OpenTelemetry follow up PR

[joao-r-reis]

• Add Distributed Tracing example
• Add db.query.text support for BoundStatement and BatchStatement
• Rename builder extension method
• Add support for speculative executions (mark pending executions as aborted when parent request is completed)

cc @simaoribeiro

[joao-r-reis]

I just realized that the way we store the node level activity might not work if there are multiple requests going to the same node as part of the same request context. I think in normal circumstances this doesn't happen but it really depends on the load balancing policy (and speculative executions probably need to be enabled as well). I'll probably add a NodeExecutionId to HostTrackingInfo and we can use that id for the key in the context dictionary.

[simaoribeiro]

Yeah, I think the NodeExecutionId makes sense. I didn't know that use case when used the HostId as part of the key

[joao-r-reis]

Yeah, I think the NodeExecutionId makes sense. I didn't know that use case when used the HostId as part of the key

yeah I just added it now, was a bit of work but it's worth it I think

[joao-r-reis]

Ok, speculative executions are now supported as well, aborted executions will show up with status "unset", while non aborted executions have the status Ok or Error.

The last thing that I wanted to take care of before releasing this was to add support for Prepared Statements. It would be very useful to have the Prepare round trips on these traces (especially with Mapper and LINQ that automatically prepare stuff internally).

I'm running out of time to get this done though so I'll evaluate tomorrow wether it is feasible to add this before the release.

[simaoribeiro]

Looks really cool.

Btw, if you pass the number of speculative executions, you can add the attribute db.cassandra.speculative_execution_count. You already did part of the job my marking it unset However, I don't think it's important for now and can be added later.

The prepared statements would be a really useful feature to add but we can also include in the documentation that is not supported for now, so the users are aware.

[joao-r-reis]

Btw, if you pass the number of speculative executions, you can add the attribute db.cassandra.speculative_execution_count. You already did part of the job my marking it unset However, I don't think it's important for now and can be added later.

Unfortunately there's no way to tell whether an execution is speculative or not atm (could just be a retry) so I'd have to implement that on the driver. Something to consider in the future though.

[joao-r-reis]

I'm going to merge this when CI finishes.