C# SemaphoreSlim array elements read/write synchronization [closed]

问题

My blocking ring queue don't use lock or Mutex, only two SemaphoreSlim (block than 0 and than max element, so write and read part of array never intersects) and two int indexes modified by Interlocked.Decrement (not determine write/read index, but make it unique and correct move). There are no lock on index calculation and read/write element to array. I think it should work. Because, reference r/w is atomic, SemaphoreSlim and Interlocked make proper memory fence, SemaphoreSlim separate read and write (read and write part of array newer cross). But, what about processors' cache? I heard .Net guaranties cache coherence on any platforms. Is it right? Should I read/write array element Thread.VolatuleRead? Or System.Threading.Volatile.Read/Write ?

   public class BlockingRingQueue<T> where T: class
    {
        const int BUFSIZE_LOG2 = 10;
        const int BUFSIZE = 1 << BUFSIZE_LOG2; //

        T[] buf = new T[BUFSIZE];
        int start = 0;
        int end = 0;
        SemaphoreSlim canReadCount = new SemaphoreSlim(0);
        SemaphoreSlim canWriteCount = new SemaphoreSlim(BUFSIZE);

        public T Dequeue()
        {            
            canReadCount.Wait();

            int i = Interlocked.Decrement(ref end);
            i = PositiveMod(i, BUFSIZE);
            T val = buf[i];

            canWriteCount.Release();            
            return val;            
        }

        public void Enqueue(T val)        
        {                        
            canWriteCount.Wait();

            int i = Interlocked.Decrement(ref start);
            i = PositiveMod(i, BUFSIZE);
            buf[i] = val;

            canReadCount.Release();            
        }

        static int PositiveMod(int a, int b) => ((a % b) + b) % b;
    }

来源：https://stackoverflow.com/questions/60348662/c-sharp-semaphoreslim-array-elements-read-write-synchronization

标签

multithreading

semaphore

lock-free

memory-barriers