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
017package com.google.common.collect;
018
019import com.google.common.annotations.Beta;
020
021import java.util.concurrent.Executor;
022
023import javax.annotation.Nullable;
024
025/**
026 * A collection of common eviction listeners.
027 *
028 * @author Charles Fry
029 * @since 7
030 */
031@Beta
032public 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}