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Groovy: A powerful multi-faceted language for the JVM
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.codehaus.groovy.runtime.memoize;
import javax.annotation.concurrent.ThreadSafe;
import java.io.Serializable;
import java.util.Collection;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.locks.ReentrantReadWriteLock;
/**
* Represents a simple key-value cache, which is thread safe and backed by a {@link java.util.Map} instance
*
* @param type of the keys
* @param type of the values
* @since 2.5.0
*/
@ThreadSafe
public class ConcurrentCommonCache implements EvictableCache, ValueConvertable, Serializable {
private static final long serialVersionUID = -7352338549333024936L;
private final ReentrantReadWriteLock rwl = new ReentrantReadWriteLock();
private final ReentrantReadWriteLock.ReadLock readLock = rwl.readLock();
private final ReentrantReadWriteLock.WriteLock writeLock = rwl.writeLock();
private final CommonCache commonCache;
/**
* Constructs a cache with unlimited size
*/
public ConcurrentCommonCache() {
commonCache = new CommonCache();
}
/**
* Constructs a cache with limited size
*
* @param initialCapacity initial capacity of the cache
* @param maxSize max size of the cache
* @param evictionStrategy LRU or FIFO, see {@link org.codehaus.groovy.runtime.memoize.EvictableCache.EvictionStrategy}
*/
public ConcurrentCommonCache(int initialCapacity, int maxSize, EvictionStrategy evictionStrategy) {
commonCache = new CommonCache(initialCapacity, maxSize, evictionStrategy);
}
/**
* Constructs a LRU cache with the specified initial capacity and max size.
* The LRU cache is slower than {@link LRUCache}
*
* @param initialCapacity initial capacity of the LRU cache
* @param maxSize max size of the LRU cache
*/
public ConcurrentCommonCache(int initialCapacity, int maxSize) {
commonCache = new CommonCache(initialCapacity, maxSize);
}
/**
* Constructs a LRU cache with the default initial capacity(16)
*
* @param maxSize max size of the LRU cache
* @see #ConcurrentCommonCache(int, int)
*/
public ConcurrentCommonCache(int maxSize) {
commonCache = new CommonCache(maxSize);
}
/**
* Constructs a cache backed by the specified {@link java.util.Map} instance
*
* @param map the {@link java.util.Map} instance
*/
public ConcurrentCommonCache(Map map) {
commonCache = new CommonCache(map);
}
/**
* {@inheritDoc}
*/
@Override
public V get(final Object key) {
return doWithReadLock(c -> c.get(key));
}
/**
* {@inheritDoc}
*/
@Override
public V put(final K key, final V value) {
return doWithWriteLock(c -> c.put(key, value));
}
/**
* {@inheritDoc}
*/
@Override
public V getAndPut(K key, ValueProvider valueProvider) {
return getAndPut(key, valueProvider, true);
}
public V getAndPut(K key, ValueProvider valueProvider, boolean shouldCache) {
V value;
readLock.lock();
try {
value = commonCache.get(key);
if (null != convertValue(value)) {
return value;
}
} finally {
readLock.unlock();
}
writeLock.lock();
try {
// try to find the cached value again
value = commonCache.get(key);
if (null != convertValue(value)) {
return value;
}
value = null == valueProvider ? null : valueProvider.provide(key);
if (shouldCache && null != convertValue(value)) {
commonCache.put(key, value);
}
} finally {
writeLock.unlock();
}
return value;
}
/**
* {@inheritDoc}
*/
@Override
public Collection values() {
return doWithReadLock(EvictableCache::values);
}
@Override
public Set> entrySet() {
return doWithReadLock(Map::entrySet);
}
/**
* {@inheritDoc}
*/
@Override
public Set keys() {
return doWithReadLock(EvictableCache::keys);
}
/**
* {@inheritDoc}
*/
@Override
public boolean containsKey(final Object key) {
return doWithReadLock(c -> c.containsKey(key));
}
@Override
public boolean containsValue(Object value) {
return doWithReadLock(c -> c.containsValue(value));
}
/**
* {@inheritDoc}
*/
@Override
public int size() {
return doWithReadLock(EvictableCache::size);
}
@Override
public boolean isEmpty() {
return size() == 0;
}
/**
* {@inheritDoc}
*/
@Override
public V remove(final Object key) {
return doWithWriteLock(c -> c.remove(key));
}
@Override
public void putAll(Map m) {
doWithWriteLock(c -> {
c.putAll(m);
return null;
});
}
@Override
public Set keySet() {
return keys();
}
/**
* {@inheritDoc}
*/
@Override
public Map clearAll() {
return doWithWriteLock(EvictableCache::clearAll);
}
/**
* {@inheritDoc}
*/
@Override
public void cleanUpNullReferences() {
doWithWriteLock(c -> {
c.cleanUpNullReferences();
return null;
});
}
/**
* {@inheritDoc}
*/
@Override
public Object convertValue(V value) {
return value;
}
/**
* deal with the backed cache guarded by write lock
* @param action the content to complete
*/
private R doWithWriteLock(Action action) {
writeLock.lock();
try {
return action.doWith(commonCache);
} finally {
writeLock.unlock();
}
}
/**
* deal with the backed cache guarded by read lock
* @param action the content to complete
*/
private R doWithReadLock(Action action) {
readLock.lock();
try {
return action.doWith(commonCache);
} finally {
readLock.unlock();
}
}
}