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      1 /*
      2  * Copyright (C) 2011 The Guava Authors
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
      5  * in compliance with the License. You may obtain a copy of the License at
      6  *
      7  * http://www.apache.org/licenses/LICENSE-2.0
      8  *
      9  * Unless required by applicable law or agreed to in writing, software distributed under the License
     10  * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
     11  * or implied. See the License for the specific language governing permissions and limitations under
     12  * the License.
     13  */
     14 
     15 package com.google.common.cache;
     16 
     17 import com.google.common.annotations.GwtCompatible;
     18 import com.google.common.annotations.GwtIncompatible;
     19 
     20 import java.util.concurrent.ConcurrentLinkedQueue;
     21 import java.util.concurrent.atomic.AtomicInteger;
     22 
     23 /**
     24  * Utility {@link RemovalListener} implementations intended for use in testing.
     25  *
     26  * @author mike nonemacher
     27  */
     28 @GwtCompatible(emulated = true)
     29 class TestingRemovalListeners {
     30 
     31   /**
     32    * Returns a new no-op {@code RemovalListener}.
     33    */
     34   static <K, V> NullRemovalListener<K, V> nullRemovalListener() {
     35     return new NullRemovalListener<K, V>();
     36   }
     37 
     38   /**
     39    * Type-inferring factory method for creating a {@link QueuingRemovalListener}.
     40    */
     41   @GwtIncompatible("ConcurrentLinkedQueue")
     42   static <K, V> QueuingRemovalListener<K, V> queuingRemovalListener() {
     43     return new QueuingRemovalListener<K,V>();
     44   }
     45 
     46   /**
     47    * Type-inferring factory method for creating a {@link CountingRemovalListener}.
     48    */
     49   static <K, V> CountingRemovalListener<K, V> countingRemovalListener() {
     50     return new CountingRemovalListener<K,V>();
     51   }
     52 
     53   /**
     54    * {@link RemovalListener} that adds all {@link RemovalNotification} objects to a queue.
     55    */
     56   @GwtIncompatible("ConcurrentLinkedQueue")
     57   static class QueuingRemovalListener<K, V>
     58       extends ConcurrentLinkedQueue<RemovalNotification<K, V>> implements RemovalListener<K, V> {
     59 
     60     @Override
     61     public void onRemoval(RemovalNotification<K, V> notification) {
     62       add(notification);
     63     }
     64   }
     65 
     66   /**
     67    * {@link RemovalListener} that counts each {@link RemovalNotification} it receives, and provides
     68    * access to the most-recently received one.
     69    */
     70   static class CountingRemovalListener<K, V> implements RemovalListener<K, V> {
     71     private final AtomicInteger count = new AtomicInteger();
     72     private volatile RemovalNotification<K, V> lastNotification;
     73 
     74     @Override
     75     public void onRemoval(RemovalNotification<K, V> notification) {
     76       count.incrementAndGet();
     77       lastNotification = notification;
     78     }
     79 
     80     public int getCount() {
     81       return count.get();
     82     }
     83 
     84     public K getLastEvictedKey() {
     85       return lastNotification.getKey();
     86     }
     87 
     88     public V getLastEvictedValue() {
     89       return lastNotification.getValue();
     90     }
     91 
     92     public RemovalNotification<K, V> getLastNotification() {
     93       return lastNotification;
     94     }
     95   }
     96 
     97   /**
     98    * No-op {@link RemovalListener}.
     99    */
    100   static class NullRemovalListener<K, V> implements RemovalListener<K, V> {
    101     @Override
    102     public void onRemoval(RemovalNotification<K, V> notification) {}
    103   }
    104 }
    105