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<article id="post-ConcurrentHashMap-JDK1-8实现深入剖析" class="article article-type-post" itemscope itemprop="blogPost">
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<a class="article-title" href="/2017/08/22/ConcurrentHashMap-JDK1-8实现深入剖析/">ConcurrentHashMap JDK1.8源码深入剖析</a>
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<h2 id="ConcurrentHashMap-JDK1-8源码深入剖析-一"><a href="#ConcurrentHashMap-JDK1-8源码深入剖析-一" class="headerlink" title="ConcurrentHashMap JDK1.8源码深入剖析(一)"></a>ConcurrentHashMap JDK1.8源码深入剖析(一)</h2><h3 id="阅读前建议掌握的知识"><a href="#阅读前建议掌握的知识" class="headerlink" title="阅读前建议掌握的知识"></a>阅读前建议掌握的知识</h3><ol>
<li>CAS操作</li>
<li>hashMap的原理</li>
<li>并发相关锁的知识</li>
<li>并发中原子性，可见性，重排序的概念</li>
</ol>
<h3 id="特性"><a href="#特性" class="headerlink" title="特性"></a>特性</h3><ul>
<li>底层实现原理为数组+链表+红黑树</li>
<li>当链表大小阀值超过8时转换为红黑树</li>
<li>大量使用CAS操作来实现无锁</li>
<li>并发扩容</li>
</ul>
<h3 id="主要属性"><a href="#主要属性" class="headerlink" title="主要属性"></a>主要属性</h3><h5 id="TREEIFY-THRESHOLD-UNTREEIFY-THRESHOLD"><a href="#TREEIFY-THRESHOLD-UNTREEIFY-THRESHOLD" class="headerlink" title="TREEIFY_THRESHOLD,UNTREEIFY_THRESHOLD"></a>TREEIFY_THRESHOLD,UNTREEIFY_THRESHOLD</h5><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line">static final int TREEIFY_THRESHOLD = 8;</span><br><span class="line">static final int UNTREEIFY_THRESHOLD = 6;</span><br></pre></td></tr></table></figure>
<p> 大于8时,链表转树阀值。</p>
<p> 小于6时树转链表，仅在扩容tranfer时才可能树转链表。</p>
<h5 id="sizeCtl"><a href="#sizeCtl" class="headerlink" title="sizeCtl"></a>sizeCtl</h5><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">private transient volatile int sizeCtl;</span><br></pre></td></tr></table></figure>
<p>hash表初始化或扩容时的一个控制位标识量。负数代表正在进行初始化或扩容操作。</p>
<ul>
<li>-1代表正在初始化。</li>
<li>-N 表示有N-1个线程正在进行扩容操作。</li>
<li>正数或0代表hash表还没有被初始化，这个数值表示初始化或下一次进行扩容的大小。</li>
</ul>
<h5 id="MOVED"><a href="#MOVED" class="headerlink" title="MOVED"></a>MOVED</h5><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line">/*</span><br><span class="line"> * Encodings for Node hash fields. See above for explanation.</span><br><span class="line"> */</span><br><span class="line"> static final int MOVED = -1; // hash for forwarding nodes</span><br></pre></td></tr></table></figure>
<p>Node的hash值，为 -1时代表该Node为<code>ForwardingNode</code></p>
<h5 id="TREEBIN"><a href="#TREEBIN" class="headerlink" title="TREEBIN"></a>TREEBIN</h5><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">static final int TREEBIN = -2;// hash for roots of trees</span><br></pre></td></tr></table></figure>
<p>树根节点的hash值</p>
<h5 id="MAX-RESIZERS"><a href="#MAX-RESIZERS" class="headerlink" title="MAX_RESIZERS"></a>MAX_RESIZERS</h5><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line">/**</span><br><span class="line"> * The maximum number of threads that can help resize.</span><br><span class="line"> * Must fit in 32 - RESIZE_STAMP_BITS bits.</span><br><span class="line"> */</span><br><span class="line">private static final int MAX_RESIZERS = (1 << (32 - RESIZE_STAMP_BITS)) - 1;</span><br></pre></td></tr></table></figure>
<p>并发扩容时最大允许的help线程总数</p>
<h3 id="Node"><a href="#Node" class="headerlink" title="Node"></a>Node</h3><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br></pre></td><td class="code"><pre><span class="line">static class Node<K,V> implements Map.Entry<K,V> {</span><br><span class="line"> final int hash;</span><br><span class="line"> final K key;</span><br><span class="line"> //让value为volatile类型，让其有可见性</span><br><span class="line"> volatile V val;</span><br><span class="line"> //</span><br><span class="line"> volatile Node<K,V> next;</span><br><span class="line"></span><br><span class="line"> Node(int hash, K key, V val, Node<K,V> next) {</span><br><span class="line">...</span><br><span class="line"> }</span><br><span class="line"></span><br><span class="line">...</span><br><span class="line"></span><br><span class="line"> //禁止直接setValue</span><br><span class="line"> public final V setValue(V value) {</span><br><span class="line"> throw new UnsupportedOperationException();</span><br><span class="line"> }</span><br><span class="line"></span><br><span class="line"> ...</span><br><span class="line"></span><br><span class="line"> Node<K,V> find(int h, Object k) {</span><br><span class="line"> Node<K,V> e = this;</span><br><span class="line"> if (k != null) {</span><br><span class="line"> do {</span><br><span class="line"> K ek;</span><br><span class="line"> if (e.hash == h &&</span><br><span class="line"> ((ek = e.key) == k || (ek != null && k.equals(ek))))</span><br><span class="line"> return e;</span><br><span class="line"> } while ((e = e.next) != null);</span><br><span class="line"> }</span><br><span class="line"> return null;</span><br><span class="line"> }</span><br><span class="line"> }</span><br></pre></td></tr></table></figure>
<p>节点是ConcurrentHashMap的核心内部类，他的设计原理是不允许call setValue来直接改变它的值,因为put需要用CAS来实现无锁线程安全操作。同时提供了find方法来通过hash值和key寻找链表中的节点，该方法被map.get()调用，被子类overriden，来实现不同类型节点的查询方法。</p>
<h3 id="关键的三个CAS方法"><a href="#关键的三个CAS方法" class="headerlink" title="关键的三个CAS方法"></a>关键的三个CAS方法</h3><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line">static final <K,V> Node<K,V> tabAt(Node<K,V>[] tab, int i) {</span><br><span class="line"> return (Node<K,V>)U.getObjectVolatile(tab, ((long)i << ASHIFT) + ABASE);</span><br><span class="line">}</span><br></pre></td></tr></table></figure>
<p>tabAt方法通过UNsafe的CAS操作来获得在i下标位置的Node</p>
<figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line">static final <K,V> boolean casTabAt(Node<K,V>[] tab, int i,</span><br><span class="line"> Node<K,V> c, Node<K,V> v) {</span><br><span class="line"> return U.compareAndSwapObject(tab, ((long)i << ASHIFT) + ABASE, c, v);</span><br><span class="line">}</span><br></pre></td></tr></table></figure>
<p> 对i下标位置上的Node进行CAS的set操作，如果有其他线程正在访问则会返回false，ASHIFT是指tab[i]中第i个元素在相对于数组第一个元素的偏移量，而ABASE就算第一数组的内存素的偏移地址,((long)i << ASHIFT) + ABASE就算i最后的地址。</p>
<figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line">static final <K,V> void setTabAt(Node<K,V>[] tab, int i, Node<K,V> v) {</span><br><span class="line"> U.putObjectVolatile(tab, ((long)i << ASHIFT) + ABASE, v);</span><br><span class="line">}</span><br></pre></td></tr></table></figure>
<p>利用volatile方法set节点位置的值,注意<code>setTabAt</code>总是在被锁定的代码块中才调用。</p>
<h3 id="Put方法"><a href="#Put方法" class="headerlink" title="Put方法"></a>Put方法</h3><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br></pre></td><td class="code"><pre><span class="line">final V putVal(K key, V value, boolean onlyIfAbsent) {</span><br><span class="line"> //不允许key或value为null</span><br><span class="line"> if (key == null || value == null) throw new NullPointerException();</span><br><span class="line"> int hash = spread(key.hashCode());</span><br><span class="line"> int binCount = 0;</span><br><span class="line"> //经典CAS操作，不set成功死不罢休</span><br><span class="line"> for (Node<K,V>[] tab = table;;) {</span><br><span class="line"> Node<K,V> f; int n, i, fh;</span><br><span class="line"> //初始化table</span><br><span class="line"> if (tab == null || (n = tab.length) == 0)</span><br><span class="line"> tab = initTable();</span><br><span class="line"> //如果节点为null，直接用cas方法尝试set,若成功直接break跳出CAS循环。</span><br><span class="line"> else if ((f = tabAt(tab, i = (n - 1) & hash)) == null) {</span><br><span class="line"> if (casTabAt(tab, i, null,</span><br><span class="line"> new Node<K,V>(hash, key, value, null)))</span><br><span class="line"> break; // no lock when adding to empty bin</span><br><span class="line"> }</span><br><span class="line"> //如果是forwardingNode节点，代表有其他线程正在扩容，于是helpTransfer辅助扩容</span><br><span class="line"> else if ((fh = f.hash) == MOVED)</span><br><span class="line"> tab = helpTransfer(tab, f);</span><br><span class="line"> //这里意味者节点下是链表或是树，通过synchronized锁住f表头，则锁住了整个链表或树</span><br><span class="line"> else {</span><br><span class="line"> V oldVal = null;</span><br><span class="line"> synchronized (f) {</span><br><span class="line"> if (tabAt(tab, i) == f) {</span><br><span class="line"> //判断是链表还是树，fh>=0则为链表</span><br><span class="line"> if (fh >= 0) {</span><br><span class="line"> binCount = 1;</span><br><span class="line"> for (Node<K,V> e = f;; ++binCount) {</span><br><span class="line"> K ek;</span><br><span class="line"> if (e.hash == hash &&</span><br><span class="line"> ((ek = e.key) == key ||</span><br><span class="line"> (ek != null && key.equals(ek)))) {</span><br><span class="line"> oldVal = e.val;</span><br><span class="line"> if (!onlyIfAbsent)</span><br><span class="line"> e.val = value;</span><br><span class="line"> break;</span><br><span class="line"> }</span><br><span class="line"> Node<K,V> pred = e;</span><br><span class="line"> //若遍历到最后一个节点，则直接将新值插入到尾部,跳出循环</span><br><span class="line"> if ((e = e.next) == null) {</span><br><span class="line"> pred.next = new Node<K,V>(hash, key,</span><br><span class="line"> value, null);</span><br><span class="line"> break;</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> //按照树节点来处理</span><br><span class="line"> else if (f instanceof TreeBin) {</span><br><span class="line"> Node<K,V> p;</span><br><span class="line"> binCount = 2;</span><br><span class="line"> if ((p = ((TreeBin<K,V>)f).putTreeVal(hash, key,</span><br><span class="line"> value)) != null) {</span><br><span class="line"> oldVal = p.val;</span><br><span class="line"> if (!onlyIfAbsent)</span><br><span class="line"> p.val = value;</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> if (binCount != 0) {</span><br><span class="line"> //大于8的阀值下将链表转化为树</span><br><span class="line"> if (binCount >= TREEIFY_THRESHOLD)</span><br><span class="line"> treeifyBin(tab, i);</span><br><span class="line"> if (oldVal != null)</span><br><span class="line"> return oldVal;</span><br><span class="line"> break;</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> //更新map大小，+1</span><br><span class="line"> addCount(1L, binCount);</span><br><span class="line"> return null;</span><br><span class="line"> }</span><br></pre></td></tr></table></figure>
<p>putVal的设计核心思想是</p>
<ul>
<li>不允许key或value为null。</li>
<li>用spread计算key的hash值再用类似取模的方法来确定在table数组中的位置。</li>
<li>若有需要则初始化table。</li>
<li>若该节点为null，无哈希碰撞，则使用CAS来进行set操作。</li>
<li>若该节点被标记为forward，则代表有其他线程正在进行扩容，当前线程也会辅助进行扩容操作。</li>
<li>若该节点为链表或树，代表哈希碰撞，则使用synchronized来锁住桶，然后进行set操作。注意若在该节点为链表时，会依次向后找到应该存放的位置，若大于阀值8则转化为红黑树，若本来就是树结构则按照树的方法存放。</li>
</ul>
<h3 id="参考"><a href="#参考" class="headerlink" title="参考"></a>参考</h3><ul>
<li><a href="http://www.cnblogs.com/huaizuo/archive/2016/04/20/5413069.html" target="_blank" rel="external">http://www.cnblogs.com/huaizuo/archive/2016/04/20/5413069.html</a></li>
<li><a href="https://my.oschina.net/hosee/blog/675884" target="_blank" rel="external">https://my.oschina.net/hosee/blog/675884</a></li>
</ul>
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<article id="post-Redis实现分布式锁" class="article article-type-post" itemscope itemprop="blogPost">
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<a href="/2017/08/08/Redis实现分布式锁/" class="article-date">
<time datetime="2017-08-08T09:30:42.000Z" itemprop="datePublished">2017-08-08</time>
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<a class="article-title" href="/2017/08/08/Redis实现分布式锁/">Redis实现分布式锁</a>
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<h2 id="Redis实现分布式锁"><a href="#Redis实现分布式锁" class="headerlink" title="Redis实现分布式锁"></a>Redis实现分布式锁</h2><h4 id="分布式锁的一些问题"><a href="#分布式锁的一些问题" class="headerlink" title="分布式锁的一些问题"></a>分布式锁的一些问题</h4><ol>
<li>并发问题，若多个客户端同时上锁，结果只允许一个客户端成功，其他失败，可以利用redis的<code>SETNX</code> 命令来实现，该命令允许若给定的 key 已经存在，则 <code>SETNX</code> 不做任何动作,设置成功，返回 1 ,设置失败，返回 0 。</li>
<li>上锁后解锁的问题，可以考虑使用redis key的ttl过期，通过<code>PEXPIRE</code>来设置key的自动过期。若不使用自动过期特性，则需要在锁定结束后使用<code>DEL</code>命令来进行解锁，这种情况有可能发生某个客户端已经crash，于是这个锁会永远锁定，导致其他客户端无法获得锁。</li>
</ol>
<h4 id="Redis2-6以后新特性"><a href="#Redis2-6以后新特性" class="headerlink" title="Redis2.6以后新特性"></a>Redis2.6以后新特性</h4><p>redis2.6.12以后 SET 命令的行为可以通过一系列参数来修改</p>
<ol>
<li>EX second ：设置键的过期时间为 second 秒。 <code>SET key value EX second</code> 效果等同于 <code>SETEX key second value</code> 。</li>
<li>PX millisecond ：设置键的过期时间为 millisecond 毫秒。 <code>SET key value PX millisecond</code> 效果等同于 <code>PSETEX key millisecond value</code> 。</li>
<li>NX ：只在键不存在时，才对键进行设置操作。 <code>SET key value NX</code> 效果等同于 <code>SETNX key value</code> 。</li>
<li>XX ：只在键已经存在时，才对键进行设置操作。</li>
</ol>
<h4 id="使用新特性来解决分布式锁"><a href="#使用新特性来解决分布式锁" class="headerlink" title="使用新特性来解决分布式锁"></a>使用新特性来解决分布式锁</h4><ol>
<li>使用命令 <code>SET key value NX EX second</code> 设置锁的同时为锁设置TTL过期时间，若当锁已经存在时返回nil。</li>
</ol>
<h4 id="Redisson解决方法"><a href="#Redisson解决方法" class="headerlink" title="Redisson解决方法"></a>Redisson解决方法</h4><p><a href="https://github.com/redisson/redisson/wiki/Redisson%E9%A1%B9%E7%9B%AE%E4%BB%8B%E7%BB%8D" target="_blank" rel="external">Redisson</a>是redis的一个java客户端,实现了分布式锁和同步器，Redisson的分布式锁RLock Java对象实现了java.util.concurrent.locks.Lock接口，同时还支持自动过期解锁。<br><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br></pre></td><td class="code"><pre><span class="line">RLock lock = redisson.getLock("anyLock");</span><br><span class="line">// 最常见的使用方法</span><br><span class="line">lock.lock();</span><br><span class="line"></span><br><span class="line">// 支持过期解锁功能</span><br><span class="line">// 10秒钟以后自动解锁</span><br><span class="line">// 无需调用unlock方法手动解锁</span><br><span class="line">lock.lock(10, TimeUnit.SECONDS);</span><br><span class="line"></span><br><span class="line">// 尝试加锁，最多等待100秒，上锁以后10秒自动解锁</span><br><span class="line">boolean res = lock.tryLock(100, 10, TimeUnit.SECONDS);</span><br><span class="line">...</span><br><span class="line">lock.unlock();</span><br></pre></td></tr></table></figure></p>
<p>以上是redisson使用锁的方法，它的原理采用了lua脚本的方式，这样能兼容redis 2.6.12之前的版本,锁的核心源码如下RedissonLock.java<br><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br></pre></td><td class="code"><pre><span class="line"><T> RFuture<T> tryLockInnerAsync(long leaseTime, TimeUnit unit, long threadId, RedisStrictCommand<T> command) {</span><br><span class="line"> internalLockLeaseTime = unit.toMillis(leaseTime);</span><br><span class="line"></span><br><span class="line"> return commandExecutor.evalWriteAsync(getName(), LongCodec.INSTANCE, command,</span><br><span class="line"> //先检查key是否存在</span><br><span class="line"> "if (redis.call('exists', KEYS[1]) == 0) then " +</span><br><span class="line"> //key不存在，创建Hash</span><br><span class="line"> "redis.call('hset', KEYS[1], ARGV[2], 1); " +</span><br><span class="line"> //设置过期时间</span><br><span class="line"> "redis.call('pexpire', KEYS[1], ARGV[1]); " +</span><br><span class="line"> "return nil; " +</span><br><span class="line"> "end; " +</span><br><span class="line"> //若锁已经存在，并且是同样获得锁的线程调用</span><br><span class="line"> "if (redis.call('hexists', KEYS[1], ARGV[2]) == 1) then " +</span><br><span class="line"> //复用锁，为锁+1</span><br><span class="line"> "redis.call('hincrby', KEYS[1], ARGV[2], 1); " +</span><br><span class="line"> //延长锁定时间</span><br><span class="line"> "redis.call('pexpire', KEYS[1], ARGV[1]); " +</span><br><span class="line"> "return nil; " +</span><br><span class="line"> "end; " +</span><br><span class="line"> //若无法获得锁，返回锁的剩余时间</span><br><span class="line"> "return redis.call('pttl', KEYS[1]);",</span><br><span class="line"> Collections.<Object>singletonList(getName()), internalLockLeaseTime, getLockName(threadId));</span><br><span class="line"> }</span><br></pre></td></tr></table></figure></p>
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<article id="post-could-not-read-Username-for-https-github-com-Invalid-argument" class="article article-type-post" itemscope itemprop="blogPost">
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<a href="/2017/08/04/could-not-read-Username-for-https-github-com-Invalid-argument/" class="article-date">
<time datetime="2017-08-04T04:23:47.000Z" itemprop="datePublished">2017-08-04</time>
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<a class="article-title" href="/2017/08/04/could-not-read-Username-for-https-github-com-Invalid-argument/">could not read Username for 'https://github.com': Invalid argument</a>
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<h2 id="could-not-read-Username-for-‘https-github-com‘-Invalid-argument"><a href="#could-not-read-Username-for-‘https-github-com‘-Invalid-argument" class="headerlink" title="could not read Username for ‘https://github.com‘: Invalid argument"></a>could not read Username for ‘<a href="https://github.com" target="_blank" rel="external">https://github.com</a>‘: Invalid argument</h2><p>好久没玩hexo blog了，今天心血来潮想恢复使用，结果发现使用<code>hexo d</code>命令时会报如下错误</p>
<figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">could not read Username for 'https://github.com': Invalid argument</span><br></pre></td></tr></table></figure>
<p>网上搜索了下，这个问题有以下几个原因：</p>
<ol>
<li><p>如果安装git客户端的时候没有勾选git命令在bash和cmd命令都有效，若是在cmd命令下则因为没有将git添加到windows的path，所以会出现这个错误，一般可以尝试在blog的目录打开git bash再尝试<code>hexo d</code>。</p>
</li>
<li><p>未将username和email加入到git，可以使用如下命令试试</p>
</li>
</ol>
<figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line">git config --global user.name "yourname"</span><br><span class="line">git config --global user.email "youremail"</span><br></pre></td></tr></table></figure>
<ol>
<li>检查<code>_config.yml</code>的配置是否正确</li>
</ol>
<figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line">deploy:</span><br><span class="line"> type: git</span><br><span class="line"> repo: https://github.com/yourname/yourname.github.io.git</span><br><span class="line"> branch: master</span><br></pre></td></tr></table></figure>
<ol>
<li>客户端太老，我遇到就是这个问题，即便切换了git bash也仍然报错，于是我升级了新客户端，结果能正常弹出github的用户名和密码输入框，确认后可以正常部署。</li>
</ol>
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<article id="post-如何配置Oracle的SQLPlus" class="article article-type-post" itemscope itemprop="blogPost">
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<a href="/2016/03/11/如何配置Oracle的SQLPlus/" class="article-date">
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<h3 id="SQL-Plus-Overview"><a href="#SQL-Plus-Overview" class="headerlink" title="SQL*Plus Overview"></a>SQL*Plus Overview</h3><p>SQL*Plus是一个用于与Oracle Database交互和执行查询的工具，我们要安装的是命令行工具。<br>
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<article id="post-Oracle-ORA-01840-input-value-not-long-enough-for-date-format" class="article article-type-post" itemscope itemprop="blogPost">
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<a href="/2016/03/08/Oracle-ORA-01840-input-value-not-long-enough-for-date-format/" class="article-date">
<time datetime="2016-03-08T07:20:33.000Z" itemprop="datePublished">2016-03-08</time>
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<a class="article-title" href="/2016/03/08/Oracle-ORA-01840-input-value-not-long-enough-for-date-format/">Oracle - ORA-01840: input value not long enough for date format</a>
</h1>
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<h2 id="错误日志："><a href="#错误日志：" class="headerlink" title="错误日志："></a>错误日志：</h2><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">Oracle - ORA-01840: input value not long enough for date format</span><br></pre></td></tr></table></figure>
<p>在程式执行查询方法时，日志中出现以上错误</p>
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<article id="post-Hexo安装教程-一" class="article article-type-post" itemscope itemprop="blogPost">
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<h2 id="什么是Hexo"><a href="#什么是Hexo" class="headerlink" title="什么是Hexo?"></a>什么是Hexo?</h2><p>Hexo 是一个快速、简洁且高效的博客框架。Hexo 使用 <a href="http://daringfireball.net/projects/markdown/">Markdown</a>（或其他渲染引擎）解析文章，在几秒内，即可利用靓丽的主题生成静态网页。</p>
<h2 id="Hexo安装环境"><a href="#Hexo安装环境" class="headerlink" title="Hexo安装环境"></a>Hexo安装环境</h2><ul>
<li>Windows7</li>
</ul>
<h2 id="Hexo安装步骤概览"><a href="#Hexo安装步骤概览" class="headerlink" title="Hexo安装步骤概览"></a>Hexo安装步骤概览</h2><ol>
<li>安装node.js</li>
<li>安装github desktop</li>
<li>安装hexo
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<p><img src="/resources/164646181173681758.jpg" alt="澳门"><br><em>没有人是天才，个人的才能是靠自己挖掘的，登上山顶，望望身后已看不见的芸芸众生，回过头来，还需要继续向上。生活本不是闲情逸致，它本就是丑陋的，这个世界不会因为谁的离开就停止送给你恶意。我们唯一要学会的就是战斗，即使遇到困难，我们也要独自无谓的战斗下去。</em></p>
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<article id="post-ORA-01882-timezone-region" class="article article-type-post" itemscope itemprop="blogPost">
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<h2 id="错误日志："><a href="#错误日志：" class="headerlink" title="错误日志："></a>错误日志：</h2><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">ORA-01882: timezone region</span><br></pre></td></tr></table></figure>
<p>用weblogic配置连接池连到oracle时报错</p>
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<article id="post-原-如何将UITableViewDelegate和UITableViewDataSource从UITableViewController中分离出来" class="article article-type-post" itemscope itemprop="blogPost">
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<p>大家都知道如果给<code>UITableViewController</code>装载一些数据和控制cell的行为(高度,样式等)都需要指定<code>UITableView</code>的delegate给自身,一般会使用IB或者在<code>viewDidLoad</code>中写上<code>self.tableView.delegate = self;</code>然后实现<code>UITableViewDelegate</code>和<code>UITableViewDataSource</code>中的方法,例如:<code>-tableView:cellForRowAtIndexPath:</code> 等等.<br>那么如何将实现<code>UITableViewDelegate</code>和<code>UITableViewDataSource</code>的方法脱离出来单独放在一个新的class中呢?<br>
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<article id="post-原-如何移动组件的位置，例如如何将UIAlertView显示在屏幕上部" class="article article-type-post" itemscope itemprop="blogPost">
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<a href="/2010/05/26/原-如何移动组件的位置，例如如何将UIAlertView显示在屏幕上部/" class="article-date">
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<a class="article-title" href="/2010/05/26/原-如何移动组件的位置，例如如何将UIAlertView显示在屏幕上部/">[原]如何移动组件的位置，例如如何将UIAlertView显示在屏幕上部</a>
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<p>苹果自带的警告框非常好用，但是它总是显示在屏幕中间，我们如何将它的位置移动呢？从Iphone SDK3开始我们可以使用CGAffineTransformTranslate</p>
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