%% -*- erlang-indent-level: 2 -*-
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%% Copyright Ericsson AB 2006-2012. All Rights Reserved.
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%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
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%%%-------------------------------------------------------------------
%%% File    : dialyzer_timing.erl
%%% Authors : Stavros Aronis <aronisstav@gmail.com>
%%% Description : Timing reports for Dialyzer
%%%-------------------------------------------------------------------

-module(dialyzer_timing).

-export([init/1, start_stamp/1, end_stamp/0, stop/0]).

-spec init(boolean()) -> ok.

init(Active) ->
  Pid = spawn(fun() -> loop_init(Active) end),
  case whereis(?MODULE) of
    undefined -> ok;
    _ -> unregister(?MODULE)
  end,
  register(?MODULE, Pid),
  ok.

loop_init(Active) ->
  case Active of
    true ->
      io:format("\n"),
      loop(now());
    false -> dummy_loop()
  end.

dummy_loop() ->
  receive
    {Pid, stop, _Now} -> Pid ! ok;
    _ -> dummy_loop()
  end.

loop(LastNow) ->
  receive
    {stamp, Msg, Now} ->
      io:format("~s\t(+~6.2fs): ", [Msg, diff(Now, LastNow)]),
      loop(Now);
    {stamp, Now} ->
      io:format("~6.2fs\n", [diff(Now, LastNow)]),
      loop(Now);
    {Pid, stop, Now} ->
      io:format("\t(+~6.2fs)\n", [diff(Now, LastNow)]),
      Pid ! ok
  end.

-spec start_stamp(string()) -> ok.

start_stamp(Msg) ->
  ?MODULE ! {stamp, Msg, now()},
  ok.

-spec end_stamp() -> ok.

end_stamp() ->
  ?MODULE ! {stamp, now()},
  ok.

-spec stop() -> ok.

stop() ->
  ?MODULE ! {self(), stop, now()},
  receive ok -> ok end.

diff(T2, T1) ->
  timer:now_diff(T2,T1) / 1000000.