1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
|
%%% File : token.erl
%%% Author : Ulf Norell
%%% Description :
%%% Created : 20 Mar 2012 by Ulf Norell
-module(token).
-export([next_name/0, get_name/0, stop/0]).
next_name() ->
rpc(next).
get_name() ->
rpc(get).
stop() ->
rpc(stop).
rpc(Msg) ->
case whereis(?MODULE) of
undefined ->
start(),
timer:sleep(1),
rpc(Msg);
Pid ->
Ref = make_ref(),
Pid ! {Msg, Ref, self()},
receive
{Ref, R} -> R
after 1000 -> {error, timeout}
end
end.
start() ->
register(?MODULE, spawn(fun() -> init() end)).
init() ->
loop(mk_name()).
loop(Name) ->
receive
{next, Tag, Pid} ->
Next = mk_name(),
Pid ! {Tag, Next},
loop(Next);
{get, Tag, Pid} ->
Pid ! {Tag, Name},
loop(Name);
{stop, Tag, Pid} ->
Pid ! {Tag, ok}
end.
mk_name() ->
{A, B, C} = erlang:now(),
lists:concat([A, "-", B, "-", C]).
|
