Duplicated spans for cassandra

[maciej-gromul]

Describe the bug
By default cassandra instrumentation attaches itself to cqlsesion. Because reactivesession wraps around sqlsession and it's being instrumented as well, we're getting spans for the same "requests" twice. Right now to fix that you can simply exclude TraceCassandraAutoConfiguration.class in @SpringBootApplication from autoloading, but it would be nice if those would detect which one should be loaded and when.

[marcingrzejszczak]

Can you provide a complete, minimal, verifiable sample that reproduces the problem ? It should be available as a GitHub (or similar) project or attached to this issue as a zip file.

Can you also provide the Sleuth version?

[maciej-gromul]

Depending on setup it sometimes happens to inserts, sometimes to selects. In our services it happens to both. With this example it mostly occurs on inserts.

https://github.com/maciej-gromul/problems-with-cassandra-autoconfiguration

[marcingrzejszczak]

@mp911de do you recall these problems?

[maciej-gromul]

When i do breakpoints it registers both CqlSession and ReactiveSession tracing so the problem is most likely somewhere in that area.

[mp911de]

Thanks for having a look. There's indeed a risk that the instrumented CqlSession serves as underlying object for ReactiveSession and that is being used later in ObservableReactiveSession. In Spring Data Cassandra, we introduced a ObservableCqlSessionFactoryBean accepting CqlSessionBuilder to mitigate that risk.

[maciej-gromul]

It seems to be closed with issue 1366