class DatanodeDescriptor extends DatanodeInfo {

  public Block[] getInvalidateBlocks(int maxblocks) {
    synchronized (invalidateBlocks) {
      Block[] deleteList = invalidateBlocks
          .pollToArray(new Block[Math.min(invalidateBlocks.size(), maxblocks)]);
      return deleteList.length == 0 ? null : deleteList;
    }
  }

  public  DatanodeDescriptor(StorageMap storageMap, DatanodeID nodeID);
  public  DatanodeDescriptor(StorageMap storageMap, DatanodeID nodeID, String
      networkLocation);

}