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-module(erlbal).
-export([make_request/1, make_request/2, start_bal/0, stop_bal/1, start_server/3, stop_server/2, list_servers/1]).
start_server(Balancer, Node, Fun) ->
PID = spawn(Node, fun() -> server_loop(Balancer, Fun) end),
Balancer ! {add_node, PID}.
stop_server(Balancer, PID) ->
Balancer ! {del_node, PID},
PID ! die.
list_servers(Balancer) ->
Balancer ! {list_nodes, self()},
receive Nodes -> Nodes end.
server_loop(Balancer, Fun) ->
receive
{request, From} ->
Ret = Fun(),
Balancer ! {response, From, Ret},
server_loop(Balancer, Fun);
{request, From, ARGS} ->
Ret = Fun(ARGS),
Balancer ! {response, From, Ret},
server_loop(Balancer, Fun);
die ->
ok
end.
start_bal() ->
spawn(fun() -> bal_loop([], 1) end).
stop_bal(Balancer) ->
Balancer ! die.
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} ->
Serv = lists:nth(Nextserver, Serverlist),
Serv ! {request, From},
NS = Nextserver + 1,
SLL = length(Serverlist),
if
NS > SLL ->
bal_loop(Serverlist, 1);
true ->
bal_loop(Serverlist, NS)
end;
{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, NS)
end;
{response, To, Ret} ->
To ! Ret,
bal_loop(Serverlist, Nextserver);
die ->
lists:foreach(fun(X) -> X ! die end, Serverlist)
end.
make_request(Balancer) ->
Balancer ! {request, self()},
receive Ret -> Ret end.
make_request(Balancer, ARGS) ->
Balancer ! {request, self(), ARGS},
receive Ret -> Ret end.
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