shave off 30% of the query count

app/uploaders/file_uploader.rb

@@ -65,10 +65,10 @@ class FileUploader < GitlabUploader
     SecureRandom.hex
   end
-  def upload_paths(filename)
+  def upload_paths(identifier)
     [
-      File.join(secret, filename),
-      File.join(base_dir(Store::REMOTE), secret, filename)
+      File.join(secret, identifier),
+      File.join(base_dir(Store::REMOTE), secret, identifier)
     ]
   end

app/uploaders/object_storage.rb

@@ -29,7 +29,7 @@ module ObjectStorage
       end
       def retrieve_from_store!(identifier)
-        paths = store_dirs.map { |store, path| File.join(path, identifier) }
+        paths = upload_paths(identifier)
         unless current_upload_satisfies?(paths, model)
           # the upload we already have isn't right, find the correct one
@@ -261,7 +261,7 @@ module ObjectStorage
     end
     def delete_migrated_file(migrated_file)
-      migrated_file.delete if exists?
+      migrated_file.delete
     end
     def exists?
@@ -279,6 +279,13 @@ module ObjectStorage
       }
     end
+    # Returns all the possible paths for an upload.
+    # the `upload.path` is a lookup parameter, and it may change
+    # depending on the `store` param.
+    def upload_paths(identifier)
+      store_dirs.map { |store, path| File.join(path, identifier) }
+    end
+
     def cache!(new_file = sanitized_file)
       # We intercept ::UploadedFile which might be stored on remote storage
       # We use that for "accelerated" uploads, where we store result on remote storage

spec/uploaders/workers/object_storage/migrate_uploads_worker_spec.rb

 require 'spec_helper'
+MIGRATION_QUERIES = 7
+
 describe ObjectStorage::MigrateUploadsWorker, :sidekiq do
   shared_context 'sanity_check! fails' do
     before do
@@ -11,6 +13,13 @@ describe ObjectStorage::MigrateUploadsWorker, :sidekiq do
   let(:uploads) { Upload.all }
   let(:to_store) { ObjectStorage::Store::REMOTE }
+  def perform(uploads)
+    binding.pry
+    described_class.new.perform(uploads.ids, model_class.to_s, mounted_as, to_store)
+  rescue ObjectStorage::MigrateUploadsWorker::Report::MigrationFailures
+    # swallow
+  end
+
   shared_examples "uploads migration worker" do
     describe '.enqueue!' do
       def enqueue!
@@ -69,12 +78,6 @@ describe ObjectStorage::MigrateUploadsWorker, :sidekiq do
     end
     describe '#perform' do
-      def perform
-        described_class.new.perform(uploads.ids, model_class.to_s, mounted_as, to_store)
-      rescue ObjectStorage::MigrateUploadsWorker::Report::MigrationFailures
-        # swallow
-      end
-
       shared_examples 'outputs correctly' do |success: 0, failures: 0|
         total = success + failures
@@ -82,7 +85,7 @@ describe ObjectStorage::MigrateUploadsWorker, :sidekiq do
           it 'outputs the reports' do
             expect(Rails.logger).to receive(:info).with(%r{Migrated #{success}/#{total} files})
-            perform
+            perform(uploads)
           end
         end
@@ -90,7 +93,7 @@ describe ObjectStorage::MigrateUploadsWorker, :sidekiq do
           it 'outputs upload failures' do
             expect(Rails.logger).to receive(:warn).with(/Error .* I am a teapot/)
-            perform
+            perform(uploads)
           end
         end
       end
@@ -98,7 +101,7 @@ describe ObjectStorage::MigrateUploadsWorker, :sidekiq do
       it_behaves_like 'outputs correctly', success: 10
       it 'migrates files' do
-        perform
+        perform(uploads)
         expect(Upload.where(store: ObjectStorage::Store::LOCAL).count).to eq(0)
       end
@@ -123,6 +126,18 @@ describe ObjectStorage::MigrateUploadsWorker, :sidekiq do
     end
     it_behaves_like "uploads migration worker"
+
+    describe "limits N+1 queries" do
+      let!(:projects) { create_list(:project, 10, :with_avatar) }
+
+      it do
+        query_count = ActiveRecord::QueryRecorder.new { perform(uploads) }
+
+        more_projects = create_list(:project, 100, :with_avatar)
+        expected_queries_per_migration = MIGRATION_QUERIES * more_projects.count
+        expect { perform(Upload.all) }.not_to exceed_query_limit(query_count).with_threshold(expected_queries_per_migration)
+      end
+    end
   end
   context "for FileUploader" do
@@ -140,5 +155,22 @@ describe ObjectStorage::MigrateUploadsWorker, :sidekiq do
     end
     it_behaves_like "uploads migration worker"
+
+    describe "limits N+1 queries" do
+      let!(:projects) { create_list(:project, 10) }
+
+      it do
+        query_count = ActiveRecord::QueryRecorder.new { perform(uploads) }
+
+        more_projects = create_list(:project, 100)
+        more_projects.map do |project|
+          uploader = FileUploader.new(project)
+          uploader.store!(fixture_file_upload('spec/fixtures/doc_sample.txt'))
+        end
+        expected_queries_per_migration = MIGRATION_QUERIES * more_projects.count
+
+        expect { perform(Upload.all) }.not_to exceed_query_limit(query_count).with_threshold(expected_queries_per_migration)
+      end
+    end
   end
 end