code: void add(long hashEntryAdr, long expireAt)
      {
          // just ignore the fact that expireAt can be less than current time
  
          int slotNum = slot(expireAt);
          slots[slotNum].add(hashEntryAdr, expireAt);
      }
docs: Add a cache entry.
  
  @param hashEntryAdr address of the cache entry
  @param expireAt     absolute expiration timestamp