Extracted from #11883

Motivation

Our current UsageSetCounter can record events of different categories (i.e., set), but cannot record multi-dimensional data (e.g., source, target). This PR contains a possible implementation for a two-dimensional multi-set counter.

We decided not to move forward with this approach until the data requirements are clearer (e.g., allow for generic analysis/materialization rather than feature-specific solutions that don't scale). Therefore, this PR is parked for now and up for discussion.

Discussion

The flat record structure (pipes:invocation:aws:sqs) is not ideal and would be cumbersome to analyze.
Something like this might be more suitable, but still not ideal if the namespace is feature-specific:

{"outer_namespace": {"inner_namespace": {"key": "count"}}}

Changes

• Add UsageMultiSetCounter
• Add unit test test_multi_set_counter