private void computeNext() {
      if (++next >= nodes.length) {
        next = 0;
      }
      if (next == start) {
        next = -1;
      }
    }
Construct an ArraymodNodeLocator over the given array of nodes and using
the given hash algorithm.

@param n the array of nodes
@param alg the hash algorithm
src/main/java/net/spy/memcached/ArrayModNodeLocator.java