RATIS-2023. Remove duplicate RefCountingMap (apache#1039)

ratis-metrics-default/src/main/java/org/apache/ratis/metrics/impl/RefCountingMap.java → ratis-common/src/main/java/org/apache/ratis/util/RefCountingMap.java

@@ -15,7 +15,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.apache.ratis.metrics.impl;
+package org.apache.ratis.util;
 
 import java.util.Collection;
 import java.util.Set;
@@ -31,7 +31,7 @@
  * call will increment the ref count, and each remove() will decrement it. The values are removed
  * from the map iff ref count == 0.
  */
-class RefCountingMap<K, V> {
+public final class RefCountingMap<K, V> {
   private static class Payload<V> {
     private final V value;
     private final AtomicInteger refCount = new AtomicInteger();
@@ -55,15 +55,15 @@ Payload<V> decrement() {
 
   private final ConcurrentMap<K, Payload<V>> map = new ConcurrentHashMap<>();
 
-  V put(K k, Supplier<V> supplier) {
+  public V put(K k, Supplier<V> supplier) {
     return map.compute(k, (k1, old) -> old != null? old: new Payload<>(supplier.get())).increment();
   }
 
-  static <V> V get(Payload<V> p) {
+  public static <V> V get(Payload<V> p) {
     return p == null ? null : p.get();
   }
 
-  V get(K k) {
+  public V get(K k) {
     return get(map.get(k));
   }
 
@@ -72,23 +72,23 @@ V get(K k) {
    * @param k the key to remove
    * @return the value associated with the specified key or null if key is removed from map.
    */
-  V remove(K k) {
+  public V remove(K k) {
     return get(map.computeIfPresent(k, (k1, v) -> v.decrement()));
   }
 
-  void clear() {
+  public void clear() {
     map.clear();
   }
 
-  Set<K> keySet() {
+  public Set<K> keySet() {
     return map.keySet();
   }
 
-  Collection<V> values() {
+  public Collection<V> values() {
     return map.values().stream().map(Payload::get).collect(Collectors.toList());
   }
 
-  int size() {
+  public int size() {
     return map.size();
   }
 }

ratis-metrics-default/src/test/java/org/apache/ratis/metrics/impl/TestRefCountingMap.java → ratis-common/src/test/java/org/apache/ratis/util/TestRefCountingMap.java

@@ -15,7 +15,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.apache.ratis.metrics.impl;
+package org.apache.ratis.util;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
@@ -26,6 +26,7 @@
 import java.util.Set;
 
 import org.apache.ratis.thirdparty.com.google.common.collect.Lists;
+import org.apache.ratis.util.RefCountingMap;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 

ratis-metrics-default/src/main/java/org/apache/ratis/metrics/impl/MetricRegistriesImpl.java

@@ -28,6 +28,7 @@
 import org.apache.ratis.metrics.MetricRegistries;
 import org.apache.ratis.metrics.MetricRegistryInfo;
 import org.apache.ratis.metrics.RatisMetricRegistry;
+import org.apache.ratis.util.RefCountingMap;
 import org.apache.ratis.util.TimeDuration;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;

ratis-metrics-dropwizard3/src/main/java/org/apache/ratis/metrics/dropwizard3/Dm3MetricRegistriesImpl.java

@@ -28,6 +28,7 @@
 import org.apache.ratis.metrics.MetricRegistries;
 import org.apache.ratis.metrics.MetricRegistryInfo;
 import org.apache.ratis.metrics.RatisMetricRegistry;
+import org.apache.ratis.util.RefCountingMap;
 import org.apache.ratis.util.TimeDuration;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;