%% -*- erlang-indent-level: 2 -*-
%%
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%% http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.
%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Copyright (c) 2001 by Erik Johansson. All Rights Reserved
%% ====================================================================
%% Module : hipe_timer
%% Purpose :
%% Notes :
%% History : * 2001-03-15 Erik Johansson ([email protected]): Created.
%% ====================================================================
%% Exports :
%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-module(hipe_timer).
-export([tr/1, t/1, timer/1, time/1, empty_time/0]).
-export([advanced/2]).
t(F) ->
{EWT,ERT} = empty_time(),
{WT,RT} = time(F),
{WT-EWT,(RT-ERT)/1000}.
tr(F) ->
{EWT,ERT} = empty_time(),
{R,{WT,RT}} = timer(F),
{R,{WT-EWT,(RT-ERT)/1000}}.
empty_time() ->
WTA = erlang:monotonic_time(),
{A,_} = erlang:statistics(runtime),
WTB = erlang:monotonic_time(),
{B,_} = erlang:statistics(runtime),
{(WTB-WTA)/erlang:convert_time_unit(1, second, native),B-A}.
time(F) ->
WTA = erlang:monotonic_time(),
{A,_} = erlang:statistics(runtime),
F(),
WTB = erlang:monotonic_time(),
{B,_} = erlang:statistics(runtime),
{(WTB-WTA)/erlang:convert_time_unit(1, second, native),B-A}.
timer(F) ->
WTA = erlang:monotonic_time(),
{A,_} = erlang:statistics(runtime),
R = F(),
WTB = erlang:monotonic_time(),
{B,_} = erlang:statistics(runtime),
{R,{(WTB-WTA)/erlang:convert_time_unit(1, second, native),B-A}}.
advanced(_Fun, I) when I < 2 -> false;
advanced(Fun, Iterations) ->
R = Fun(),
Measurements = [t(Fun) || _ <- lists:seq(1, Iterations)],
{Wallclock, RunTime} = split(Measurements),
WMin = lists:min(Wallclock),
RMin = lists:min(RunTime),
WMax = lists:max(Wallclock),
RMax = lists:max(RunTime),
WMean = mean(Wallclock),
RMean = mean(RunTime),
WMedian = median(Wallclock),
RMedian = median(RunTime),
WVariance = variance(Wallclock),
RVariance = variance(RunTime),
WStddev = stddev(Wallclock),
RStddev = stddev(RunTime),
WVarCoff = 100 * WStddev / WMean,
RVarCoff = 100 * RStddev / RMean,
WSum = lists:sum(Wallclock),
RSum = lists:sum(RunTime),
[{wallclock,[{min, WMin},
{max, WMax},
{mean, WMean},
{median, WMedian},
{variance, WVariance},
{stdev, WStddev},
{varcoff, WVarCoff},
{sum, WSum},
{values, Wallclock}]},
{runtime,[{min, RMin},
{max, RMax},
{mean, RMean},
{median, RMedian},
{variance, RVariance},
{stdev, RStddev},
{varcoff, RVarCoff},
{sum, RSum},
{values, RunTime}]},
{iterations, Iterations},
{result, R}].
split(M) ->
split(M, [], []).
split([{W,R}|More], AccW, AccR) ->
split(More, [W|AccW], [R|AccR]);
split([], AccW, AccR) ->
{AccW, AccR}.
mean(L) ->
mean(L, 0, 0).
mean([V|Vs], No, Sum) ->
mean(Vs, No+1, Sum+V);
mean([], No, Sum) when No > 0 ->
Sum/No;
mean([], _No, _Sum) ->
exit(empty_list).
median(L) ->
S = length(L),
SL = lists:sort(L),
case even(S) of
true ->
(lists:nth((S div 2), SL) + lists:nth((S div 2) + 1, SL)) / 2;
false ->
lists:nth((S div 2), SL)
end.
even(S) ->
(S band 1) =:= 0.
%% diffs(L, V) ->
%% [X - V || X <- L].
square_diffs(L, V) ->
[(X - V) * (X - V) || X <- L].
variance(L) ->
Mean = mean(L),
N = length(L),
if N > 1 ->
lists:sum(square_diffs(L,Mean)) / (N-1);
true -> exit('too few values')
end.
stddev(L) ->
math:sqrt(variance(L)).
