Fix unhandled case of empty cs buckets response

[engelsanchez]

the PB translation generates a single token instead of a default record
when the entire message has only default values. This was uncovered in
1.4.4, where the cs buckets query was broken.

[seancribbs]

Is there a related riak_test (or giddyup failure) where this is exercised?

[engelsanchez]

There is a specific commit in the 1.4 history for Riak where the query is broken and you hit this error. I'll post it here in a bit.

[engelsanchez]

It's basho/riak_kv@0503431. Basically get riak 1.4.2 tags and that, and you'll hit this as the query returns nothing during the test and there's a function clause error there.

[seancribbs]

@engelsanchez Thanks. Honestly we should probably (for 2.0?) fix that endpoint. It shouldn't be sending empty results to the client.

[engelsanchez]

I'm not sure what you mean. It is fixed in 1.4.4. That commit is from a point in time when it was broken. This was found while I was debugging and fixing the issue.

[seancribbs]

@engelsanchez I mean the PB service that replies to this request, does it not emit empty (non-done) responses?

[engelsanchez]

Nope. It's been fixed. I didn't look at the semantics of the request though. If you think now that it's fixed this is moot, fine. But having it just crash on a function_clause seemed a bit harsh at the time.

[seancribbs]

Ok. The impact of this change is minimal, and some people are liable to be running a broken version, so it's worth fixing. Thanks for bearing with me.

👍 💃 🍻

[engelsanchez]

Thanks for looking at this!