private int addScanner(ResultScanner scanner) {
    int id = nextScannerId.getAndIncrement();
    scannerMap.put(id, scanner);
    return id;
  }
Assigns a unique ID to the scanner and adds the mapping to an internal HashMap.
@param scanner to add
@return Id for this Scanner
hbase-thrift/src/main/java/org/apache/hadoop/hbase/thrift2/ThriftHBaseServiceHandler.java