[HDFS-13155] BlockPlacementPolicyDefault.chooseTargetInOrder Not Checking Return Value for NULL

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 3.0.0
• Fix Version/s: 3.2.0, 3.1.1, 3.0.4
• Component/s: namenode
• Assignee: Zsolt Venczel
• Reporter: David Mollitor
• Created: 16/Feb/18 15:38
• Updated: 02/Oct/19 17:14
• Resolved: 04/Jun/18 14:05

Description

BlockPlacementPolicyDefault.java

protected Node chooseTargetInOrder(int numOfReplicas, 
                                 Node writer,
                                 final Set<Node> excludedNodes,
                                 final long blocksize,
                                 final int maxNodesPerRack,
                                 final List<DatanodeStorageInfo> results,
                                 final boolean avoidStaleNodes,
                                 final boolean newBlock,
                                 EnumMap<StorageType, Integer> storageTypes)
                                 throws NotEnoughReplicasException {
    final int numOfResults = results.size();
    if (numOfResults == 0) {
      writer = chooseLocalStorage(writer, excludedNodes, blocksize,
          maxNodesPerRack, results, avoidStaleNodes, storageTypes, true)
          .getDatanodeDescriptor();
      if (--numOfReplicas == 0) {
        return writer;
      }
    }
...

The method chooseLocalStorage can return a null value but it's not being checked here and the method getDatanodeDescriptor() is immediately being called on the result. Please check for a null value first.