Add counter for update_retried method of Ci::ProcessPipelineService

This counter is temporary.
It will be used to check whether if we still use this method or not
after setting correct value of GenericCommitStatus#retried.

app/services/ci/process_pipeline_service.rb

@@ -38,10 +38,15 @@ module Ci
 
       # mark builds that are retried
       if latest_statuses.any?
-        pipeline.latest_statuses
-          .where(name: latest_statuses.map(&:second))
-          .where.not(id: latest_statuses.map(&:first))
-          .update_all(retried: true)
+        updated_count = pipeline.latest_statuses
+                          .where(name: latest_statuses.map(&:second))
+                          .where.not(id: latest_statuses.map(&:first))
+                          .update_all(retried: true)
+
+        # This counter is temporary. It will be used to check whether if we still use this method or not
+        # after setting correct value of `GenericCommitStatus#retried`.
+        # More info: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/50465#note_491657115
+        metrics.legacy_update_jobs_counter.increment if updated_count > 0
       end
     end
     # rubocop: enable CodeReuse/ActiveRecord

lib/gitlab/ci/pipeline/metrics.rb

@@ -45,6 +45,15 @@ module Gitlab
             Gitlab::Metrics.counter(name, comment)
           end
         end
+
+        def legacy_update_jobs_counter
+          strong_memoize(:legacy_update_jobs_counter) do
+            name = :ci_legacy_update_jobs_as_retried_total
+            comment = 'Counter of occurrences when jobs were not being set as retried before update_retried'
+
+            Gitlab::Metrics.counter(name, comment)
+          end
+        end
       end
     end
   end

spec/services/ci/process_pipeline_service_spec.rb

@@ -50,6 +50,35 @@ RSpec.describe Ci::ProcessPipelineService do
       expect(all_builds.retried).to contain_exactly(build_retried)
     end
 
+    context 'counter ci_legacy_update_jobs_as_retried_total' do
+      let(:counter) { double(increment: true) }
+
+      before do
+        allow(Gitlab::Metrics).to receive(:counter).and_call_original
+        allow(Gitlab::Metrics).to receive(:counter)
+                                    .with(:ci_legacy_update_jobs_as_retried_total, anything)
+                                    .and_return(counter)
+      end
+
+      it 'increments the counter' do
+        expect(counter).to receive(:increment)
+
+        subject.execute
+      end
+
+      context 'when the previous build has already retried column true' do
+        before do
+          build_retried.update_columns(retried: true)
+        end
+
+        it 'does not increment the counter' do
+          expect(counter).not_to receive(:increment)
+
+          subject.execute
+        end
+      end
+    end
+
     def create_build(name, **opts)
       create(:ci_build, :created, pipeline: pipeline, name: name, **opts)
     end