Use memoize with retrievers and extract useful methods

ee/lib/gitlab/geo/replication/file_retriever.rb

@@ -9,36 +9,34 @@ module Gitlab
       #
       class FileRetriever < BaseRetriever
         def execute
-          recorded_file = fetch_resource
-
           return error('Upload not found') unless recorded_file
           return file_not_found(recorded_file) unless recorded_file.exist?
-          return error('Upload not found') unless valid?(recorded_file)
+          return error('Upload not found') unless valid?
 
           success(CarrierWave::SanitizedFile.new(recorded_file.absolute_path))
         end
 
         private
 
-        # rubocop: disable CodeReuse/ActiveRecord
-
-        def fetch_resource
-          Upload.find_by(id: object_db_id)
+        def recorded_file
+          strong_memoize(:recorded_file) do
+            Upload.find_by_id(object_db_id)
+          end
         end
 
-        # rubocop: enable CodeReuse/ActiveRecord
-
-        def valid?(recorded_file)
-          matches_requested_model?(recorded_file) &&
-            matches_checksum?(recorded_file)
+        def valid?
+          matches_requested_model? && matches_checksum?
         end
 
-        def matches_requested_model?(recorded_file)
+        def matches_requested_model?
           message[:id] == recorded_file.model_id &&
             message[:type] == recorded_file.model_type
         end
 
-        def matches_checksum?(recorded_file)
+        def matches_checksum?
+          # Remove this when we implement checksums for files on the Object Storage
+          return true unless recorded_file.local?
+
           message[:checksum] == Upload.hexdigest(recorded_file.absolute_path)
         end
       end

ee/lib/gitlab/geo/replication/job_artifact_retriever.rb

@@ -9,8 +9,6 @@ module Gitlab
       #
       class JobArtifactRetriever < BaseRetriever
         def execute
-          job_artifact = fetch_resource
-
           unless job_artifact.present?
             return error('Job artifact not found')
           end
@@ -26,13 +24,11 @@ module Gitlab
 
         private
 
-        # rubocop: disable CodeReuse/ActiveRecord
-
-        def fetch_resource
-          ::Ci::JobArtifact.find_by(id: object_db_id)
+        def job_artifact
+          strong_memoize(:job_artifact) do
+            ::Ci::JobArtifact.find_by_id(object_db_id)
+          end
         end
-
-        # rubocop: enable CodeReuse/ActiveRecord
       end
     end
   end

ee/lib/gitlab/geo/replication/lfs_retriever.rb

@@ -9,10 +9,8 @@ module Gitlab
       #
       class LfsRetriever < BaseRetriever
         def execute
-          lfs_object = fetch_resource
-
           return error('LFS object not found') unless lfs_object
-          return error('LFS object not found') if message[:checksum] != lfs_object.oid
+          return error('LFS object not found') unless matches_checksum?
 
           unless lfs_object.file.present? && lfs_object.file.exists?
             log_error("Could not upload LFS object because it does not have a file", id: lfs_object.id)
@@ -25,13 +23,15 @@ module Gitlab
 
         private
 
-        # rubocop: disable CodeReuse/ActiveRecord
-
-        def fetch_resource
-          LfsObject.find_by(id: object_db_id)
+        def lfs_object
+          strong_memoize(:lfs_object) do
+            LfsObject.find_by_id(object_db_id)
+          end
         end
 
-        # rubocop: enable CodeReuse/ActiveRecord
+        def matches_checksum?
+          message[:checksum] == lfs_object.oid
+        end
       end
     end
   end