001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.apache.shiro.cache;
020
021import java.util.Collection;
022import java.util.Set;
023
024/**
025 * A Cache efficiently stores temporary objects primarily to improve an application's performance.
026 *
027 * <p>Shiro doesn't implement a full Cache mechanism itself, since that is outside the core competency of a
028 * Security framework.  Instead, this interface provides an abstraction (wrapper) API on top of an underlying
029 * cache framework's cache instance (e.g. JCache, Ehcache, JCS, OSCache, JBossCache, TerraCotta, Coherence,
030 * GigaSpaces, etc., etc.), allowing a Shiro user to configure any cache mechanism they choose.
031 *
032 * @param <K> K
033 * @param <V> V
034 * @since 0.2
035 */
036public interface Cache<K, V> {
037
038    /**
039     * Returns the Cached value stored under the specified {@code key} or
040     * {@code null} if there is no Cache entry for that {@code key}.
041     *
042     * @param key the key that the value was previous added with
043     * @return the cached object or {@code null} if there is no entry for the specified {@code key}
044     * @throws CacheException if there is a problem accessing the underlying cache system
045     */
046    V get(K key) throws CacheException;
047
048    /**
049     * Adds a Cache entry.
050     *
051     * @param key   the key used to identify the object being stored.
052     * @param value the value to be stored in the cache.
053     * @return the previous value associated with the given {@code key} or {@code null} if there was previous value
054     * @throws CacheException if there is a problem accessing the underlying cache system
055     */
056    V put(K key, V value) throws CacheException;
057
058    /**
059     * Remove the cache entry corresponding to the specified key.
060     *
061     * @param key the key of the entry to be removed.
062     * @return the previous value associated with the given {@code key} or {@code null} if there was previous value
063     * @throws CacheException if there is a problem accessing the underlying cache system
064     */
065    V remove(K key) throws CacheException;
066
067    /**
068     * Clear all entries from the cache.
069     *
070     * @throws CacheException if there is a problem accessing the underlying cache system
071     */
072    void clear() throws CacheException;
073
074    /**
075     * Returns the number of entries in the cache.
076     *
077     * @return the number of entries in the cache.
078     */
079    int size();
080
081    /**
082     * Returns a view of all the keys for entries contained in this cache.
083     *
084     * @return a view of all the keys for entries contained in this cache.
085     */
086    Set<K> keys();
087
088    /**
089     * Returns a view of all of the values contained in this cache.
090     *
091     * @return a view of all of the values contained in this cache.
092     */
093    Collection<V> values();
094}