001    /*
002     * Copyright (C) 2011 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.cache;
018    
019    import com.google.common.annotations.Beta;
020    
021    /**
022     * Calculates the weights of cache entries.
023     *
024     * @author fry@google.com (Charles Fry)
025     * @since 11.0
026     */
027    @Beta
028    public interface Weigher<K, V> {
029    
030      /**
031       * Returns the weight of a cache entry. There is no unit for entry weights; rather they are simply
032       * relative to each other.
033       *
034       * @return the weight of the entry; must be non-negative
035       */
036      int weigh(K key, V value);
037    
038    }