ActiveSupport::Cache#read_multi is not instrumented when using ActiveSupport::Cache::RedisCacheStore

[beauraF]

Hello 👋

Current behaviour
When using Rails.cache.read_multi, using ActiveSupport::Cache::RedisCacheStore, the action is not instrumented. While read, write, fetch, write_multi and fetch_multi are.

This is because ActiveSupport::Cache::RedisCacheStore defines its own read_multi method, and we never go down into ddtrace wrapper method: https://github.com/rails/rails/blob/edbe4672e6b070ebaa5cd60810859e76c283a35a/activesupport/lib/active_support/cache/redis_cache_store.rb#L172

=> [#<Class:#<ActiveSupport::Cache::RedisCacheStore:0x000000013eb1ac30>>,
 ActiveSupport::Cache::Strategy::LocalCache,
 ActiveSupport::Cache::RedisCacheStore,
 Datadog::Tracing::Contrib::ActiveSupport::Cache::Instrumentation::Delete,
 Datadog::Tracing::Contrib::ActiveSupport::Cache::Instrumentation::WriteMulti,
 Datadog::Tracing::Contrib::ActiveSupport::Cache::Instrumentation::Write,
 Datadog::Tracing::Contrib::ActiveSupport::Cache::Instrumentation::FetchMulti,
 Datadog::Tracing::Contrib::ActiveSupport::Cache::Instrumentation::Fetch,
 Datadog::Tracing::Contrib::ActiveSupport::Cache::Instrumentation::ReadMulti,
 Datadog::Tracing::Contrib::ActiveSupport::Cache::Instrumentation::Read,
 Datadog::Tracing::Contrib::ActiveSupport::Cache::Instrumentation::InstanceMethods,
 ActiveSupport::Cache::Store,
...
]

Expected behaviour
ActiveSupport::Cache::RedisCacheStore#read_multi is instrumented.

Environment

• datadog version: 1.21.1
• Relevant library versions:
  • Rails 7.1.3.2

[naveg]

duplicate of #3549, I believe

[beauraF]

Clearly linked. But in our case that's the other way around, as we have rails > 5.2 and don't use activesupport-redis, that's what I wanted to put in light. In our case, only ActiveSupport::Cache::Store is patched, and not ActiveSupport::Cache::RedisCacheStore

[naveg]

ah, yes - you are correct