testm.erl

-module(testm).

-behaviour(gen_statem).

-export([start_link/0, run/1, run/2]).

-export([callback_mode/0, init/1, terminate/3]).
-export([handle_event/4]).

-define(SERVER, ?MODULE).

start_link() ->
    gen_statem:start_link({local, ?SERVER}, ?MODULE, [], []).

callback_mode() -> handle_event_function.

init([]) ->
    process_flag(trap_exit, true),
    Data = data_next(#{cnt => 0}),
    {ok, state_name, Data}.

handle_event({call,From}, _Msg, State, Data0) ->
    Data = data_next(Data0),
    {next_state, State, Data, [{reply,From,ok}]}.

terminate(_Reason, _State, _Data) ->
    void.

data_next(#{cnt := Cnt0} = Data) ->
    Cnt = (Cnt0 + 1) rem 256,
    Data#{cnt => Cnt, bin => binary:copy(<<Cnt:8>>, 1024)}.

run(Cnt, Repeat) ->
    io:format("exec time | min ms | max ms~n"
	      "----------+--------+--------~n"),
    lists:foreach(
      fun(X) ->
	      {Min, Max} = run(Cnt),
	      io:format(" ~8w | ~6w | ~6w~n", [X, Min, Max])
      end, lists:seq(1, Repeat)),
    ok.

run(Cnt) ->
    {ok, Pid} = start_link(),
    L = lists:seq(1, Cnt),
    Ts0 = lists:map(
	   fun(_) ->
		   {T, _} = timer:tc(gen_statem, call, [Pid, do]),
		   T
	   end, L),
    erlang:exit(Pid, normal),
    Ts = lists:sort(Ts0),
    {hd(Ts), lists:last(Ts)}.