bench_format.erl

#!/usr/bin/env escript
%! -env ERL_LIBS deps -pa deps/io_libc/ebin

-mode(compile).

main([]) ->
  code:add_pathz("deps/io_libc/ebin"),
  Time = {{2015,3,21},{17,30,57}},
  Count = 100000,

  {{Y,Mo,D}, {H,Mn,S}} = Time,

  io:format("native: ~s\n",[io_lib:format("~4.10.0B-~2.10.0B-~2.10.0BT~2.10.0B:~2.10.0B:~2.10.0BZ", [Y, Mo, D, H, Mn, S])]),
  Native = fun Native(0) -> ok;
    Native(N) -> 
      io_lib:format("~4.10.0B-~2.10.0B-~2.10.0BT~2.10.0B:~2.10.0B:~2.10.0BZ", [Y, Mo, D, H, Mn, S]),
      Native(N-1)
  end,

  io:format("nif: ~s\n", [io_libc:format("%04d-%02d-%02dT%02d:%02d:%02dZ", [Y, Mo, D, H, Mn, S])]),
  Nif = fun Nif(0) -> ok;
    Nif(N) -> 
      io_libc:format("%04d-%02d-%02dT%02d:%02d:%02dZ", [Y, Mo, D, H, Mn, S]),
      Nif(N-1)
  end,


  io:format("erlang: ~s\n", [iso8601(Time)]),

  Erl = fun Erl(0) -> ok;
    Erl(N) ->
      iso8601(Time),
      Erl(N-1)
  end,

  {T1,_} = timer:tc(fun() -> Native(Count) end),
  {T2,_} = timer:tc(fun() -> Nif(Count) end),
  {T3,_} = timer:tc(fun() -> Erl(Count) end),
  io:format("native: ~p\n", [T1 div Count]),
  io:format("nif: ~p\n", [T2 div Count]),
  io:format("erlang: ~p\n", [T3 div Count]),
  ok.


iso8601({{Y,Mo,D}, {H,Mn,S}}) ->
    list_to_binary([integer_to_list(Y), $-,
                    two_digit_str(Mo),  $-,
                    two_digit_str(D),   $T,
                    two_digit_str(H),   $:,
                    two_digit_str(Mn),  $:,
                    two_digit_str(S),   $Z]).

two_digit_str(X) when X < 10 ->
    [$0 | integer_to_list(X)];
two_digit_str(X) ->
    integer_to_list(X).