ring.erl

-module(ring).
-export([bench/2, ring/2]).

bench(N, M) ->
  timer:tc(?MODULE, ring, [N, M]).

ring(N, M) ->
  SPID = spawn(fun() -> createstartnode() end),
  LPID = create_ring(N-1, SPID),
  SPID ! LPID,
  SPID ! (M+1),
  ok.

create_ring(0, PID) ->
  PID;
create_ring(N, PID) ->
  NPID = spawn(fun() -> anode(PID) end),
  create_ring(N-1, NPID).

createstartnode() ->
  receive
    PID when is_pid(PID) ->
      startnode(PID)
  end.

startnode(PID) ->
  receive
    0 ->
      PID ! 0;
    N when is_integer(N) ->
      PID ! (N-1),
      startnode(PID)
  end.

anode(PID) ->
  receive
    0 ->
      PID ! 0;
    N when is_integer(N) ->
      PID ! N,
      anode(PID)
  end.

% $ erl
% Erlang R16B03 (erts-5.10.4) [source] [64-bit] [smp:4:4] [async-threads:10] [kernel-poll:false]
%
% Eshell V5.10.4  (abort with ^G)
% 1> c(ring).
% {ok,ring}
% 2> ring:bench(50000, 100000).
% {145984,ok}