code: public static <T> Queue<T> newFixedMpscQueue(int capacity) {
          return hasUnsafe() ? new MpscArrayQueue<T>(capacity) : new MpscAtomicArrayQueue<T>(capacity);
      }
docs: Create a new {@link Queue} which is safe to use for multiple producers (different threads) and a single
  consumer (one thread!) with the given fixes {@code capacity}.