SynchronizedCache.java

/*
 *    Copyright 2009-2014 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.apache.ibatis.cache.decorators;

import java.util.concurrent.locks.ReadWriteLock;

import org.apache.ibatis.cache.Cache;

/**
 * @author Clinton Begin
 */
/**
 * 同步缓存
 * 防止多线程问题
 * 核心: 加锁
 *  ReadWriteLock.readLock().lock()/unlock()
 *  ReadWriteLock.writeLock().lock()/unlock()
 *  
 *  3.2.6以后这个类已经没用了，考虑到Hazelcast, EhCache已经有锁机制了，所以这个锁就画蛇添足了。
 * bug见https://github.com/mybatis/mybatis-3/issues/159
 *
 */
public class SynchronizedCache implements Cache {

  private Cache delegate;
  
  public SynchronizedCache(Cache delegate) {
    this.delegate = delegate;
  }

  @Override
  public String getId() {
    return delegate.getId();
  }

  @Override
  public synchronized int getSize() {
    return delegate.getSize();
  }

  @Override
  public synchronized void putObject(Object key, Object object) {
    delegate.putObject(key, object);
  }

  @Override
  public synchronized Object getObject(Object key) {
    return delegate.getObject(key);
  }

  @Override
  public synchronized Object removeObject(Object key) {
    return delegate.removeObject(key);
  }

  @Override
  public synchronized void clear() {
    delegate.clear();
  }

  @Override
  public int hashCode() {
    return delegate.hashCode();
  }

  @Override
  public boolean equals(Object obj) {
    return delegate.equals(obj);
  }

  @Override
  public ReadWriteLock getReadWriteLock() {
    return null;
  }

}