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<section id="module-selectors">
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<span id="selectors-high-level-i-o-multiplexing"></span><h1><a class="reference internal" href="#module-selectors" title="selectors: High-level I/O multiplexing."><code class="xref py py-mod docutils literal notranslate"><span class="pre">selectors</span></code></a> --- 高级 I/O 复用库<a class="headerlink" href="#module-selectors" title="永久链接至标题">¶</a></h1>
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<p><span class="versionmodified added">3.4 新版功能.</span></p>
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<p><strong>源码:</strong> <a class="reference external" href="https://github.com/python/cpython/tree/3.8/Lib/selectors.py">Lib/selectors.py</a></p>
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<section id="introduction">
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<h2>概述<a class="headerlink" href="#introduction" title="永久链接至标题">¶</a></h2>
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<p>此模块允许高层级且高效率的 I/O 复用，它建立在 <a class="reference internal" href="select.html#module-select" title="select: Wait for I/O completion on multiple streams."><code class="xref py py-mod docutils literal notranslate"><span class="pre">select</span></code></a> 模块原型的基础之上。 推荐用户改用此模块，除非他们希望对所使用的 OS 层级原型进行精确控制。</p>
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<p>它定义了一个 <a class="reference internal" href="#selectors.BaseSelector" title="selectors.BaseSelector"><code class="xref py py-class docutils literal notranslate"><span class="pre">BaseSelector</span></code></a> 抽象基类，以及多个实际的实现 (<a class="reference internal" href="#selectors.KqueueSelector" title="selectors.KqueueSelector"><code class="xref py py-class docutils literal notranslate"><span class="pre">KqueueSelector</span></code></a>, <a class="reference internal" href="#selectors.EpollSelector" title="selectors.EpollSelector"><code class="xref py py-class docutils literal notranslate"><span class="pre">EpollSelector</span></code></a>...)，它们可被用于在多个文件对象上等待 I/O 就绪通知。 在下文中，"文件对象" 是指任何具有 <code class="xref py py-meth docutils literal notranslate"><span class="pre">fileno()</span></code> 方法的对象，或是一个原始文件描述器。 参见 <a class="reference internal" href="../glossary.html#term-file-object"><span class="xref std std-term">file object</span></a>。</p>
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<p><a class="reference internal" href="#selectors.DefaultSelector" title="selectors.DefaultSelector"><code class="xref py py-class docutils literal notranslate"><span class="pre">DefaultSelector</span></code></a> 是一个指向当前平台上可用的最高效实现的别名：这应为大多数用户的默认选择。</p>
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<div class="admonition note">
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<p class="admonition-title">注解</p>
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<p>受支持的文件对象类型取决于具体平台：在 Windows 上，支持套接字但不支持管道，而在 Unix 上两者均受支持（某些其他类型也可能受支持，例如 fifo 或特殊文件设备等）。</p>
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</div>
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<div class="admonition seealso">
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<p class="admonition-title">参见</p>
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<dl class="simple">
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<dt><a class="reference internal" href="select.html#module-select" title="select: Wait for I/O completion on multiple streams."><code class="xref py py-mod docutils literal notranslate"><span class="pre">select</span></code></a></dt><dd><p>低层级的 I/O 多路复用模块。</p>
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</dd>
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</dl>
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</div>
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</section>
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<section id="classes">
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<h2>类<a class="headerlink" href="#classes" title="永久链接至标题">¶</a></h2>
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<p>类的层次结构:</p>
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<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="n">BaseSelector</span>
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<span class="o">+--</span> <span class="n">SelectSelector</span>
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<span class="o">+--</span> <span class="n">PollSelector</span>
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<span class="o">+--</span> <span class="n">EpollSelector</span>
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<span class="o">+--</span> <span class="n">DevpollSelector</span>
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<span class="o">+--</span> <span class="n">KqueueSelector</span>
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</pre></div>
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</div>
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<p>下文中，<em>events</em> 一个位掩码，指明哪些 I/O 事件要在给定的文件对象上执行等待。 它可以是以下模块级常量的组合:</p>
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<blockquote>
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<div><table class="docutils align-default">
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<colgroup>
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<col style="width: 33%" />
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<col style="width: 67%" />
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</colgroup>
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<thead>
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<tr class="row-odd"><th class="head"><p>常数</p></th>
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<th class="head"><p>含义</p></th>
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</tr>
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</thead>
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<tbody>
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<tr class="row-even"><td><p><code class="xref py py-const docutils literal notranslate"><span class="pre">EVENT_READ</span></code></p></td>
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<td><p>可读</p></td>
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</tr>
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<tr class="row-odd"><td><p><code class="xref py py-const docutils literal notranslate"><span class="pre">EVENT_WRITE</span></code></p></td>
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<td><p>可写</p></td>
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</tr>
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</tbody>
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</table>
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</div></blockquote>
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<dl class="class">
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<dt id="selectors.SelectorKey">
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<em class="property">class </em><code class="sig-prename descclassname">selectors.</code><code class="sig-name descname">SelectorKey</code><a class="headerlink" href="#selectors.SelectorKey" title="永久链接至目标">¶</a></dt>
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<dd><p><a class="reference internal" href="#selectors.SelectorKey" title="selectors.SelectorKey"><code class="xref py py-class docutils literal notranslate"><span class="pre">SelectorKey</span></code></a> 是一个 <a class="reference internal" href="collections.html#collections.namedtuple" title="collections.namedtuple"><code class="xref py py-class docutils literal notranslate"><span class="pre">namedtuple</span></code></a>，用来将文件对象关联到其下层的文件描述器、选定事件掩码和附加数据等。 它会被某些 <a class="reference internal" href="#selectors.BaseSelector" title="selectors.BaseSelector"><code class="xref py py-class docutils literal notranslate"><span class="pre">BaseSelector</span></code></a> 方法返回。</p>
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<dl class="attribute">
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<dt id="selectors.SelectorKey.fileobj">
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<code class="sig-name descname">fileobj</code><a class="headerlink" href="#selectors.SelectorKey.fileobj" title="永久链接至目标">¶</a></dt>
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<dd><p>已注册的文件对象。</p>
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</dd></dl>
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<dl class="attribute">
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<dt id="selectors.SelectorKey.fd">
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<code class="sig-name descname">fd</code><a class="headerlink" href="#selectors.SelectorKey.fd" title="永久链接至目标">¶</a></dt>
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<dd><p>下层的文件描述器。</p>
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</dd></dl>
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<dl class="attribute">
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<dt id="selectors.SelectorKey.events">
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<code class="sig-name descname">events</code><a class="headerlink" href="#selectors.SelectorKey.events" title="永久链接至目标">¶</a></dt>
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<dd><p>必须在此文件对象上被等待的事件。</p>
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</dd></dl>
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<dl class="attribute">
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<dt id="selectors.SelectorKey.data">
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<code class="sig-name descname">data</code><a class="headerlink" href="#selectors.SelectorKey.data" title="永久链接至目标">¶</a></dt>
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<dd><p>可选的关联到此文件对象的不透明数据：例如，这可被用来存储各个客户端的会话 ID。</p>
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</dd></dl>
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</dd></dl>
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<dl class="class">
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<dt id="selectors.BaseSelector">
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<em class="property">class </em><code class="sig-prename descclassname">selectors.</code><code class="sig-name descname">BaseSelector</code><a class="headerlink" href="#selectors.BaseSelector" title="永久链接至目标">¶</a></dt>
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<dd><p>一个 <a class="reference internal" href="#selectors.BaseSelector" title="selectors.BaseSelector"><code class="xref py py-class docutils literal notranslate"><span class="pre">BaseSelector</span></code></a>，用来在多个文件对象上等待 I/O 事件就绪。 它支持文件流注册、注销，以及在这些流上等待 I/O 事件的方法。 它是一个抽象基类，因此不能被实例化。 请改用 <a class="reference internal" href="#selectors.DefaultSelector" title="selectors.DefaultSelector"><code class="xref py py-class docutils literal notranslate"><span class="pre">DefaultSelector</span></code></a>，或者 <a class="reference internal" href="#selectors.SelectSelector" title="selectors.SelectSelector"><code class="xref py py-class docutils literal notranslate"><span class="pre">SelectSelector</span></code></a>, <a class="reference internal" href="#selectors.KqueueSelector" title="selectors.KqueueSelector"><code class="xref py py-class docutils literal notranslate"><span class="pre">KqueueSelector</span></code></a> 等。 如果你想要指明使用某个实现，并且你的平台支持它的话。 <a class="reference internal" href="#selectors.BaseSelector" title="selectors.BaseSelector"><code class="xref py py-class docutils literal notranslate"><span class="pre">BaseSelector</span></code></a> 及其具体实现支持 <a class="reference internal" href="../glossary.html#term-context-manager"><span class="xref std std-term">context manager</span></a> 协议。</p>
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<dl class="method">
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<dt id="selectors.BaseSelector.register">
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<em class="property">abstractmethod </em><code class="sig-name descname">register</code><span class="sig-paren">(</span><em class="sig-param">fileobj</em>, <em class="sig-param">events</em>, <em class="sig-param">data=None</em><span class="sig-paren">)</span><a class="headerlink" href="#selectors.BaseSelector.register" title="永久链接至目标">¶</a></dt>
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<dd><p>注册一个用于选择的文件对象，在其上监视 I/O 事件。</p>
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<p><em>fileobj</em> 是要监视的文件对象。 它可以是整数形式的文件描述符或者具有 <code class="docutils literal notranslate"><span class="pre">fileno()</span></code> 方法的对象。 <em>events</em> 是要监视的事件的位掩码。 <em>data</em> 是一个不透明对象。</p>
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<p>这将返回一个新的 <a class="reference internal" href="#selectors.SelectorKey" title="selectors.SelectorKey"><code class="xref py py-class docutils literal notranslate"><span class="pre">SelectorKey</span></code></a> 实例，或在出现无效事件掩码或文件描述符时引发 <a class="reference internal" href="exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a>，或在文件对象已被注册时引发 <a class="reference internal" href="exceptions.html#KeyError" title="KeyError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">KeyError</span></code></a>。</p>
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</dd></dl>
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<dl class="method">
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<dt id="selectors.BaseSelector.unregister">
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<em class="property">abstractmethod </em><code class="sig-name descname">unregister</code><span class="sig-paren">(</span><em class="sig-param">fileobj</em><span class="sig-paren">)</span><a class="headerlink" href="#selectors.BaseSelector.unregister" title="永久链接至目标">¶</a></dt>
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<dd><p>注销对一个文件对象的选择，移除对它的监视。 在文件对象被关闭之前应当先将其注销。</p>
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<p><em>fileobj</em> 必须是之前已注册的文件对象。</p>
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<p>这将返回已关联的 <a class="reference internal" href="#selectors.SelectorKey" title="selectors.SelectorKey"><code class="xref py py-class docutils literal notranslate"><span class="pre">SelectorKey</span></code></a> 实例，或者如果 <em>fileobj</em> 未注册则会引发 <a class="reference internal" href="exceptions.html#KeyError" title="KeyError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">KeyError</span></code></a>。 It will raise <a class="reference internal" href="exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a> 如果 <em>fileobj</em> 无效（例如它没有 <code class="docutils literal notranslate"><span class="pre">fileno()</span></code> 方法或其 <code class="docutils literal notranslate"><span class="pre">fileno()</span></code> 方法返回无效值）。</p>
|
|
</dd></dl>
|
|
|
|
<dl class="method">
|
|
<dt id="selectors.BaseSelector.modify">
|
|
<code class="sig-name descname">modify</code><span class="sig-paren">(</span><em class="sig-param">fileobj</em>, <em class="sig-param">events</em>, <em class="sig-param">data=None</em><span class="sig-paren">)</span><a class="headerlink" href="#selectors.BaseSelector.modify" title="永久链接至目标">¶</a></dt>
|
|
<dd><p>更改已注册文件对象所监视的事件或所附带的数据。</p>
|
|
<p>这等价于 <code class="xref py py-meth docutils literal notranslate"><span class="pre">BaseSelector.unregister(fileobj)()</span></code> 加 <code class="xref py py-meth docutils literal notranslate"><span class="pre">BaseSelector.register(fileobj,</span> <span class="pre">events,</span> <span class="pre">data)()</span></code>，区别在于它可以被更高效地实现。</p>
|
|
<p>这将返回一个新的 <a class="reference internal" href="#selectors.SelectorKey" title="selectors.SelectorKey"><code class="xref py py-class docutils literal notranslate"><span class="pre">SelectorKey</span></code></a> 实例，或在出现无效事件掩码或文件描述符时引发 <a class="reference internal" href="exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a>，或在文件对象未被注册时引发 <a class="reference internal" href="exceptions.html#KeyError" title="KeyError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">KeyError</span></code></a>。</p>
|
|
</dd></dl>
|
|
|
|
<dl class="method">
|
|
<dt id="selectors.BaseSelector.select">
|
|
<em class="property">abstractmethod </em><code class="sig-name descname">select</code><span class="sig-paren">(</span><em class="sig-param">timeout=None</em><span class="sig-paren">)</span><a class="headerlink" href="#selectors.BaseSelector.select" title="永久链接至目标">¶</a></dt>
|
|
<dd><p>等待直到有已注册的文件对象就绪，或是超过时限。</p>
|
|
<p>如果 <code class="docutils literal notranslate"><span class="pre">timeout</span> <span class="pre">></span> <span class="pre">0</span></code>，这指定以秒数表示的最大等待时间。 如果 <code class="docutils literal notranslate"><span class="pre">timeout</span> <span class="pre"><=</span> <span class="pre">0</span></code>，调用将不会阻塞，并将报告当前就绪的文件对象。 如果 <em>timeout</em> 为 <code class="docutils literal notranslate"><span class="pre">None</span></code>，调用将阻塞直到某个被监视的文件对象就绪。</p>
|
|
<p>这将返回由 <code class="docutils literal notranslate"><span class="pre">(key,</span> <span class="pre">events)</span></code> 元组构成的列表，每项各表示一个就绪的文件对象。</p>
|
|
<p><em>key</em> 是对应于就绪文件对象的 <a class="reference internal" href="#selectors.SelectorKey" title="selectors.SelectorKey"><code class="xref py py-class docutils literal notranslate"><span class="pre">SelectorKey</span></code></a> 实例。 <em>events</em> 是在此文件对象上等待的事件位掩码。</p>
|
|
<div class="admonition note">
|
|
<p class="admonition-title">注解</p>
|
|
<p>如果当前进程收到一个信号，此方法可在任何文件对象就绪之前或超出时限时返回：在此情况下，将返回一个空列表。</p>
|
|
</div>
|
|
<div class="versionchanged">
|
|
<p><span class="versionmodified changed">在 3.5 版更改: </span>现在当被某个信号中断时，如果信号处理程序没有引发异常，选择器会用重新计算的超时值进行重试（请查看 <span class="target" id="index-2"></span><a class="pep reference external" href="https://www.python.org/dev/peps/pep-0475"><strong>PEP 475</strong></a> 其理由），而不是在超时之前返回空的事件列表。</p>
|
|
</div>
|
|
</dd></dl>
|
|
|
|
<dl class="method">
|
|
<dt id="selectors.BaseSelector.close">
|
|
<code class="sig-name descname">close</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#selectors.BaseSelector.close" title="永久链接至目标">¶</a></dt>
|
|
<dd><p>关闭选择器。</p>
|
|
<p>必须调用这个方法以确保下层资源会被释放。 选择器被关闭后将不可再使用。</p>
|
|
</dd></dl>
|
|
|
|
<dl class="method">
|
|
<dt id="selectors.BaseSelector.get_key">
|
|
<code class="sig-name descname">get_key</code><span class="sig-paren">(</span><em class="sig-param">fileobj</em><span class="sig-paren">)</span><a class="headerlink" href="#selectors.BaseSelector.get_key" title="永久链接至目标">¶</a></dt>
|
|
<dd><p>返回关联到某个已注册文件对象的键。</p>
|
|
<p>此方法将返回关联到文件对象的 <a class="reference internal" href="#selectors.SelectorKey" title="selectors.SelectorKey"><code class="xref py py-class docutils literal notranslate"><span class="pre">SelectorKey</span></code></a> 实例，或在文件对象未注册时引发 <a class="reference internal" href="exceptions.html#KeyError" title="KeyError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">KeyError</span></code></a>。</p>
|
|
</dd></dl>
|
|
|
|
<dl class="method">
|
|
<dt id="selectors.BaseSelector.get_map">
|
|
<em class="property">abstractmethod </em><code class="sig-name descname">get_map</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#selectors.BaseSelector.get_map" title="永久链接至目标">¶</a></dt>
|
|
<dd><p>返回从文件对象到选择器键的映射。</p>
|
|
<p>这将返回一个将已注册文件对象映射到与其相关联的 <a class="reference internal" href="#selectors.SelectorKey" title="selectors.SelectorKey"><code class="xref py py-class docutils literal notranslate"><span class="pre">SelectorKey</span></code></a> 实例的 <a class="reference internal" href="collections.abc.html#collections.abc.Mapping" title="collections.abc.Mapping"><code class="xref py py-class docutils literal notranslate"><span class="pre">Mapping</span></code></a> 实例。</p>
|
|
</dd></dl>
|
|
|
|
</dd></dl>
|
|
|
|
<dl class="class">
|
|
<dt id="selectors.DefaultSelector">
|
|
<em class="property">class </em><code class="sig-prename descclassname">selectors.</code><code class="sig-name descname">DefaultSelector</code><a class="headerlink" href="#selectors.DefaultSelector" title="永久链接至目标">¶</a></dt>
|
|
<dd><p>默认的选择器类，使用当前平台上可用的最高效实现。 这应为大多数用户的默认选择。</p>
|
|
</dd></dl>
|
|
|
|
<dl class="class">
|
|
<dt id="selectors.SelectSelector">
|
|
<em class="property">class </em><code class="sig-prename descclassname">selectors.</code><code class="sig-name descname">SelectSelector</code><a class="headerlink" href="#selectors.SelectSelector" title="永久链接至目标">¶</a></dt>
|
|
<dd><p>基于 <a class="reference internal" href="select.html#select.select" title="select.select"><code class="xref py py-func docutils literal notranslate"><span class="pre">select.select()</span></code></a> 的选择器。</p>
|
|
</dd></dl>
|
|
|
|
<dl class="class">
|
|
<dt id="selectors.PollSelector">
|
|
<em class="property">class </em><code class="sig-prename descclassname">selectors.</code><code class="sig-name descname">PollSelector</code><a class="headerlink" href="#selectors.PollSelector" title="永久链接至目标">¶</a></dt>
|
|
<dd><p>基于 <a class="reference internal" href="select.html#select.poll" title="select.poll"><code class="xref py py-func docutils literal notranslate"><span class="pre">select.poll()</span></code></a> 的选择器。</p>
|
|
</dd></dl>
|
|
|
|
<dl class="class">
|
|
<dt id="selectors.EpollSelector">
|
|
<em class="property">class </em><code class="sig-prename descclassname">selectors.</code><code class="sig-name descname">EpollSelector</code><a class="headerlink" href="#selectors.EpollSelector" title="永久链接至目标">¶</a></dt>
|
|
<dd><p>基于 <a class="reference internal" href="select.html#select.epoll" title="select.epoll"><code class="xref py py-func docutils literal notranslate"><span class="pre">select.epoll()</span></code></a> 的选择器。</p>
|
|
<dl class="method">
|
|
<dt id="selectors.EpollSelector.fileno">
|
|
<code class="sig-name descname">fileno</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#selectors.EpollSelector.fileno" title="永久链接至目标">¶</a></dt>
|
|
<dd><p>此方法将返回由下层 <a class="reference internal" href="select.html#select.epoll" title="select.epoll"><code class="xref py py-func docutils literal notranslate"><span class="pre">select.epoll()</span></code></a> 对象所使用的文件描述符。</p>
|
|
</dd></dl>
|
|
|
|
</dd></dl>
|
|
|
|
<dl class="class">
|
|
<dt id="selectors.DevpollSelector">
|
|
<em class="property">class </em><code class="sig-prename descclassname">selectors.</code><code class="sig-name descname">DevpollSelector</code><a class="headerlink" href="#selectors.DevpollSelector" title="永久链接至目标">¶</a></dt>
|
|
<dd><p>基于 <a class="reference internal" href="select.html#select.devpoll" title="select.devpoll"><code class="xref py py-func docutils literal notranslate"><span class="pre">select.devpoll()</span></code></a> 的选择器。</p>
|
|
<dl class="method">
|
|
<dt id="selectors.DevpollSelector.fileno">
|
|
<code class="sig-name descname">fileno</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#selectors.DevpollSelector.fileno" title="永久链接至目标">¶</a></dt>
|
|
<dd><p>此方法将返回由下层 <a class="reference internal" href="select.html#select.devpoll" title="select.devpoll"><code class="xref py py-func docutils literal notranslate"><span class="pre">select.devpoll()</span></code></a> 对象所使用的文件描述符。</p>
|
|
</dd></dl>
|
|
|
|
<div class="versionadded">
|
|
<p><span class="versionmodified added">3.5 新版功能.</span></p>
|
|
</div>
|
|
</dd></dl>
|
|
|
|
<dl class="class">
|
|
<dt id="selectors.KqueueSelector">
|
|
<em class="property">class </em><code class="sig-prename descclassname">selectors.</code><code class="sig-name descname">KqueueSelector</code><a class="headerlink" href="#selectors.KqueueSelector" title="永久链接至目标">¶</a></dt>
|
|
<dd><p>基于 <a class="reference internal" href="select.html#select.kqueue" title="select.kqueue"><code class="xref py py-func docutils literal notranslate"><span class="pre">select.kqueue()</span></code></a> 的选择器。</p>
|
|
<dl class="method">
|
|
<dt id="selectors.KqueueSelector.fileno">
|
|
<code class="sig-name descname">fileno</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#selectors.KqueueSelector.fileno" title="永久链接至目标">¶</a></dt>
|
|
<dd><p>此方法将返回由下层 <a class="reference internal" href="select.html#select.kqueue" title="select.kqueue"><code class="xref py py-func docutils literal notranslate"><span class="pre">select.kqueue()</span></code></a> 对象所使用的文件描述符。</p>
|
|
</dd></dl>
|
|
|
|
</dd></dl>
|
|
|
|
</section>
|
|
<section id="examples">
|
|
<h2>例子<a class="headerlink" href="#examples" title="永久链接至标题">¶</a></h2>
|
|
<p>下面是一个简单的回显服务器实现:</p>
|
|
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">selectors</span>
|
|
<span class="kn">import</span> <span class="nn">socket</span>
|
|
|
|
<span class="n">sel</span> <span class="o">=</span> <span class="n">selectors</span><span class="o">.</span><span class="n">DefaultSelector</span><span class="p">()</span>
|
|
|
|
<span class="k">def</span> <span class="nf">accept</span><span class="p">(</span><span class="n">sock</span><span class="p">,</span> <span class="n">mask</span><span class="p">):</span>
|
|
<span class="n">conn</span><span class="p">,</span> <span class="n">addr</span> <span class="o">=</span> <span class="n">sock</span><span class="o">.</span><span class="n">accept</span><span class="p">()</span> <span class="c1"># Should be ready</span>
|
|
<span class="nb">print</span><span class="p">(</span><span class="s1">'accepted'</span><span class="p">,</span> <span class="n">conn</span><span class="p">,</span> <span class="s1">'from'</span><span class="p">,</span> <span class="n">addr</span><span class="p">)</span>
|
|
<span class="n">conn</span><span class="o">.</span><span class="n">setblocking</span><span class="p">(</span><span class="kc">False</span><span class="p">)</span>
|
|
<span class="n">sel</span><span class="o">.</span><span class="n">register</span><span class="p">(</span><span class="n">conn</span><span class="p">,</span> <span class="n">selectors</span><span class="o">.</span><span class="n">EVENT_READ</span><span class="p">,</span> <span class="n">read</span><span class="p">)</span>
|
|
|
|
<span class="k">def</span> <span class="nf">read</span><span class="p">(</span><span class="n">conn</span><span class="p">,</span> <span class="n">mask</span><span class="p">):</span>
|
|
<span class="n">data</span> <span class="o">=</span> <span class="n">conn</span><span class="o">.</span><span class="n">recv</span><span class="p">(</span><span class="mi">1000</span><span class="p">)</span> <span class="c1"># Should be ready</span>
|
|
<span class="k">if</span> <span class="n">data</span><span class="p">:</span>
|
|
<span class="nb">print</span><span class="p">(</span><span class="s1">'echoing'</span><span class="p">,</span> <span class="nb">repr</span><span class="p">(</span><span class="n">data</span><span class="p">),</span> <span class="s1">'to'</span><span class="p">,</span> <span class="n">conn</span><span class="p">)</span>
|
|
<span class="n">conn</span><span class="o">.</span><span class="n">send</span><span class="p">(</span><span class="n">data</span><span class="p">)</span> <span class="c1"># Hope it won't block</span>
|
|
<span class="k">else</span><span class="p">:</span>
|
|
<span class="nb">print</span><span class="p">(</span><span class="s1">'closing'</span><span class="p">,</span> <span class="n">conn</span><span class="p">)</span>
|
|
<span class="n">sel</span><span class="o">.</span><span class="n">unregister</span><span class="p">(</span><span class="n">conn</span><span class="p">)</span>
|
|
<span class="n">conn</span><span class="o">.</span><span class="n">close</span><span class="p">()</span>
|
|
|
|
<span class="n">sock</span> <span class="o">=</span> <span class="n">socket</span><span class="o">.</span><span class="n">socket</span><span class="p">()</span>
|
|
<span class="n">sock</span><span class="o">.</span><span class="n">bind</span><span class="p">((</span><span class="s1">'localhost'</span><span class="p">,</span> <span class="mi">1234</span><span class="p">))</span>
|
|
<span class="n">sock</span><span class="o">.</span><span class="n">listen</span><span class="p">(</span><span class="mi">100</span><span class="p">)</span>
|
|
<span class="n">sock</span><span class="o">.</span><span class="n">setblocking</span><span class="p">(</span><span class="kc">False</span><span class="p">)</span>
|
|
<span class="n">sel</span><span class="o">.</span><span class="n">register</span><span class="p">(</span><span class="n">sock</span><span class="p">,</span> <span class="n">selectors</span><span class="o">.</span><span class="n">EVENT_READ</span><span class="p">,</span> <span class="n">accept</span><span class="p">)</span>
|
|
|
|
<span class="k">while</span> <span class="kc">True</span><span class="p">:</span>
|
|
<span class="n">events</span> <span class="o">=</span> <span class="n">sel</span><span class="o">.</span><span class="n">select</span><span class="p">()</span>
|
|
<span class="k">for</span> <span class="n">key</span><span class="p">,</span> <span class="n">mask</span> <span class="ow">in</span> <span class="n">events</span><span class="p">:</span>
|
|
<span class="n">callback</span> <span class="o">=</span> <span class="n">key</span><span class="o">.</span><span class="n">data</span>
|
|
<span class="n">callback</span><span class="p">(</span><span class="n">key</span><span class="o">.</span><span class="n">fileobj</span><span class="p">,</span> <span class="n">mask</span><span class="p">)</span>
|
|
</pre></div>
|
|
</div>
|
|
</section>
|
|
</section>
|
|
|
|
|
|
</div>
|
|
</div>
|
|
</div>
|
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<div class="sphinxsidebar" role="navigation" aria-label="main navigation">
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<div class="sphinxsidebarwrapper">
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<h3><a href="../contents.html">目录</a></h3>
|
|
<ul>
|
|
<li><a class="reference internal" href="#"><code class="xref py py-mod docutils literal notranslate"><span class="pre">selectors</span></code> --- 高级 I/O 复用库</a><ul>
|
|
<li><a class="reference internal" href="#introduction">概述</a></li>
|
|
<li><a class="reference internal" href="#classes">类</a></li>
|
|
<li><a class="reference internal" href="#examples">例子</a></li>
|
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</ul>
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</li>
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<h4>上一个主题</h4>
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<p class="topless"><a href="select.html"
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title="上一章"><code class="xref py py-mod docutils literal notranslate"><span class="pre">select</span></code> --- 等待 I/O 完成</a></p>
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<h4>下一个主题</h4>
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<p class="topless"><a href="asyncore.html"
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title="下一章"><code class="xref py py-mod docutils literal notranslate"><span class="pre">asyncore</span></code> --- 异步套接字处理器</a></p>
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<div role="note" aria-label="source link">
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<h3>本页</h3>
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<ul class="this-page-menu">
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<li><a href="../bugs.html">报告 Bug</a></li>
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<li>
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<a href="https://github.com/python/cpython/blob/3.8/Doc/library/selectors.rst"
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rel="nofollow">显示源代码
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>索引</a></li>
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