[HDDS-449] Add a NULL check to protect DeadNodeHandler#onMessage

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 0.2.1
• Labels: EasyFix
• Assignee: LiXin Ge
• Reporter: LiXin Ge
• Created: 13/Sep/18 11:09
• Updated: 12/Nov/18 11:10
• Resolved: 15/Sep/18 12:25

Description

Add a NULL check to protect the situation below(may only happened in the case of unit test):
1.A new datanode register to SCM.
2. There is no container allocated in the new datanode temporarily.
3.The new datanode dead and an event was fired to DeadNodeHandler
4.In function DeadNodeHandler#onMessage, there will get nothing in node2ContainerMap and containers will be NULL
5.NullPointerException will be throwen in the following iterate of containers like:

[ERROR] Tests run: 2, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 0.535 s <<< FAILURE! - in org.apache.hadoop.hdds.scm.node.TestDeadNodeHandler
[ERROR] testStatisticsUpdate(org.apache.hadoop.hdds.scm.node.TestDeadNodeHandler)  Time elapsed: 0.33 s  <<< ERROR!
java.lang.NullPointerException
        at org.apache.hadoop.hdds.scm.node.DeadNodeHandler.onMessage(DeadNodeHandler.java:68)
        at org.apache.hadoop.hdds.scm.node.TestDeadNodeHandler.testStatisticsUpdate(TestDeadNodeHandler.java:179)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)