Add Housekeeping to wiki repositories

In this commit we add housekeeping to wiki repositories. It is
behind the feature flag :wiki_housekeeping.

The housekeeping is only triggered after a git push operation.

app/services/git/wiki_push_service.rb

@@ -16,6 +16,7 @@ module Git
       wiki.after_post_receive
 
       process_changes
+      perform_housekeeping if Feature.enabled?(:wiki_housekeeping, wiki.container)
     end
 
     private
@@ -72,6 +73,14 @@ module Git
     def default_branch_changes
       @default_branch_changes ||= changes.select { |change| on_default_branch?(change) }
     end
+
+    def perform_housekeeping
+      housekeeping = Repositories::HousekeepingService.new(wiki)
+      housekeeping.increment!
+      housekeeping.execute if housekeeping.needed?
+    rescue Repositories::HousekeepingService::LeaseTaken
+      # no-op
+    end
   end
 end
 

app/workers/projects/git_garbage_collect_worker.rb

@@ -7,6 +7,17 @@ module Projects
 
     private
 
+    # At the moment this was added, the default key was like this.
+    # With the addition of wikis to housekeeping, this will bring a
+    # problem because the wiki for project 1 will have the same
+    # lease key as project 1.
+    #
+    # In the `GitGarbageCollectMethods` we namespaced the resource,
+    # giving us the option to have different resources. Nevertheless,
+    # we kept this override in order for backward compatibility and avoid
+    # starting all projects from scratch.
+    #
+    # See https://gitlab.com/gitlab-org/gitlab/-/issues/299903
     override :default_lease_key
     def default_lease_key(task, resource)
       "git_gc:#{task}:#{resource.id}"

config/feature_flags/development/wiki_housekeeping.yml

+---
+name: wiki_housekeeping
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/51576
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/299343
+milestone: '13.9'
+type: development
+group: group::editor
+default_enabled: false

spec/services/git/wiki_push_service_spec.rb

@@ -257,6 +257,56 @@ RSpec.describe Git::WikiPushService, services: true do
     end
   end
 
+  describe '#perform_housekeeping', :clean_gitlab_redis_shared_state do
+    let(:housekeeping) { Repositories::HousekeepingService.new(wiki) }
+
+    subject { create_service(current_sha).execute }
+
+    before do
+      allow(Repositories::HousekeepingService).to receive(:new).and_return(housekeeping)
+    end
+
+    it 'does not perform housekeeping when not needed' do
+      expect(housekeeping).not_to receive(:execute)
+
+      subject
+    end
+
+    context 'when housekeeping is needed' do
+      before do
+        allow(housekeeping).to receive(:needed?).and_return(true)
+      end
+
+      it 'performs housekeeping' do
+        expect(housekeeping).to receive(:execute)
+
+        subject
+      end
+
+      it 'does not raise an exception' do
+        allow(housekeeping).to receive(:try_obtain_lease).and_return(false)
+
+        expect { subject }.not_to raise_error
+      end
+
+      context 'when feature flag :wiki_housekeeping is disabled' do
+        it 'does not perform housekeeping' do
+          stub_feature_flags(wiki_housekeeping: false)
+
+          expect(housekeeping).not_to receive(:execute)
+
+          subject
+        end
+      end
+    end
+
+    it 'increments the push counter' do
+      expect(housekeeping).to receive(:increment!)
+
+      subject
+    end
+  end
+
   # In order to construct the correct GitPostReceive object that represents the
   # changes we are applying, we need to describe the changes between old-ref and
   # new-ref. Old ref (the base sha) we have to capture before we perform any