ProcessorIdCache.cs

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using System.Diagnostics;
using System.Runtime.CompilerServices;
 
namespace System.Threading;
 
internal static class ProcessorIdCache
{
    [ThreadStatic]
    private static int t_currentProcessorIdCache;
 
    private static int s_processorIdRefreshRate;
 
    private static int RefreshCurrentProcessorId()
    {
        int num = Thread.GetCurrentProcessorNumber();
        if (num < 0)
        {
            num = Environment.CurrentManagedThreadId;
        }
        t_currentProcessorIdCache = ((num << 16) & 0x7FFFFFFF) | s_processorIdRefreshRate;
        return num;
    }
 
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    internal static int GetCurrentProcessorId()
    {
        int num = t_currentProcessorIdCache--;
        if ((num & 0xFFFF) == 0)
        {
            return RefreshCurrentProcessorId();
        }
        return num >> 16;
    }
 
    internal static bool ProcessorNumberSpeedCheck()
    {
        double num = double.MaxValue;
        double num2 = double.MaxValue;
        UninlinedThreadStatic();
        if (Thread.GetCurrentProcessorNumber() < 0)
        {
            s_processorIdRefreshRate = 65535;
            return false;
        }
        long num3 = Stopwatch.Frequency / 1000000 + 1;
        for (int i = 0; i < 10; i++)
        {
            int num4 = 8;
            long timestamp;
            do
            {
                num4 *= 2;
                timestamp = Stopwatch.GetTimestamp();
                for (int j = 0; j < num4; j++)
                {
                    Thread.GetCurrentProcessorNumber();
                }
                timestamp = Stopwatch.GetTimestamp() - timestamp;
            }
            while (timestamp < num3);
            num = Math.Min(num, (double)timestamp / (double)num4);
            num4 /= 4;
            do
            {
                num4 *= 2;
                timestamp = Stopwatch.GetTimestamp();
                for (int k = 0; k < num4; k++)
                {
                    UninlinedThreadStatic();
                }
                timestamp = Stopwatch.GetTimestamp() - timestamp;
            }
            while (timestamp < num3);
            num2 = Math.Min(num2, (double)timestamp / (double)num4);
        }
        s_processorIdRefreshRate = Math.Min((int)(num * 5.0 / num2), 5000);
        return s_processorIdRefreshRate <= 5;
    }
 
    [MethodImpl(MethodImplOptions.NoInlining)]
    internal static int UninlinedThreadStatic()
    {
        return t_currentProcessorIdCache;
    }
}