public void reset() {
        numElements = 0;
        longArray.zeroOut();

        while (dataPages.size() > 0) {
            MemoryBlock dataPage = dataPages.removeLast();
            freePage(dataPage);
        }
        currentPage = null;
        pageCursor = 0;
    }
Reset this map to initialized state.
indexr-query-opt/src/main/java/org/apache/spark/unsafe/map/BytesToBytesMap.java