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
12   * under the License.
13   */
14  
15  package com.google.common.cache;
16  
17  import com.google.common.annotations.Beta;
18  import com.google.common.annotations.GwtCompatible;
19  
20  /**
21   * Calculates the weights of cache entries.
22   *
23   * @author Charles Fry
24   * @since 11.0
25   */
26  @Beta
27  @GwtCompatible
28  public interface Weigher<K, V> {
29  
30    /**
31     * Returns the weight of a cache entry. There is no unit for entry weights; rather they are simply
32     * relative to each other.
33     *
34     * @return the weight of the entry; must be non-negative
35     */
36    int weigh(K key, V value);
37  }