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| <section id="cancellation-of-futures-f-nocancel-cancelonshutdownexecutor"> |
| <h1>Cancellation of futures: <code class="docutils literal notranslate"><span class="pre">f_nocancel</span></code>, <code class="docutils literal notranslate"><span class="pre">CancelOnShutdownExecutor</span></code><a class="headerlink" href="#cancellation-of-futures-f-nocancel-cancelonshutdownexecutor" title="Permalink to this headline">¶</a></h1> |
| <section id="futures-api"> |
| <h2>Futures API<a class="headerlink" href="#futures-api" title="Permalink to this headline">¶</a></h2> |
| <dl class="py function"> |
| <dt class="sig sig-object py" id="more_executors.f_nocancel"> |
| <span class="sig-prename descclassname"><span class="pre">more_executors.</span></span><span class="sig-name descname"><span class="pre">f_nocancel</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">future</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#more_executors.f_nocancel" title="Permalink to this definition">¶</a></dt> |
| <dd><p>Wrap a future to block cancellation.</p> |
| <p>Signature: <code class="code docutils literal notranslate"><span class="pre">Future<X></span> <span class="pre">⟶</span> <span class="pre">Future<X></span></code></p> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Parameters</dt> |
| <dd class="field-odd"><p><strong>future</strong> (<a class="reference external" href="https://docs.python.org/3/library/concurrent.futures.html#concurrent.futures.Future" title="(in Python v3.11)"><em>Future</em></a>) – Any future.</p> |
| </dd> |
| <dt class="field-even">Returns</dt> |
| <dd class="field-even"><p><dl class="simple"> |
| <dt><a class="reference external" href="https://docs.python.org/3/library/concurrent.futures.html#concurrent.futures.Future" title="(in Python v3.11)"><code class="xref py py-class docutils literal notranslate"><span class="pre">Future</span></code></a></dt><dd><p>A wrapped version of <code class="xref py py-obj docutils literal notranslate"><span class="pre">future</span></code> which cannot be cancelled.</p> |
| </dd> |
| </dl> |
| </p> |
| </dd> |
| </dl> |
| <div class="versionadded"> |
| <p><span class="versionmodified added">New in version 1.19.0.</span></p> |
| </div> |
| </dd></dl> |
| |
| </section> |
| <section id="executors-api"> |
| <h2>Executors API<a class="headerlink" href="#executors-api" title="Permalink to this headline">¶</a></h2> |
| <dl class="py class"> |
| <dt class="sig sig-object py" id="more_executors.CancelOnShutdownExecutor"> |
| <em class="property"><span class="pre">class</span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">more_executors.</span></span><span class="sig-name descname"><span class="pre">CancelOnShutdownExecutor</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">delegate</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">logger</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">name</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">'default'</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#more_executors.CancelOnShutdownExecutor" title="Permalink to this definition">¶</a></dt> |
| <dd><p>An executor which delegates to another executor and cancels all |
| futures when the executor is shut down.</p> |
| <p>This class is useful in conjunction with executors having custom cancel |
| behavior, such as <a class="reference internal" href="poll.html#more_executors.PollExecutor" title="more_executors.PollExecutor"><code class="xref py py-class docutils literal notranslate"><span class="pre">PollExecutor</span></code></a>.</p> |
| <div class="admonition note"> |
| <p class="admonition-title">Note</p> |
| <p>From Python 3.9 onwards, the standard |
| <a class="reference external" href="https://docs.python.org/3/library/concurrent.futures.html#concurrent.futures.Executor.shutdown" title="(in Python v3.11)"><code class="xref py py-meth docutils literal notranslate"><span class="pre">shutdown()</span></code></a> method includes a |
| <code class="docutils literal notranslate"><span class="pre">cancel_futures</span></code> parameter which can be used to cancel futures |
| on shutdown.</p> |
| <p>These two approaches of cancelling futures on shutdown have the |
| following differences:</p> |
| <ul class="simple"> |
| <li><p><code class="docutils literal notranslate"><span class="pre">cancel_futures=True</span></code> will only cancel futures which have not |
| yet started running.</p></li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">CancelOnShutdownExecutor</span></code> will attempt to cancel <em>all</em> incomplete |
| futures, including those which are running.</p></li> |
| </ul> |
| <p>If you’re using other executors from this library and you want to |
| ensure futures are cancelled on shutdown, <code class="docutils literal notranslate"><span class="pre">CancelOnShutdownExecutor</span></code> |
| should be preferred because several of the executor classes in this |
| library do support cancellation of running futures (unlike the executors |
| in the standard library).</p> |
| </div> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Parameters</dt> |
| <dd class="field-odd"><ul class="simple"> |
| <li><p><strong>delegate</strong> (<a class="reference external" href="https://docs.python.org/3/library/concurrent.futures.html#concurrent.futures.Executor" title="(in Python v3.11)"><em>Executor</em></a>) – executor to which callables will be submitted</p></li> |
| <li><p><strong>logger</strong> (<a class="reference external" href="https://docs.python.org/3/library/logging.html#logging.Logger" title="(in Python v3.11)"><em>Logger</em></a>) – a logger used for messages from this executor</p></li> |
| <li><p><strong>name</strong> (<a class="reference external" href="https://docs.python.org/3/library/stdtypes.html#str" title="(in Python v3.11)"><em>str</em></a>) – a name for this executor</p></li> |
| </ul> |
| </dd> |
| </dl> |
| <div class="versionchanged"> |
| <p><span class="versionmodified changed">Changed in version 2.7.0: </span>Introduced <code class="docutils literal notranslate"><span class="pre">name</span></code>.</p> |
| </div> |
| <dl class="py method"> |
| <dt class="sig sig-object py" id="more_executors.CancelOnShutdownExecutor.shutdown"> |
| <span class="sig-name descname"><span class="pre">shutdown</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">wait</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">True</span></span></em>, <em class="sig-param"><span class="o"><span class="pre">**</span></span><span class="n"><span class="pre">_kwargs</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#more_executors.CancelOnShutdownExecutor.shutdown" title="Permalink to this definition">¶</a></dt> |
| <dd><p>Shut down the executor.</p> |
| <p>All futures created by this executor which have not yet been completed |
| will have <a class="reference external" href="https://docs.python.org/3/library/concurrent.futures.html#concurrent.futures.Future.cancel" title="(in Python v3.11)"><code class="xref py py-meth docutils literal notranslate"><span class="pre">cancel()</span></code></a> invoked.</p> |
| <p>Note that there is no guarantee that the cancel will succeed, and only a single |
| attempt is made to cancel any future.</p> |
| </dd></dl> |
| |
| </dd></dl> |
| |
| <dl class="py method"> |
| <dt class="sig sig-object py" id="more_executors.Executors.with_cancel_on_shutdown"> |
| <em class="property"><span class="pre">classmethod</span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">Executors.</span></span><span class="sig-name descname"><span class="pre">with_cancel_on_shutdown</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">executor</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">logger</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="#more_executors.Executors.with_cancel_on_shutdown" title="Permalink to this definition">¶</a></dt> |
| <dd><dl class="field-list simple"> |
| <dt class="field-odd">Returns</dt> |
| <dd class="field-odd"><p>a new executor which attempts to cancel any pending futures when |
| the executor is shut down.</p> |
| </dd> |
| <dt class="field-even">Return type</dt> |
| <dd class="field-even"><p><a class="reference internal" href="#more_executors.CancelOnShutdownExecutor" title="more_executors.CancelOnShutdownExecutor"><em>CancelOnShutdownExecutor</em></a></p> |
| </dd> |
| </dl> |
| </dd></dl> |
| |
| </section> |
| </section> |
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