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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.37 by root, Fri Aug 7 16:47:23 2009 UTC vs.
Revision 1.67 by root, Fri Aug 28 22:21:53 2009 UTC

…		…
8		8
9	$NODE # contains this node's noderef	9	$NODE # contains this node's noderef
10	NODE # returns this node's noderef	10	NODE # returns this node's noderef
11	NODE $port # returns the noderef of the port	11	NODE $port # returns the noderef of the port
12		12
		13	$SELF # receiving/own port id in rcv callbacks
		14
		15	# initialise the node so it can send/receive messages
		16	initialise_node;
		17
		18	# ports are message endpoints
		19
		20	# sending messages
13	snd $port, type => data...;	21	snd $port, type => data...;
		22	snd $port, @msg;
		23	snd @msg_with_first_element_being_a_port;
14		24
15	$SELF # receiving/own port id in rcv callbacks	25	# creating/using ports, the simple way
		26	my $simple_port = port { my @msg = @_; 0 };
16		27
17	rcv $port, smartmatch => $cb->($port, @msg);	28	# creating/using ports, tagged message matching
18		29	my $port = port;
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	30	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
21	rcv $port1, pong => sub { warn "pong received\n" };	31	rcv $port, pong => sub { warn "pong received\n"; 0 };
22	snd $port2, ping => $port1;
23		32
24	# more, smarter, matches (_any_ is exported by this module)	33	# create a port on another node
25	rcv $port, [child_died => $pid] => sub { ...	34	my $port = spawn $node, $initfunc, @initdata;
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
27		35
28	# monitoring	36	# monitoring
29	mon $port, $cb->(@msg) # callback is invoked on death	37	mon $port, $cb->(@msg) # callback is invoked on death
30	mon $port, $otherport # kill otherport on abnormal death	38	mon $port, $otherport # kill otherport on abnormal death
31	mon $port, $otherport, @msg # send message on death	39	mon $port, $otherport, @msg # send message on death
32		40
		41	=head1 CURRENT STATUS
		42
		43	AnyEvent::MP - stable API, should work
		44	AnyEvent::MP::Intro - outdated
		45	AnyEvent::MP::Kernel - mostly stable
		46	AnyEvent::MP::Global - mostly stable
		47	AnyEvent::MP::Node - mostly stable, but internal anyways
		48	AnyEvent::MP::Transport - mostly stable, but internal anyways
		49
		50	stay tuned.
		51
33	=head1 DESCRIPTION	52	=head1 DESCRIPTION
34		53
35	This module (-family) implements a simple message passing framework.	54	This module (-family) implements a simple message passing framework.
36		55
37	Despite its simplicity, you can securely message other processes running	56	Despite its simplicity, you can securely message other processes running
38	on the same or other hosts.	57	on the same or other hosts, and you can supervise entities remotely.
39		58
40	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	59	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
41	manual page.	60	manual page and the examples under F<eg/>.
42		61
43	At the moment, this module family is severly broken and underdocumented,	62	At the moment, this module family is a bit underdocumented.
44	so do not use. This was uploaded mainly to reserve the CPAN namespace -
45	stay tuned! The basic API should be finished, however.
46		63
47	=head1 CONCEPTS	64	=head1 CONCEPTS
48		65
49	=over 4	66	=over 4
50		67
51	=item port	68	=item port
52		69
53	A port is something you can send messages to (with the C<snd> function).	70	A port is something you can send messages to (with the C<snd> function).
54		71
55	Some ports allow you to register C<rcv> handlers that can match specific	72	Ports allow you to register C<rcv> handlers that can match all or just
56	messages. All C<rcv> handlers will receive messages they match, messages	73	some messages. Messages send to ports will not be queued, regardless of
57	will not be queued.	74	anything was listening for them or not.
58		75
59	=item port id - C<noderef#portname>	76	=item port ID - C<nodeid#portname>
60		77
61	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	78	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as
62	separator, and a port name (a printable string of unspecified format). An	79	separator, and a port name (a printable string of unspecified format).
63	exception is the the node port, whose ID is identical to its node
64	reference.
65		80
66	=item node	81	=item node
67		82
68	A node is a single process containing at least one port - the node	83	A node is a single process containing at least one port - the node port,
69	port. You can send messages to node ports to find existing ports or to	84	which enables nodes to manage each other remotely, and to create new
70	create new ports, among other things.	85	ports.
71		86
72	Nodes are either private (single-process only), slaves (connected to a	87	Nodes are either public (have one or more listening ports) or private
73	master node only) or public nodes (connectable from unrelated nodes).	88	(no listening ports). Private nodes cannot talk to other private nodes
		89	currently.
74		90
75	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	91	=item node ID - C<[a-za-Z0-9_\-.:]+>
76		92
77	A node reference is a string that either simply identifies the node (for	93	A node ID is a string that uniquely identifies the node within a
78	private and slave nodes), or contains a recipe on how to reach a given	94	network. Depending on the configuration used, node IDs can look like a
79	node (for public nodes).	95	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
		96	doesn't interpret node IDs in any way.
80		97
81	This recipe is simply a comma-separated list of C<address:port> pairs (for	98	=item binds - C<ip:port>
82	TCP/IP, other protocols might look different).
83		99
84	Node references come in two flavours: resolved (containing only numerical	100	Nodes can only talk to each other by creating some kind of connection to
85	addresses) or unresolved (where hostnames are used instead of addresses).	101	each other. To do this, nodes should listen on one or more local transport
		102	endpoints - binds. Currently, only standard C<ip:port> specifications can
		103	be used, which specify TCP ports to listen on.
86		104
87	Before using an unresolved node reference in a message you first have to	105	=item seeds - C<host:port>
88	resolve it.	106
		107	When a node starts, it knows nothing about the network. To teach the node
		108	about the network it first has to contact some other node within the
		109	network. This node is called a seed.
		110
		111	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes
		112	are expected to be long-running, and at least one of those should always
		113	be available. When nodes run out of connections (e.g. due to a network
		114	error), they try to re-establish connections to some seednodes again to
		115	join the network.
		116
		117	Apart from being sued for seeding, seednodes are not special in any way -
		118	every public node can be a seednode.
89		119
90	=back	120	=back
91		121
92	=head1 VARIABLES/FUNCTIONS	122	=head1 VARIABLES/FUNCTIONS
93		123
…		…
95		125
96	=cut	126	=cut
97		127
98	package AnyEvent::MP;	128	package AnyEvent::MP;
99		129
100	use AnyEvent::MP::Base;	130	use AnyEvent::MP::Kernel;
101		131
102	use common::sense;	132	use common::sense;
103		133
104	use Carp ();	134	use Carp ();
105		135
106	use AE ();	136	use AE ();
107		137
108	use base "Exporter";	138	use base "Exporter";
109		139
110	our $VERSION = '0.1';	140	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		141
111	our @EXPORT = qw(	142	our @EXPORT = qw(
112	NODE $NODE *SELF node_of _any_	143	NODE $NODE *SELF node_of after
113	resolve_node initialise_node	144	initialise_node
114	snd rcv mon kil reg psub	145	snd rcv mon mon_guard kil reg psub spawn
115	port	146	port
116	);	147	);
117		148
118	our $SELF;	149	our $SELF;
119		150
…		…
123	kil $SELF, die => $msg;	154	kil $SELF, die => $msg;
124	}	155	}
125		156
126	=item $thisnode = NODE / $NODE	157	=item $thisnode = NODE / $NODE
127		158
128	The C<NODE> function returns, and the C<$NODE> variable contains	159	The C<NODE> function returns, and the C<$NODE> variable contains, the node
129	the noderef of the local node. The value is initialised by a call	160	ID of the node running in the current process. This value is initialised by
130	to C<become_public> or C<become_slave>, after which all local port	161	a call to C<initialise_node>.
131	identifiers become invalid.
132		162
133	=item $noderef = node_of $port	163	=item $nodeid = node_of $port
134		164
135	Extracts and returns the noderef from a portid or a noderef.	165	Extracts and returns the node ID from a port ID or a node ID.
136		166
137	=item initialise_node $noderef, $seednode, $seednode...	167	=item initialise_node $profile_name
138		168
139	=item initialise_node "slave/", $master, $master...
140
141	Before a node can talk to other nodes on the network it has to initialise	169	Before a node can talk to other nodes on the network (i.e. enter
142	itself - the minimum a node needs to know is it's own name, and optionally	170	"distributed mode") it has to initialise itself - the minimum a node needs
143	it should know the noderefs of some other nodes in the network.	171	to know is its own name, and optionally it should know the addresses of
		172	some other nodes in the network to discover other nodes.
144		173
145	This function initialises a node - it must be called exactly once (or	174	This function initialises a node - it must be called exactly once (or
146	never) before calling other AnyEvent::MP functions.	175	never) before calling other AnyEvent::MP functions.
147		176
148	All arguments are noderefs, which can be either resolved or unresolved.	177	The first argument is a profile name. If it is C<undef> or missing, then
		178	the current nodename will be used instead (i.e. F<uname -n>).
149		179
150	There are two types of networked nodes, public nodes and slave nodes:	180	The function then looks up the profile in the aemp configuration (see the
		181	L<aemp> commandline utility).
151		182
152	=over 4	183	If the profile specifies a node ID, then this will become the node ID of
		184	this process. If not, then the profile name will be used as node ID. The
		185	special node ID of C<anon/> will be replaced by a random node ID.
153		186
154	=item public nodes	187	The next step is to look up the binds in the profile, followed by binding
		188	aemp protocol listeners on all binds specified (it is possible and valid
		189	to have no binds, meaning that the node cannot be contacted form the
		190	outside. This means the node cannot talk to other nodes that also have no
		191	binds, but it can still talk to all "normal" nodes).
155		192
156	For public nodes, C<$noderef> must either be a (possibly unresolved)	193	If the profile does not specify a binds list, then the node ID will be
157	noderef, in which case it will be resolved, or C<undef> (or missing), in	194	treated as if it were of the form C<host:port>, which will be resolved and
158	which case the noderef will be guessed.	195	used as binds list.
159		196
160	Afterwards, the node will bind itself on all endpoints and try to connect	197	Lastly, the seeds list from the profile is passed to the
161	to all additional C<$seednodes> that are specified. Seednodes are optional	198	L<AnyEvent::MP::Global> module, which will then use it to keep
162	and can be used to quickly bootstrap the node into an existing network.	199	connectivity with at least on of those seed nodes at any point in time.
163		200
164	=item slave nodes	201	Example: become a distributed node listening on the guessed noderef, or
165		202	the one specified via C<aemp> for the current node. This should be the
166	When the C<$noderef> is the special string C<slave/>, then the node will	203	most common form of invocation for "daemon"-type nodes.
167	become a slave node. Slave nodes cannot be contacted from outside and will
168	route most of their traffic to the master node that they attach to.
169
170	At least one additional noderef is required: The node will try to connect
171	to all of them and will become a slave attached to the first node it can
172	successfully connect to.
173
174	=back
175
176	This function will block until all nodes have been resolved and, for slave
177	nodes, until it has successfully established a connection to a master
178	server.
179
180	Example: become a public node listening on the default node.
181		204
182	initialise_node;	205	initialise_node;
183		206
184	Example: become a public node, and try to contact some well-known master	207	Example: become an anonymous node. This form is often used for commandline
185	servers to become part of the network.	208	clients.
186		209
187	initialise_node undef, "master1", "master2";
188
189	Example: become a public node listening on port C<4041>.
190
191	initialise_node 4041;	210	initialise_node "anon/";
192		211
193	Example: become a public node, only visible on localhost port 4044.	212	Example: become a distributed node. If there is no profile of the given
		213	name, or no binds list was specified, resolve C<localhost:4044> and bind
		214	on the resulting addresses.
194		215
195	initialise_node "locahost:4044";	216	initialise_node "localhost:4044";
196
197	Example: become a slave node to any of the specified master servers.
198
199	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
200
201	=item $cv = resolve_node $noderef
202
203	Takes an unresolved node reference that may contain hostnames and
204	abbreviated IDs, resolves all of them and returns a resolved node
205	reference.
206
207	In addition to C<address:port> pairs allowed in resolved noderefs, the
208	following forms are supported:
209
210	=over 4
211
212	=item the empty string
213
214	An empty-string component gets resolved as if the default port (4040) was
215	specified.
216
217	=item naked port numbers (e.g. C<1234>)
218
219	These are resolved by prepending the local nodename and a colon, to be
220	further resolved.
221
222	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
223
224	These are resolved by using AnyEvent::DNS to resolve them, optionally
225	looking up SRV records for the C<aemp=4040> port, if no port was
226	specified.
227
228	=back
229		217
230	=item $SELF	218	=item $SELF
231		219
232	Contains the current port id while executing C<rcv> callbacks or C<psub>	220	Contains the current port id while executing C<rcv> callbacks or C<psub>
233	blocks.	221	blocks.
234		222
235	=item SELF, %SELF, @SELF...	223	=item *SELF, SELF, %SELF, @SELF...
236		224
237	Due to some quirks in how perl exports variables, it is impossible to	225	Due to some quirks in how perl exports variables, it is impossible to
238	just export C<$SELF>, all the symbols called C<SELF> are exported by this	226	just export C<$SELF>, all the symbols named C<SELF> are exported by this
239	module, but only C<$SELF> is currently used.	227	module, but only C<$SELF> is currently used.
240		228
241	=item snd $port, type => @data	229	=item snd $port, type => @data
242		230
243	=item snd $port, @msg	231	=item snd $port, @msg
244		232
245	Send the given message to the given port ID, which can identify either	233	Send the given message to the given port, which can identify either a
246	a local or a remote port, and can be either a string or soemthignt hat	234	local or a remote port, and must be a port ID.
247	stringifies a sa port ID (such as a port object :).
248		235
249	While the message can be about anything, it is highly recommended to use a	236	While the message can be almost anything, it is highly recommended to
250	string as first element (a portid, or some word that indicates a request	237	use a string as first element (a port ID, or some word that indicates a
251	type etc.).	238	request type etc.) and to consist if only simple perl values (scalars,
		239	arrays, hashes) - if you think you need to pass an object, think again.
252		240
253	The message data effectively becomes read-only after a call to this	241	The message data logically becomes read-only after a call to this
254	function: modifying any argument is not allowed and can cause many	242	function: modifying any argument (or values referenced by them) is
255	problems.	243	forbidden, as there can be considerable time between the call to C<snd>
		244	and the time the message is actually being serialised - in fact, it might
		245	never be copied as within the same process it is simply handed to the
		246	receiving port.
256		247
257	The type of data you can transfer depends on the transport protocol: when	248	The type of data you can transfer depends on the transport protocol: when
258	JSON is used, then only strings, numbers and arrays and hashes consisting	249	JSON is used, then only strings, numbers and arrays and hashes consisting
259	of those are allowed (no objects). When Storable is used, then anything	250	of those are allowed (no objects). When Storable is used, then anything
260	that Storable can serialise and deserialise is allowed, and for the local	251	that Storable can serialise and deserialise is allowed, and for the local
261	node, anything can be passed.	252	node, anything can be passed. Best rely only on the common denominator of
		253	these.
262		254
263	=item $local_port = port	255	=item $local_port = port
264		256
265	Create a new local port object that can be used either as a pattern	257	Create a new local port object and returns its port ID. Initially it has
266	matching port ("full port") or a single-callback port ("miniport"),	258	no callbacks set and will throw an error when it receives messages.
267	depending on how C<rcv> callbacks are bound to the object.
268		259
269	=item $port = port { my @msg = @_; $finished }	260	=item $local_port = port { my @msg = @_ }
270		261
271	Creates a "miniport", that is, a very lightweight port without any pattern	262	Creates a new local port, and returns its ID. Semantically the same as
272	matching behind it, and returns its ID. Semantically the same as creating
273	a port and calling C<rcv $port, $callback> on it.	263	creating a port and calling C<rcv $port, $callback> on it.
274		264
275	The block will be called for every message received on the port. When the	265	The block will be called for every message received on the port, with the
276	callback returns a true value its job is considered "done" and the port	266	global variable C<$SELF> set to the port ID. Runtime errors will cause the
277	will be destroyed. Otherwise it will stay alive.	267	port to be C<kil>ed. The message will be passed as-is, no extra argument
		268	(i.e. no port ID) will be passed to the callback.
278		269
279	The message will be passed as-is, no extra argument (i.e. no port id) will	270	If you want to stop/destroy the port, simply C<kil> it:
280	be passed to the callback.
281		271
282	If you need the local port id in the callback, this works nicely:	272	my $port = port {
283		273	my @msg = @_;
284	my $port; $port = port {	274	...
285	snd $otherport, reply => $port;	275	kil $SELF;
286	};	276	};
287		277
288	=cut	278	=cut
289		279
290	sub rcv($@);	280	sub rcv($@);
		281
		282	sub _kilme {
		283	die "received message on port without callback";
		284	}
291		285
292	sub port(;&) {	286	sub port(;&) {
293	my $id = "$UNIQ." . $ID++;	287	my $id = "$UNIQ." . $ID++;
294	my $port = "$NODE#$id";	288	my $port = "$NODE#$id";
295		289
296	if (@_) {	290	rcv $port, shift \|\| \&_kilme;
297	rcv $port, shift;
298	} else {
299	$PORT{$id} = sub { }; # nop
300	}
301		291
302	$port	292	$port
303	}	293	}
304		294
305	=item reg $port, $name
306
307	=item reg $name
308
309	Registers the given port (or C<$SELF><<< if missing) under the name
310	C<$name>. If the name already exists it is replaced.
311
312	A port can only be registered under one well known name.
313
314	A port automatically becomes unregistered when it is killed.
315
316	=cut
317
318	sub reg(@) {
319	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
320
321	$REG{$_[0]} = $port;
322	}
323
324	=item rcv $port, $callback->(@msg)	295	=item rcv $local_port, $callback->(@msg)
325		296
326	Replaces the callback on the specified miniport (after converting it to	297	Replaces the default callback on the specified port. There is no way to
327	one if required).	298	remove the default callback: use C<sub { }> to disable it, or better
328		299	C<kil> the port when it is no longer needed.
329	=item rcv $port, tagstring => $callback->(@msg), ...
330
331	=item rcv $port, $smartmatch => $callback->(@msg), ...
332
333	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
334
335	Register callbacks to be called on matching messages on the given full
336	port (after converting it to one if required) and return the port.
337
338	The callback has to return a true value when its work is done, after
339	which is will be removed, or a false value in which case it will stay
340	registered.
341		300
342	The global C<$SELF> (exported by this module) contains C<$port> while	301	The global C<$SELF> (exported by this module) contains C<$port> while
343	executing the callback.	302	executing the callback. Runtime errors during callback execution will
		303	result in the port being C<kil>ed.
344		304
345	Runtime errors wdurign callback execution will result in the port being	305	The default callback received all messages not matched by a more specific
346	C<kil>ed.	306	C<tag> match.
347		307
348	If the match is an array reference, then it will be matched against the	308	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
349	first elements of the message, otherwise only the first element is being
350	matched.
351		309
352	Any element in the match that is specified as C<_any_> (a function	310	Register (or replace) callbacks to be called on messages starting with the
353	exported by this module) matches any single element of the message.	311	given tag on the given port (and return the port), or unregister it (when
		312	C<$callback> is C<$undef> or missing). There can only be one callback
		313	registered for each tag.
354		314
355	While not required, it is highly recommended that the first matching	315	The original message will be passed to the callback, after the first
356	element is a string identifying the message. The one-string-only match is	316	element (the tag) has been removed. The callback will use the same
357	also the most efficient match (by far).	317	environment as the default callback (see above).
358		318
359	Example: create a port and bind receivers on it in one go.	319	Example: create a port and bind receivers on it in one go.
360		320
361	my $port = rcv port,	321	my $port = rcv port,
362	msg1 => sub { ...; 0 },	322	msg1 => sub { ... },
363	msg2 => sub { ...; 0 },	323	msg2 => sub { ... },
364	;	324	;
365		325
366	Example: create a port, bind receivers and send it in a message elsewhere	326	Example: create a port, bind receivers and send it in a message elsewhere
367	in one go:	327	in one go:
368		328
369	snd $otherport, reply =>	329	snd $otherport, reply =>
370	rcv port,	330	rcv port,
371	msg1 => sub { ...; 0 },	331	msg1 => sub { ... },
372	...	332	...
373	;	333	;
		334
		335	Example: temporarily register a rcv callback for a tag matching some port
		336	(e.g. for a rpc reply) and unregister it after a message was received.
		337
		338	rcv $port, $otherport => sub {
		339	my @reply = @_;
		340
		341	rcv $SELF, $otherport;
		342	};
374		343
375	=cut	344	=cut
376		345
377	sub rcv($@) {	346	sub rcv($@) {
378	my $port = shift;	347	my $port = shift;
379	my ($noderef, $portid) = split /#/, $port, 2;	348	my ($noderef, $portid) = split /#/, $port, 2;
380		349
381	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	350	$NODE{$noderef} == $NODE{""}
382	or Carp::croak "$port: rcv can only be called on local ports, caught";	351	or Carp::croak "$port: rcv can only be called on local ports, caught";
383		352
384	if (@_ == 1) {	353	while (@_) {
		354	if (ref $_[0]) {
		355	if (my $self = $PORT_DATA{$portid}) {
		356	"AnyEvent::MP::Port" eq ref $self
		357	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		358
		359	$self->[2] = shift;
		360	} else {
385	my $cb = shift;	361	my $cb = shift;
386	delete $PORT_DATA{$portid};
387	$PORT{$portid} = sub {	362	$PORT{$portid} = sub {
388	local $SELF = $port;	363	local $SELF = $port;
389	eval {	364	eval { &$cb }; _self_die if $@;
390	&$cb	365	};
391	and kil $port;
392	};	366	}
393	_self_die if $@;	367	} elsif (defined $_[0]) {
394	};
395	} else {
396	my $self = $PORT_DATA{$portid} \|\|= do {	368	my $self = $PORT_DATA{$portid} \|\|= do {
397	my $self = bless {	369	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
398	id => $port,
399	}, "AnyEvent::MP::Port";
400		370
401	$PORT{$portid} = sub {	371	$PORT{$portid} = sub {
402	local $SELF = $port;	372	local $SELF = $port;
403		373
404	eval {
405	for (@{ $self->{rc0}{$_[0]} }) {	374	if (my $cb = $self->[1]{$_[0]}) {
406	$_ && &{$_->[0]}	375	shift;
407	&& undef $_;	376	eval { &$cb }; _self_die if $@;
408	}	377	} else {
409
410	for (@{ $self->{rcv}{$_[0]} }) {
411	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
412	&& &{$_->[0]}	378	&{ $self->[0] };
413	&& undef $_;
414	}
415
416	for (@{ $self->{any} }) {
417	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
418	&& &{$_->[0]}
419	&& undef $_;
420	}	379	}
421	};	380	};
422	_self_die if $@;	381
		382	$self
423	};	383	};
424		384
425	$self
426	};
427
428	"AnyEvent::MP::Port" eq ref $self	385	"AnyEvent::MP::Port" eq ref $self
429	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	386	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
430		387
431	while (@_) {
432	my ($match, $cb) = splice @_, 0, 2;	388	my ($tag, $cb) = splice @_, 0, 2;
433		389
434	if (!ref $match) {	390	if (defined $cb) {
435	push @{ $self->{rc0}{$match} }, [$cb];	391	$self->[1]{$tag} = $cb;
436	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
437	my ($type, @match) = @$match;
438	@match
439	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
440	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
441	} else {	392	} else {
442	push @{ $self->{any} }, [$cb, $match];	393	delete $self->[1]{$tag};
443	}	394	}
444	}	395	}
445	}	396	}
446		397
447	$port	398	$port
…		…
483	$res	434	$res
484	}	435	}
485	}	436	}
486	}	437	}
487		438
488	=item $guard = mon $port, $cb->(@reason)	439	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
489		440
490	=item $guard = mon $port, $rcvport	441	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
491		442
492	=item $guard = mon $port	443	=item $guard = mon $port # kill $SELF when $port dies
493		444
494	=item $guard = mon $port, $rcvport, @msg	445	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
495		446
496	Monitor the given port and do something when the port is killed, and	447	Monitor the given port and do something when the port is killed or
497	optionally return a guard that can be used to stop monitoring again.	448	messages to it were lost, and optionally return a guard that can be used
		449	to stop monitoring again.
		450
		451	C<mon> effectively guarantees that, in the absence of hardware failures,
		452	after starting the monitor, either all messages sent to the port will
		453	arrive, or the monitoring action will be invoked after possible message
		454	loss has been detected. No messages will be lost "in between" (after
		455	the first lost message no further messages will be received by the
		456	port). After the monitoring action was invoked, further messages might get
		457	delivered again.
		458
		459	Note that monitoring-actions are one-shot: once messages are lost (and a
		460	monitoring alert was raised), they are removed and will not trigger again.
498		461
499	In the first form (callback), the callback is simply called with any	462	In the first form (callback), the callback is simply called with any
500	number of C<@reason> elements (no @reason means that the port was deleted	463	number of C<@reason> elements (no @reason means that the port was deleted
501	"normally"). Note also that I<< the callback B<must> never die >>, so use	464	"normally"). Note also that I<< the callback B<must> never die >>, so use
502	C<eval> if unsure.	465	C<eval> if unsure.
503		466
504	In the second form (another port given), the other port (C<$rcvport)	467	In the second form (another port given), the other port (C<$rcvport>)
505	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on	468	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
506	"normal" kils nothing happens, while under all other conditions, the other	469	"normal" kils nothing happens, while under all other conditions, the other
507	port is killed with the same reason.	470	port is killed with the same reason.
508		471
509	The third form (kill self) is the same as the second form, except that	472	The third form (kill self) is the same as the second form, except that
…		…
536	sub mon {	499	sub mon {
537	my ($noderef, $port) = split /#/, shift, 2;	500	my ($noderef, $port) = split /#/, shift, 2;
538		501
539	my $node = $NODE{$noderef} \|\| add_node $noderef;	502	my $node = $NODE{$noderef} \|\| add_node $noderef;
540		503
541	my $cb = @_ ? $_[0] : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	504	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
542		505
543	unless (ref $cb) {	506	unless (ref $cb) {
544	if (@_) {	507	if (@_) {
545	# send a kill info message	508	# send a kill info message
546	my (@msg) = @_;	509	my (@msg) = ($cb, @_);
547	$cb = sub { snd @msg, @_ };	510	$cb = sub { snd @msg, @_ };
548	} else {	511	} else {
549	# simply kill other port	512	# simply kill other port
550	my $port = $cb;	513	my $port = $cb;
551	$cb = sub { kil $port, @_ if @_ };	514	$cb = sub { kil $port, @_ if @_ };
…		…
564	is killed, the references will be freed.	527	is killed, the references will be freed.
565		528
566	Optionally returns a guard that will stop the monitoring.	529	Optionally returns a guard that will stop the monitoring.
567		530
568	This function is useful when you create e.g. timers or other watchers and	531	This function is useful when you create e.g. timers or other watchers and
569	want to free them when the port gets killed:	532	want to free them when the port gets killed (note the use of C<psub>):
570		533
571	$port->rcv (start => sub {	534	$port->rcv (start => sub {
572	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	535	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
573	undef $timer if 0.9 < rand;	536	undef $timer if 0.9 < rand;
574	});	537	});
575	});	538	});
576		539
577	=cut	540	=cut
…		…
586		549
587	=item kil $port[, @reason]	550	=item kil $port[, @reason]
588		551
589	Kill the specified port with the given C<@reason>.	552	Kill the specified port with the given C<@reason>.
590		553
591	If no C<@reason> is specified, then the port is killed "normally" (linked	554	If no C<@reason> is specified, then the port is killed "normally" (ports
592	ports will not be kileld, or even notified).	555	monitoring other ports will not necessarily die because a port dies
		556	"normally").
593		557
594	Otherwise, linked ports get killed with the same reason (second form of	558	Otherwise, linked ports get killed with the same reason (second form of
595	C<mon>, see below).	559	C<mon>, see above).
596		560
597	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	561	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
598	will be reported as reason C<< die => $@ >>.	562	will be reported as reason C<< die => $@ >>.
599		563
600	Transport/communication errors are reported as C<< transport_error =>	564	Transport/communication errors are reported as C<< transport_error =>
601	$message >>.	565	$message >>.
602		566
603	=back
604
605	=head1 NODE MESSAGES
606
607	Nodes understand the following messages sent to them. Many of them take
608	arguments called C<@reply>, which will simply be used to compose a reply
609	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
610	the remaining arguments are simply the message data.
611
612	While other messages exist, they are not public and subject to change.
613
614	=over 4
615
616	=cut	567	=cut
617		568
618	=item lookup => $name, @reply	569	=item $port = spawn $node, $initfunc[, @initdata]
619		570
620	Replies with the port ID of the specified well-known port, or C<undef>.	571	Creates a port on the node C<$node> (which can also be a port ID, in which
		572	case it's the node where that port resides).
621		573
622	=item devnull => ...	574	The port ID of the newly created port is returned immediately, and it is
		575	possible to immediately start sending messages or to monitor the port.
623		576
624	Generic data sink/CPU heat conversion.	577	After the port has been created, the init function is called on the remote
		578	node, in the same context as a C<rcv> callback. This function must be a
		579	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
		580	specify a function in the main program, use C<::name>.
625		581
626	=item relay => $port, @msg	582	If the function doesn't exist, then the node tries to C<require>
		583	the package, then the package above the package and so on (e.g.
		584	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		585	exists or it runs out of package names.
627		586
628	Simply forwards the message to the given port.	587	The init function is then called with the newly-created port as context
		588	object (C<$SELF>) and the C<@initdata> values as arguments.
629		589
630	=item eval => $string[ @reply]	590	A common idiom is to pass a local port, immediately monitor the spawned
		591	port, and in the remote init function, immediately monitor the passed
		592	local port. This two-way monitoring ensures that both ports get cleaned up
		593	when there is a problem.
631		594
632	Evaluates the given string. If C<@reply> is given, then a message of the	595	Example: spawn a chat server port on C<$othernode>.
633	form C<@reply, $@, @evalres> is sent.
634		596
635	Example: crash another node.	597	# this node, executed from within a port context:
		598	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		599	mon $server;
636		600
637	snd $othernode, eval => "exit";	601	# init function on C<$othernode>
		602	sub connect {
		603	my ($srcport) = @_;
638		604
639	=item time => @reply	605	mon $srcport;
640		606
641	Replies the the current node time to C<@reply>.	607	rcv $SELF, sub {
		608	...
		609	};
		610	}
642		611
643	Example: tell the current node to send the current time to C<$myport> in a	612	=cut
644	C<timereply> message.
645		613
646	snd $NODE, time => $myport, timereply => 1, 2;	614	sub _spawn {
647	# => snd $myport, timereply => 1, 2, <time>	615	my $port = shift;
		616	my $init = shift;
		617
		618	local $SELF = "$NODE#$port";
		619	eval {
		620	&{ load_func $init }
		621	};
		622	_self_die if $@;
		623	}
		624
		625	sub spawn(@) {
		626	my ($noderef, undef) = split /#/, shift, 2;
		627
		628	my $id = "$RUNIQ." . $ID++;
		629
		630	$_[0] =~ /::/
		631	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		632
		633	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
		634
		635	"$noderef#$id"
		636	}
		637
		638	=item after $timeout, @msg
		639
		640	=item after $timeout, $callback
		641
		642	Either sends the given message, or call the given callback, after the
		643	specified number of seconds.
		644
		645	This is simply a utility function that comes in handy at times - the
		646	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		647	so it may go away in the future.
		648
		649	=cut
		650
		651	sub after($@) {
		652	my ($timeout, @action) = @_;
		653
		654	my $t; $t = AE::timer $timeout, 0, sub {
		655	undef $t;
		656	ref $action[0]
		657	? $action[0]()
		658	: snd @action;
		659	};
		660	}
648		661
649	=back	662	=back
650		663
651	=head1 AnyEvent::MP vs. Distributed Erlang	664	=head1 AnyEvent::MP vs. Distributed Erlang
652		665
…		…
662		675
663	Despite the similarities, there are also some important differences:	676	Despite the similarities, there are also some important differences:
664		677
665	=over 4	678	=over 4
666		679
667	=item * Node references contain the recipe on how to contact them.	680	=item * Node IDs are arbitrary strings in AEMP.
668		681
669	Erlang relies on special naming and DNS to work everywhere in the	682	Erlang relies on special naming and DNS to work everywhere in the same
670	same way. AEMP relies on each node knowing it's own address(es), with	683	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
671	convenience functionality.	684	configuraiton or DNS), but will otherwise discover other odes itself.
672		685
673	This means that AEMP requires a less tightly controlled environment at the	686	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
674	cost of longer node references and a slightly higher management overhead.	687	uses "local ports are like remote ports".
		688
		689	The failure modes for local ports are quite different (runtime errors
		690	only) then for remote ports - when a local port dies, you I<know> it dies,
		691	when a connection to another node dies, you know nothing about the other
		692	port.
		693
		694	Erlang pretends remote ports are as reliable as local ports, even when
		695	they are not.
		696
		697	AEMP encourages a "treat remote ports differently" philosophy, with local
		698	ports being the special case/exception, where transport errors cannot
		699	occur.
675		700
676	=item * Erlang uses processes and a mailbox, AEMP does not queue.	701	=item * Erlang uses processes and a mailbox, AEMP does not queue.
677		702
678	Erlang uses processes that selctively receive messages, and therefore	703	Erlang uses processes that selectively receive messages, and therefore
679	needs a queue. AEMP is event based, queuing messages would serve no useful	704	needs a queue. AEMP is event based, queuing messages would serve no
680	purpose.	705	useful purpose. For the same reason the pattern-matching abilities of
		706	AnyEvent::MP are more limited, as there is little need to be able to
		707	filter messages without dequeing them.
681		708
682	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	709	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
683		710
684	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	711	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
685		712
686	Sending messages in Erlang is synchronous and blocks the process. AEMP	713	Sending messages in Erlang is synchronous and blocks the process (and
687	sends are immediate, connection establishment is handled in the	714	so does not need a queue that can overflow). AEMP sends are immediate,
688	background.	715	connection establishment is handled in the background.
689		716
690	=item * Erlang can silently lose messages, AEMP cannot.	717	=item * Erlang suffers from silent message loss, AEMP does not.
691		718
692	Erlang makes few guarantees on messages delivery - messages can get lost	719	Erlang makes few guarantees on messages delivery - messages can get lost
693	without any of the processes realising it (i.e. you send messages a, b,	720	without any of the processes realising it (i.e. you send messages a, b,
694	and c, and the other side only receives messages a and c).	721	and c, and the other side only receives messages a and c).
695		722
696	AEMP guarantees correct ordering, and the guarantee that there are no	723	AEMP guarantees correct ordering, and the guarantee that after one message
697	holes in the message sequence.	724	is lost, all following ones sent to the same port are lost as well, until
698		725	monitoring raises an error, so there are no silent "holes" in the message
699	=item * In Erlang, processes can be declared dead and later be found to be	726	sequence.
700	alive.
701
702	In Erlang it can happen that a monitored process is declared dead and
703	linked processes get killed, but later it turns out that the process is
704	still alive - and can receive messages.
705
706	In AEMP, when port monitoring detects a port as dead, then that port will
707	eventually be killed - it cannot happen that a node detects a port as dead
708	and then later sends messages to it, finding it is still alive.
709		727
710	=item * Erlang can send messages to the wrong port, AEMP does not.	728	=item * Erlang can send messages to the wrong port, AEMP does not.
711		729
712	In Erlang it is quite possible that a node that restarts reuses a process	730	In Erlang it is quite likely that a node that restarts reuses a process ID
713	ID known to other nodes for a completely different process, causing	731	known to other nodes for a completely different process, causing messages
714	messages destined for that process to end up in an unrelated process.	732	destined for that process to end up in an unrelated process.
715		733
716	AEMP never reuses port IDs, so old messages or old port IDs floating	734	AEMP never reuses port IDs, so old messages or old port IDs floating
717	around in the network will not be sent to an unrelated port.	735	around in the network will not be sent to an unrelated port.
718		736
719	=item * Erlang uses unprotected connections, AEMP uses secure	737	=item * Erlang uses unprotected connections, AEMP uses secure
720	authentication and can use TLS.	738	authentication and can use TLS.
721		739
722	AEMP can use a proven protocol - SSL/TLS - to protect connections and	740	AEMP can use a proven protocol - TLS - to protect connections and
723	securely authenticate nodes.	741	securely authenticate nodes.
724		742
725	=item * The AEMP protocol is optimised for both text-based and binary	743	=item * The AEMP protocol is optimised for both text-based and binary
726	communications.	744	communications.
727		745
728	The AEMP protocol, unlike the Erlang protocol, supports both	746	The AEMP protocol, unlike the Erlang protocol, supports both programming
729	language-independent text-only protocols (good for debugging) and binary,	747	language independent text-only protocols (good for debugging) and binary,
730	language-specific serialisers (e.g. Storable).	748	language-specific serialisers (e.g. Storable). By default, unless TLS is
		749	used, the protocol is actually completely text-based.
731		750
732	It has also been carefully designed to be implementable in other languages	751	It has also been carefully designed to be implementable in other languages
733	with a minimum of work while gracefully degrading fucntionality to make the	752	with a minimum of work while gracefully degrading functionality to make the
734	protocol simple.	753	protocol simple.
735		754
736	=item * AEMP has more flexible monitoring options than Erlang.	755	=item * AEMP has more flexible monitoring options than Erlang.
737		756
738	In Erlang, you can chose to receive I<all> exit signals as messages	757	In Erlang, you can chose to receive I<all> exit signals as messages
…		…
741	Erlang, as one can choose between automatic kill, exit message or callback	760	Erlang, as one can choose between automatic kill, exit message or callback
742	on a per-process basis.	761	on a per-process basis.
743		762
744	=item * Erlang tries to hide remote/local connections, AEMP does not.	763	=item * Erlang tries to hide remote/local connections, AEMP does not.
745		764
746	Monitoring in Erlang is not an indicator of process death/crashes,	765	Monitoring in Erlang is not an indicator of process death/crashes, in the
747	as linking is (except linking is unreliable in Erlang).	766	same way as linking is (except linking is unreliable in Erlang).
748		767
749	In AEMP, you don't "look up" registered port names or send to named ports	768	In AEMP, you don't "look up" registered port names or send to named ports
750	that might or might not be persistent. Instead, you normally spawn a port	769	that might or might not be persistent. Instead, you normally spawn a port
751	on the remote node. The init function monitors the you, and you monitor	770	on the remote node. The init function monitors you, and you monitor the
752	the remote port. Since both monitors are local to the node, they are much	771	remote port. Since both monitors are local to the node, they are much more
753	more reliable.	772	reliable (no need for C<spawn_link>).
754		773
755	This also saves round-trips and avoids sending messages to the wrong port	774	This also saves round-trips and avoids sending messages to the wrong port
756	(hard to do in Erlang).	775	(hard to do in Erlang).
757		776
758	=back	777	=back
759		778
		779	=head1 RATIONALE
		780
		781	=over 4
		782
		783	=item Why strings for port and node IDs, why not objects?
		784
		785	We considered "objects", but found that the actual number of methods
		786	that can be called are quite low. Since port and node IDs travel over
		787	the network frequently, the serialising/deserialising would add lots of
		788	overhead, as well as having to keep a proxy object everywhere.
		789
		790	Strings can easily be printed, easily serialised etc. and need no special
		791	procedures to be "valid".
		792
		793	And as a result, a miniport consists of a single closure stored in a
		794	global hash - it can't become much cheaper.
		795
		796	=item Why favour JSON, why not a real serialising format such as Storable?
		797
		798	In fact, any AnyEvent::MP node will happily accept Storable as framing
		799	format, but currently there is no way to make a node use Storable by
		800	default (although all nodes will accept it).
		801
		802	The default framing protocol is JSON because a) JSON::XS is many times
		803	faster for small messages and b) most importantly, after years of
		804	experience we found that object serialisation is causing more problems
		805	than it solves: Just like function calls, objects simply do not travel
		806	easily over the network, mostly because they will always be a copy, so you
		807	always have to re-think your design.
		808
		809	Keeping your messages simple, concentrating on data structures rather than
		810	objects, will keep your messages clean, tidy and efficient.
		811
		812	=back
		813
760	=head1 SEE ALSO	814	=head1 SEE ALSO
761		815
762	L<AnyEvent>.	816	L<AnyEvent>.
763		817
764	=head1 AUTHOR	818	=head1 AUTHOR

Diff Legend

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

Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.37 by root, Fri Aug 7 16:47:23 2009 UTC vs. Revision 1.67 by root, Fri Aug 28 22:21:53 2009 UTC

Diff Legend

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.37 by root, Fri Aug 7 16:47:23 2009 UTC vs.
Revision 1.67 by root, Fri Aug 28 22:21:53 2009 UTC