KAFKA-10770: Remove duplicate defination of Metrics#getTags (#9659)

Reviewers: Chia-Ping Tsai <chia7712@gmail.com>

clients/src/main/java/org/apache/kafka/common/metrics/Metrics.java

@@ -18,6 +18,7 @@ package org.apache.kafka.common.metrics;
 
 import org.apache.kafka.common.MetricName;
 import org.apache.kafka.common.MetricNameTemplate;
+import org.apache.kafka.common.metrics.internals.MetricsUtils;
 import org.apache.kafka.common.utils.KafkaThread;
 import org.apache.kafka.common.utils.Time;
 import org.slf4j.Logger;
@@ -227,7 +228,7 @@ public class Metrics implements Closeable {
      * @param keyValue      additional key/value attributes of the metric (must come in pairs)
      */
     public MetricName metricName(String name, String group, String description, String... keyValue) {
-        return metricName(name, group, description, getTags(keyValue));
+        return metricName(name, group, description, MetricsUtils.getTags(keyValue));
     }
 
     /**
@@ -242,16 +243,6 @@ public class Metrics implements Closeable {
         return metricName(name, group, "", tags);
     }
 
-    private static Map<String, String> getTags(String... keyValue) {
-        if ((keyValue.length % 2) != 0)
-            throw new IllegalArgumentException("keyValue needs to be specified in pairs");
-        Map<String, String> tags = new LinkedHashMap<>();
-
-        for (int i = 0; i < keyValue.length; i += 2)
-            tags.put(keyValue[i], keyValue[i + 1]);
-        return tags;
-    }
-
     /**
      * Use the specified domain and metric name templates to generate an HTML table documenting the metrics. A separate table section
      * will be generated for each of the MBeans and the associated attributes. The MBean names are lexicographically sorted to
@@ -633,7 +624,7 @@ public class Metrics implements Closeable {
     }
 
     public MetricName metricInstance(MetricNameTemplate template, String... keyValue) {
-        return metricInstance(template, getTags(keyValue));
+        return metricInstance(template, MetricsUtils.getTags(keyValue));
     }
 
     public MetricName metricInstance(MetricNameTemplate template, Map<String, String> tags) {

clients/src/main/java/org/apache/kafka/common/metrics/internals/MetricsUtils.java

@@ -16,6 +16,10 @@
  */
 package org.apache.kafka.common.metrics.internals;
 
+import org.apache.kafka.common.metrics.Metrics;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
 import java.util.concurrent.TimeUnit;
 
 public class MetricsUtils {
@@ -43,4 +47,20 @@ public class MetricsUtils {
                 throw new IllegalStateException("Unknown unit: " + unit);
         }
     }
+
+    /**
+     * Create a set of tags using the supplied key and value pairs. The order of the tags will be kept.
+     *
+     * @param keyValue the key and value pairs for the tags; must be an even number
+     * @return the map of tags that can be supplied to the {@link Metrics} methods; never null
+     */
+    public static Map<String, String> getTags(String... keyValue) {
+        if ((keyValue.length % 2) != 0)
+            throw new IllegalArgumentException("keyValue needs to be specified in pairs");
+        Map<String, String> tags = new LinkedHashMap<>(keyValue.length / 2);
+
+        for (int i = 0; i < keyValue.length; i += 2)
+            tags.put(keyValue[i], keyValue[i + 1]);
+        return tags;
+    }
 }

clients/src/test/java/org/apache/kafka/common/metrics/internals/MetricsUtilsTest.java

@@ -0,0 +1,40 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.kafka.common.metrics.internals;
+
+import org.junit.Test;
+
+import java.util.Map;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertThrows;
+
+public class MetricsUtilsTest {
+
+    @Test
+    public void testCreatingTags() {
+        Map<String, String> tags = MetricsUtils.getTags("k1", "v1", "k2", "v2");
+        assertEquals("v1", tags.get("k1"));
+        assertEquals("v2", tags.get("k2"));
+        assertEquals(2, tags.size());
+    }
+
+    @Test
+    public void testCreatingTagsWithOddNumberOfTags() {
+        assertThrows(IllegalArgumentException.class, () -> MetricsUtils.getTags("k1", "v1", "k2", "v2", "extra"));
+    }
+}

connect/runtime/src/main/java/org/apache/kafka/connect/runtime/ConnectMetrics.java

@@ -27,6 +27,7 @@ import org.apache.kafka.common.metrics.Metrics;
 import org.apache.kafka.common.metrics.MetricsContext;
 import org.apache.kafka.common.metrics.MetricsReporter;
 import org.apache.kafka.common.metrics.Sensor;
+import org.apache.kafka.common.metrics.internals.MetricsUtils;
 import org.apache.kafka.common.utils.AppInfoParser;
 import org.apache.kafka.common.utils.Time;
 import org.apache.kafka.connect.runtime.distributed.DistributedConfig;
@@ -148,7 +149,7 @@ public class ConnectMetrics {
     }
 
     protected MetricGroupId groupId(String groupName, String... tagKeyValues) {
-        Map<String, String> tags = tags(tagKeyValues);
+        Map<String, String> tags = MetricsUtils.getTags(tagKeyValues);
         return new MetricGroupId(groupName, tags);
     }
 
@@ -433,22 +434,6 @@ public class ConnectMetrics {
         T metricValue(long now);
     }
 
-    /**
-     * Create a set of tags using the supplied key and value pairs. The order of the tags will be kept.
-     *
-     * @param keyValue the key and value pairs for the tags; must be an even number
-     * @return the map of tags that can be supplied to the {@link Metrics} methods; never null
-     */
-    static Map<String, String> tags(String... keyValue) {
-        if ((keyValue.length % 2) != 0)
-            throw new IllegalArgumentException("keyValue needs to be specified in pairs");
-        Map<String, String> tags = new LinkedHashMap<>();
-        for (int i = 0; i < keyValue.length; i += 2) {
-            tags.put(keyValue[i], keyValue[i + 1]);
-        }
-        return tags;
-    }
-
     /**
      * Utility to generate the documentation for the Connect metrics.
      *

connect/runtime/src/test/java/org/apache/kafka/connect/runtime/ConnectMetricsTest.java

@@ -67,19 +67,6 @@ public class ConnectMetricsTest {
         assertNotNull(metrics.metrics());
     }
 
-    @Test
-    public void testCreatingTags() {
-        Map<String, String> tags = ConnectMetrics.tags("k1", "v1", "k2", "v2");
-        assertEquals("v1", tags.get("k1"));
-        assertEquals("v2", tags.get("k2"));
-        assertEquals(2, tags.size());
-    }
-
-    @Test(expected = IllegalArgumentException.class)
-    public void testCreatingTagsWithOddNumberOfTags() {
-        ConnectMetrics.tags("k1", "v1", "k2", "v2", "extra");
-    }
-
     @Test(expected = IllegalArgumentException.class)
     public void testGettingGroupWithOddNumberOfTags() {
         metrics.group("name", "k1", "v1", "k2", "v2", "extra");