Make merge_jid handling less stateful in MergeService

app/models/merge_request.rb

@@ -396,7 +396,9 @@ class MergeRequest < ActiveRecord::Base
   end
   def merge_ongoing?
-    !!merge_jid && !merged? && Gitlab::SidekiqStatus.running?(merge_jid)
+    # While the MergeRequest is locked, it should present itself as 'merge ongoing'.
+    # The unlocking process is handled by StuckMergeJobsWorker scheduled in Cron.
+    locked? || !!merge_jid && !merged? && Gitlab::SidekiqStatus.running?(merge_jid)
   end
   def closed_without_fork?

app/services/merge_requests/merge_service.rb

@@ -82,16 +82,9 @@ module MergeRequests
         @merge_request.can_remove_source_branch?(branch_deletion_user)
     end
-    # Logs merge error message and cleans `MergeRequest#merge_jid`.
-    #
     def handle_merge_error(log_message:, save_message_on_model: false)
       Rails.logger.error("MergeService ERROR: #{merge_request_info} - #{log_message}")
-
-      if save_message_on_model
-        @merge_request.update(merge_error: log_message, merge_jid: nil)
-      else
-        clean_merge_jid
-      end
+      @merge_request.update(merge_error: log_message) if save_message_on_model
     end
     def merge_request_info

app/workers/stuck_merge_jobs_worker.rb

@@ -23,7 +23,7 @@ class StuckMergeJobsWorker
     merge_requests = MergeRequest.where(id: completed_ids)
     merge_requests.where.not(merge_commit_sha: nil).update_all(state: :merged)
-    merge_requests.where(merge_commit_sha: nil).update_all(state: :opened)
+    merge_requests.where(merge_commit_sha: nil).update_all(state: :opened, merge_jid: nil)
     Rails.logger.info("Updated state of locked merge jobs. JIDs: #{completed_jids.join(', ')}")
   end

spec/models/merge_request_spec.rb

@@ -1460,6 +1460,12 @@ describe MergeRequest do
   end
   describe '#merge_ongoing?' do
+    it 'returns true when the merge request is locked' do
+      merge_request = build_stubbed(:merge_request, state: :locked)
+
+      expect(merge_request.merge_ongoing?).to be(true)
+    end
+
     it 'returns true when merge_id, MR is not merged and it has no running job' do
       merge_request = build_stubbed(:merge_request, state: :open, merge_jid: 'foo')
       allow(Gitlab::SidekiqStatus).to receive(:running?).with('foo') { true }

spec/services/merge_requests/merge_service_spec.rb

@@ -12,55 +12,6 @@ describe MergeRequests::MergeService do
   end
   describe '#execute' do
-    context 'MergeRequest#merge_jid' do
-      let(:service) do
-        described_class.new(project, user, commit_message: 'Awesome message')
-      end
-
-      before do
-        merge_request.update_column(:merge_jid, 'hash-123')
-      end
-
-      it 'is cleaned when no error is raised' do
-        service.execute(merge_request)
-
-        expect(merge_request.reload.merge_jid).to be_nil
-      end
-
-      it 'is cleaned when expected error is raised' do
-        allow(service).to receive(:commit).and_raise(described_class::MergeError)
-
-        service.execute(merge_request)
-
-        expect(merge_request.reload.merge_jid).to be_nil
-      end
-
-      it 'is cleaned when merge request is not mergeable' do
-        allow(merge_request).to receive(:mergeable?).and_return(false)
-
-        service.execute(merge_request)
-
-        expect(merge_request.reload.merge_jid).to be_nil
-      end
-
-      it 'is cleaned when no source is found' do
-        allow(merge_request).to receive(:diff_head_sha).and_return(nil)
-
-        service.execute(merge_request)
-
-        expect(merge_request.reload.merge_jid).to be_nil
-      end
-
-      it 'is not cleaned when unexpected error is raised' do
-        service = described_class.new(project, user, commit_message: 'Awesome message')
-        allow(service).to receive(:commit).and_raise(StandardError)
-
-        expect { service.execute(merge_request) }.to raise_error(StandardError)
-
-        expect(merge_request.reload.merge_jid).to be_present
-      end
-    end
-
     context 'valid params' do
       let(:service) { described_class.new(project, user, commit_message: 'Awesome message') }

spec/workers/stuck_merge_jobs_worker_spec.rb

@@ -12,8 +12,13 @@ describe StuckMergeJobsWorker do
         worker.perform
-        expect(mr_with_sha.reload).to be_merged
-        expect(mr_without_sha.reload).to be_opened
+        mr_with_sha.reload
+        mr_without_sha.reload
+
+        expect(mr_with_sha).to be_merged
+        expect(mr_without_sha).to be_opened
+        expect(mr_with_sha.merge_jid).to be_present
+        expect(mr_without_sha.merge_jid).to be_nil
       end
       it 'updates merge request to opened when locked but has not been merged' do