Question

I have an array of ints that track the completion of 10,000 concurrent tasks, where the value is either 1 or 0. I think it would be more efficient if this array was an array of Bits and each concurrent thread used interlocked.CompareExchange (or similar) to alter a single bit.

How should I approach this if Interlocked doesn’t have an overload for “bit”?

Answer 1

You can fake it with Interlocked.CompareExchange(ref int, int, int) in a loop, but I don’t think it would be more efficient:

private static void SetBit(ref int valueToUpdate, int bitToSet)
{
   while (true)
   {
      int oldValue = valueToUpdate;
      int newValue = oldValue | bitToSet;
      int result = Interlocked.CompareExchange(ref valueToUpdate, newValue, oldValue);
      if (result == oldValue) break;
   }
}