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<section id="module-selectors">
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<span id="selectors-high-level-i-o-multiplexing"></span><h1><code class="xref py py-mod docutils literal notranslate"><span class="pre">selectors</span></code> — High-level I/O multiplexing<a class="headerlink" href="#module-selectors" title="Link to this heading">¶</a></h1>
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<div class="versionadded">
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<p><span class="versionmodified added">Added in version 3.4.</span></p>
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<p><strong>Source code:</strong> <a class="extlink-source reference external" href="https://github.com/python/cpython/tree/3.13/Lib/selectors.py">Lib/selectors.py</a></p>
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<section id="introduction">
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<h2>Introduction<a class="headerlink" href="#introduction" title="Link to this heading">¶</a></h2>
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<p>This module allows high-level and efficient I/O multiplexing, built upon the
|
||
<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> module primitives. Users are encouraged to use this module
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instead, unless they want precise control over the OS-level primitives used.</p>
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<p>It defines a <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> abstract base class, along with several
|
||
concrete implementations (<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>…),
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that can be used to wait for I/O readiness notification on multiple file
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objects. In the following, “file object” refers to any object with a
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||
<a class="reference internal" href="io.html#io.IOBase.fileno" title="io.IOBase.fileno"><code class="xref py py-meth docutils literal notranslate"><span class="pre">fileno()</span></code></a> method, or a raw file descriptor. See <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> is an alias to the most efficient implementation
|
||
available on the current platform: this should be the default choice for most
|
||
users.</p>
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<div class="admonition note">
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<p class="admonition-title">Note</p>
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<p>The type of file objects supported depends on the platform: on Windows,
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sockets are supported, but not pipes, whereas on Unix, both are supported
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(some other types may be supported as well, such as fifos or special file
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devices).</p>
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</div>
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<div class="admonition seealso">
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<p class="admonition-title">See also</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>Low-level I/O multiplexing module.</p>
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</dd>
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</dl>
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</div>
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<div class="availability docutils container">
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<p><a class="reference internal" href="intro.html#availability"><span class="std std-ref">Availability</span></a>: not WASI.</p>
|
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<p>This module does not work or is not available on WebAssembly. See
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<a class="reference internal" href="intro.html#wasm-availability"><span class="std std-ref">WebAssembly platforms</span></a> for more information.</p>
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||
</div>
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</section>
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<section id="classes">
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<h2>Classes<a class="headerlink" href="#classes" title="Link to this heading">¶</a></h2>
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<p>Classes hierarchy:</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>In the following, <em>events</em> is a bitwise mask indicating which I/O events should
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be waited for on a given file object. It can be a combination of the modules
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constants below:</p>
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<blockquote>
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<div><table class="docutils align-default">
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<thead>
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<tr class="row-odd"><th class="head"><p>Constant</p></th>
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<th class="head"><p>Meaning</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><dl class="py data">
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<dt class="sig sig-object py" id="selectors.EVENT_READ">
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<span class="sig-prename descclassname"><span class="pre">selectors.</span></span><span class="sig-name descname"><span class="pre">EVENT_READ</span></span><a class="headerlink" href="#selectors.EVENT_READ" title="Link to this definition">¶</a></dt>
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<dd></dd></dl>
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</td>
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<td><p>Available for read</p></td>
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</tr>
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<tr class="row-odd"><td><dl class="py data">
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<dt class="sig sig-object py" id="selectors.EVENT_WRITE">
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<span class="sig-prename descclassname"><span class="pre">selectors.</span></span><span class="sig-name descname"><span class="pre">EVENT_WRITE</span></span><a class="headerlink" href="#selectors.EVENT_WRITE" title="Link to this definition">¶</a></dt>
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<dd></dd></dl>
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|
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</td>
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<td><p>Available for write</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="py class">
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||
<dt class="sig sig-object py" id="selectors.SelectorKey">
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||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">selectors.</span></span><span class="sig-name descname"><span class="pre">SelectorKey</span></span><a class="headerlink" href="#selectors.SelectorKey" title="Link to this definition">¶</a></dt>
|
||
<dd><p>A <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> is a <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> used to
|
||
associate a file object to its underlying file descriptor, selected event
|
||
mask and attached data. It is returned by several <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>
|
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methods.</p>
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<dl class="py attribute">
|
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<dt class="sig sig-object py" id="selectors.SelectorKey.fileobj">
|
||
<span class="sig-name descname"><span class="pre">fileobj</span></span><a class="headerlink" href="#selectors.SelectorKey.fileobj" title="Link to this definition">¶</a></dt>
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<dd><p>File object registered.</p>
|
||
</dd></dl>
|
||
|
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<dl class="py attribute">
|
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<dt class="sig sig-object py" id="selectors.SelectorKey.fd">
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<span class="sig-name descname"><span class="pre">fd</span></span><a class="headerlink" href="#selectors.SelectorKey.fd" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Underlying file descriptor.</p>
|
||
</dd></dl>
|
||
|
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<dl class="py attribute">
|
||
<dt class="sig sig-object py" id="selectors.SelectorKey.events">
|
||
<span class="sig-name descname"><span class="pre">events</span></span><a class="headerlink" href="#selectors.SelectorKey.events" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Events that must be waited for on this file object.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="py attribute">
|
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<dt class="sig sig-object py" id="selectors.SelectorKey.data">
|
||
<span class="sig-name descname"><span class="pre">data</span></span><a class="headerlink" href="#selectors.SelectorKey.data" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Optional opaque data associated to this file object: for example, this
|
||
could be used to store a per-client session ID.</p>
|
||
</dd></dl>
|
||
|
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</dd></dl>
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|
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<dl class="py class">
|
||
<dt class="sig sig-object py" id="selectors.BaseSelector">
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||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">selectors.</span></span><span class="sig-name descname"><span class="pre">BaseSelector</span></span><a class="headerlink" href="#selectors.BaseSelector" title="Link to this definition">¶</a></dt>
|
||
<dd><p>A <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> is used to wait for I/O event readiness on multiple
|
||
file objects. It supports file stream registration, unregistration, and a
|
||
method to wait for I/O events on those streams, with an optional timeout.
|
||
It’s an abstract base class, so cannot be instantiated. Use
|
||
<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> instead, or one of <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> etc. if you want to specifically use an
|
||
implementation, and your platform supports it.
|
||
<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> and its concrete implementations support the
|
||
<a class="reference internal" href="../glossary.html#term-context-manager"><span class="xref std std-term">context manager</span></a> protocol.</p>
|
||
<dl class="py method">
|
||
<dt class="sig sig-object py" id="selectors.BaseSelector.register">
|
||
<em class="property"><span class="k"><span class="pre">abstractmethod</span></span><span class="w"> </span></em><span class="sig-name descname"><span class="pre">register</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">fileobj</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">events</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">data</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#selectors.BaseSelector.register" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Register a file object for selection, monitoring it for I/O events.</p>
|
||
<p><em>fileobj</em> is the file object to monitor. It may either be an integer
|
||
file descriptor or an object with a <code class="docutils literal notranslate"><span class="pre">fileno()</span></code> method.
|
||
<em>events</em> is a bitwise mask of events to monitor.
|
||
<em>data</em> is an opaque object.</p>
|
||
<p>This returns a new <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> instance, or raises a
|
||
<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> in case of invalid event mask or file descriptor, or
|
||
<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> if the file object is already registered.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="py method">
|
||
<dt class="sig sig-object py" id="selectors.BaseSelector.unregister">
|
||
<em class="property"><span class="k"><span class="pre">abstractmethod</span></span><span class="w"> </span></em><span class="sig-name descname"><span class="pre">unregister</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">fileobj</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#selectors.BaseSelector.unregister" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Unregister a file object from selection, removing it from monitoring. A
|
||
file object shall be unregistered prior to being closed.</p>
|
||
<p><em>fileobj</em> must be a file object previously registered.</p>
|
||
<p>This returns the associated <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> instance, or raises a
|
||
<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> if <em>fileobj</em> is not registered. 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> if <em>fileobj</em> is invalid (e.g. it has no <code class="docutils literal notranslate"><span class="pre">fileno()</span></code>
|
||
method or its <code class="docutils literal notranslate"><span class="pre">fileno()</span></code> method has an invalid return value).</p>
|
||
</dd></dl>
|
||
|
||
<dl class="py method">
|
||
<dt class="sig sig-object py" id="selectors.BaseSelector.modify">
|
||
<span class="sig-name descname"><span class="pre">modify</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">fileobj</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">events</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">data</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#selectors.BaseSelector.modify" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Change a registered file object’s monitored events or attached data.</p>
|
||
<p>This is equivalent to <code class="docutils literal notranslate"><span class="pre">BaseSelector.unregister(fileobj)</span></code> followed
|
||
by <code class="docutils literal notranslate"><span class="pre">BaseSelector.register(fileobj,</span> <span class="pre">events,</span> <span class="pre">data)</span></code>, except that it
|
||
can be implemented more efficiently.</p>
|
||
<p>This returns a new <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> instance, or raises a
|
||
<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> in case of invalid event mask or file descriptor, or
|
||
<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> if the file object is not registered.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="py method">
|
||
<dt class="sig sig-object py" id="selectors.BaseSelector.select">
|
||
<em class="property"><span class="k"><span class="pre">abstractmethod</span></span><span class="w"> </span></em><span class="sig-name descname"><span class="pre">select</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">timeout</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#selectors.BaseSelector.select" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Wait until some registered file objects become ready, or the timeout
|
||
expires.</p>
|
||
<p>If <code class="docutils literal notranslate"><span class="pre">timeout</span> <span class="pre">></span> <span class="pre">0</span></code>, this specifies the maximum wait time, in seconds.
|
||
If <code class="docutils literal notranslate"><span class="pre">timeout</span> <span class="pre"><=</span> <span class="pre">0</span></code>, the call won’t block, and will report the currently
|
||
ready file objects.
|
||
If <em>timeout</em> is <code class="docutils literal notranslate"><span class="pre">None</span></code>, the call will block until a monitored file object
|
||
becomes ready.</p>
|
||
<p>This returns a list of <code class="docutils literal notranslate"><span class="pre">(key,</span> <span class="pre">events)</span></code> tuples, one for each ready file
|
||
object.</p>
|
||
<p><em>key</em> is the <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> instance corresponding to a ready file
|
||
object.
|
||
<em>events</em> is a bitmask of events ready on this file object.</p>
|
||
<div class="admonition note">
|
||
<p class="admonition-title">Note</p>
|
||
<p>This method can return before any file object becomes ready or the
|
||
timeout has elapsed if the current process receives a signal: in this
|
||
case, an empty list will be returned.</p>
|
||
</div>
|
||
<div class="versionchanged">
|
||
<p><span class="versionmodified changed">Changed in version 3.5: </span>The selector is now retried with a recomputed timeout when interrupted
|
||
by a signal if the signal handler did not raise an exception (see
|
||
<span class="target" id="index-0"></span><a class="pep reference external" href="https://peps.python.org/pep-0475/"><strong>PEP 475</strong></a> for the rationale), instead of returning an empty list
|
||
of events before the timeout.</p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="py method">
|
||
<dt class="sig sig-object py" id="selectors.BaseSelector.close">
|
||
<span class="sig-name descname"><span class="pre">close</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#selectors.BaseSelector.close" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Close the selector.</p>
|
||
<p>This must be called to make sure that any underlying resource is freed.
|
||
The selector shall not be used once it has been closed.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="py method">
|
||
<dt class="sig sig-object py" id="selectors.BaseSelector.get_key">
|
||
<span class="sig-name descname"><span class="pre">get_key</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">fileobj</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#selectors.BaseSelector.get_key" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Return the key associated with a registered file object.</p>
|
||
<p>This returns the <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> instance associated to this file
|
||
object, or raises <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> if the file object is not registered.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="py method">
|
||
<dt class="sig sig-object py" id="selectors.BaseSelector.get_map">
|
||
<em class="property"><span class="k"><span class="pre">abstractmethod</span></span><span class="w"> </span></em><span class="sig-name descname"><span class="pre">get_map</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#selectors.BaseSelector.get_map" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Return a mapping of file objects to selector keys.</p>
|
||
<p>This returns a <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> instance mapping
|
||
registered file objects to their associated <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>
|
||
instance.</p>
|
||
</dd></dl>
|
||
|
||
</dd></dl>
|
||
|
||
<dl class="py class">
|
||
<dt class="sig sig-object py" id="selectors.DefaultSelector">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">selectors.</span></span><span class="sig-name descname"><span class="pre">DefaultSelector</span></span><a class="headerlink" href="#selectors.DefaultSelector" title="Link to this definition">¶</a></dt>
|
||
<dd><p>The default selector class, using the most efficient implementation
|
||
available on the current platform. This should be the default choice for
|
||
most users.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="py class">
|
||
<dt class="sig sig-object py" id="selectors.SelectSelector">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">selectors.</span></span><span class="sig-name descname"><span class="pre">SelectSelector</span></span><a class="headerlink" href="#selectors.SelectSelector" title="Link to this definition">¶</a></dt>
|
||
<dd><p><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>-based selector.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="py class">
|
||
<dt class="sig sig-object py" id="selectors.PollSelector">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">selectors.</span></span><span class="sig-name descname"><span class="pre">PollSelector</span></span><a class="headerlink" href="#selectors.PollSelector" title="Link to this definition">¶</a></dt>
|
||
<dd><p><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>-based selector.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="py class">
|
||
<dt class="sig sig-object py" id="selectors.EpollSelector">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">selectors.</span></span><span class="sig-name descname"><span class="pre">EpollSelector</span></span><a class="headerlink" href="#selectors.EpollSelector" title="Link to this definition">¶</a></dt>
|
||
<dd><p><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>-based selector.</p>
|
||
<dl class="py method">
|
||
<dt class="sig sig-object py" id="selectors.EpollSelector.fileno">
|
||
<span class="sig-name descname"><span class="pre">fileno</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#selectors.EpollSelector.fileno" title="Link to this definition">¶</a></dt>
|
||
<dd><p>This returns the file descriptor used by the underlying
|
||
<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> object.</p>
|
||
</dd></dl>
|
||
|
||
</dd></dl>
|
||
|
||
<dl class="py class">
|
||
<dt class="sig sig-object py" id="selectors.DevpollSelector">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">selectors.</span></span><span class="sig-name descname"><span class="pre">DevpollSelector</span></span><a class="headerlink" href="#selectors.DevpollSelector" title="Link to this definition">¶</a></dt>
|
||
<dd><p><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>-based selector.</p>
|
||
<dl class="py method">
|
||
<dt class="sig sig-object py" id="selectors.DevpollSelector.fileno">
|
||
<span class="sig-name descname"><span class="pre">fileno</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#selectors.DevpollSelector.fileno" title="Link to this definition">¶</a></dt>
|
||
<dd><p>This returns the file descriptor used by the underlying
|
||
<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> object.</p>
|
||
</dd></dl>
|
||
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.5.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="py class">
|
||
<dt class="sig sig-object py" id="selectors.KqueueSelector">
|
||
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">selectors.</span></span><span class="sig-name descname"><span class="pre">KqueueSelector</span></span><a class="headerlink" href="#selectors.KqueueSelector" title="Link to this definition">¶</a></dt>
|
||
<dd><p><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>-based selector.</p>
|
||
<dl class="py method">
|
||
<dt class="sig sig-object py" id="selectors.KqueueSelector.fileno">
|
||
<span class="sig-name descname"><span class="pre">fileno</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#selectors.KqueueSelector.fileno" title="Link to this definition">¶</a></dt>
|
||
<dd><p>This returns the file descriptor used by the underlying
|
||
<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> object.</p>
|
||
</dd></dl>
|
||
|
||
</dd></dl>
|
||
|
||
</section>
|
||
<section id="examples">
|
||
<h2>Examples<a class="headerlink" href="#examples" title="Link to this heading">¶</a></h2>
|
||
<p>Here is a simple echo server implementation:</p>
|
||
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span><span class="w"> </span><span class="nn">selectors</span>
|
||
<span class="kn">import</span><span class="w"> </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="w"> </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="w"> </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 class="clearer"></div>
|
||
</div>
|
||
</div>
|
||
</div>
|
||
<div class="sphinxsidebar" role="navigation" aria-label="Main">
|
||
<div class="sphinxsidebarwrapper">
|
||
<div>
|
||
<h3><a href="../contents.html">Table of Contents</a></h3>
|
||
<ul>
|
||
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