:4044";	243	# or provide a nicer-to-remember nodeid
191		244	# 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		245
225	=item $SELF	246	=item $SELF
226		247
227	Contains the current port id while executing C<rcv> callbacks or C<psub>	248	Contains the current port id while executing C<rcv> callbacks or C<psub>
228	blocks.	249	blocks.
229		250
230	=item SELF, %SELF, @SELF...	251	=item *SELF, SELF, %SELF, @SELF...
231		252
232	Due to some quirks in how perl exports variables, it is impossible to	253	Due to some quirks in how perl exports variables, it is impossible to
233	just export C<$SELF>, all the symbols called C<SELF> are exported by this	254	just export C<$SELF>, all the symbols named C<SELF> are exported by this
234	module, but only C<$SELF> is currently used.	255	module, but only C<$SELF> is currently used.
235		256
236	=item snd $port, type => @data	257	=item snd $port, type => @data
237		258
238	=item snd $port, @msg	259	=item snd $port, @msg
239		260
240	Send the given message to the given port ID, which can identify either	261	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	262	local or a remote port, and must be a port ID.
242	stringifies a sa port ID (such as a port object :).
243		263
244	While the message can be about anything, it is highly recommended to use a	264	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	265	use a string as first element (a port ID, or some word that indicates a
246	type etc.).	266	request type etc.) and to consist if only simple perl values (scalars,
		267	arrays, hashes) - if you think you need to pass an object, think again.
247		268
248	The message data effectively becomes read-only after a call to this	269	The message data logically becomes read-only after a call to this
249	function: modifying any argument is not allowed and can cause many	270	function: modifying any argument (or values referenced by them) is
250	problems.	271	forbidden, as there can be considerable time between the call to C<snd>
		272	and the time the message is actually being serialised - in fact, it might
		273	never be copied as within the same process it is simply handed to the
		274	receiving port.
251		275
252	The type of data you can transfer depends on the transport protocol: when	276	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	277	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	278	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	279	that Storable can serialise and deserialise is allowed, and for the local
256	node, anything can be passed.	280	node, anything can be passed. Best rely only on the common denominator of
		281	these.
257		282
258	=item $local_port = port	283	=item $local_port = port
259		284
260	Create a new local port object that can be used either as a pattern	285	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"),	286	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		287
264	=item $port = port { my @msg = @_; $finished }	288	=item $local_port = port { my @msg = @_ }
265		289
266	Creates a "miniport", that is, a very lightweight port without any pattern	290	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.	291	creating a port and calling C<rcv $port, $callback> on it.
269		292
270	The block will be called for every message received on the port. When the	293	The block will be called for every message received on the port, with the
271	callback returns a true value its job is considered "done" and the port	294	global variable C<$SELF> set to the port ID. Runtime errors will cause the
272	will be destroyed. Otherwise it will stay alive.	295	port to be C<kil>ed. The message will be passed as-is, no extra argument
		296	(i.e. no port ID) will be passed to the callback.
273		297
274	The message will be passed as-is, no extra argument (i.e. no port id) will	298	If you want to stop/destroy the port, simply C<kil> it:
275	be passed to the callback.
276		299
277	If you need the local port id in the callback, this works nicely:	300	my $port = port {
278		301	my @msg = @_;
279	my $port; $port = port {	302	...
280	snd $otherport, reply => $port;	303	kil $SELF;
281	};	304	};
282		305
283	=cut	306	=cut
284		307
285	sub rcv($@);	308	sub rcv($@);
		309
		310	sub _kilme {
		311	die "received message on port without callback";
		312	}
286		313
287	sub port(;&) {	314	sub port(;&) {
288	my $id = "$UNIQ." . $ID++;	315	my $id = "$UNIQ." . $ID++;
289	my $port = "$NODE#$id";	316	my $port = "$NODE#$id";
290		317
291	if (@_) {	318	rcv $port, shift \|\| \&_kilme;
292	rcv $port, shift;
293	} else {
294	$PORT{$id} = sub { }; # nop
295	}
296		319
297	$port	320	$port
298	}	321	}
299		322
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)	323	=item rcv $local_port, $callback->(@msg)
318		324
319	Replaces the callback on the specified miniport (after converting it to	325	Replaces the default callback on the specified port. There is no way to
320	one if required).	326	remove the default callback: use C<sub { }> to disable it, or better
321		327	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...] => $callback->(@msg), ...
327
328	Register callbacks to be called on matching messages on the given full
329	port (after converting it to one if required).
330
331	The callback has to return a true value when its work is done, after
332	which is will be removed, or a false value in which case it will stay
333	registered.
334		328
335	The global C<$SELF> (exported by this module) contains C<$port> while	329	The global C<$SELF> (exported by this module) contains C<$port> while
336	executing the callback.	330	executing the callback. Runtime errors during callback execution will
		331	result in the port being C<kil>ed.
337		332
338	Runtime errors wdurign callback execution will result in the port being	333	The default callback received all messages not matched by a more specific
339	C<kil>ed.	334	C<tag> match.
340		335
341	If the match is an array reference, then it will be matched against the	336	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
342	first elements of the message, otherwise only the first element is being
343	matched.
344		337
345	Any element in the match that is specified as C<_any_> (a function	338	Register (or replace) callbacks to be called on messages starting with the
346	exported by this module) matches any single element of the message.	339	given tag on the given port (and return the port), or unregister it (when
		340	C<$callback> is C<$undef> or missing). There can only be one callback
		341	registered for each tag.
347		342
348	While not required, it is highly recommended that the first matching	343	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	344	element (the tag) has been removed. The callback will use the same
350	also the most efficient match (by far).	345	environment as the default callback (see above).
		346
		347	Example: create a port and bind receivers on it in one go.
		348
		349	my $port = rcv port,
		350	msg1 => sub { ... },
		351	msg2 => sub { ... },
		352	;
		353
		354	Example: create a port, bind receivers and send it in a message elsewhere
		355	in one go:
		356
		357	snd $otherport, reply =>
		358	rcv port,
		359	msg1 => sub { ... },
		360	...
		361	;
		362
		363	Example: temporarily register a rcv callback for a tag matching some port
		364	(e.g. for a rpc reply) and unregister it after a message was received.
		365
		366	rcv $port, $otherport => sub {
		367	my @reply = @_;
		368
		369	rcv $SELF, $otherport;
		370	};
351		371
352	=cut	372	=cut
353		373
354	sub rcv($@) {	374	sub rcv($@) {
355	my $port = shift;	375	my $port = shift;
356	my ($noderef, $portid) = split /#/, $port, 2;	376	my ($nodeid, $portid) = split /#/, $port, 2;
357		377
358	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	378	$NODE{$nodeid} == $NODE{""}
359	or Carp::croak "$port: rcv can only be called on local ports, caught";	379	or Carp::croak "$port: rcv can only be called on local ports, caught";
360		380
361	if (@_ == 1) {	381	while (@_) {
		382	if (ref $_[0]) {
		383	if (my $self = $PORT_DATA{$portid}) {
		384	"AnyEvent::MP::Port" eq ref $self
		385	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		386
		387	$self->[2] = shift;
		388	} else {
362	my $cb = shift;	389	my $cb = shift;
363	delete $PORT_DATA{$portid};
364	$PORT{$portid} = sub {	390	$PORT{$portid} = sub {
365	local $SELF = $port;	391	local $SELF = $port;
366	eval {	392	eval { &$cb }; _self_die if $@;
367	&$cb	393	};
368	and kil $port;
369	};	394	}
370	_self_die if $@;	395	} elsif (defined $_[0]) {
371	};
372	} else {
373	my $self = $PORT_DATA{$portid} \|\|= do {	396	my $self = $PORT_DATA{$portid} \|\|= do {
374	my $self = bless {	397	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
375	id => $port,
376	}, "AnyEvent::MP::Port";
377		398
378	$PORT{$portid} = sub {	399	$PORT{$portid} = sub {
379	local $SELF = $port;	400	local $SELF = $port;
380		401
381	eval {
382	for (@{ $self->{rc0}{$_[0]} }) {	402	if (my $cb = $self->[1]{$_[0]}) {
383	$_ && &{$_->[0]}	403	shift;
384	&& undef $_;	404	eval { &$cb }; _self_die if $@;
385	}	405	} else {
386
387	for (@{ $self->{rcv}{$_[0]} }) {
388	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
389	&& &{$_->[0]}	406	&{ $self->[0] };
390	&& undef $_;
391	}
392
393	for (@{ $self->{any} }) {
394	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
395	&& &{$_->[0]}
396	&& undef $_;
397	}	407	}
398	};	408	};
399	_self_die if $@;	409
		410	$self
400	};	411	};
401		412
402	$self
403	};
404
405	"AnyEvent::MP::Port" eq ref $self	413	"AnyEvent::MP::Port" eq ref $self
406	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	414	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
407		415
408	while (@_) {
409	my ($match, $cb) = splice @_, 0, 2;	416	my ($tag, $cb) = splice @_, 0, 2;
410		417
411	if (!ref $match) {	418	if (defined $cb) {
412	push @{ $self->{rc0}{$match} }, [$cb];	419	$self->[1]{$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 {	420	} else {
419	push @{ $self->{any} }, [$cb, $match];	421	delete $self->[1]{$tag};
420	}	422	}
421	}	423	}
422	}	424	}
423		425
424	$port	426	$port
…		…
460	$res	462	$res
461	}	463	}
462	}	464	}
463	}	465	}
464		466
465	=item $guard = mon $port, $cb->(@reason)	467	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
466		468
467	=item $guard = mon $port, $otherport	469	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
468		470
469	=item $guard = mon $port, $otherport, @msg	471	=item $guard = mon $port # kill $SELF when $port dies
470		472
		473	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
		474
471	Monitor the given port and do something when the port is killed.	475	Monitor the given port and do something when the port is killed or
		476	messages to it were lost, and optionally return a guard that can be used
		477	to stop monitoring again.
472		478
		479	C<mon> effectively guarantees that, in the absence of hardware failures,
		480	after starting the monitor, either all messages sent to the port will
		481	arrive, or the monitoring action will be invoked after possible message
		482	loss has been detected. No messages will be lost "in between" (after
		483	the first lost message no further messages will be received by the
		484	port). After the monitoring action was invoked, further messages might get
		485	delivered again.
		486
		487	Note that monitoring-actions are one-shot: once messages are lost (and a
		488	monitoring alert was raised), they are removed and will not trigger again.
		489
473	In the first form, the callback is simply called with any number	490	In the first form (callback), the callback is simply called with any
474	of C<@reason> elements (no @reason means that the port was deleted	491	number of C<@reason> elements (no @reason means that the port was deleted
475	"normally"). Note also that I<< the callback B<must> never die >>, so use	492	"normally"). Note also that I<< the callback B<must> never die >>, so use
476	C<eval> if unsure.	493	C<eval> if unsure.
477		494
478	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	495	In the second form (another port given), the other port (C<$rcvport>)
479	a @reason was specified, i.e. on "normal" kils nothing happens, while	496	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
480	under all other conditions, the other port is killed with the same reason.	497	"normal" kils nothing happens, while under all other conditions, the other
		498	port is killed with the same reason.
481		499
		500	The third form (kill self) is the same as the second form, except that
		501	C<$rvport> defaults to C<$SELF>.
		502
482	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	503	In the last form (message), a message of the form C<@msg, @reason> will be
		504	C<snd>.
		505
		506	As a rule of thumb, monitoring requests should always monitor a port from
		507	a local port (or callback). The reason is that kill messages might get
		508	lost, just like any other message. Another less obvious reason is that
		509	even monitoring requests can get lost (for exmaple, when the connection
		510	to the other node goes down permanently). When monitoring a port locally
		511	these problems do not exist.
483		512
484	Example: call a given callback when C<$port> is killed.	513	Example: call a given callback when C<$port> is killed.
485		514
486	mon $port, sub { warn "port died because of <@_>\n" };	515	mon $port, sub { warn "port died because of <@_>\n" };
487		516
488	Example: kill ourselves when C<$port> is killed abnormally.	517	Example: kill ourselves when C<$port> is killed abnormally.
489		518
490	mon $port, $self;	519	mon $port;
491		520
492	Example: send us a restart message another C<$port> is killed.	521	Example: send us a restart message when another C<$port> is killed.
493		522
494	mon $port, $self => "restart";	523	mon $port, $self => "restart";
495		524
496	=cut	525	=cut
497		526
498	sub mon {	527	sub mon {
499	my ($noderef, $port) = split /#/, shift, 2;	528	my ($nodeid, $port) = split /#/, shift, 2;
500		529
501	my $node = $NODE{$noderef} \|\| add_node $noderef;	530	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
502		531
503	my $cb = shift;	532	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
504		533
505	unless (ref $cb) {	534	unless (ref $cb) {
506	if (@_) {	535	if (@_) {
507	# send a kill info message	536	# send a kill info message
508	my (@msg) = ($cb, @_);	537	my (@msg) = ($cb, @_);
…		…
526	is killed, the references will be freed.	555	is killed, the references will be freed.
527		556
528	Optionally returns a guard that will stop the monitoring.	557	Optionally returns a guard that will stop the monitoring.
529		558
530	This function is useful when you create e.g. timers or other watchers and	559	This function is useful when you create e.g. timers or other watchers and
531	want to free them when the port gets killed:	560	want to free them when the port gets killed (note the use of C<psub>):
532		561
533	$port->rcv (start => sub {	562	$port->rcv (start => sub {
534	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	563	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
535	undef $timer if 0.9 < rand;	564	undef $timer if 0.9 < rand;
536	});	565	});
537	});	566	});
538		567
539	=cut	568	=cut
540		569
541	sub mon_guard {	570	sub mon_guard {
542	my ($port, @refs) = @_;	571	my ($port, @refs) = @_;
543		572
		573	#TODO: mon-less form?
		574
544	mon $port, sub { 0 && @refs }	575	mon $port, sub { 0 && @refs }
545	}	576	}
546		577
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]	578	=item kil $port[, @reason]
558		579
559	Kill the specified port with the given C<@reason>.	580	Kill the specified port with the given C<@reason>.
560		581
561	If no C<@reason> is specified, then the port is killed "normally" (linked	582	If no C<@reason> is specified, then the port is killed "normally" (ports
562	ports will not be kileld, or even notified).	583	monitoring other ports will not necessarily die because a port dies
		584	"normally").
563		585
564	Otherwise, linked ports get killed with the same reason (second form of	586	Otherwise, linked ports get killed with the same reason (second form of
565	C<mon>, see below).	587	C<mon>, see above).
566		588
567	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	589	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
568	will be reported as reason C<< die => $@ >>.	590	will be reported as reason C<< die => $@ >>.
569		591
570	Transport/communication errors are reported as C<< transport_error =>	592	Transport/communication errors are reported as C<< transport_error =>
571	$message >>.	593	$message >>.
572		594
		595	=cut
		596
		597	=item $port = spawn $node, $initfunc[, @initdata]
		598
		599	Creates a port on the node C<$node> (which can also be a port ID, in which
		600	case it's the node where that port resides).
		601
		602	The port ID of the newly created port is returned immediately, and it is
		603	possible to immediately start sending messages or to monitor the port.
		604
		605	After the port has been created, the init function is called on the remote
		606	node, in the same context as a C<rcv> callback. This function must be a
		607	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
		608	specify a function in the main program, use C<::name>.
		609
		610	If the function doesn't exist, then the node tries to C<require>
		611	the package, then the package above the package and so on (e.g.
		612	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		613	exists or it runs out of package names.
		614
		615	The init function is then called with the newly-created port as context
		616	object (C<$SELF>) and the C<@initdata> values as arguments.
		617
		618	A common idiom is to pass a local port, immediately monitor the spawned
		619	port, and in the remote init function, immediately monitor the passed
		620	local port. This two-way monitoring ensures that both ports get cleaned up
		621	when there is a problem.
		622
		623	Example: spawn a chat server port on C<$othernode>.
		624
		625	# this node, executed from within a port context:
		626	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		627	mon $server;
		628
		629	# init function on C<$othernode>
		630	sub connect {
		631	my ($srcport) = @_;
		632
		633	mon $srcport;
		634
		635	rcv $SELF, sub {
		636	...
		637	};
		638	}
		639
		640	=cut
		641
		642	sub _spawn {
		643	my $port = shift;
		644	my $init = shift;
		645
		646	local $SELF = "$NODE#$port";
		647	eval {
		648	&{ load_func $init }
		649	};
		650	_self_die if $@;
		651	}
		652
		653	sub spawn(@) {
		654	my ($nodeid, undef) = split /#/, shift, 2;
		655
		656	my $id = "$RUNIQ." . $ID++;
		657
		658	$_[0] =~ /::/
		659	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		660
		661	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
		662
		663	"$nodeid#$id"
		664	}
		665
		666	=item after $timeout, @msg
		667
		668	=item after $timeout, $callback
		669
		670	Either sends the given message, or call the given callback, after the
		671	specified number of seconds.
		672
		673	This is simply a utility function that comes in handy at times - the
		674	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		675	so it may go away in the future.
		676
		677	=cut
		678
		679	sub after($@) {
		680	my ($timeout, @action) = @_;
		681
		682	my $t; $t = AE::timer $timeout, 0, sub {
		683	undef $t;
		684	ref $action[0]
		685	? $action[0]()
		686	: snd @action;
		687	};
		688	}
		689
573	=back	690	=back
574		691
575	=head1 NODE MESSAGES	692	=head1 AnyEvent::MP vs. Distributed Erlang
576		693
577	Nodes understand the following messages sent to them. Many of them take	694	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
578	arguments called C<@reply>, which will simply be used to compose a reply	695	== aemp node, Erlang process == aemp port), so many of the documents and
579	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and	696	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
580	the remaining arguments are simply the message data.	697	sample:
581		698
582	While other messages exist, they are not public and subject to change.	699	http://www.Erlang.se/doc/programming_rules.shtml
		700	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		701	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		702	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		703
		704	Despite the similarities, there are also some important differences:
583		705
584	=over 4	706	=over 4
585		707
586	=cut	708	=item * Node IDs are arbitrary strings in AEMP.
587		709
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	710	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	711	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
641	convenience functionality.	712	configuraiton or DNS), but will otherwise discover other odes itself.
642		713
643	This means that AEMP requires a less tightly controlled environment at the	714	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
644	cost of longer node references and a slightly higher management overhead.	715	uses "local ports are like remote ports".
		716
		717	The failure modes for local ports are quite different (runtime errors
		718	only) then for remote ports - when a local port dies, you I<know> it dies,
		719	when a connection to another node dies, you know nothing about the other
		720	port.
		721
		722	Erlang pretends remote ports are as reliable as local ports, even when
		723	they are not.
		724
		725	AEMP encourages a "treat remote ports differently" philosophy, with local
		726	ports being the special case/exception, where transport errors cannot
		727	occur.
645		728
646	=item * Erlang uses processes and a mailbox, AEMP does not queue.	729	=item * Erlang uses processes and a mailbox, AEMP does not queue.
647		730
648	Erlang uses processes that selctively receive messages, and therefore	731	Erlang uses processes that selectively receive messages, and therefore
649	needs a queue. AEMP is event based, queuing messages would serve no useful	732	needs a queue. AEMP is event based, queuing messages would serve no
650	purpose.	733	useful purpose. For the same reason the pattern-matching abilities of
		734	AnyEvent::MP are more limited, as there is little need to be able to
		735	filter messages without dequeing them.
651		736
652	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	737	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
653		738
654	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	739	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
655		740
656	Sending messages in erlang is synchronous and blocks the process. AEMP	741	Sending messages in Erlang is synchronous and blocks the process (and
657	sends are immediate, connection establishment is handled in the	742	so does not need a queue that can overflow). AEMP sends are immediate,
658	background.	743	connection establishment is handled in the background.
659		744
660	=item * Erlang can silently lose messages, AEMP cannot.	745	=item * Erlang suffers from silent message loss, AEMP does not.
661		746
662	Erlang makes few guarantees on messages delivery - messages can get lost	747	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,	748	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).	749	and c, and the other side only receives messages a and c).
665		750
666	AEMP guarantees correct ordering, and the guarantee that there are no	751	AEMP guarantees correct ordering, and the guarantee that after one message
667	holes in the message sequence.	752	is lost, all following ones sent to the same port are lost as well, until
668		753	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	754	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		755
680	=item * Erlang can send messages to the wrong port, AEMP does not.	756	=item * Erlang can send messages to the wrong port, AEMP does not.
681		757
682	In erlang it is quite possible that a node that restarts reuses a process	758	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	759	known to other nodes for a completely different process, causing messages
684	messages destined for that process to end up in an unrelated process.	760	destined for that process to end up in an unrelated process.
685		761
686	AEMP never reuses port IDs, so old messages or old port IDs floating	762	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.	763	around in the network will not be sent to an unrelated port.
688		764
689	=item * Erlang uses unprotected connections, AEMP uses secure	765	=item * Erlang uses unprotected connections, AEMP uses secure
690	authentication and can use TLS.	766	authentication and can use TLS.
691		767
692	AEMP can use a proven protocol - SSL/TLS - to protect connections and	768	AEMP can use a proven protocol - TLS - to protect connections and
693	securely authenticate nodes.	769	securely authenticate nodes.
694		770
695	=item * The AEMP protocol is optimised for both text-based and binary	771	=item * The AEMP protocol is optimised for both text-based and binary
696	communications.	772	communications.
697		773
698	The AEMP protocol, unlike the erlang protocol, supports both	774	The AEMP protocol, unlike the Erlang protocol, supports both programming
699	language-independent text-only protocols (good for debugging) and binary,	775	language independent text-only protocols (good for debugging) and binary,
700	language-specific serialisers (e.g. Storable).	776	language-specific serialisers (e.g. Storable). By default, unless TLS is
		777	used, the protocol is actually completely text-based.
701		778
702	It has also been carefully designed to be implementable in other languages	779	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	780	with a minimum of work while gracefully degrading functionality to make the
704	protocol simple.	781	protocol simple.
705		782
		783	=item * AEMP has more flexible monitoring options than Erlang.
		784
		785	In Erlang, you can chose to receive I<all> exit signals as messages
		786	or I<none>, there is no in-between, so monitoring single processes is
		787	difficult to implement. Monitoring in AEMP is more flexible than in
		788	Erlang, as one can choose between automatic kill, exit message or callback
		789	on a per-process basis.
		790
		791	=item * Erlang tries to hide remote/local connections, AEMP does not.
		792
		793	Monitoring in Erlang is not an indicator of process death/crashes, in the
		794	same way as linking is (except linking is unreliable in Erlang).
		795
		796	In AEMP, you don't "look up" registered port names or send to named ports
		797	that might or might not be persistent. Instead, you normally spawn a port
		798	on the remote node. The init function monitors you, and you monitor the
		799	remote port. Since both monitors are local to the node, they are much more
		800	reliable (no need for C<spawn_link>).
		801
		802	This also saves round-trips and avoids sending messages to the wrong port
		803	(hard to do in Erlang).
		804
706	=back	805	=back
707		806
		807	=head1 RATIONALE
		808
		809	=over 4
		810
		811	=item Why strings for port and node IDs, why not objects?
		812
		813	We considered "objects", but found that the actual number of methods
		814	that can be called are quite low. Since port and node IDs travel over
		815	the network frequently, the serialising/deserialising would add lots of
		816	overhead, as well as having to keep a proxy object everywhere.
		817
		818	Strings can easily be printed, easily serialised etc. and need no special
		819	procedures to be "valid".
		820
		821	And as a result, a miniport consists of a single closure stored in a
		822	global hash - it can't become much cheaper.
		823
		824	=item Why favour JSON, why not a real serialising format such as Storable?
		825
		826	In fact, any AnyEvent::MP node will happily accept Storable as framing
		827	format, but currently there is no way to make a node use Storable by
		828	default (although all nodes will accept it).
		829
		830	The default framing protocol is JSON because a) JSON::XS is many times
		831	faster for small messages and b) most importantly, after years of
		832	experience we found that object serialisation is causing more problems
		833	than it solves: Just like function calls, objects simply do not travel
		834	easily over the network, mostly because they will always be a copy, so you
		835	always have to re-think your design.
		836
		837	Keeping your messages simple, concentrating on data structures rather than
		838	objects, will keep your messages clean, tidy and efficient.
		839
		840	=back
		841
708	=head1 SEE ALSO	842	=head1 SEE ALSO
		843
		844	L<AnyEvent::MP::Intro> - a gentle introduction.
		845
		846	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		847
		848	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		849	your applications.
709		850
710	L<AnyEvent>.	851	L<AnyEvent>.
711		852
712	=head1 AUTHOR	853	=head1 AUTHOR
713		854

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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 1.75 by root, Mon Aug 31 13:18:06 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 1.75 by root, Mon Aug 31 13:18:06 2009 UTC