@Override
    public int getNonRootSize() {
      return Bytes.SIZEOF_INT // Number of entries
        + Bytes.SIZEOF_INT * (blockKeys.size() + 1) // Secondary index
        + curTotalNonRootEntrySize; // All entries
    }
Returns the size of this chunk if stored in the non-root index block format
hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlockIndex.java