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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>BRPOP — Redis 命令参考</title>
<link rel="stylesheet" href="../_static/pyramid.css" type="text/css" />
<link rel="stylesheet" href="../_static/pygments.css" type="text/css" />
<script type="text/javascript">
var DOCUMENTATION_OPTIONS = {
URL_ROOT: '../',
VERSION: '2.8',
COLLAPSE_INDEX: false,
FILE_SUFFIX: '.html',
HAS_SOURCE: true
};
</script>
<script type="text/javascript" src="../_static/jquery.js"></script>
<script type="text/javascript" src="../_static/underscore.js"></script>
<script type="text/javascript" src="../_static/doctools.js"></script>
<link rel="top" title="Redis 命令参考" href="../index.html" />
<link rel="up" title="List（列表）" href="index.html" />
<link rel="next" title="BRPOPLPUSH" href="brpoplpush.html" />
<link rel="prev" title="BLPOP" href="blpop.html" />
<!--[if lte IE 6]>
<link rel="stylesheet" href="../_static/ie6.css" type="text/css" media="screen" charset="utf-8" />
<![endif]-->
</head>
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<li class="right" style="margin-right: 10px">
<a href="../genindex.html" title="General Index"
accesskey="I">index</a></li>
<li class="right" >
<a href="brpoplpush.html" title="BRPOPLPUSH"
accesskey="N">next</a> |</li>
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<a href="blpop.html" title="BLPOP"
accesskey="P">previous</a> |</li>
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<div class="documentwrapper">
<div class="bodywrapper">
<div class="body">
<div class="section" id="brpop">
<span id="id1"></span><h1>BRPOP<a class="headerlink" href="#brpop" title="Permalink to this headline">¶</a></h1>
<p><strong>BRPOP key [key ...] timeout</strong></p>
<p><a class="reference internal" href="#brpop">BRPOP</a> 是列表的阻塞式(blocking)弹出原语。</p>
<p>它是 <a class="reference internal" href="rpop.html#rpop"><span>RPOP</span></a> 命令的阻塞版本，当给定列表内没有任何元素可供弹出的时候，连接将被 <a class="reference internal" href="#brpop">BRPOP</a> 命令阻塞，直到等待超时或发现可弹出元素为止。</p>
<p>当给定多个 <code class="docutils literal"><span class="pre">key</span></code> 参数时，按参数 <code class="docutils literal"><span class="pre">key</span></code> 的先后顺序依次检查各个列表，弹出第一个非空列表的尾部元素。</p>
<p>关于阻塞操作的更多信息，请查看 <a class="reference internal" href="blpop.html#blpop"><span>BLPOP</span></a> 命令， <a class="reference internal" href="#brpop">BRPOP</a> 除了弹出元素的位置和 <a class="reference internal" href="blpop.html#blpop"><span>BLPOP</span></a> 不同之外，其他表现一致。</p>
<dl class="docutils">
<dt><strong>可用版本：</strong></dt>
<dd>>= 2.0.0</dd>
<dt><strong>时间复杂度：</strong></dt>
<dd>O(1)</dd>
<dt><strong>返回值：</strong></dt>
<dd><div class="first last line-block">
<div class="line">假如在指定时间内没有任何元素被弹出，则返回一个 <code class="docutils literal"><span class="pre">nil</span></code> 和等待时长。</div>
<div class="line">反之，返回一个含有两个元素的列表，第一个元素是被弹出元素所属的 <code class="docutils literal"><span class="pre">key</span></code> ，第二个元素是被弹出元素的值。</div>
</div>
</dd>
</dl>
<div class="highlight-python"><div class="highlight"><pre>redis> LLEN course
(integer) 0
redis> RPUSH course algorithm001
(integer) 1
redis> RPUSH course c++101
(integer) 2
redis> BRPOP course 30
1) "course" # 被弹出元素所属的列表键
2) "c++101" # 被弹出的元素
</pre></div>
</div>
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>index</a></li>
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