LowLevelSpinWaiter.cs

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namespace System.Threading;
 
internal struct LowLevelSpinWaiter
{
    private int _spinningThreadCount;
 
    public bool SpinWaitForCondition(Func<bool> condition, int spinCount, int sleep0Threshold)
    {
        int processorCount = Environment.ProcessorCount;
        int num = Interlocked.Increment(ref _spinningThreadCount);
        try
        {
            if (num <= processorCount)
            {
                for (int i = ((processorCount <= 1) ? sleep0Threshold : 0); i < spinCount; i++)
                {
                    Wait(i, sleep0Threshold, processorCount);
                    if (condition())
                    {
                        return true;
                    }
                }
            }
        }
        finally
        {
            Interlocked.Decrement(ref _spinningThreadCount);
        }
        return false;
    }
 
    public static void Wait(int spinIndex, int sleep0Threshold, int processorCount)
    {
        if (processorCount > 1 && (spinIndex < sleep0Threshold || (spinIndex - sleep0Threshold) % 2 != 0))
        {
            int num = Thread.OptimalMaxSpinWaitsPerSpinIteration;
            if (spinIndex <= 30 && 1 << spinIndex < num)
            {
                num = 1 << spinIndex;
            }
            Thread.SpinWait(num);
        }
        else
        {
            Thread.UninterruptibleSleep0();
        }
    }
}