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class="tag-list-item"><a class="tag-list-link" href="/tags/Trapping-Rain-Water/" rel="tag">Trapping Rain Water</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/WeakReference/" rel="tag">WeakReference</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/Web/" rel="tag">Web</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/Webhook/" rel="tag">Webhook</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/WordPress/" rel="tag">WordPress</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/aqs/" rel="tag">aqs</a><span class="tag-list-count">3</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/await/" rel="tag">await</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/bloom-filter/" rel="tag">bloom filter</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/c/" rel="tag">c++</a><span class="tag-list-count">14</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/cglib/" rel="tag">cglib</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/cgroup/" rel="tag">cgroup</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/cluster/" rel="tag">cluster</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/condition/" rel="tag">condition</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/docker/" rel="tag">docker</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/dp/" rel="tag">dp</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/dubbo/" rel="tag">dubbo</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/echo/" rel="tag">echo</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/environment/" rel="tag">environment</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/gap-lock/" rel="tag">gap lock</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/gc/" rel="tag">gc</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/git/" rel="tag">git</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/grep/" rel="tag">grep</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/hadoop/" rel="tag">hadoop</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/icu4c/" rel="tag">icu4c</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/im/" rel="tag">im</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/is-not-null/" rel="tag">is not null</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/is-null/" rel="tag">is null</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/j-u-c/" rel="tag">j.u.c</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/java/" rel="tag">java</a><span class="tag-list-count">33</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/jvm/" rel="tag">jvm</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/leetcode/" rel="tag">leetcode</a><span class="tag-list-count">40</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/leetcode-155/" rel="tag">leetcode 155</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/linked-list/" rel="tag">linked list</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/linux/" rel="tag">linux</a><span class="tag-list-count">3</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/lock/" rel="tag">lock</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/mfc/" rel="tag">mfc</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/min-stack/" rel="tag">min stack</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/mq/" rel="tag">mq</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/mvcc/" rel="tag">mvcc</a><span class="tag-list-count">3</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/mysql/" rel="tag">mysql</a><span class="tag-list-count">6</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/namespace/" rel="tag">namespace</a><span class="tag-list-count">3</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/next-key-lock/" rel="tag">next-key lock</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/nginx/" rel="tag">nginx</a><span class="tag-list-count">3</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/nullsfirst/" rel="tag">nullsfirst</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/openresty/" rel="tag">openresty</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/php/" rel="tag">php</a><span class="tag-list-count">4</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/procedure/" rel="tag">procedure</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/python/" rel="tag">python</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/read-view/" rel="tag">read view</a><span class="tag-list-count">3</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/redis/" rel="tag">redis</a><span class="tag-list-count">12</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/scp/" rel="tag">scp</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/signal/" rel="tag">signal</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/sort/" rel="tag">sort</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/spark/" rel="tag">spark</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/ssh/" rel="tag">ssh</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/stack/" rel="tag">stack</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/stream/" rel="tag">stream</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/string/" rel="tag">string</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/swoole/" rel="tag">swoole</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/top/" rel="tag">top</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/uname/" rel="tag">uname</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/unlock/" rel="tag">unlock</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/utf8/" rel="tag">utf8</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/utf8mb4/" rel="tag">utf8mb4</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/utf8mb4-0900-ai-ci/" rel="tag">utf8mb4_0900_ai_ci</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/utf8mb4-general-ci/" rel="tag">utf8mb4_general_ci</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/utf8mb4-unicode-ci/" rel="tag">utf8mb4_unicode_ci</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/value/" rel="tag">value</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/websocket/" rel="tag">websocket</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/zookeeper/" rel="tag">zookeeper</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/zsh/" rel="tag">zsh</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E4%B8%89%E9%98%B6%E6%AE%B5%E6%8F%90%E4%BA%A4/" rel="tag">三阶段提交</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E4%B8%8D%E5%8F%AF%E5%8F%98%E5%BC%95%E7%94%A8/" rel="tag">不可变引用</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E4%B8%9C%E4%BA%AC%E5%A5%A5%E8%BF%90%E4%BC%9A/" rel="tag">东京奥运会</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E4%B8%A4%E9%98%B6%E6%AE%B5%E6%8F%90%E4%BA%A4/" rel="tag">两阶段提交</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E4%B8%AD%E5%B1%B1%E8%B7%AF/" rel="tag">中山路</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E4%B8%AD%E5%BA%8F/" rel="tag">中序</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E4%B8%AD%E9%97%B4%E4%BB%B6/" rel="tag">中间件</a><span class="tag-list-count">4</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E4%B8%BE%E9%87%8D/" rel="tag">举重</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E4%B9%92%E4%B9%93%E7%90%83/" rel="tag">乒乓球</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E4%BA%8B%E5%8A%A1/" rel="tag">事务</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E4%BA%8C%E5%8F%89%E6%A0%91/" rel="tag">二叉树</a><span class="tag-list-count">3</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E4%BA%92%E6%96%A5%E9%94%81/" rel="tag">互斥锁</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E4%BB%A3%E7%A0%81%E9%A2%98%E8%A7%A3/" rel="tag">代码题解</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E4%BF%AE%E7%94%B5%E8%84%91%E7%9A%84/" rel="tag">修电脑的</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%81%8F%E5%90%91%E9%94%81/" rel="tag">偏向锁</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%81%A5%E5%BA%B7%E7%A0%81/" rel="tag">健康码</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%85%AC%E4%BA%A4/" rel="tag">公交</a><span class="tag-list-count">3</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%85%AC%E4%BA%A4%E8%BD%A6/" rel="tag">公交车</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%86%85%E5%AD%98%E5%88%86%E5%B8%83/" rel="tag">内存分布</a><span class="tag-list-count">3</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%86%85%E5%AD%98%E6%B3%84%E6%BC%8F/" rel="tag">内存泄漏</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%87%86%E5%A4%87/" rel="tag">准备</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%87%8F%E8%82%A5/" rel="tag">减肥</a><span class="tag-list-count">6</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%88%86%E5%B8%83%E5%BC%8F%E4%BA%8B%E5%8A%A1/" rel="tag">分布式事务</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%88%86%E5%B8%83%E5%BC%8F%E9%94%81/" rel="tag">分布式锁</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%88%87%E7%89%87/" rel="tag">切片</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%88%9D%E5%A7%8B%E5%8C%96/" rel="tag">初始化</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%89%8A%E5%B3%B0%E5%A1%AB%E8%B0%B7/" rel="tag">削峰填谷</a><span class="tag-list-count">4</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%89%8D%E5%BA%8F/" rel="tag">前序</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%8A%A0%E5%A1%9E/" rel="tag">加塞</a><span class="tag-list-count">3</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%8A%A0%E8%BD%BD/" rel="tag">加载</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%8D%95%E4%BE%8B/" rel="tag">单例</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%8D%9A%E5%AE%A2%EF%BC%8C%E6%96%87%E7%AB%A0/" rel="tag">博客,文章</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%8E%A6%E9%97%A8/" rel="tag">厦门</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%8F%8C%E4%BA%B2%E5%A7%94%E6%B4%BE/" rel="tag">双亲委派</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%8F%91%E8%A1%8C%E7%89%88/" rel="tag">发行版</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%8F%A3%E7%BD%A9/" rel="tag">口罩</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%8F%AF%E5%8F%98%E5%BC%95%E7%94%A8/" rel="tag">可变引用</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%90%90%E6%A7%BD/" rel="tag">吐槽</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%9B%A4%E7%89%A9%E8%B5%84/" rel="tag">囤物资</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%9E%83%E5%9C%BE%E5%9B%9E%E6%94%B6/" rel="tag">垃圾回收</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%9F%BA%E7%A1%80%E8%AE%BE%E6%96%BD/" rel="tag">基础设施</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%A4%A7%E6%89%AB%E9%99%A4/" rel="tag">大扫除</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%AD%97%E7%AC%A6%E9%9B%86/" rel="tag">字符集</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%AE%89%E5%85%A8/" rel="tag">安全</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%AE%B9%E9%94%99%E6%9C%BA%E5%88%B6/" rel="tag">容错机制</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%AF%84%E7%94%9F%E8%99%AB/" rel="tag">寄生虫</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%B0%84%E5%87%BB/" rel="tag">射击</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%B0%8F%E6%8A%80%E5%B7%A7/" rel="tag">小技巧</a><span class="tag-list-count">5</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%B1%80%E5%8F%A3%E8%A1%97/" rel="tag">局口街</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%B8%83%E9%9A%86%E8%BF%87%E6%BB%A4%E5%99%A8/" rel="tag">布隆过滤器</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%B9%B2%E6%B4%BB/" rel="tag">干活</a><span class="tag-list-count">5</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%B9%B4%E4%B8%AD%E6%80%BB%E7%BB%93/" rel="tag">年中总结</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%B9%B4%E7%BB%88%E6%80%BB%E7%BB%93/" 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class="post-title" itemprop="name headline">AQS篇二 之 Condition 浅析笔记</h1><div class="post-meta-container"><div class="post-meta"><span class="post-meta-item"><span class="post-meta-item-icon"><i class="far fa-calendar"></i> </span><span class="post-meta-item-text">发表于</span> <time title="创建时间:2021-02-21 21:27:06" itemprop="dateCreated datePublished" datetime="2021-02-21T21:27:06+08:00">2021-02-21</time> </span><span class="post-meta-item"><span class="post-meta-item-icon"><i class="far fa-calendar-check"></i> </span><span class="post-meta-item-text">更新于</span> <time title="修改时间:2022-06-11 22:45:11" itemprop="dateModified" datetime="2022-06-11T22:45:11+08:00">2022-06-11</time> </span><span class="post-meta-item"><span class="post-meta-item-icon"><i class="far fa-folder"></i> </span><span class="post-meta-item-text">分类于</span> <span itemprop="about" itemscope itemtype="http://schema.org/Thing"><a href="/categories/Java/" itemprop="url" rel="index"><span itemprop="name">Java</span></a> </span><span itemprop="about" itemscope itemtype="http://schema.org/Thing"><a href="/categories/Java/%E5%B9%B6%E5%8F%91/" itemprop="url" rel="index"><span itemprop="name">并发</span></a> </span></span><span id="/2021/02/21/AQS-%E4%B9%8B-Condition-%E6%B5%85%E6%9E%90%E7%AC%94%E8%AE%B0/" class="post-meta-item leancloud_visitors" data-flag-title="AQS篇二 之 Condition 浅析笔记" title="阅读次数"><span class="post-meta-item-icon"><i class="far fa-eye"></i> </span><span class="post-meta-item-text">阅读次数:</span> <span class="leancloud-visitors-count"></span> </span><span class="post-meta-item" title="阅读次数" id="busuanzi_container_page_pv"><span class="post-meta-item-icon"><i class="far fa-eye"></i> </span><span class="post-meta-item-text">阅读次数:</span> <span id="busuanzi_value_page_pv"></span> </span><span class="post-meta-item"><span class="post-meta-item-icon"><i class="far fa-comment"></i> </span><span class="post-meta-item-text">Disqus:</span> <a title="disqus" href="/2021/02/21/AQS-%E4%B9%8B-Condition-%E6%B5%85%E6%9E%90%E7%AC%94%E8%AE%B0/#disqus_thread" itemprop="discussionUrl"><span class="post-comments-count disqus-comment-count" data-disqus-identifier="2021/02/21/AQS-之-Condition-浅析笔记/" itemprop="commentCount"></span></a></span></div></div></header><div class="post-body" itemprop="articleBody"><p>Condition也是 AQS 中很重要的一块内容,可以先看段示例代码,这段代码应该来自于Doug Lea大大,可以在 javadoc 中的 <a target="_blank" rel="noopener" href="https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/locks/Condition.html">condition</a> 部分找到,其实大大原来写过基于 <code>synchronized</code> 实现的,后面我也贴下代码</p><pre class="line-numbers language-java" data-language="java"><code class="language-java"><span class="token keyword">import</span> <span class="token import"><span class="token namespace">java<span class="token punctuation">.</span>util<span class="token punctuation">.</span>concurrent<span class="token punctuation">.</span>locks<span class="token punctuation">.</span></span><span class="token class-name">Condition</span></span><span class="token punctuation">;</span>
<span class="token keyword">import</span> <span class="token import"><span class="token namespace">java<span class="token punctuation">.</span>util<span class="token punctuation">.</span>concurrent<span class="token punctuation">.</span>locks<span class="token punctuation">.</span></span><span class="token class-name">Lock</span></span><span class="token punctuation">;</span>
<span class="token keyword">import</span> <span class="token import"><span class="token namespace">java<span class="token punctuation">.</span>util<span class="token punctuation">.</span>concurrent<span class="token punctuation">.</span>locks<span class="token punctuation">.</span></span><span class="token class-name">ReentrantLock</span></span><span class="token punctuation">;</span>
<span class="token keyword">class</span> <span class="token class-name">BoundedBuffer</span> <span class="token punctuation">&#123;</span>
<span class="token keyword">final</span> <span class="token class-name">Lock</span> lock <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">ReentrantLock</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">// condition 依赖于 lock 来产生</span>
<span class="token keyword">final</span> <span class="token class-name">Condition</span> notFull <span class="token operator">=</span> lock<span class="token punctuation">.</span><span class="token function">newCondition</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">final</span> <span class="token class-name">Condition</span> notEmpty <span class="token operator">=</span> lock<span class="token punctuation">.</span><span class="token function">newCondition</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">// 对象池子,put 跟 take 的就是这里的</span>
<span class="token keyword">final</span> <span class="token class-name">Object</span><span class="token punctuation">[</span><span class="token punctuation">]</span> items <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Object</span><span class="token punctuation">[</span><span class="token number">100</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
<span class="token keyword">int</span> putptr<span class="token punctuation">,</span> takeptr<span class="token punctuation">,</span> count<span class="token punctuation">;</span>
<span class="token comment">// 生产</span>
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">put</span><span class="token punctuation">(</span><span class="token class-name">Object</span> x<span class="token punctuation">)</span> <span class="token keyword">throws</span> <span class="token class-name">InterruptedException</span> <span class="token punctuation">&#123;</span>
<span class="token comment">// 这里也说明了,需要先拥有锁</span>
lock<span class="token punctuation">.</span><span class="token function">lock</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">try</span> <span class="token punctuation">&#123;</span>
<span class="token keyword">while</span> <span class="token punctuation">(</span>count <span class="token operator">==</span> items<span class="token punctuation">.</span>length<span class="token punctuation">)</span>
notFull<span class="token punctuation">.</span><span class="token function">await</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 队列已满,等待,直到 not full 才能继续生产</span>
items<span class="token punctuation">[</span>putptr<span class="token punctuation">]</span> <span class="token operator">=</span> x<span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token operator">++</span>putptr <span class="token operator">==</span> items<span class="token punctuation">.</span>length<span class="token punctuation">)</span> putptr <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span>
<span class="token operator">++</span>count<span class="token punctuation">;</span>
notEmpty<span class="token punctuation">.</span><span class="token function">signal</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 生产成功,队列已经 not empty 了,发个通知出去</span>
<span class="token punctuation">&#125;</span> <span class="token keyword">finally</span> <span class="token punctuation">&#123;</span>
lock<span class="token punctuation">.</span><span class="token function">unlock</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token punctuation">&#125;</span>
<span class="token comment">// 消费</span>
<span class="token keyword">public</span> <span class="token class-name">Object</span> <span class="token function">take</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token keyword">throws</span> <span class="token class-name">InterruptedException</span> <span class="token punctuation">&#123;</span>
lock<span class="token punctuation">.</span><span class="token function">lock</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">try</span> <span class="token punctuation">&#123;</span>
<span class="token keyword">while</span> <span class="token punctuation">(</span>count <span class="token operator">==</span> <span class="token number">0</span><span class="token punctuation">)</span>
notEmpty<span class="token punctuation">.</span><span class="token function">await</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 队列为空,等待,直到队列 not empty,才能继续消费</span>
<span class="token class-name">Object</span> x <span class="token operator">=</span> items<span class="token punctuation">[</span>takeptr<span class="token punctuation">]</span><span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token operator">++</span>takeptr <span class="token operator">==</span> items<span class="token punctuation">.</span>length<span class="token punctuation">)</span> takeptr <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span>
<span class="token operator">--</span>count<span class="token punctuation">;</span>
notFull<span class="token punctuation">.</span><span class="token function">signal</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 被我消费掉一个,队列 not full 了,发个通知出去</span>
<span class="token keyword">return</span> x<span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span> <span class="token keyword">finally</span> <span class="token punctuation">&#123;</span>
lock<span class="token punctuation">.</span><span class="token function">unlock</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token punctuation">&#125;</span>
<span class="token punctuation">&#125;</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p>介绍下 Condition 的结构</p><pre class="line-numbers language-java" data-language="java"><code class="language-java"><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">ConditionObject</span> <span class="token keyword">implements</span> <span class="token class-name">Condition</span><span class="token punctuation">,</span> <span class="token class-name"><span class="token namespace">java<span class="token punctuation">.</span>io<span class="token punctuation">.</span></span>Serializable</span> <span class="token punctuation">&#123;</span>
<span class="token keyword">private</span> <span class="token keyword">static</span> <span class="token keyword">final</span> <span class="token keyword">long</span> serialVersionUID <span class="token operator">=</span> <span class="token number">1173984872572414699L</span><span class="token punctuation">;</span>
<span class="token comment">/** First node of condition queue. */</span>
<span class="token keyword">private</span> <span class="token keyword">transient</span> <span class="token class-name">Node</span> firstWaiter<span class="token punctuation">;</span>
<span class="token comment">/** Last node of condition queue. */</span>
<span class="token keyword">private</span> <span class="token keyword">transient</span> <span class="token class-name">Node</span> lastWaiter<span class="token punctuation">;</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p>主要的就这么点,而且也复用了 AQS 阻塞队列或者大大叫 <code>lock queue</code>中同样的 Node 节点,只不过它没有使用其中的双向队列,也就是prev 和 next,而是在 Node 中的 nextWaiter,所以只是个单向的队列,没使用 next 其实还有个用处,后面会提到,看下结构的示意图<br><img data-src="https://img.nicksxs.com/uPic/Ss9oFX.png"><br>然后主要是看两个方法,<code>await</code><code>signal</code>,<br>先来看下 await</p><pre class="line-numbers language-java" data-language="java"><code class="language-java"><span class="token comment">/**
* Implements interruptible condition wait.
* &lt;ol>
* &lt;li> If current thread is interrupted, throw InterruptedException.
* &lt;li> Save lock state returned by &#123;@link #getState&#125;.
* &lt;li> Invoke &#123;@link #release&#125; with saved state as argument,
* throwing IllegalMonitorStateException if it fails.
* &lt;li> Block until signalled or interrupted.
* &lt;li> Reacquire by invoking specialized version of
* &#123;@link #acquire&#125; with saved state as argument.
* &lt;li> If interrupted while blocked in step 4, throw InterruptedException.
* &lt;/ol>
*/</span>
<span class="token keyword">public</span> <span class="token keyword">final</span> <span class="token keyword">void</span> <span class="token function">await</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token keyword">throws</span> <span class="token class-name">InterruptedException</span> <span class="token punctuation">&#123;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token class-name">Thread</span><span class="token punctuation">.</span><span class="token function">interrupted</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span>
<span class="token keyword">throw</span> <span class="token keyword">new</span> <span class="token class-name">InterruptedException</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">// 将当前节点包装成一个 condition waiter node 节点</span>
<span class="token class-name">Node</span> node <span class="token operator">=</span> <span class="token function">addConditionWaiter</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">// 完全释放占有的锁,这里需要是占有锁的线程</span>
<span class="token keyword">int</span> savedState <span class="token operator">=</span> <span class="token function">fullyRelease</span><span class="token punctuation">(</span>node<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">int</span> interruptMode <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span>
<span class="token comment">// 判断下是否在阻塞队列中,因为有可能被其他节点从等待队列移动到阻塞队列</span>
<span class="token keyword">while</span> <span class="token punctuation">(</span><span class="token operator">!</span><span class="token function">isOnSyncQueue</span><span class="token punctuation">(</span>node<span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
<span class="token comment">// park等待,等待被唤醒</span>
<span class="token class-name">LockSupport</span><span class="token punctuation">.</span><span class="token function">park</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token punctuation">(</span>interruptMode <span class="token operator">=</span> <span class="token function">checkInterruptWhileWaiting</span><span class="token punctuation">(</span>node<span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token operator">!=</span> <span class="token number">0</span><span class="token punctuation">)</span>
<span class="token keyword">break</span><span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token comment">// 被唤醒后进入阻塞队列,等待获取锁,这里继续用了fullyRelease返回的 state</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token function">acquireQueued</span><span class="token punctuation">(</span>node<span class="token punctuation">,</span> savedState<span class="token punctuation">)</span> <span class="token operator">&amp;&amp;</span> interruptMode <span class="token operator">!=</span> <span class="token constant">THROW_IE</span><span class="token punctuation">)</span>
interruptMode <span class="token operator">=</span> <span class="token constant">REINTERRUPT</span><span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>node<span class="token punctuation">.</span>nextWaiter <span class="token operator">!=</span> <span class="token keyword">null</span><span class="token punctuation">)</span> <span class="token comment">// clean up if cancelled</span>
<span class="token function">unlinkCancelledWaiters</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>interruptMode <span class="token operator">!=</span> <span class="token number">0</span><span class="token punctuation">)</span>
<span class="token function">reportInterruptAfterWait</span><span class="token punctuation">(</span>interruptMode<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p>添加条件队列节点</p><pre class="line-numbers language-java" data-language="java"><code class="language-java"><span class="token comment">/**
* Adds a new waiter to wait queue.
* @return its new wait node
*/</span>
<span class="token keyword">private</span> <span class="token class-name">Node</span> <span class="token function">addConditionWaiter</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
<span class="token class-name">Node</span> t <span class="token operator">=</span> lastWaiter<span class="token punctuation">;</span>
<span class="token comment">// If lastWaiter is cancelled, clean out.</span>
<span class="token comment">// 如果节点已经不是 CONDITION 状态了,表示已经取消了</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>t <span class="token operator">!=</span> <span class="token keyword">null</span> <span class="token operator">&amp;&amp;</span> t<span class="token punctuation">.</span>waitStatus <span class="token operator">!=</span> <span class="token class-name">Node</span><span class="token punctuation">.</span><span class="token constant">CONDITION</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
<span class="token comment">// 把等待队列中取消的节点清理出去</span>
<span class="token function">unlinkCancelledWaiters</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
t <span class="token operator">=</span> lastWaiter<span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token comment">// 把当前线程包装成waitStatus=CONDITION 的节点</span>
<span class="token class-name">Node</span> node <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Node</span><span class="token punctuation">(</span><span class="token class-name">Thread</span><span class="token punctuation">.</span><span class="token function">currentThread</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token class-name">Node</span><span class="token punctuation">.</span><span class="token constant">CONDITION</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">// 没有 lastWaiter 节点,直接是 firstWaiter</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>t <span class="token operator">==</span> <span class="token keyword">null</span><span class="token punctuation">)</span>
firstWaiter <span class="token operator">=</span> node<span class="token punctuation">;</span>
<span class="token keyword">else</span>
<span class="token comment">// 不然就接在 lastWaiter 后面</span>
t<span class="token punctuation">.</span>nextWaiter <span class="token operator">=</span> node<span class="token punctuation">;</span>
<span class="token comment">// 当前节点就会变成新的 lastWaiter</span>
lastWaiter <span class="token operator">=</span> node<span class="token punctuation">;</span>
<span class="token keyword">return</span> node<span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p>清理取消的节点</p><pre class="line-numbers language-java" data-language="java"><code class="language-java"><span class="token comment">/**
* Unlinks cancelled waiter nodes from condition queue.
* Called only while holding lock. This is called when
* cancellation occurred during condition wait, and upon
* insertion of a new waiter when lastWaiter is seen to have
* been cancelled. This method is needed to avoid garbage
* retention in the absence of signals. So even though it may
* require a full traversal, it comes into play only when
* timeouts or cancellations occur in the absence of
* signals. It traverses all nodes rather than stopping at a
* particular target to unlink all pointers to garbage nodes
* without requiring many re-traversals during cancellation
* storms.
*/</span>
<span class="token keyword">private</span> <span class="token keyword">void</span> <span class="token function">unlinkCancelledWaiters</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
<span class="token class-name">Node</span> t <span class="token operator">=</span> firstWaiter<span class="token punctuation">;</span>
<span class="token class-name">Node</span> trail <span class="token operator">=</span> <span class="token keyword">null</span><span class="token punctuation">;</span>
<span class="token comment">// 循环遍历单向链表的节点,如果状态不是 CONDITION 就清出去</span>
<span class="token keyword">while</span> <span class="token punctuation">(</span>t <span class="token operator">!=</span> <span class="token keyword">null</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
<span class="token class-name">Node</span> next <span class="token operator">=</span> t<span class="token punctuation">.</span>nextWaiter<span class="token punctuation">;</span>
<span class="token comment">// 循环链表操作,清掉取消的节点</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>t<span class="token punctuation">.</span>waitStatus <span class="token operator">!=</span> <span class="token class-name">Node</span><span class="token punctuation">.</span><span class="token constant">CONDITION</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
t<span class="token punctuation">.</span>nextWaiter <span class="token operator">=</span> <span class="token keyword">null</span><span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>trail <span class="token operator">==</span> <span class="token keyword">null</span><span class="token punctuation">)</span>
firstWaiter <span class="token operator">=</span> next<span class="token punctuation">;</span>
<span class="token keyword">else</span>
trail<span class="token punctuation">.</span>nextWaiter <span class="token operator">=</span> next<span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>next <span class="token operator">==</span> <span class="token keyword">null</span><span class="token punctuation">)</span>
lastWaiter <span class="token operator">=</span> trail<span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token keyword">else</span>
trail <span class="token operator">=</span> t<span class="token punctuation">;</span>
t <span class="token operator">=</span> next<span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token punctuation">&#125;</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p>完全释放锁</p><pre class="line-numbers language-java" data-language="java"><code class="language-java"><span class="token comment">/**
* Invokes release with current state value; returns saved state.
* Cancels node and throws exception on failure.
* @param node the condition node for this wait
* @return previous sync state
*/</span>
<span class="token keyword">final</span> <span class="token keyword">int</span> <span class="token function">fullyRelease</span><span class="token punctuation">(</span><span class="token class-name">Node</span> node<span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
<span class="token keyword">boolean</span> failed <span class="token operator">=</span> <span class="token boolean">true</span><span class="token punctuation">;</span>
<span class="token keyword">try</span> <span class="token punctuation">&#123;</span>
<span class="token comment">// 获取下当前的 state 值,因为是可重入的,所以这个值要保存下来</span>
<span class="token keyword">int</span> savedState <span class="token operator">=</span> <span class="token function">getState</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">// 这里还包含比较多操作,不过跟前面分析 AQS 的释放比较类似,不深入了</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token function">release</span><span class="token punctuation">(</span>savedState<span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
failed <span class="token operator">=</span> <span class="token boolean">false</span><span class="token punctuation">;</span>
<span class="token comment">// 返回这个值</span>
<span class="token keyword">return</span> savedState<span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span> <span class="token keyword">else</span> <span class="token punctuation">&#123;</span>
<span class="token keyword">throw</span> <span class="token keyword">new</span> <span class="token class-name">IllegalMonitorStateException</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token punctuation">&#125;</span> <span class="token keyword">finally</span> <span class="token punctuation">&#123;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>failed<span class="token punctuation">)</span>
node<span class="token punctuation">.</span>waitStatus <span class="token operator">=</span> <span class="token class-name">Node</span><span class="token punctuation">.</span><span class="token constant">CANCELLED</span><span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token punctuation">&#125;</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p>判断是否在阻塞队列中</p><pre class="line-numbers language-java" data-language="java"><code class="language-java"><span class="token comment">/**
* Returns true if a node, always one that was initially placed on
* a condition queue, is now waiting to reacquire on sync queue.
* @param node the node
* @return true if is reacquiring
*/</span>
<span class="token keyword">final</span> <span class="token keyword">boolean</span> <span class="token function">isOnSyncQueue</span><span class="token punctuation">(</span><span class="token class-name">Node</span> node<span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
<span class="token comment">// 如果waitStatus 是 CONDITION 或者没有 prev 前置节点肯定就不在</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>node<span class="token punctuation">.</span>waitStatus <span class="token operator">==</span> <span class="token class-name">Node</span><span class="token punctuation">.</span><span class="token constant">CONDITION</span> <span class="token operator">||</span> node<span class="token punctuation">.</span>prev <span class="token operator">==</span> <span class="token keyword">null</span><span class="token punctuation">)</span>
<span class="token keyword">return</span> <span class="token boolean">false</span><span class="token punctuation">;</span>
<span class="token comment">// 这里就是我前面提到的 next 的作用</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>node<span class="token punctuation">.</span>next <span class="token operator">!=</span> <span class="token keyword">null</span><span class="token punctuation">)</span> <span class="token comment">// If has successor, it must be on queue</span>
<span class="token keyword">return</span> <span class="token boolean">true</span><span class="token punctuation">;</span>
<span class="token comment">// 从 tail 开始找,是否在阻塞队列中</span>
<span class="token comment">/*
* node.prev can be non-null, but not yet on queue because
* the CAS to place it on queue can fail. So we have to
* traverse from tail to make sure it actually made it. It
* will always be near the tail in calls to this method, and
* unless the CAS failed (which is unlikely), it will be
* there, so we hardly ever traverse much.
*/</span>
<span class="token keyword">return</span> <span class="token function">findNodeFromTail</span><span class="token punctuation">(</span>node<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token comment">/**
* Returns true if node is on sync queue by searching backwards from tail.
* Called only when needed by isOnSyncQueue.
* @return true if present
*/</span>
<span class="token keyword">private</span> <span class="token keyword">boolean</span> <span class="token function">findNodeFromTail</span><span class="token punctuation">(</span><span class="token class-name">Node</span> node<span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
<span class="token class-name">Node</span> t <span class="token operator">=</span> tail<span class="token punctuation">;</span>
<span class="token comment">// 从 tail 开始,从后往前找</span>
<span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token punctuation">;</span><span class="token punctuation">;</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>t <span class="token operator">==</span> node<span class="token punctuation">)</span>
<span class="token keyword">return</span> <span class="token boolean">true</span><span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>t <span class="token operator">==</span> <span class="token keyword">null</span><span class="token punctuation">)</span>
<span class="token keyword">return</span> <span class="token boolean">false</span><span class="token punctuation">;</span>
t <span class="token operator">=</span> t<span class="token punctuation">.</span>prev<span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token punctuation">&#125;</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p>await 的逻辑差不多就是这样子,主要的就是把自己包成一个 Node 节点,waitStatus 的状态是 CONDITION,挂在等待队列的最后,然后完全释放锁,park 等待</p><h2 id="signal"><a href="#signal" class="headerlink" title="signal"></a>signal</h2><pre class="line-numbers language-java" data-language="java"><code class="language-java"><span class="token comment">/**
* Moves the longest-waiting thread, if one exists, from the
* wait queue for this condition to the wait queue for the
* owning lock.
*
* @throws IllegalMonitorStateException if &#123;@link #isHeldExclusively&#125;
* returns &#123;@code false&#125;
*/</span>
<span class="token keyword">public</span> <span class="token keyword">final</span> <span class="token keyword">void</span> <span class="token function">signal</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token operator">!</span><span class="token function">isHeldExclusively</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span>
<span class="token keyword">throw</span> <span class="token keyword">new</span> <span class="token class-name">IllegalMonitorStateException</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">// firstWaiter 肯定是最早开始等待的</span>
<span class="token class-name">Node</span> first <span class="token operator">=</span> firstWaiter<span class="token punctuation">;</span>
<span class="token comment">// 如果不为空就唤醒</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>first <span class="token operator">!=</span> <span class="token keyword">null</span><span class="token punctuation">)</span>
<span class="token function">doSignal</span><span class="token punctuation">(</span>first<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token comment">/**
* Removes and transfers nodes until hit non-cancelled one or
* null. Split out from signal in part to encourage compilers
* to inline the case of no waiters.
* @param first (non-null) the first node on condition queue
*/</span>
<span class="token keyword">private</span> <span class="token keyword">void</span> <span class="token function">doSignal</span><span class="token punctuation">(</span><span class="token class-name">Node</span> first<span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
<span class="token keyword">do</span> <span class="token punctuation">&#123;</span>
<span class="token comment">// 因为要去唤醒 first 节点了,firstWaiter 需要再从后面找一个</span>
<span class="token comment">// 并且判断是否为空,如果是空的话就直接可以把 lastWaiter 设置成空了</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span> <span class="token punctuation">(</span>firstWaiter <span class="token operator">=</span> first<span class="token punctuation">.</span>nextWaiter<span class="token punctuation">)</span> <span class="token operator">==</span> <span class="token keyword">null</span><span class="token punctuation">)</span>
lastWaiter <span class="token operator">=</span> <span class="token keyword">null</span><span class="token punctuation">;</span>
<span class="token comment">// first 不需要继续保存后面的 waiter 了,因为 firstWaiter 已经是 first 的后置节点了</span>
first<span class="token punctuation">.</span>nextWaiter <span class="token operator">=</span> <span class="token keyword">null</span><span class="token punctuation">;</span>
<span class="token comment">// 如果 first 节点转移不成功,并且 firstWaiter 节点不为空,则继续进入循环</span>
<span class="token punctuation">&#125;</span> <span class="token keyword">while</span> <span class="token punctuation">(</span><span class="token operator">!</span><span class="token function">transferForSignal</span><span class="token punctuation">(</span>first<span class="token punctuation">)</span> <span class="token operator">&amp;&amp;</span>
<span class="token punctuation">(</span>first <span class="token operator">=</span> firstWaiter<span class="token punctuation">)</span> <span class="token operator">!=</span> <span class="token keyword">null</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token comment">/**
* Transfers a node from a condition queue onto sync queue.
* Returns true if successful.
* @param node the node
* @return true if successfully transferred (else the node was
* cancelled before signal)
*/</span>
<span class="token keyword">final</span> <span class="token keyword">boolean</span> <span class="token function">transferForSignal</span><span class="token punctuation">(</span><span class="token class-name">Node</span> node<span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
<span class="token comment">/*
* If cannot change waitStatus, the node has been cancelled.
*/</span>
<span class="token comment">// 如果状态已经不是 CONDITION 就不会设置成功,返回 false</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token operator">!</span><span class="token function">compareAndSetWaitStatus</span><span class="token punctuation">(</span>node<span class="token punctuation">,</span> <span class="token class-name">Node</span><span class="token punctuation">.</span><span class="token constant">CONDITION</span><span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">)</span>
<span class="token keyword">return</span> <span class="token boolean">false</span><span class="token punctuation">;</span>
<span class="token comment">/*
* Splice onto queue and try to set waitStatus of predecessor to
* indicate that thread is (probably) waiting. If cancelled or
* attempt to set waitStatus fails, wake up to resync (in which
* case the waitStatus can be transiently and harmlessly wrong).
*/</span>
<span class="token comment">// 调用跟aqs 第一篇中一样的 enq 方法进入阻塞队列,返回入队后的前一节点</span>
<span class="token class-name">Node</span> p <span class="token operator">=</span> <span class="token function">enq</span><span class="token punctuation">(</span>node<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">int</span> ws <span class="token operator">=</span> p<span class="token punctuation">.</span>waitStatus<span class="token punctuation">;</span>
<span class="token comment">// 将前置节点状态设置成SIGNAL,表示后面有节点在等了</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>ws <span class="token operator">></span> <span class="token number">0</span> <span class="token operator">||</span> <span class="token operator">!</span><span class="token function">compareAndSetWaitStatus</span><span class="token punctuation">(</span>p<span class="token punctuation">,</span> ws<span class="token punctuation">,</span> <span class="token class-name">Node</span><span class="token punctuation">.</span><span class="token constant">SIGNAL</span><span class="token punctuation">)</span><span class="token punctuation">)</span>
<span class="token class-name">LockSupport</span><span class="token punctuation">.</span><span class="token function">unpark</span><span class="token punctuation">(</span>node<span class="token punctuation">.</span>thread<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">// 返回 true,上一个方法的循环就退出了</span>
<span class="token keyword">return</span> <span class="token boolean">true</span><span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p>这里其实就是把 condition 等待队列的第一个未取消的节点入队到阻塞队列去争锁</p><h2 id="附录"><a href="#附录" class="headerlink" title="附录"></a>附录</h2><p><code>synchronized</code> 版的 BoundedBuffer</p><pre class="line-numbers language-java" data-language="java"><code class="language-java"><span class="token comment">/*
File: BoundedBuffer.java
Originally written by Doug Lea and released into the public domain.
This may be used for any purposes whatsoever without acknowledgment.
Thanks for the assistance and support of Sun Microsystems Labs,
and everyone contributing, testing, and using this code.
History:
Date Who What
11Jun1998 dl Create public version
17Jul1998 dl Simplified by eliminating wait counts
25aug1998 dl added peek
5May1999 dl replace % with conditional (slightly faster)
*/</span>
<span class="token keyword">package</span> <span class="token constant">EDU</span><span class="token punctuation">.</span>oswego<span class="token punctuation">.</span>cs<span class="token punctuation">.</span>dl<span class="token punctuation">.</span>util<span class="token punctuation">.</span>concurrent<span class="token punctuation">;</span>
<span class="token comment">/**
* Efficient array-based bounded buffer class.
* Adapted from CPJ, chapter 8, which describes design.
* &lt;p>[&lt;a href="http://gee.cs.oswego.edu/dl/classes/EDU/oswego/cs/dl/util/concurrent/intro.html"> Introduction to this package. &lt;/a>] &lt;p>
**/</span>
<span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">BoundedBuffer</span> <span class="token keyword">implements</span> <span class="token class-name">BoundedChannel</span> <span class="token punctuation">&#123;</span>
<span class="token keyword">protected</span> <span class="token keyword">final</span> <span class="token class-name">Object</span><span class="token punctuation">[</span><span class="token punctuation">]</span> array_<span class="token punctuation">;</span> <span class="token comment">// the elements</span>
<span class="token keyword">protected</span> <span class="token keyword">int</span> takePtr_ <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> <span class="token comment">// circular indices</span>
<span class="token keyword">protected</span> <span class="token keyword">int</span> putPtr_ <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span>
<span class="token keyword">protected</span> <span class="token keyword">int</span> usedSlots_ <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> <span class="token comment">// length</span>
<span class="token keyword">protected</span> <span class="token keyword">int</span> emptySlots_<span class="token punctuation">;</span> <span class="token comment">// capacity - length</span>
<span class="token comment">/**
* Helper monitor to handle puts.
**/</span>
<span class="token keyword">protected</span> <span class="token keyword">final</span> <span class="token class-name">Object</span> putMonitor_ <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Object</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">/**
* Create a BoundedBuffer with the given capacity.
* @exception IllegalArgumentException if capacity less or equal to zero
**/</span>
<span class="token keyword">public</span> <span class="token class-name">BoundedBuffer</span><span class="token punctuation">(</span><span class="token keyword">int</span> capacity<span class="token punctuation">)</span> <span class="token keyword">throws</span> <span class="token class-name">IllegalArgumentException</span> <span class="token punctuation">&#123;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>capacity <span class="token operator">&lt;=</span> <span class="token number">0</span><span class="token punctuation">)</span> <span class="token keyword">throw</span> <span class="token keyword">new</span> <span class="token class-name">IllegalArgumentException</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
array_ <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Object</span><span class="token punctuation">[</span>capacity<span class="token punctuation">]</span><span class="token punctuation">;</span>
emptySlots_ <span class="token operator">=</span> capacity<span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token comment">/**
* Create a buffer with the current default capacity
**/</span>
<span class="token keyword">public</span> <span class="token class-name">BoundedBuffer</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
<span class="token keyword">this</span><span class="token punctuation">(</span><span class="token class-name">DefaultChannelCapacity</span><span class="token punctuation">.</span><span class="token function">get</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token comment">/**
* Return the number of elements in the buffer.
* This is only a snapshot value, that may change
* immediately after returning.
**/</span>
<span class="token keyword">public</span> <span class="token keyword">synchronized</span> <span class="token keyword">int</span> <span class="token function">size</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span> <span class="token keyword">return</span> usedSlots_<span class="token punctuation">;</span> <span class="token punctuation">&#125;</span>
<span class="token keyword">public</span> <span class="token keyword">int</span> <span class="token function">capacity</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span> <span class="token keyword">return</span> array_<span class="token punctuation">.</span>length<span class="token punctuation">;</span> <span class="token punctuation">&#125;</span>
<span class="token keyword">protected</span> <span class="token keyword">void</span> <span class="token function">incEmptySlots</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
<span class="token keyword">synchronized</span><span class="token punctuation">(</span>putMonitor_<span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
<span class="token operator">++</span>emptySlots_<span class="token punctuation">;</span>
putMonitor_<span class="token punctuation">.</span><span class="token function">notify</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token punctuation">&#125;</span>
<span class="token keyword">protected</span> <span class="token keyword">synchronized</span> <span class="token keyword">void</span> <span class="token function">incUsedSlots</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
<span class="token operator">++</span>usedSlots_<span class="token punctuation">;</span>
<span class="token function">notify</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token keyword">protected</span> <span class="token keyword">final</span> <span class="token keyword">void</span> <span class="token function">insert</span><span class="token punctuation">(</span><span class="token class-name">Object</span> x<span class="token punctuation">)</span> <span class="token punctuation">&#123;</span> <span class="token comment">// mechanics of put</span>
<span class="token operator">--</span>emptySlots_<span class="token punctuation">;</span>
array_<span class="token punctuation">[</span>putPtr_<span class="token punctuation">]</span> <span class="token operator">=</span> x<span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token operator">++</span>putPtr_ <span class="token operator">>=</span> array_<span class="token punctuation">.</span>length<span class="token punctuation">)</span> putPtr_ <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token keyword">protected</span> <span class="token keyword">final</span> <span class="token class-name">Object</span> <span class="token function">extract</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span> <span class="token comment">// mechanics of take</span>
<span class="token operator">--</span>usedSlots_<span class="token punctuation">;</span>
<span class="token class-name">Object</span> old <span class="token operator">=</span> array_<span class="token punctuation">[</span>takePtr_<span class="token punctuation">]</span><span class="token punctuation">;</span>
array_<span class="token punctuation">[</span>takePtr_<span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token keyword">null</span><span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token operator">++</span>takePtr_ <span class="token operator">>=</span> array_<span class="token punctuation">.</span>length<span class="token punctuation">)</span> takePtr_ <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span>
<span class="token keyword">return</span> old<span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token keyword">public</span> <span class="token class-name">Object</span> <span class="token function">peek</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
<span class="token keyword">synchronized</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>usedSlots_ <span class="token operator">></span> <span class="token number">0</span><span class="token punctuation">)</span>
<span class="token keyword">return</span> array_<span class="token punctuation">[</span>takePtr_<span class="token punctuation">]</span><span class="token punctuation">;</span>
<span class="token keyword">else</span>
<span class="token keyword">return</span> <span class="token keyword">null</span><span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token punctuation">&#125;</span>
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">put</span><span class="token punctuation">(</span><span class="token class-name">Object</span> x<span class="token punctuation">)</span> <span class="token keyword">throws</span> <span class="token class-name">InterruptedException</span> <span class="token punctuation">&#123;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>x <span class="token operator">==</span> <span class="token keyword">null</span><span class="token punctuation">)</span> <span class="token keyword">throw</span> <span class="token keyword">new</span> <span class="token class-name">IllegalArgumentException</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token class-name">Thread</span><span class="token punctuation">.</span><span class="token function">interrupted</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token keyword">throw</span> <span class="token keyword">new</span> <span class="token class-name">InterruptedException</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">synchronized</span><span class="token punctuation">(</span>putMonitor_<span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
<span class="token keyword">while</span> <span class="token punctuation">(</span>emptySlots_ <span class="token operator">&lt;=</span> <span class="token number">0</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
<span class="token keyword">try</span> <span class="token punctuation">&#123;</span> putMonitor_<span class="token punctuation">.</span><span class="token function">wait</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token punctuation">&#125;</span>
<span class="token keyword">catch</span> <span class="token punctuation">(</span><span class="token class-name">InterruptedException</span> ex<span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
putMonitor_<span class="token punctuation">.</span><span class="token function">notify</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">throw</span> ex<span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token punctuation">&#125;</span>
<span class="token function">insert</span><span class="token punctuation">(</span>x<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token function">incUsedSlots</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token keyword">public</span> <span class="token keyword">boolean</span> <span class="token function">offer</span><span class="token punctuation">(</span><span class="token class-name">Object</span> x<span class="token punctuation">,</span> <span class="token keyword">long</span> msecs<span class="token punctuation">)</span> <span class="token keyword">throws</span> <span class="token class-name">InterruptedException</span> <span class="token punctuation">&#123;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>x <span class="token operator">==</span> <span class="token keyword">null</span><span class="token punctuation">)</span> <span class="token keyword">throw</span> <span class="token keyword">new</span> <span class="token class-name">IllegalArgumentException</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token class-name">Thread</span><span class="token punctuation">.</span><span class="token function">interrupted</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token keyword">throw</span> <span class="token keyword">new</span> <span class="token class-name">InterruptedException</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">synchronized</span><span class="token punctuation">(</span>putMonitor_<span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
<span class="token keyword">long</span> start <span class="token operator">=</span> <span class="token punctuation">(</span>msecs <span class="token operator">&lt;=</span> <span class="token number">0</span><span class="token punctuation">)</span><span class="token operator">?</span> <span class="token number">0</span> <span class="token operator">:</span> <span class="token class-name">System</span><span class="token punctuation">.</span><span class="token function">currentTimeMillis</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">long</span> waitTime <span class="token operator">=</span> msecs<span class="token punctuation">;</span>
<span class="token keyword">while</span> <span class="token punctuation">(</span>emptySlots_ <span class="token operator">&lt;=</span> <span class="token number">0</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>waitTime <span class="token operator">&lt;=</span> <span class="token number">0</span><span class="token punctuation">)</span> <span class="token keyword">return</span> <span class="token boolean">false</span><span class="token punctuation">;</span>
<span class="token keyword">try</span> <span class="token punctuation">&#123;</span> putMonitor_<span class="token punctuation">.</span><span class="token function">wait</span><span class="token punctuation">(</span>waitTime<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token punctuation">&#125;</span>
<span class="token keyword">catch</span> <span class="token punctuation">(</span><span class="token class-name">InterruptedException</span> ex<span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
putMonitor_<span class="token punctuation">.</span><span class="token function">notify</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">throw</span> ex<span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
waitTime <span class="token operator">=</span> msecs <span class="token operator">-</span> <span class="token punctuation">(</span><span class="token class-name">System</span><span class="token punctuation">.</span><span class="token function">currentTimeMillis</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-</span> start<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token function">insert</span><span class="token punctuation">(</span>x<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token function">incUsedSlots</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">return</span> <span class="token boolean">true</span><span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token keyword">public</span> <span class="token class-name">Object</span> <span class="token function">take</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token keyword">throws</span> <span class="token class-name">InterruptedException</span> <span class="token punctuation">&#123;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token class-name">Thread</span><span class="token punctuation">.</span><span class="token function">interrupted</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token keyword">throw</span> <span class="token keyword">new</span> <span class="token class-name">InterruptedException</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token class-name">Object</span> old <span class="token operator">=</span> <span class="token keyword">null</span><span class="token punctuation">;</span>
<span class="token keyword">synchronized</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
<span class="token keyword">while</span> <span class="token punctuation">(</span>usedSlots_ <span class="token operator">&lt;=</span> <span class="token number">0</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
<span class="token keyword">try</span> <span class="token punctuation">&#123;</span> <span class="token function">wait</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token punctuation">&#125;</span>
<span class="token keyword">catch</span> <span class="token punctuation">(</span><span class="token class-name">InterruptedException</span> ex<span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
<span class="token function">notify</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">throw</span> ex<span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token punctuation">&#125;</span>
old <span class="token operator">=</span> <span class="token function">extract</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token function">incEmptySlots</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">return</span> old<span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token keyword">public</span> <span class="token class-name">Object</span> <span class="token function">poll</span><span class="token punctuation">(</span><span class="token keyword">long</span> msecs<span class="token punctuation">)</span> <span class="token keyword">throws</span> <span class="token class-name">InterruptedException</span> <span class="token punctuation">&#123;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token class-name">Thread</span><span class="token punctuation">.</span><span class="token function">interrupted</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token keyword">throw</span> <span class="token keyword">new</span> <span class="token class-name">InterruptedException</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token class-name">Object</span> old <span class="token operator">=</span> <span class="token keyword">null</span><span class="token punctuation">;</span>
<span class="token keyword">synchronized</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
<span class="token keyword">long</span> start <span class="token operator">=</span> <span class="token punctuation">(</span>msecs <span class="token operator">&lt;=</span> <span class="token number">0</span><span class="token punctuation">)</span><span class="token operator">?</span> <span class="token number">0</span> <span class="token operator">:</span> <span class="token class-name">System</span><span class="token punctuation">.</span><span class="token function">currentTimeMillis</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">long</span> waitTime <span class="token operator">=</span> msecs<span class="token punctuation">;</span>
<span class="token keyword">while</span> <span class="token punctuation">(</span>usedSlots_ <span class="token operator">&lt;=</span> <span class="token number">0</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>waitTime <span class="token operator">&lt;=</span> <span class="token number">0</span><span class="token punctuation">)</span> <span class="token keyword">return</span> <span class="token keyword">null</span><span class="token punctuation">;</span>
<span class="token keyword">try</span> <span class="token punctuation">&#123;</span> <span class="token function">wait</span><span class="token punctuation">(</span>waitTime<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token punctuation">&#125;</span>
<span class="token keyword">catch</span> <span class="token punctuation">(</span><span class="token class-name">InterruptedException</span> ex<span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
<span class="token function">notify</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">throw</span> ex<span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
waitTime <span class="token operator">=</span> msecs <span class="token operator">-</span> <span class="token punctuation">(</span><span class="token class-name">System</span><span class="token punctuation">.</span><span class="token function">currentTimeMillis</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-</span> start<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
old <span class="token operator">=</span> <span class="token function">extract</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token function">incEmptySlots</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">return</span> old<span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>
<span class="token punctuation">&#125;</span>
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