Untitled

-module(ring_bench).
-export([start/1]).

%%  start([N, M])
%%  Create N processes into ring and sned message round the ring M times

start([A, B]) ->
    N = list_to_integer(atom_to_list(A)),
    M = list_to_integer(atom_to_list(B)),
    Self = self(),
    Max = erlang:system_info(process_limit),
    io:format("Maximum allowed processes: ~p~n", [Max]),
    statistics(runtime),
    statistics(wall_clock),
    Pids = for(1, N, fun() -> spawn(fun() -> loop(Self, N * M) end) end),

    [H | _] = Pids,
    H ! {0, Pids},

    receive
        done ->
            lists:foreach(fun(Pid) -> Pid ! die end, Pids),
            {_, Time1} = statistics(runtime),
            {_, Time2} = statistics(wall_clock),
            U1 = Time1 / 1000,
            U2 = Time2 / 1000,
            io:format("Time=~p (~p) seconds~n", [U1, U2]),
            init:stop()
    end.

loop(Master, N) ->
    receive
        die ->
            void;

        {I, _} when I =:= N->
            Master ! done;

        {I, Pids} ->
            [H | T] = Pids,
            NextPids = lists:reverse([H | lists:reverse(T)]),
%            io:format("~p ~p ~p ~n", [I, self(), NextPids]),
            H ! {I+1, NextPids},
            loop(Master, N)
    end.

for(N, N, F) -> [F()];
for(I, N, F) -> [F()|for(I+1, N, F)].