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
56
57
58
|
-module(erlbal).
-export([make_request/2, start_bal/1, kill_bal/1, start_server/2]).
start_server(Balancer, Fun) ->
PID = spawn(fun() -> server_loop(Balancer, Fun) end),
Balancer ! {add_node, PID}.
server_loop(Balancer, Fun) ->
receive
{request, From, ARGS} ->
Ret = Fun(ARGS),
Balancer ! {response, From, Ret},
server_loop(Balancer, Fun);
die ->
ok
end.
start_bal(Name) ->
register(Name, spawn(fun() -> bal_loop([], 1) end)).
kill_bal(Balancer) ->
Balancer ! die,
unregister(Balancer).
bal_loop(Serverlist, Nextserver) ->
receive
{add_node, PID} ->
bal_loop(Serverlist ++ [PID], Nextserver);
{del_node, PID} ->
bal_loop(Serverlist -- [PID], Nextserver);
{list_nodes, From} ->
From ! Serverlist,
bal_loop(Serverlist, Nextserver);
{request, From, ARGS} ->
Serv = lists:nth(Nextserver, Serverlist),
Serv ! {request, From, ARGS},
NS = Nextserver + 1,
SLL = length(Serverlist),
if
NS > SLL ->
bal_loop(Serverlist, 1);
true ->
bal_loop(Serverlist, Nextserver+1)
end;
{response, To, Ret} ->
To ! Ret,
bal_loop(Serverlist, Nextserver);
die ->
lists:foreach(fun(X) -> X ! die end, Serverlist)
end.
make_request(Balancer, ARGS) ->
Balancer ! {request, self(), ARGS},
receive
Ret ->
Ret
end.
|
