ActiveSupport::Cache instrumentation missing namespace

[jcoleman]

Current behaviour
set_cache_key (https://github.com/DataDog/dd-trace-rb/blob/master/lib/datadog/tracing/contrib/active_support/cache/instrumentation.rb#L61) calls don't include the namespace, and the key is not necessarily meaningful on its own. For example, if I configured a cache with namespace: "my_model" and then cache the key 123 (e.g., from the primary key), then the DataDog span will include key: 123 which isn't really the full key -- it's missing the namespace and makes that span worthless.

Expected behaviour
Cache spans should include the namespace.

Steps to reproduce
Instrument ActiveSupport:Cache. Configure a cache with the namespace option.

How does datadog help you?
I'm trying to understand a trace with lots of cache spans but can't determine where to improve the application because the span is missing the necessary information.

Environment

• datadog version: Current (but this goes back to older ones as well)
• Configuration block (Datadog.configure ...):
• Ruby version: 3.3
• Operating system: Debian
• Relevant library versions: N/A