RATIS-1391. Update library dropwizard.metrics version to 4.x

[SpriCoder]

See more details: https://issues.apache.org/jira/browse/RATIS-1391 and https://issues.apache.org/jira/browse/RATIS-1565

[SpriCoder]

@szetszwo PTAL!

[szetszwo]

@SpriCoder , TestRaftLogMetrics failed in a few re-runs. Could you take a look? See https://github.com/apache/ratis/runs/6035048607?check_suite_focus=true#step:5:511

[SpriCoder]

@szetszwo I have already find the reason, that is the implementation of DefaultObjectNameFactory in dropwizard are different between 3.2.5 and 4.2.7. So, I will implement RatisObjectNameFactory.class to compatible with pre-version of ratis.

[SpriCoder]

@szetszwo Thanks for your time! I have already fix naming problem.

[SpriCoder]

@szetszwo I have already checked CI, it seems like there are some test out of time, can you take a look?

[szetszwo]

@SpriCoder , thanks for update. Just have started re-running the failed jobs.

[szetszwo]

@SpriCoder , TestLeaderElectionMetrics.testOnLeaderElectionCompletion failed again. Could you take a look?

[SpriCoder]

@szetszwo I run this test locally and have passed in ten times, so can you help me to rerun this test?

[szetszwo]

@SpriCoder , sure, let's try again.

[SpriCoder]

@szetszwo , it's sad that the unit test is failed again. I need your help. What I am confused is that whether the LAST_LEADER_ELECTION_ELAPSED_TIME gauge can be zero?

[szetszwo]

@SpriCoder , not sure. Let's print out the map and the value as below?

diff --git a/ratis-server/src/test/java/org/apache/ratis/server/metrics/TestLeaderElectionMetrics.java b/ratis-server/src/test/java/org/apache/ratis/server/metrics/TestLeaderElectionMetrics.java
index 62707845..af000f3a 100644
--- a/ratis-server/src/test/java/org/apache/ratis/server/metrics/TestLeaderElectionMetrics.java
+++ b/ratis-server/src/test/java/org/apache/ratis/server/metrics/TestLeaderElectionMetrics.java
@@ -23,6 +23,8 @@ import static org.apache.ratis.server.metrics.LeaderElectionMetrics.LEADER_ELECT
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 
+import com.codahale.metrics.Gauge;
+import org.apache.ratis.BaseTest;
 import org.apache.ratis.metrics.RatisMetricRegistry;
 import org.apache.ratis.protocol.RaftGroupId;
 import org.apache.ratis.protocol.RaftGroupMemberId;
@@ -30,10 +32,12 @@ import org.apache.ratis.protocol.RaftPeerId;
 import org.junit.BeforeClass;
 import org.junit.Test;
 
+import java.util.SortedMap;
+
 /**
  * Test for LeaderElectionMetrics.
  */
-public class TestLeaderElectionMetrics {
+public class TestLeaderElectionMetrics extends BaseTest {
 
   private static LeaderElectionMetrics leaderElectionMetrics;
   private static RatisMetricRegistry ratisMetricRegistry;
@@ -50,9 +54,11 @@ public class TestLeaderElectionMetrics {
   @Test
   public void testOnLeaderElectionCompletion() throws Exception {
     leaderElectionMetrics.onNewLeaderElectionCompletion();
-    Long leaderElectionLatency = (Long) ratisMetricRegistry.getGauges((s, metric) ->
-        s.contains(LAST_LEADER_ELECTION_ELAPSED_TIME)).values().iterator().next().getValue();
-    assertTrue(leaderElectionLatency > 0L);
+    final SortedMap<String, Gauge> gauges = ratisMetricRegistry.getGauges(
+        (s, metric) -> s.contains(LAST_LEADER_ELECTION_ELAPSED_TIME));
+    LOG.info("{} gauges: {}", LAST_LEADER_ELECTION_ELAPSED_TIME, gauges);
+    final Long leaderElectionLatency = (Long)gauges.values().iterator().next().getValue();
+    assertTrue("leaderElectionLatency = " + leaderElectionLatency, leaderElectionLatency > 0L);
   }
 
   @Test

[SpriCoder]

@szetszwo Thanks for your suggestion, I have already modified.

[szetszwo]

@SpriCoder , all the tests have passed now. Let's document the incompatibility of this change. I have posted some questions in https://issues.apache.org/jira/browse/RATIS-1391 , please take a look.

[SpriCoder]

@szetszwo Great! So is there anything to do before merge?

[szetszwo]

@SpriCoder , unfortunately, there is no response to our questions from the mailing list. We are currently preparing the the 2.3.0 release. Let's merge this once the 2.3.0 has been released.