public long getReadPoint(IsolationLevel isolationLevel) {
    if (isolationLevel != null && isolationLevel == IsolationLevel.READ_UNCOMMITTED) {
      // This scan can read even uncommitted transactions
      return Long.MAX_VALUE;
    }
    return mvcc.getReadPoint();
  }
Returns readpoint considering given IsolationLevel. Pass {@code null} for default
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java