STORM-3048 : A Potential NPE

[lujiefsi]

We have developed a static analysis tool NPEDetector to find some potential NPE. Our analysis shows that some callees may return null in corner case(e.g. node crash , IO exception), some of their callers have !=null check but some do not have.

Bug:

Cluster#getAssignmentById has 20 callers, 18 callers have null checker like this:

SchedulerAssignment assignment = cluster.getAssignmentById(td.getId());
if (assignment != null) {
    cpuNeeded -= getCpuUsed(assignment);
     memoryNeeded -= getMemoryUsed(assignment);
}

the caller have no null checker :ConstraintSolverStrategy#checkSpreadSchedulingValid ConstraintSolverStrategy#checkConstraintsSatisfied.

I was feel uncertain about whether add null checker here, so i only add assert. If this bug are false positive, please tell me.

[revans2]

+1

The changes are strictly not needed, because the code only runs to verify that a scheduling is correct, so if there is no scheduling at all, which is the case for the NPE, then something really really bad has happened. But because these are in the context of a test the asserts are fine.

[Ethanlm]

nit: space before and after !=. same for the below code changes.

[revans2]

I am getting a failure now of

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-checkstyle-plugin:2.17:check (validate) on project storm-server: You have 792 Checkstyle violations. The maximum number of allowed violations is 783. -> [Help 1]

Specifically

/Users/evans/src/apache-commit/storm-server/src/main/java/org/apache/storm/scheduler/resource/strategies/scheduling/ConstraintSolverStrategy.java
	101: WhitespaceAround: 'assert' is not followed by whitespace. Empty blocks may only be represented as {} when not part of a multi-block statement (4.1.3)
	101: WhitespaceAround: '!=' is not preceded with whitespace.
	101: WhitespaceAround: '!=' is not followed by whitespace. Empty blocks may only be represented as {} when not part of a multi-block statement (4.1.3)
	139: WhitespaceAround: 'assert' is not followed by whitespace. Empty blocks may only be represented as {} when not part of a multi-block statement (4.1.3)
	139: WhitespaceAround: '!=' is not preceded with whitespace.
	139: WhitespaceAround: '!=' is not followed by whitespace. Empty blocks may only be represented as {} when not part of a multi-block statement (4.1.3)
	178: WhitespaceAround: 'assert' is not followed by whitespace. Empty blocks may only be represented as {} when not part of a multi-block statement (4.1.3)
	178: WhitespaceAround: '!=' is not preceded with whitespace.
	178: WhitespaceAround: '!=' is not followed by whitespace. Empty blocks may only be represented as {} when not part of a multi-block statement (4.1.3)

[HeartSaVioR]

+1