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<p class='location'>Trait Executor</p><div class="sidebar-elems"><div class="block items"><a class="sidebar-title" href="#required-methods">Required Methods</a><div class="sidebar-links"><a href="#tymethod.spawn">spawn</a></div><a class="sidebar-title" href="#provided-methods">Provided Methods</a><div class="sidebar-links"><a href="#method.status">status</a></div><a class="sidebar-title" href="#foreign-impls">Implementations on Foreign Types</a><div class="sidebar-links"><a href="#impl-Executor">Box<E></a></div><a class="sidebar-title" href="#implementors">Implementors</a></div><p class='location'><a href='index.html'>tokio_executor</a></p><script>window.sidebarCurrent = {name: 'Executor', ty: 'trait', relpath: ''};</script><script defer src="sidebar-items.js"></script></div>
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<h1 class='fqn'><span class='in-band'>Trait <a href='index.html'>tokio_executor</a>::<wbr><a class="trait" href=''>Executor</a></span><span class='out-of-band'><span id='render-detail'>
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[<span class='inner'>−</span>]
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</span><a class='srclink' href='../src/tokio_executor/lib.rs.html#111-185' title='goto source code'>[src]</a></span></h1>
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<pre class='rust trait'>pub trait Executor {
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fn <a href='#tymethod.spawn' class='fnname'>spawn</a>(<br> &mut self, <br> future: <a class="struct" href="https://doc.rust-lang.org/nightly/alloc/boxed/struct.Box.html" title="struct alloc::boxed::Box">Box</a><<a class="trait" href="../futures/future/trait.Future.html" title="trait futures::future::Future">Future</a><Item = <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.unit.html">()</a>, Error = <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.unit.html">()</a>> + <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Send.html" title="trait core::marker::Send">Send</a>><br> ) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.unit.html">()</a>, <a class="struct" href="../tokio_executor/struct.SpawnError.html" title="struct tokio_executor::SpawnError">SpawnError</a>>;
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fn <a href='#method.status' class='fnname'>status</a>(&self) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.unit.html">()</a>, <a class="struct" href="../tokio_executor/struct.SpawnError.html" title="struct tokio_executor::SpawnError">SpawnError</a>> { ... }
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}</pre><div class='docblock'><p>A value that executes futures.</p>
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<p>The <a href="#tymethod.spawn"><code>spawn</code></a> function is used to submit a future to an executor. Once
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submitted, the executor takes ownership of the future and becomes
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responsible for driving the future to completion.</p>
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<p>The strategy employed by the executor to handle the future is less defined
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and is left up to the <code>Executor</code> implementation. The <code>Executor</code> instance is
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expected to call <a href="https://docs.rs/futures/0.1/futures/future/trait.Future.html#tymethod.poll"><code>poll</code></a> on the future once it has been notified, however
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the "when" and "how" can vary greatly.</p>
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<p>For example, the executor might be a thread pool, in which case a set of
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threads have already been spawned up and the future is inserted into a
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queue. A thread will acquire the future and poll it.</p>
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<p>The <code>Executor</code> trait is only for futures that <strong>are</strong> <code>Send</code>. These are most
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common. There currently is no trait that describes executors that operate
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entirely on the current thread (i.e., are able to spawn futures that are not
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<code>Send</code>). Note that single threaded executors can still implement <code>Executor</code>,
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but only futures that are <code>Send</code> can be spawned via the trait.</p>
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<h1 id="errors" class="section-header"><a href="#errors">Errors</a></h1>
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<p>The <a href="#tymethod.spawn"><code>spawn</code></a> function returns <code>Result</code> with an error type of <code>SpawnError</code>.
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This error type represents the reason that the executor was unable to spawn
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the future. The two current represented scenarios are:</p>
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<ul>
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<li>An executor being at capacity or full. As such, the executor is not able
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to accept a new future. This error state is expected to be transient.</li>
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<li>An executor has been shutdown and can no longer accept new futures. This
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error state is expected to be permanent.</li>
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</ul>
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<p>If a caller encounters an at capacity error, the caller should try to shed
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load. This can be as simple as dropping the future that was spawned.</p>
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<p>If the caller encounters a shutdown error, the caller should attempt to
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gracefully shutdown.</p>
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<h1 id="examples" class="section-header"><a href="#examples">Examples</a></h1>
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<pre class="rust rust-example-rendered">
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<span class="kw">use</span> <span class="ident">futures</span>::<span class="ident">future</span>::<span class="ident">lazy</span>;
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<span class="ident">my_executor</span>.<span class="ident">spawn</span>(<span class="ident">Box</span>::<span class="ident">new</span>(<span class="ident">lazy</span>(<span class="op">||</span> {
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<span class="macro">println</span><span class="macro">!</span>(<span class="string">"running on the executor"</span>);
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<span class="prelude-val">Ok</span>(())
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}))).<span class="ident">unwrap</span>();</pre>
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</div>
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<h2 id='required-methods' class='small-section-header'>
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Required Methods<a href='#required-methods' class='anchor'></a>
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</h2>
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<div class='methods'>
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<h3 id='tymethod.spawn' class='method'><span id='spawn.v' class='invisible'><code>fn <a href='#tymethod.spawn' class='fnname'>spawn</a>(<br> &mut self, <br> future: <a class="struct" href="https://doc.rust-lang.org/nightly/alloc/boxed/struct.Box.html" title="struct alloc::boxed::Box">Box</a><<a class="trait" href="../futures/future/trait.Future.html" title="trait futures::future::Future">Future</a><Item = <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.unit.html">()</a>, Error = <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.unit.html">()</a>> + <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Send.html" title="trait core::marker::Send">Send</a>><br>) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.unit.html">()</a>, <a class="struct" href="../tokio_executor/struct.SpawnError.html" title="struct tokio_executor::SpawnError">SpawnError</a>></code></span></h3><div class='docblock'><p>Spawns a future object to run on this executor.</p>
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<p><code>future</code> is passed to the executor, which will begin running it. The
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future may run on the current thread or another thread at the discretion
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of the <code>Executor</code> implementation.</p>
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<h1 id="panics" class="section-header"><a href="#panics">Panics</a></h1>
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<p>Implementors are encouraged to avoid panics. However, a panic is
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permitted and the caller should check the implementation specific
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||
documentation for more details on possible panics.</p>
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<h1 id="examples-1" class="section-header"><a href="#examples-1">Examples</a></h1>
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<pre class="rust rust-example-rendered">
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<span class="kw">use</span> <span class="ident">futures</span>::<span class="ident">future</span>::<span class="ident">lazy</span>;
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<span class="ident">my_executor</span>.<span class="ident">spawn</span>(<span class="ident">Box</span>::<span class="ident">new</span>(<span class="ident">lazy</span>(<span class="op">||</span> {
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<span class="macro">println</span><span class="macro">!</span>(<span class="string">"running on the executor"</span>);
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<span class="prelude-val">Ok</span>(())
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}))).<span class="ident">unwrap</span>();</pre>
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</div></div>
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<h2 id='provided-methods' class='small-section-header'>
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Provided Methods<a href='#provided-methods' class='anchor'></a>
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</h2>
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<div class='methods'>
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<h3 id='method.status' class='method'><span id='status.v' class='invisible'><code>fn <a href='#method.status' class='fnname'>status</a>(&self) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.unit.html">()</a>, <a class="struct" href="../tokio_executor/struct.SpawnError.html" title="struct tokio_executor::SpawnError">SpawnError</a>></code></span></h3><div class='docblock'><p>Provides a best effort <strong>hint</strong> to whether or not <code>spawn</code> will succeed.</p>
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<p>This function may return both false positives <strong>and</strong> false negatives.
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If <code>status</code> returns <code>Ok</code>, then a call to <code>spawn</code> will <em>probably</em>
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succeed, but may fail. If <code>status</code> returns <code>Err</code>, a call to <code>spawn</code> will
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<em>probably</em> fail, but may succeed.</p>
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<p>This allows a caller to avoid creating the task if the call to <code>spawn</code>
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has a high likelihood of failing.</p>
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<h1 id="panics-1" class="section-header"><a href="#panics-1">Panics</a></h1>
|
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<p>This function must not panic. Implementors must ensure that panics do
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not happen.</p>
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<h1 id="examples-2" class="section-header"><a href="#examples-2">Examples</a></h1>
|
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<pre class="rust rust-example-rendered">
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<span class="kw">use</span> <span class="ident">futures</span>::<span class="ident">future</span>::<span class="ident">lazy</span>;
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<span class="kw">if</span> <span class="ident">my_executor</span>.<span class="ident">status</span>().<span class="ident">is_ok</span>() {
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<span class="ident">my_executor</span>.<span class="ident">spawn</span>(<span class="ident">Box</span>::<span class="ident">new</span>(<span class="ident">lazy</span>(<span class="op">||</span> {
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<span class="macro">println</span><span class="macro">!</span>(<span class="string">"running on the executor"</span>);
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<span class="prelude-val">Ok</span>(())
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||
}))).<span class="ident">unwrap</span>();
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} <span class="kw">else</span> {
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<span class="macro">println</span><span class="macro">!</span>(<span class="string">"the executor is not in a good state"</span>);
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||
}</pre>
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</div></div>
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<h2 id='foreign-impls' class='small-section-header'>
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Implementations on Foreign Types<a href='#foreign-impls' class='anchor'></a>
|
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</h2>
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<h3 id='impl-Executor' class='impl'><span class='in-band'><code>impl<E: <a class="trait" href="../tokio_executor/trait.Executor.html" title="trait tokio_executor::Executor">Executor</a> + ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>> <a class="trait" href="../tokio_executor/trait.Executor.html" title="trait tokio_executor::Executor">Executor</a> for <a class="struct" href="https://doc.rust-lang.org/nightly/alloc/boxed/struct.Box.html" title="struct alloc::boxed::Box">Box</a><E></code><a href='#impl-Executor' class='anchor'></a></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../src/tokio_executor/lib.rs.html#187-204' title='goto source code'>[src]</a></span></h3>
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<span class='docblock autohide'><div class='impl-items'><h4 id='method.spawn' class="method"><span id='spawn.v-1' class='invisible'><code>fn <a href='#method.spawn' class='fnname'>spawn</a>(<br> &mut self, <br> future: <a class="struct" href="https://doc.rust-lang.org/nightly/alloc/boxed/struct.Box.html" title="struct alloc::boxed::Box">Box</a><<a class="trait" href="../futures/future/trait.Future.html" title="trait futures::future::Future">Future</a><Item = <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.unit.html">()</a>, Error = <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.unit.html">()</a>> + <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Send.html" title="trait core::marker::Send">Send</a>><br>) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.unit.html">()</a>, <a class="struct" href="../tokio_executor/struct.SpawnError.html" title="struct tokio_executor::SpawnError">SpawnError</a>></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../src/tokio_executor/lib.rs.html#188-192' title='goto source code'>[src]</a></span></h4>
|
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<h4 id='method.status-1' class="method"><span id='status.v-1' class='invisible'><code>fn <a href='#method.status' class='fnname'>status</a>(&self) -> <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.unit.html">()</a>, <a class="struct" href="../tokio_executor/struct.SpawnError.html" title="struct tokio_executor::SpawnError">SpawnError</a>></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../src/tokio_executor/lib.rs.html#201-203' title='goto source code'>[src]</a></span></h4>
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<li><div class='out-of-band'><a class='srclink' href='../src/tokio_executor/global.rs.html#75-95' title='goto source code'>[src]</a></div><code>impl Executor for <a class="struct" href="../tokio_executor/struct.DefaultExecutor.html" title="struct tokio_executor::DefaultExecutor">DefaultExecutor</a></code></li>
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