Use upload ID instead of model ID in lease key

For FileUploaders it's possible that a model has many uploads
and if lease key is created only from model id, it causes that
the model's uploads can not be migrated in parallel because the
exclusive lease key would be same for all uploads of the model.

app/uploaders/object_storage.rb

@@ -298,6 +298,15 @@ module ObjectStorage
       super
     end
+    def exclusive_lease_key
+      # For FileUploaders, model may have many uploaders. In that case
+      # we want to use exclusive key per upload, not per model to allow
+      # parallel migration
+      key_object = self.is_a?(RecordsUploads::Concern) && upload ? upload : model
+
+      "object_storage_migrate:#{key_object.class}:#{key_object.id}"
+    end
+
     private
     def schedule_background_upload?
@@ -364,10 +373,6 @@ module ObjectStorage
       end
     end
-    def exclusive_lease_key
-      "object_storage_migrate:#{model.class}:#{model.id}"
-    end
-
     def with_exclusive_lease
       uuid = Gitlab::ExclusiveLease.new(exclusive_lease_key, timeout: 1.hour.to_i).try_obtain
       raise 'exclusive lease already taken' unless uuid

changelogs/unreleased/47513-upload-migration-lease-key-is-incorrect-for-non-mounted-uploaders.yml

+---
+title: Use upload ID for creating lease key for file uploaders.
+merge_request:
+author:
+type: fixed

spec/support/shared_examples/uploaders/object_storage_shared_examples.rb

@@ -76,10 +76,8 @@ shared_examples "migrates" do |to_store:, from_store: nil|
   end
   context 'when migrate! is occupied by another process' do
-    let(:exclusive_lease_key) { "object_storage_migrate:#{subject.model.class}:#{subject.model.id}" }
-
     before do
-      @uuid = Gitlab::ExclusiveLease.new(exclusive_lease_key, timeout: 1.hour.to_i).try_obtain
+      @uuid = Gitlab::ExclusiveLease.new(subject.exclusive_lease_key, timeout: 1.hour.to_i).try_obtain
     end
     it 'does not execute migrate!' do
@@ -95,7 +93,7 @@ shared_examples "migrates" do |to_store:, from_store: nil|
     end
     after do
-      Gitlab::ExclusiveLease.cancel(exclusive_lease_key, @uuid)
+      Gitlab::ExclusiveLease.cancel(subject.exclusive_lease_key, @uuid)
     end
   end

spec/uploaders/object_storage_spec.rb

@@ -332,6 +332,18 @@ describe ObjectStorage do
         expect { uploader.use_file }.to raise_error('exclusive lease already taken')
       end
     end
+
+    it 'can still migrate other files of the same model' do
+      uploader2 = uploader_class.new(object, :file)
+      uploader2.upload = create(:upload)
+      uploader.upload = create(:upload)
+
+      when_file_is_in_use do
+        expect(uploader2).to receive(:unsafe_migrate!)
+
+        uploader2.migrate!(described_class::Store::REMOTE)
+      end
+    end
   end
   describe '#fog_credentials' do