001/*
002 * Copyright (C) 2011 The Guava Authors
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
005 * in compliance with the License. You may obtain a copy of the License at
006 *
007 * http://www.apache.org/licenses/LICENSE-2.0
008 *
009 * Unless required by applicable law or agreed to in writing, software distributed under the License
010 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
011 * or implied. See the License for the specific language governing permissions and limitations under
012 * the License.
013 */
014
015package com.google.common.cache;
016
017import com.google.common.annotations.GwtCompatible;
018
019/**
020 * Calculates the weights of cache entries.
021 *
022 * @author Charles Fry
023 * @since 11.0
024 */
025@GwtCompatible
026@ElementTypesAreNonnullByDefault
027public interface Weigher<K, V> {
028
029  /**
030   * Returns the weight of a cache entry. There is no unit for entry weights; rather they are simply
031   * relative to each other.
032   *
033   * @return the weight of the entry; must be non-negative
034   */
035  int weigh(K key, V value);
036}