ActiveSupport::Cache integration does not support multiple cache backends

[naveg]

Current behaviour
If redis-activesupport is present, then only ActiveSupport::Cache::RedisStore is patched (for methods that it has), and ActiveSupport::Cache::Store is not patched.

dd-trace-rb/lib/datadog/tracing/contrib/active_support/cache/redis.rb

Lines 25 to 38 in 210ed96

	def patch_redis?(meth)
	!Gem.loaded_specs['redis-activesupport'].nil? \
	&& defined?(::ActiveSupport::Cache::RedisStore) \
	&& ::ActiveSupport::Cache::RedisStore.instance_methods(false).include?(meth)
	end
	def cache_store_class(meth)
	if patch_redis?(meth)
	::ActiveSupport::Cache::RedisStore
	else
	super
	end
	end
	end

Expected behaviour
ActiveSupport::Cache::Store is always patched, because it may be used with cache backends other than redis.

Steps to reproduce

• Create an application with with redis-activesupport present
• Create a cache using a non-redis backend (eg ActiveSupport::Cache::MemCacheStore)
• Note that cache writes are not instrumented (because we didn't patch the :write method of ActiveSupport::Cache::Store)

One solution could be to patch multiple classes - ie if redis is present and defines the method, patch both classes, rather than one or the other.

Environment

• ddtrace version: 1.12
• Configuration block (Datadog.configure ...):
• Ruby version: 3.0.6
• Operating system: Linux
• Relevant library versions:

[TonyCTHsu]

👋 @naveg We just released v2.2.0. Give it a try!