MeanValue.h

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// Copyright Epic Games, Inc. All Rights Reserved.
#pragma once
 
#include "CoreTypes.h"
#include "Math/UnrealMathUtility.h"
 
namespace BuildPatchServices
{
    class FMeanValue
    {
    public:
 
        FMeanValue()
            : ReliabilityCount(10)
            , Count(0)
            , Total(0)
            , TotalSqs(0)
        { }
 
        FMeanValue(uint64 InReliabilityCount)
            : ReliabilityCount(InReliabilityCount)
            , Count(0)
            , Total(0)
            , TotalSqs(0)
        { }
 
        void Reset()
        {
            Count = 0;
            Total = 0;
            TotalSqs = 0;
        }
 
        bool IsReliable() const
        {
            return Count > ReliabilityCount;
        }
 
        void GetValues(double& Mean, double& Std) const
        {
            Mean = GetMean();
            Std = GetStd(Mean);
        }
 
        void AddSample(double Sample)
        {
            Total += Sample;
            TotalSqs += Sample * Sample;
            ++Count;
        }
 
    private:
        double GetMean() const
        {
            checkSlow(Count > 0);
            return Total / Count;
        }
 
        double GetStd(double Mean) const
        {
            return FMath::Sqrt((TotalSqs / Count) - (Mean * Mean));
        }
 
    private:
        const uint64 ReliabilityCount;
        uint64 Count;
        double Total;
        double TotalSqs;
    };
}