fix null pointer in jaeger-spark-dependencies

[moolen]

Which problem is this PR solving?

fixes jaegertracing/jaeger-operator#1113

I'm not sure if other fields have the same issue.

[yurishkuro]

Is the expectation that any list must not be null, or just references? For example, logs() function also may return nil.

[moolen]

It depends on the consumer, i guess. speaking for jaeger-spark-dependencies: tags and process must be non-nil (otherwise we'll see a null pointer exception).

see SpanDeserializer.java / ObjectMapper.java.

While taking a look at #2295:

OTEL data model is directly transformed to Jaeger ES model

I think writing null into $storage is a bug.

@pavolloffay you're much deeper into this, can you confirm this? If so i'll change tags and process accordingly.

*edit* i fixed tags and process aswell

[yurishkuro]

we could avoid some memory allocations by using constants in these cases, like

const emptyReferenceList = []dbmodel.Reference{}

the most impact will be for logs, since it's quite rare to find spans without references or tags.

BTW, I wonder if there is another bug in the translator from OTEL that fails to create a CHILD_OF reference to the parent span ID, which is required in the Jaeger model since we don't store parentSpanID in the database.

[moolen]

Thanks for your feedback, i made changes accordingly.
I don't see where there could be a bug (...or i don't get it 😄 ). The CHILD_OF refs are tested properly as far as i can tell. It either creates a reference or it errors out.

[codecov]

Codecov Report

Merging #2327 into master will decrease coverage by 0.00%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2327      +/-   ##
==========================================
- Coverage   95.65%   95.64%   -0.01%     
==========================================
  Files         205      205              
  Lines       10529    10529              
==========================================
- Hits        10071    10070       -1     
- Misses        391      393       +2     
+ Partials       67       66       -1     

Impacted Files	Coverage Δ
...lugin/sampling/strategystore/adaptive/processor.go	99.20% <0.00%> (-0.80%)	⬇️
plugin/storage/integration/integration.go	80.38% <0.00%> (-0.48%)	⬇️
cmd/query/app/server.go	93.18% <0.00%> (+2.27%)	⬆️

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[yurishkuro]

please group all vars at the top of the file (after constants, if any)

var (
    emptyReferenceList = []dbmodel.Reference{}
    emptyTagList = []dbmodel.KeyValue{}
    etc
)

[yurishkuro]

Thank you!