@Override
      public int compareTo(byte[] buffer1, int offset1, int length1, byte[] buffer2, int offset2,
        int length2) {
        // Short circuit equal case
        if (buffer1 == buffer2 && offset1 == offset2 && length1 == length2) {
          return 0;
        }
        // Bring WritableComparator code local
        int end1 = offset1 + length1;
        int end2 = offset2 + length2;
        for (int i = offset1, j = offset2; i < end1 && j < end2; i++, j++) {
          int a = (buffer1[i] & 0xff);
          int b = (buffer2[j] & 0xff);
          if (a != b) {
            return a - b;
          }
        }
        return length1 - length2;
      }
Returns the Unsafe-using Comparer, or falls back to the pure-Java implementation if unable to
do so.
hbase-common/src/main/java/org/apache/hadoop/hbase/util/Bytes.java