Eliminate N+1 queries in LFS file locks checks during a push

This significantly improves performance when a user pushes many references.

project.path_locks.any? doesn't cache the output and runs `SELECT 1 AS one
FROM "path_locks" WHERE project_id = N` each time. When there are thousands
of refs being pushed, this can time out the unicorn worker.

CE port for https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/6159.

1 files changed, 16 insertions, 0 deletions

diff --git a/spec/models/project_spec.rb b/spec/models/project_spec.rb
index bc9cce6b0c3..a2f8fac2f38 100644
--- a/spec/models/project_spec.rb
+++ b/spec/models/project_spec.rb
@@ -2339,6 +2339,22 @@ describe Project do
     end
   end
 
+  describe '#any_lfs_file_locks?', :request_store do
+    set(:project) { create(:project) }
+
+    it 'returns false when there are no LFS file locks' do
+      expect(project.any_lfs_file_locks?).to be_falsey
+    end
+
+    it 'returns a cached true when there are LFS file locks' do
+      create(:lfs_file_lock, project: project)
+
+      expect(project.lfs_file_locks).to receive(:any?).once.and_call_original
+
+      2.times { expect(project.any_lfs_file_locks?).to be_truthy }
+    end
+  end
+
   describe '#protected_for?' do
     let(:project) { create(:project) }