/*
* Copyright 2002-2016 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.cache.concurrent;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import org.springframework.beans.factory.BeanClassLoaderAware;
import org.springframework.cache.Cache;
import org.springframework.cache.CacheManager;
import org.springframework.core.serializer.support.SerializationDelegate;
/**
* {@link CacheManager} implementation that lazily builds {@link ConcurrentMapCache}
* instances for each {@link #getCache} request. Also supports a 'static' mode where
* the set of cache names is pre-defined through {@link #setCacheNames}, with no
* dynamic creation of further cache regions at runtime.
*
* <p>Note: This is by no means a sophisticated CacheManager; it comes with no
* cache configuration options. However, it may be useful for testing or simple
* caching scenarios. For advanced local caching needs, consider
* {@link org.springframework.cache.jcache.JCacheCacheManager},
* {@link org.springframework.cache.ehcache.EhCacheCacheManager},
* {@link org.springframework.cache.caffeine.CaffeineCacheManager}.
*
* @author Juergen Hoeller
* @since 3.1
* @see ConcurrentMapCache
*/
public class ConcurrentMapCacheManager implements CacheManager, BeanClassLoaderAware {
private final ConcurrentMap<String, Cache> cacheMap = new ConcurrentHashMap<>(16);
private boolean dynamic = true;
private boolean allowNullValues = true;
private boolean storeByValue = false;
private SerializationDelegate serialization;
/**
* Construct a dynamic ConcurrentMapCacheManager,
* lazily creating cache instances as they are being requested.
*/
public ConcurrentMapCacheManager() {
}
/**
* Construct a static ConcurrentMapCacheManager,
* managing caches for the specified cache names only.
*/
public ConcurrentMapCacheManager(String... cacheNames) {
setCacheNames(Arrays.asList(cacheNames));
}
/**
* Specify the set of cache names for this CacheManager's 'static' mode.
* <p>The number of caches and their names will be fixed after a call to this method,
* with no creation of further cache regions at runtime.
* <p>Calling this with a {@code null} collection argument resets the
* mode to 'dynamic', allowing for further creation of caches again.
*/
public void setCacheNames(Collection<String> cacheNames) {
if (cacheNames != null) {
for (String name : cacheNames) {
this.cacheMap.put(name, createConcurrentMapCache(name));
}
this.dynamic = false;
}
else {
this.dynamic = true;
}
}
/**
* Specify whether to accept and convert {@code null} values for all caches
* in this cache manager.
* <p>Default is "true", despite ConcurrentHashMap itself not supporting {@code null}
* values. An internal holder object will be used to store user-level {@code null}s.
* <p>Note: A change of the null-value setting will reset all existing caches,
* if any, to reconfigure them with the new null-value requirement.
*/
public void setAllowNullValues(boolean allowNullValues) {
if (allowNullValues != this.allowNullValues) {
this.allowNullValues = allowNullValues;
// Need to recreate all Cache instances with the new null-value configuration...
recreateCaches();
}
}
/**
* Return whether this cache manager accepts and converts {@code null} values
* for all of its caches.
*/
public boolean isAllowNullValues() {
return this.allowNullValues;
}
/**
* Specify whether this cache manager stores a copy of each entry ({@code true}
* or the reference ({@code false} for all of its caches.
* <p>Default is "false" so that the value itself is stored and no serializable
* contract is required on cached values.
* <p>Note: A change of the store-by-value setting will reset all existing caches,
* if any, to reconfigure them with the new store-by-value requirement.
* @since 4.3
*/
public void setStoreByValue(boolean storeByValue) {
if (storeByValue != this.storeByValue) {
this.storeByValue = storeByValue;
// Need to recreate all Cache instances with the new store-by-value configuration...
recreateCaches();
}
}
/**
* Return whether this cache manager stores a copy of each entry or
* a reference for all its caches. If store by value is enabled, any
* cache entry must be serializable.
* @since 4.3
*/
public boolean isStoreByValue() {
return this.storeByValue;
}
@Override
public void setBeanClassLoader(ClassLoader classLoader) {
this.serialization = new SerializationDelegate(classLoader);
// Need to recreate all Cache instances with new ClassLoader in store-by-value mode...
if (isStoreByValue()) {
recreateCaches();
}
}
@Override
public Collection<String> getCacheNames() {
return Collections.unmodifiableSet(this.cacheMap.keySet());
}
@Override
public Cache getCache(String name) {
Cache cache = this.cacheMap.get(name);
if (cache == null && this.dynamic) {
synchronized (this.cacheMap) {
cache = this.cacheMap.get(name);
if (cache == null) {
cache = createConcurrentMapCache(name);
this.cacheMap.put(name, cache);
}
}
}
return cache;
}
private void recreateCaches() {
for (Map.Entry<String, Cache> entry : this.cacheMap.entrySet()) {
entry.setValue(createConcurrentMapCache(entry.getKey()));
}
}
/**
* Create a new ConcurrentMapCache instance for the specified cache name.
* @param name the name of the cache
* @return the ConcurrentMapCache (or a decorator thereof)
*/
protected Cache createConcurrentMapCache(String name) {
SerializationDelegate actualSerialization = (isStoreByValue() ? this.serialization : null);
return new ConcurrentMapCache(name, new ConcurrentHashMap<>(256),
isAllowNullValues(), actualSerialization);
}
}