Returning custom grpc code when reaching series/chunk limits

[alanprot]

• I added CHANGELOG entry for this change.
• Change is not relevant to the end user.

Changes

This change allow to return a different/custom GRPC code - other than the generic Aborted - when the limits are hit via SeriesLimiter or ChunksLimiter.

The reason for this change is that it is hard for the caller to differentiate when the error returned by Series method was generated by a limiter or if it was a generic/transient error. Propagating the error code generated by the limiter will create the possibility to return any GRPC code on those cases.

• If the error generated by the SeriesLimiter and ChunksLimiter is a GRPC error, the Series will return a GRPC error with the same errorcode.

Verification

• Unit tests

[pracucci]

I'm 👍 with the change but I'm not sure the unit test makes much sense from the Thanos perspective. This change originates from a need we have in Cortex and the test is trying to mimick it, but from Thanos perspective how we're going to use it is irrelevant. Because of this I'm wondering if we should keep the change but revert the unit test changes.

[alanprot]

Hi @pracucci, Thanks for your reply.

I can remove the tests but i think if we are coding a behaviour here we should also test it here to make sure it does not change right?

[bwplotka]

I think I like it and the test makes sense too - it makes sure we preserve the error handling. Let's do this 💪🏽 Thanks! LGTM