source code
% The Computer Language Benchmarks Game
% http://benchmarksgame.alioth.debian.org/
% Contributed by John Shahbazian
-module(threadring).
-export([main/1,process_spawner/2,ring_node/1]).
-define(TOTAL_PROCESSES, 503).
main([Arg]) ->
N = list_to_integer(Arg),
Pid = process_spawner(?TOTAL_PROCESSES,[]),
Pid ! N.
process_spawner(Num_Processes,[]) ->
Pid = spawn(threadring,ring_node,[self()]),
register(list_to_atom("number" ++ integer_to_list(1)),Pid),
Next_Pid = spawn(threadring,ring_node,[process_spawner(Num_Processes-2,Pid)]),
register(list_to_atom("number" ++ integer_to_list(2)),Next_Pid),
Pid ! {update,Next_Pid},
Pid;
process_spawner(1,Starter_Pid) ->
Pid = spawn(threadring,ring_node,[Starter_Pid]),
register(list_to_atom("number" ++ integer_to_list(?TOTAL_PROCESSES)),Pid),
Pid;
process_spawner(Num_Processes,Starter_Pid) ->
Pid = spawn(threadring,ring_node,[process_spawner(Num_Processes-1,Starter_Pid)]),
register(list_to_atom("number" ++ integer_to_list(?TOTAL_PROCESSES - (Num_Processes-1) )),Pid),
Pid.
ring_node(Send_To_Pid) ->
receive
{update, New_Pid} ->
ring_node(New_Pid);
0 ->
{_,Process_Name} = process_info(self(),registered_name),
Process_Name2 = string:sub_string(atom_to_list(Process_Name),7),
io:fwrite("~s~n",[Process_Name2]),
erlang:halt();
N ->
Send_To_Pid ! (N-1),
ring_node(Send_To_Pid)
end.