content: /*
   * Copyright (C) 2010-2101 Alibaba Group Holding Limited.
   *
   * 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 com.alibaba.otter.shared.arbitrate.impl.zookeeper.lock;
  
  import java.text.MessageFormat;
  import java.util.concurrent.locks.ReentrantLock;
  
  import org.apache.zookeeper.KeeperException;
  
  /**
   * 基于{@linkplain ReentrantLock}和{@linkplain DistributedLock} 的功能组合，实现多进程+多线程全方位的lock控制
   * 
   * @author jianghang 2011-9-30 上午09:48:05
   * @version 4.0.0
   */
  public class DistributedReentrantLock extends DistributedLock {
  
      private static final String ID_FORMAT     = "Thread[{0}] Distributed[{1}]";
      private ReentrantLock       reentrantLock = new ReentrantLock();
  
      public DistributedReentrantLock(String root){
          super(root);
      }
  
      public void lock() throws InterruptedException, KeeperException {
          reentrantLock.lock();//多线程竞争时，先拿到第一层锁
          super.lock();
      }
  
      public boolean tryLock() throws KeeperException {
          //多线程竞争时，先拿到第一层锁
          return reentrantLock.tryLock() && super.tryLock();
      }
  
      public void unlock() throws KeeperException {
          super.unlock();
          reentrantLock.unlock();//多线程竞争时，释放最外层锁
      }
  
      @Override
      public String getId() {
          return MessageFormat.format(ID_FORMAT, Thread.currentThread().getId(), super.getId());
      }
  
      @Override
      public boolean isOwner() {
          return reentrantLock.isHeldByCurrentThread() && super.isOwner();
      }
  
  }
  