Additional logging and handling for missing schedule errors

lib/sidekiq_scheduler_backoff_service.rb

@@ -11,12 +11,16 @@ def record_success
     initial_interval = current_interval
     target_interval = [initial_interval - 1, min_interval].max
     restart_schedule(target_interval) if target_interval != initial_interval
+  rescue StandardError
+    notify_missing_schedule
   end
 
   def record_failure
     initial_interval = current_interval
     target_interval = [initial_interval * 2, max_interval].min
     restart_schedule(target_interval) if target_interval != initial_interval
+  rescue StandardError
+    notify_missing_schedule
   end
 
 private
@@ -30,4 +34,11 @@ def restart_schedule(target_interval)
     schedule = Sidekiq.get_schedule[name]
     Sidekiq.set_schedule(name, schedule.merge("every" => "#{target_interval}s"))
   end
+
+  def notify_missing_schedule
+    GovukError.notify(
+      "Queue schedule missing",
+      extra: { available_schedules: Sidekiq.get_schedule.keys },
+    )
+  end
 end

spec/lib/sidekiq_scheduler_backoff_service_spec.rb

@@ -50,6 +50,15 @@
         expect(scheduled_interval).to eq("#{max_interval}s")
       end
     end
+
+    context "when the schedule is missing" do
+      subject { SidekiqSchedulerBackoffService.new(name: "non-existing-queue", min_interval:, max_interval:) }
+
+      it "records the problem to GovukError" do
+        expect(GovukError).to receive(:notify)
+        subject.record_failure
+      end
+    end
   end
 
   describe "#record_success" do
@@ -96,6 +105,15 @@
         expect(scheduled_interval).to eq("#{max_interval}s")
       end
     end
+
+    context "when the schedule is missing" do
+      subject { SidekiqSchedulerBackoffService.new(name: "non-existing-queue", min_interval:, max_interval:) }
+
+      it "records the problem to GovukError" do
+        expect(GovukError).to receive(:notify)
+        subject.record_success
+      end
+    end
   end
 end