1 files changed, 49 insertions, 7 deletions

diff --git a/spec/models/namespace/traversal_hierarchy_spec.rb b/spec/models/namespace/traversal_hierarchy_spec.rb
index 83e6d704640..b166d541171 100644
--- a/spec/models/namespace/traversal_hierarchy_spec.rb
+++ b/spec/models/namespace/traversal_hierarchy_spec.rb
@@ -43,21 +43,63 @@ RSpec.describe Namespace::TraversalHierarchy, type: :model do
     end
   end
 
+  shared_examples 'locked update query' do
+    it 'locks query with FOR UPDATE' do
+      qr = ActiveRecord::QueryRecorder.new do
+        subject
+      end
+      expect(qr.count).to eq 1
+      expect(qr.log.first).to match /FOR UPDATE/
+    end
+  end
+
   describe '#incorrect_traversal_ids' do
-    subject { described_class.new(root).incorrect_traversal_ids }
+    let!(:hierarchy) { described_class.new(root) }
+
+    subject { hierarchy.incorrect_traversal_ids }
+
+    before do
+      Namespace.update_all(traversal_ids: [])
+    end
 
     it { is_expected.to match_array Namespace.all }
+
+    context 'when lock is true' do
+      subject { hierarchy.incorrect_traversal_ids(lock: true).load }
+
+      it_behaves_like 'locked update query'
+    end
   end
 
   describe '#sync_traversal_ids!' do
-    let(:hierarchy) { described_class.new(root) }
+    let!(:hierarchy) { described_class.new(root) }
 
-    before do
-      hierarchy.sync_traversal_ids!
-      root.reload
-    end
+    subject { hierarchy.sync_traversal_ids! }
 
-    it_behaves_like 'hierarchy with traversal_ids'
     it { expect(hierarchy.incorrect_traversal_ids).to be_empty }
+
+    it_behaves_like 'hierarchy with traversal_ids'
+    it_behaves_like 'locked update query'
+
+    context 'when deadlocked' do
+      before do
+        connection_double = double(:connection)
+
+        allow(Namespace).to receive(:connection).and_return(connection_double)
+        allow(connection_double).to receive(:exec_query) { raise ActiveRecord::Deadlocked.new }
+      end
+
+      it { expect { subject }.to raise_error(ActiveRecord::Deadlocked) }
+
+      it 'increment db_deadlock counter' do
+        expect { subject rescue nil }.to change { db_deadlock_total('Namespace#sync_traversal_ids!') }.by(1)
+      end
+    end
+  end
+
+  def db_deadlock_total(source)
+    Gitlab::Metrics
+      .counter(:db_deadlock, 'Counts the times we have deadlocked in the database')
+      .get(source: source)
   end
 end