001    /*
002     * Copyright (C) 2010 The Guava Authors
003     *
004     * Licensed under the Apache License, Version 2.0 (the "License");
005     * you may not use this file except in compliance with the License.
006     * You may obtain a copy of the License at
007     *
008     * http://www.apache.org/licenses/LICENSE-2.0
009     *
010     * Unless required by applicable law or agreed to in writing, software
011     * distributed under the License is distributed on an "AS IS" BASIS,
012     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013     * See the License for the specific language governing permissions and
014     * limitations under the License.
015     */
016    
017    package com.google.common.collect;
018    
019    import com.google.common.annotations.Beta;
020    
021    import java.util.concurrent.Executor;
022    
023    import javax.annotation.Nullable;
024    
025    /**
026     * A collection of common eviction listeners.
027     *
028     * @author Charles Fry
029     * @since 7
030     */
031    @Beta
032    public final class EvictionListeners {
033    
034      private EvictionListeners() {}
035    
036      /**
037       * Returns an asynchronous {@code MapEvictionListener} which processes all
038       * eviction notifications asynchronously, using {@code executor}.
039       *
040       * @param listener the backing listener
041       * @param executor the executor with which eviciton notifications are
042       *     asynchronously executed
043       */
044      public static <K, V> MapEvictionListener<K, V> asynchronous(
045          final MapEvictionListener<K, V> listener, final Executor executor) {
046        return new MapEvictionListener<K, V>() {
047          @Override
048          public void onEviction(@Nullable final K key, @Nullable final V value) {
049            executor.execute(new Runnable() {
050              @Override
051              public void run() {
052                listener.onEviction(key, value);
053              }
054            });
055          }
056        };
057      }
058    
059    }