001/*
002 * Copyright 2002-2020 the original author or 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 *      https://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 org.springframework.cache.support;
018
019import java.util.Collection;
020import java.util.Collections;
021import java.util.LinkedHashSet;
022import java.util.Set;
023import java.util.concurrent.ConcurrentHashMap;
024import java.util.concurrent.ConcurrentMap;
025
026import org.springframework.cache.Cache;
027import org.springframework.cache.CacheManager;
028import org.springframework.lang.Nullable;
029
030/**
031 * A basic, no operation {@link CacheManager} implementation suitable
032 * for disabling caching, typically used for backing cache declarations
033 * without an actual backing store.
034 *
035 * <p>Will simply accept any items into the cache not actually storing them.
036 *
037 * @author Costin Leau
038 * @author Stephane Nicoll
039 * @since 3.1
040 * @see NoOpCache
041 */
042public class NoOpCacheManager implements CacheManager {
043
044        private final ConcurrentMap<String, Cache> caches = new ConcurrentHashMap<>(16);
045
046        private final Set<String> cacheNames = new LinkedHashSet<>(16);
047
048
049        /**
050         * This implementation always returns a {@link Cache} implementation that will not store items.
051         * Additionally, the request cache will be remembered by the manager for consistency.
052         */
053        @Override
054        @Nullable
055        public Cache getCache(String name) {
056                Cache cache = this.caches.get(name);
057                if (cache == null) {
058                        this.caches.computeIfAbsent(name, key -> new NoOpCache(name));
059                        synchronized (this.cacheNames) {
060                                this.cacheNames.add(name);
061                        }
062                }
063
064                return this.caches.get(name);
065        }
066
067        /**
068         * This implementation returns the name of the caches previously requested.
069         */
070        @Override
071        public Collection<String> getCacheNames() {
072                synchronized (this.cacheNames) {
073                        return Collections.unmodifiableSet(this.cacheNames);
074                }
075        }
076
077}