gistfile1.hrl

-module(p81).
-compile(export_all).

bench(ProcN, MsgN) ->
  ProcRing = for(1, ProcN, fun() -> spawn(fun wait/0) end),
  statistics(runtime),
  statistics(wall_clock),
  sendMsgs(ProcRing, ping, ProcN*MsgN),
  {_, Time1} = statistics(runtime),
  {_, Time2} = statistics(wall_clock),
  U1 = Time1 * 1000 / ProcN,
  U2 = Time2 * 1000 / ProcN,
  io:format("Process spawn time=~p (~p) microseconds~n", [U1, U2]),
  %% do I need to kill them afterwards or will the gc do it automatically?
  lists:foreach(fun(Pid) -> Pid ! die end, ProcRing).

wait() ->
  receive
    die -> void;
    ping -> wait()
  end.

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

sendMsgs(_, _, 0) -> ok;
sendMsgs(ProcList, Msg, MsgN) ->
  lists:foreach(fun(Pid) -> Pid ! Msg end, ProcList),
  sendMsgs(ProcList, Msg, MsgN-length(ProcList)).