Add Rails 6 memory allocations to default log (with fixed tests!)

lib/lograge/log_subscribers/base.rb

@@ -29,6 +29,7 @@ def process_main_event(event)
       def extract_request(event, payload)
         data = initial_data(payload)
         data.merge!(extract_status(payload))
+        data.merge!(extract_allocations(event))
         data.merge!(extract_runtimes(event, payload))
         data.merge!(extract_location)
         data.merge!(extract_unpermitted_params)
@@ -59,6 +60,14 @@ def get_error_status_code(exception_class_name)
         ActionDispatch::ExceptionWrapper.status_code_for_exception(exception_class_name)
       end
 
+      def extract_allocations(event)
+        if (allocations = (event.respond_to?(:allocations) && event.allocations))
+          { allocations: allocations }
+        else
+          {}
+        end
+      end
+
       def custom_options(event)
         options = Lograge.custom_options(event) || {}
         options.merge event.payload[:custom_payload] || {}

spec/log_subscribers/action_controller_spec.rb

@@ -209,6 +209,28 @@
       subscriber.process_action(event)
       expect(log_output.string).to_not include('unpermitted_params=')
     end
+
+    context 'with memory allocations' do
+      it 'includes allocations when available' do
+        event_with_allocations = event.dup
+        event_with_allocations.define_singleton_method :allocations do
+          231
+        end
+
+        subscriber.process_action(event_with_allocations)
+        expect(log_output.string).to match(/allocations=231/)
+      end
+
+      it 'fails gracefully when allocations are unavailable' do
+        event_without_allocations = event.dup
+        if event_without_allocations.respond_to? :allocations
+          event_without_allocations.instance_eval('undef :allocations', __FILE__, __LINE__)
+        end
+
+        subscriber.process_action(event_without_allocations)
+        expect(log_output.string).to_not match(/allocations=/)
+      end
+    end
   end
 
   context 'with custom_options configured for lograge output' do