1588

Author: p

lib/mongo/server/round_trip_time_averager.rb

@@ -36,9 +36,15 @@ def measure
           rv = yield
         rescue Exception => exc
         end
-        @last_round_trip_time = Time.now - start
+        last_round_trip_time = Time.now - start
 
-        update_average_round_trip_time
+        # If ismaster fails, we need to return the last round trip time
+        # because it is used in the heartbeat failed SDAM event,
+        # but we must not update the round trip time recorded in the server.
+        unless exc
+          @last_round_trip_time = last_round_trip_time
+          update_average_round_trip_time
+        end
 
         [rv, exc, last_round_trip_time, average_round_trip_time]
       end

spec/mongo/server/round_trip_time_averager_spec.rb

@@ -21,4 +21,23 @@
       end
     end
   end
+
+  describe '#measure' do
+    context 'block does not raise' do
+      it 'updates average rtt' do
+        expect(averager).to receive(:update_average_round_trip_time)
+        averager.measure do
+        end
+      end
+    end
+
+    context 'block raises' do
+      it 'does not update average rtt' do
+        expect(averager).not_to receive(:update_average_round_trip_time)
+        averager.measure do
+          raise "Problem"
+        end
+      end
+    end
+  end
 end