SizeHelper.cs

Posted on July 30, 2020Tags , , ,   Leave a comment on SizeHelper.cs

Non-Linear Array Size Adjustment Class

using System;
using System.Collections.Generic;
using Microsoft.VisualBasic.Devices;
public class SizeHelper<T>
{
    private static readonly FixedIntXPrimality bp = new FixedIntXPrimality(64);
    private readonly        int                AllocatedSizeLimit;
    public                  int[]              Curve;
    private                 int                Resizes;
    public SizeHelper()
    {
        var measure   = new MeasureSize<T>();
        var sizeOfOne = measure.GetByteSize();
        var am        = new ComputerInfo().AvailablePhysicalMemory;
        AllocatedSizeLimit = (int) ((long) am / sizeOfOne);
    }
    public int GetNewSize(int currentSize)
    {
        Resizes++;
        if (Curve == null)
            BuildCurve(currentSize);
        foreach (var v in Curve)
            if (v > currentSize)
                return v;
        var nv = GetNextValue(currentSize);
        return nv != -1 ? nv : int.MaxValue;
    }
    private int GetNextValue(int currentValue)
    {
        for (var value = currentValue | 1; value < AllocatedSizeLimit; value += 16384)
        {
            if (value < 0)
                break;
            if (bp.IsPrime(value))
                return value + 1;
        }
        return -1;
    }
    private void BuildCurve(int Size)
    {
        int Sizer(int oldSize)
        {
            try
            {
                oldSize = (int) (uint) oldSize;
                var log     = Math.Log(oldSize);
                var inv     = 1.0 / log * 4;
                var newSize = oldSize   * (1.0 + inv);
                return (int) (uint) newSize;
            }
            catch
            {
                return AllocatedSizeLimit;
            }
        }
        var curlst = new List<int>();
        var value  = Size | 1;
        do
        {
            value = Sizer(value);
            if (value < 0)
                break;
            if (value < AllocatedSizeLimit)
                curlst.Add(value);
        } while (value < AllocatedSizeLimit);
        Curve = curlst.ToArray();
        var dl   = new List<int>();
        var last = 0;
        for (var i = 0; i < Curve.Length; ++i)
        {
            if (i > 0)
                last = Curve[i - 1];
            var v = Curve[i];
            dl.Add(v - last);
        }
        var str = "";
        foreach (var v in dl)
            str += $"{v},";
    }
}