Extract some project logic into new RepositoryStorageMovable concern

We're going to allow snippets to move the repository storage of
their repositories (and later with group wikiws). For this, we
need to reuse some of the existent functionality in projects.

Therefore, the best way to do it is to extract it into a concern
and include it in snippets.

app/models/concerns/can_move_repository_storage.rb

+# frozen_string_literal: true
+
+module CanMoveRepositoryStorage
+  extend ActiveSupport::Concern
+
+  RepositoryReadOnlyError = Class.new(StandardError)
+
+  # Tries to set repository as read_only, checking for existing Git transfers in
+  # progress beforehand. Setting a repository read-only will fail if it is
+  # already in that state.
+  #
+  # @return nil. Failures will raise an exception
+  def set_repository_read_only!(skip_git_transfer_check: false)
+    with_lock do
+      raise RepositoryReadOnlyError, _('Git transfer in progress') if
+        !skip_git_transfer_check && git_transfer_in_progress?
+
+      raise RepositoryReadOnlyError, _('Repository already read-only') if
+        self.class.where(id: id).pick(:repository_read_only)
+
+      raise ActiveRecord::RecordNotSaved, _('Database update failed') unless
+        update_column(:repository_read_only, true)
+
+      nil
+    end
+  end
+
+  # Set repository as writable again. Unlike setting it read-only, this will
+  # succeed if the repository is already writable.
+  def set_repository_writable!
+    with_lock do
+      raise ActiveRecord::RecordNotSaved, _('Database update failed') unless
+        update_column(:repository_read_only, false)
+
+      nil
+    end
+  end
+
+  def git_transfer_in_progress?
+    reference_counter(type: repository.repo_type).value > 0
+  end
+
+  def reference_counter(type:)
+    Gitlab::ReferenceCounter.new(type.identifier_for_container(self))
+  end
+end

app/models/project.rb

@@ -19,6 +19,7 @@ class Project < ApplicationRecord
   include Presentable
   include HasRepository
   include HasWiki
+  include CanMoveRepositoryStorage
   include Routable
   include GroupDescendant
   include Gitlab::SQL::Pattern
@@ -2112,39 +2113,6 @@ class Project < ApplicationRecord
     (auto_devops || build_auto_devops)&.predefined_variables
   end
 
-  RepositoryReadOnlyError = Class.new(StandardError)
-
-  # Tries to set repository as read_only, checking for existing Git transfers in
-  # progress beforehand. Setting a repository read-only will fail if it is
-  # already in that state.
-  #
-  # @return nil. Failures will raise an exception
-  def set_repository_read_only!(skip_git_transfer_check: false)
-    with_lock do
-      raise RepositoryReadOnlyError, _('Git transfer in progress') if
-        !skip_git_transfer_check && git_transfer_in_progress?
-
-      raise RepositoryReadOnlyError, _('Repository already read-only') if
-        self.class.where(id: id).pick(:repository_read_only)
-
-      raise ActiveRecord::RecordNotSaved, _('Database update failed') unless
-        update_column(:repository_read_only, true)
-
-      nil
-    end
-  end
-
-  # Set repository as writable again. Unlike setting it read-only, this will
-  # succeed if the repository is already writable.
-  def set_repository_writable!
-    with_lock do
-      raise ActiveRecord::RecordNotSaved, _('Database update failed') unless
-        update_column(:repository_read_only, false)
-
-      nil
-    end
-  end
-
   def pushes_since_gc
     Gitlab::Redis::SharedState.with { |redis| redis.get(pushes_since_gc_redis_shared_state_key).to_i }
   end
@@ -2294,6 +2262,7 @@ class Project < ApplicationRecord
     end
   end
 
+  override :git_transfer_in_progress?
   def git_transfer_in_progress?
     GL_REPOSITORY_TYPES.any? do |type|
       reference_counter(type: type).value > 0
@@ -2306,10 +2275,6 @@ class Project < ApplicationRecord
     @storage = nil if storage_version_changed?
   end
 
-  def reference_counter(type: Gitlab::GlRepository::PROJECT)
-    Gitlab::ReferenceCounter.new(type.identifier_for_container(self))
-  end
-
   def badges
     return project_badges unless group
 

app/models/snippet.rb

@@ -15,6 +15,7 @@ class Snippet < ApplicationRecord
   include FromUnion
   include IgnorableColumns
   include HasRepository
+  include CanMoveRepositoryStorage
   include AfterCommitQueue
   extend ::Gitlab::Utils::Override
 

spec/models/project_spec.rb

@@ -147,6 +147,10 @@ RSpec.describe Project, factory_default: :keep do
       let(:container_without_wiki) { create(:project) }
     end
 
+    it_behaves_like 'can move repository storage' do
+      let_it_be(:container) { create(:project, :repository) }
+    end
+
     it 'has an inverse relationship with merge requests' do
       expect(described_class.reflect_on_association(:merge_requests).has_inverse?).to eq(:target_project)
     end
@@ -3040,50 +3044,6 @@ RSpec.describe Project, factory_default: :keep do
     end
   end
 
-  describe '#set_repository_read_only!' do
-    let(:project) { create(:project) }
-
-    it 'makes the repository read-only' do
-      expect { project.set_repository_read_only! }
-        .to change(project, :repository_read_only?)
-        .from(false)
-        .to(true)
-    end
-
-    it 'raises an error if the project is already read-only' do
-      project.set_repository_read_only!
-
-      expect { project.set_repository_read_only! }.to raise_error(described_class::RepositoryReadOnlyError, /already read-only/)
-    end
-
-    it 'raises an error when there is an existing git transfer in progress' do
-      allow(project).to receive(:git_transfer_in_progress?) { true }
-
-      expect { project.set_repository_read_only! }.to raise_error(described_class::RepositoryReadOnlyError, /in progress/)
-    end
-
-    context 'skip_git_transfer_check is true' do
-      it 'makes the project read-only when git transfers are in progress' do
-        allow(project).to receive(:git_transfer_in_progress?) { true }
-
-        expect { project.set_repository_read_only!(skip_git_transfer_check: true) }
-          .to change(project, :repository_read_only?)
-          .from(false)
-          .to(true)
-      end
-    end
-  end
-
-  describe '#set_repository_writable!' do
-    it 'sets repository_read_only to false' do
-      project = create(:project, :read_only)
-
-      expect { project.set_repository_writable! }
-        .to change(project, :repository_read_only)
-        .from(true).to(false)
-    end
-  end
-
   describe '#pushes_since_gc' do
     let(:project) { build_stubbed(:project) }
 

spec/models/snippet_spec.rb

@@ -769,4 +769,30 @@ RSpec.describe Snippet do
       it { is_expected.to be_falsey }
     end
   end
+
+  describe '#git_transfer_in_progress?' do
+    let(:snippet) { build(:snippet) }
+
+    subject { snippet.git_transfer_in_progress? }
+
+    it 'returns true when there are git transfers' do
+      allow(snippet).to receive(:reference_counter).with(type: Gitlab::GlRepository::SNIPPET) do
+        double(:reference_counter, value: 2)
+      end
+
+      expect(subject).to eq true
+    end
+
+    it 'returns false when there are not git transfers' do
+      allow(snippet).to receive(:reference_counter).with(type: Gitlab::GlRepository::SNIPPET) do
+        double(:reference_counter, value: 0)
+      end
+
+      expect(subject).to eq false
+    end
+  end
+
+  it_behaves_like 'can move repository storage' do
+    let_it_be(:container) { create(:snippet, :repository) }
+  end
 end

spec/support/shared_examples/models/concerns/can_move_repository_storage_shared_examples.rb

+# frozen_string_literal: true
+
+RSpec.shared_examples 'can move repository storage' do
+  let(:container) { raise NotImplementedError }
+
+  describe '#set_repository_read_only!' do
+    it 'makes the repository read-only' do
+      expect { container.set_repository_read_only! }
+        .to change(container, :repository_read_only?)
+        .from(false)
+        .to(true)
+    end
+
+    it 'raises an error if the project is already read-only' do
+      container.set_repository_read_only!
+
+      expect { container.set_repository_read_only! }.to raise_error(described_class::RepositoryReadOnlyError, /already read-only/)
+    end
+
+    it 'raises an error when there is an existing git transfer in progress' do
+      allow(container).to receive(:git_transfer_in_progress?) { true }
+
+      expect { container.set_repository_read_only! }.to raise_error(described_class::RepositoryReadOnlyError, /in progress/)
+    end
+
+    context 'skip_git_transfer_check is true' do
+      it 'makes the project read-only when git transfers are in progress' do
+        allow(container).to receive(:git_transfer_in_progress?) { true }
+
+        expect { container.set_repository_read_only!(skip_git_transfer_check: true) }
+          .to change(container, :repository_read_only?)
+          .from(false)
+          .to(true)
+      end
+    end
+  end
+
+  describe '#set_repository_writable!' do
+    it 'sets repository_read_only to false' do
+      expect { container.set_repository_writable! }
+        .to change(container, :repository_read_only)
+        .from(true).to(false)
+    end
+  end
+
+  describe '#reference_counter' do
+    it 'returns a Gitlab::ReferenceCounter object' do
+      expect(Gitlab::ReferenceCounter).to receive(:new).with(container.repository.gl_repository).and_call_original
+
+      result = container.reference_counter(type: container.repository.repo_type)
+
+      expect(result).to be_a Gitlab::ReferenceCounter
+    end
+  end
+end