HBASE-19609 Fixed Checkstyle errors in hbase-metrics and enabled Checkstyle to fail on violations

hbase-metrics/pom.xml

@@ -68,6 +68,22 @@
           </execution>
         </executions>
       </plugin>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-checkstyle-plugin</artifactId>
+        <executions>
+          <execution>
+            <id>checkstyle</id>
+            <phase>validate</phase>
+            <goals>
+              <goal>check</goal>
+            </goals>
+            <configuration>
+              <failOnViolation>true</failOnViolation>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
     </plugins>
   </build>
 

hbase-metrics/src/main/java/org/apache/hadoop/hbase/metrics/impl/CounterImpl.java

@@ -19,8 +19,8 @@ package org.apache.hadoop.hbase.metrics.impl;
 
 import java.util.concurrent.atomic.LongAdder;
 
-import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.hadoop.hbase.metrics.Counter;
+import org.apache.yetus.audience.InterfaceAudience;
 
 /**
  * Custom implementation of {@link org.apache.hadoop.hbase.metrics.Counter} using LongAdder.

hbase-metrics/src/main/java/org/apache/hadoop/hbase/metrics/impl/DropwizardMeter.java

@@ -17,12 +17,12 @@
  */
 package org.apache.hadoop.hbase.metrics.impl;
 
+import com.codahale.metrics.Meter;
+
 import java.util.Objects;
 
 import org.apache.yetus.audience.InterfaceAudience;
 
-import com.codahale.metrics.Meter;
-
 /**
  * Dropwizard metrics implementation of {@link org.apache.hadoop.hbase.metrics.Meter}.
  */

hbase-metrics/src/main/java/org/apache/hadoop/hbase/metrics/impl/FastLongHistogram.java

@@ -22,10 +22,10 @@ import java.util.concurrent.atomic.AtomicLong;
 import java.util.concurrent.atomic.LongAdder;
 import java.util.stream.Stream;
 
-import org.apache.yetus.audience.InterfaceAudience;
-import org.apache.yetus.audience.InterfaceStability;
 import org.apache.hadoop.hbase.metrics.Snapshot;
 import org.apache.hadoop.hbase.util.AtomicUtils;
+import org.apache.yetus.audience.InterfaceAudience;
+import org.apache.yetus.audience.InterfaceStability;
 
 /**
  * FastLongHistogram is a thread-safe class that estimate distribution of data and computes the

hbase-metrics/src/main/java/org/apache/hadoop/hbase/metrics/impl/HistogramImpl.java

@@ -16,13 +16,11 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
-
 package org.apache.hadoop.hbase.metrics.impl;
 
-import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.hadoop.hbase.metrics.Histogram;
 import org.apache.hadoop.hbase.metrics.Snapshot;
+import org.apache.yetus.audience.InterfaceAudience;
 
 /**
  * Custom histogram implementation based on FastLongHistogram. Dropwizard-based histograms are

hbase-metrics/src/main/java/org/apache/hadoop/hbase/metrics/impl/MetricRegistriesImpl.java

@@ -16,8 +16,6 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
-
 package org.apache.hadoop.hbase.metrics.impl;
 
 import java.util.Collection;
@@ -25,11 +23,11 @@ import java.util.Collections;
 import java.util.Optional;
 import java.util.Set;
 
-import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.hadoop.hbase.metrics.MetricRegistries;
 import org.apache.hadoop.hbase.metrics.MetricRegistry;
 import org.apache.hadoop.hbase.metrics.MetricRegistryFactory;
 import org.apache.hadoop.hbase.metrics.MetricRegistryInfo;
+import org.apache.yetus.audience.InterfaceAudience;
 
 /**
  * Implementation of MetricRegistries that does ref-counting.

hbase-metrics/src/main/java/org/apache/hadoop/hbase/metrics/impl/MetricRegistryFactoryImpl.java

@@ -16,14 +16,12 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
-
 package org.apache.hadoop.hbase.metrics.impl;
 
-import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.hadoop.hbase.metrics.MetricRegistry;
 import org.apache.hadoop.hbase.metrics.MetricRegistryFactory;
 import org.apache.hadoop.hbase.metrics.MetricRegistryInfo;
+import org.apache.yetus.audience.InterfaceAudience;
 
 @InterfaceAudience.Private
 public class MetricRegistryFactoryImpl implements MetricRegistryFactory {

hbase-metrics/src/main/java/org/apache/hadoop/hbase/metrics/impl/MetricRegistryImpl.java

@@ -22,7 +22,6 @@ import java.util.Optional;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
 
-import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.hadoop.hbase.metrics.Counter;
 import org.apache.hadoop.hbase.metrics.Gauge;
 import org.apache.hadoop.hbase.metrics.Histogram;
@@ -33,6 +32,7 @@ import org.apache.hadoop.hbase.metrics.MetricRegistryInfo;
 import org.apache.hadoop.hbase.metrics.MetricSet;
 import org.apache.hadoop.hbase.metrics.Timer;
 import org.apache.hadoop.hbase.util.CollectionUtils;
+import org.apache.yetus.audience.InterfaceAudience;
 
 /**
  * Custom implementation of {@link MetricRegistry}.

hbase-metrics/src/main/java/org/apache/hadoop/hbase/metrics/impl/RefCountingMap.java

@@ -16,8 +16,6 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
-
 package org.apache.hadoop.hbase.metrics.impl;
 
 import java.util.Collection;
@@ -69,7 +67,7 @@ class RefCountingMap<K, V> {
    * @return the value associated with the specified key or null if key is removed from map.
    */
   V remove(K k) {
-    Payload<V> p = map.computeIfPresent(k, (k1, v) -> --v.refCount <= 0 ? null : v );
+    Payload<V> p = map.computeIfPresent(k, (k1, v) -> --v.refCount <= 0 ? null : v);
     return p == null ? null : p.v;
   }
 

hbase-metrics/src/main/java/org/apache/hadoop/hbase/metrics/impl/TimerImpl.java

@@ -19,8 +19,8 @@ package org.apache.hadoop.hbase.metrics.impl;
 
 import java.util.concurrent.TimeUnit;
 
-import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.hadoop.hbase.metrics.Timer;
+import org.apache.yetus.audience.InterfaceAudience;
 
 /**
  * Custom implementation of {@link Timer}.

hbase-metrics/src/test/java/org/apache/hadoop/hbase/metrics/impl/TestDropwizardMeter.java

@@ -17,14 +17,14 @@
  */
 package org.apache.hadoop.hbase.metrics.impl;
 
+import com.codahale.metrics.Meter;
+
 import org.apache.hadoop.hbase.testclassification.SmallTests;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.experimental.categories.Category;
 import org.mockito.Mockito;
 
-import com.codahale.metrics.Meter;
-
 /**
  * Test class for {@link DropwizardMeter}.
  */

hbase-metrics/src/test/java/org/apache/hadoop/hbase/metrics/impl/TestRefCountingMap.java

@@ -16,8 +16,6 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
-
 package org.apache.hadoop.hbase.metrics.impl;
 
 import static org.junit.Assert.assertEquals;
@@ -135,7 +133,7 @@ public class TestRefCountingMap {
     Set<String> keys = map.keySet();
     assertEquals(3, keys.size());
 
-    Lists.newArrayList("foo", "bar", "baz").stream().forEach( v -> assertTrue(keys.contains(v)));
+    Lists.newArrayList("foo", "bar", "baz").stream().forEach(v -> assertTrue(keys.contains(v)));
   }
 
   @Test
@@ -148,7 +146,7 @@ public class TestRefCountingMap {
     Collection<String> values = map.values();
     assertEquals(3, values.size());
 
-    Lists.newArrayList("foovalue", "foovalue3", "foovalue4").stream().forEach(
+    Lists.newArrayList("foovalue", "foovalue3", "foovalue4").stream()
-        v -> assertTrue(values.contains(v)));
+            .forEach(v -> assertTrue(values.contains(v)));
   }
 }