+ # We store a list of cache keys related to an activity in a
+ # separate cache, scrubber_management_cache. It has the same
+ # size as scrubber_cache (see application.ex). Every time we add
+ # a cache to scrubber_cache, we update scrubber_management_cache.
+ #
+ # The most recent write of a certain key in the management cache
+ # is the same as the most recent write of any record related to that
+ # key in the main cache.
+ # Assuming LRW ( https://hexdocs.pm/cachex/Cachex.Policy.LRW.html ),
+ # this means when the management cache is evicted by cachex, all
+ # related records in the main cache will also have been evicted.
+
+ defp get_cache_keys_for(activity_id) do
+ with {:ok, list} when is_list(list) <- @cachex.get(:scrubber_management_cache, activity_id) do
+ list
+ else
+ _ -> []
+ end
+ end
+
+ defp add_cache_key_for(activity_id, additional_key) do
+ current = get_cache_keys_for(activity_id)
+
+ unless additional_key in current do
+ @cachex.put(:scrubber_management_cache, activity_id, [additional_key | current])
+ end
+ end
+
+ def invalidate_cache_for(activity_id) do
+ keys = get_cache_keys_for(activity_id)
+ Enum.map(keys, &@cachex.del(:scrubber_cache, &1))
+ @cachex.del(:scrubber_management_cache, activity_id)
+ end
+