* User-specific offset.
* @return the index to the data Block if such block exists; or -1 otherwise.
*/
public int getBlockIndexNear(long offset) {
ArrayList<BlockRegion> list = dataIndex.getBlockRegionList();
int idx = Utils.lowerBound(list, new ScalarLong(offset), new ScalarComparator());
if (idx == list.size()) {
return -1;
}