Cache feature check for 5 minutes for MethodCall instrumentation toggle

lib/gitlab/metrics/method_call.rb

@@ -72,7 +72,9 @@ module Gitlab
       end
 
       def call_measurement_enabled?
-        Feature.get(:prometheus_metrics_method_instrumentation).enabled?
+        Rails.cache.fetch(:prometheus_metrics_method_instrumentation_enabled, expires_in: 5.minutes) do
+          Feature.get(:prometheus_metrics_method_instrumentation).enabled?
+        end
       end
     end
   end

spec/lib/gitlab/metrics/method_call_spec.rb

@@ -23,6 +23,17 @@ describe Gitlab::Metrics::MethodCall do
           Feature.get(:prometheus_metrics_method_instrumentation).enable
         end
 
+        it 'feature check is cached for 5 minutes' do
+          allow(Feature.get(:prometheus_metrics_method_instrumentation)).to receive(:enabled?).and_call_original
+          allow(Rails.cache).to receive(:fetch).and_call_original
+
+          method_call.measure { 'foo' }
+          method_call.measure { 'foo' }
+
+          expect(Feature.get(:prometheus_metrics_method_instrumentation)).to have_received(:enabled?).twice
+          expect(Rails.cache).to have_received(:fetch).with(:prometheus_metrics_method_instrumentation_enabled, expires_in: 5.minutes).twice
+        end
+
         it 'observes the performance of the supplied block' do
           expect(described_class.call_duration_histogram)
             .to receive(:observe)