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<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Seek bytes asynchronously."><title>AsyncSeek in futures_io - Rust</title><script>if(window.location.protocol!=="file:")document.head.insertAdjacentHTML("beforeend","SourceSerif4-Regular-6b053e98.ttf.woff2,FiraSans-Regular-0fe48ade.woff2,FiraSans-Medium-e1aa3f0a.woff2,SourceCodePro-Regular-8badfe75.ttf.woff2,SourceCodePro-Semibold-aa29a496.ttf.woff2".split(",").map(f=>`<link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/${f}">`).join(""))</script><link rel="stylesheet" href="../static.files/normalize-9960930a.css"><link rel="stylesheet" href="../static.files/rustdoc-42caa33d.css"><meta name="rustdoc-vars" data-root-path="../" data-static-root-path="../static.files/" data-current-crate="futures_io" data-themes="" data-resource-suffix="" data-rustdoc-version="1.84.0 (9fc6b4312 2025-01-07)" data-channel="1.84.0" data-search-js="search-92e6798f.js" data-settings-js="settings-0f613d39.js" ><script src="../static.files/storage-59e33391.js"></script><script defer src="sidebar-items.js"></script><script defer src="../static.files/main-5f194d8c.js"></script><noscript><link rel="stylesheet" href="../static.files/noscript-893ab5e7.css"></noscript><link rel="alternate icon" type="image/png" href="../static.files/favicon-32x32-6580c154.png"><link rel="icon" type="image/svg+xml" href="../static.files/favicon-044be391.svg"></head><body class="rustdoc trait"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="mobile-topbar"><button class="sidebar-menu-toggle" title="show sidebar"></button></nav><nav class="sidebar"><div class="sidebar-crate"><h2><a href="../futures_io/index.html">futures_<wbr>io</a><span class="version">0.3.31</span></h2></div><div class="sidebar-elems"><section id="rustdoc-toc"><h2 class="location"><a href="#">Async<wbr>Seek</a></h2><h3><a href="#required-methods">Required Methods</a></h3><ul class="block"><li><a href="#tymethod.poll_seek" title="poll_seek">poll_seek</a></li></ul><h3><a href="#foreign-impls">Implementations on Foreign Types</a></h3><ul class="block"><li><a href="#impl-AsyncSeek-for-%26mut+T" title="&#38;mut T">&#38;mut T</a></li><li><a href="#impl-AsyncSeek-for-Box%3CT%3E" title="Box&#60;T&#62;">Box&#60;T&#62;</a></li><li><a href="#impl-AsyncSeek-for-Pin%3CP%3E" title="Pin&#60;P&#62;">Pin&#60;P&#62;</a></li></ul><h3><a href="#implementors">Implementors</a></h3></section><div id="rustdoc-modnav"><h2 class="in-crate"><a href="index.html">In crate futures_<wbr>io</a></h2></div></div></nav><div class="sidebar-resizer"></div><main><div class="width-limiter"><rustdoc-search></rustdoc-search><section id="main-content" class="content"><div class="main-heading"><span class="rustdoc-breadcrumbs"><a href="index.html">futures_io</a></span><h1>Trait <span class="trait">AsyncSeek</span><button id="copy-path" title="Copy item path to clipboard">Copy item path</button></h1><rustdoc-toolbar></rustdoc-toolbar><span class="sub-heading"><a class="src" href="../src/futures_io/lib.rs.html#220-245">Source</a> </span></div><pre class="rust item-decl"><code>pub trait AsyncSeek {
// Required method
fn <a href="#tymethod.poll_seek" class="fn">poll_seek</a>(
self: <a class="struct" href="https://doc.rust-lang.org/1.84.0/core/pin/struct.Pin.html" title="struct core::pin::Pin">Pin</a>&lt;&amp;mut Self&gt;,
cx: &amp;mut <a class="struct" href="https://doc.rust-lang.org/1.84.0/core/task/wake/struct.Context.html" title="struct core::task::wake::Context">Context</a>&lt;'_&gt;,
pos: <a class="enum" href="https://doc.rust-lang.org/1.84.0/std/io/enum.SeekFrom.html" title="enum std::io::SeekFrom">SeekFrom</a>,
) -&gt; <a class="enum" href="https://doc.rust-lang.org/1.84.0/core/task/poll/enum.Poll.html" title="enum core::task::poll::Poll">Poll</a>&lt;<a class="type" href="https://doc.rust-lang.org/1.84.0/std/io/error/type.Result.html" title="type std::io::error::Result">Result</a>&lt;<a class="primitive" href="https://doc.rust-lang.org/1.84.0/std/primitive.u64.html">u64</a>&gt;&gt;;
}</code></pre><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Seek bytes asynchronously.</p>
<p>This trait is analogous to the <code>std::io::Seek</code> trait, but integrates
with the asynchronous task system. In particular, the <code>poll_seek</code>
method, unlike <code>Seek::seek</code>, will automatically queue the current task
for wakeup and return if data is not yet available, rather than blocking
the calling thread.</p>
</div></details><h2 id="required-methods" class="section-header">Required Methods<a href="#required-methods" class="anchor">§</a></h2><div class="methods"><details class="toggle method-toggle" open><summary><section id="tymethod.poll_seek" class="method"><a class="src rightside" href="../src/futures_io/lib.rs.html#240-244">Source</a><h4 class="code-header">fn <a href="#tymethod.poll_seek" class="fn">poll_seek</a>(
self: <a class="struct" href="https://doc.rust-lang.org/1.84.0/core/pin/struct.Pin.html" title="struct core::pin::Pin">Pin</a>&lt;&amp;mut Self&gt;,
cx: &amp;mut <a class="struct" href="https://doc.rust-lang.org/1.84.0/core/task/wake/struct.Context.html" title="struct core::task::wake::Context">Context</a>&lt;'_&gt;,
pos: <a class="enum" href="https://doc.rust-lang.org/1.84.0/std/io/enum.SeekFrom.html" title="enum std::io::SeekFrom">SeekFrom</a>,
) -&gt; <a class="enum" href="https://doc.rust-lang.org/1.84.0/core/task/poll/enum.Poll.html" title="enum core::task::poll::Poll">Poll</a>&lt;<a class="type" href="https://doc.rust-lang.org/1.84.0/std/io/error/type.Result.html" title="type std::io::error::Result">Result</a>&lt;<a class="primitive" href="https://doc.rust-lang.org/1.84.0/std/primitive.u64.html">u64</a>&gt;&gt;</h4></section></summary><div class="docblock"><p>Attempt to seek to an offset, in bytes, in a stream.</p>
<p>A seek beyond the end of a stream is allowed, but behavior is defined
by the implementation.</p>
<p>If the seek operation completed successfully,
this method returns the new position from the start of the stream.
That position can be used later with <a href="https://doc.rust-lang.org/1.84.0/std/io/enum.SeekFrom.html#variant.Start" title="variant std::io::SeekFrom::Start"><code>SeekFrom::Start</code></a>.</p>
<h5 id="errors"><a class="doc-anchor" href="#errors">§</a>Errors</h5>
<p>Seeking to a negative offset is considered an error.</p>
<h5 id="implementation"><a class="doc-anchor" href="#implementation">§</a>Implementation</h5>
<p>This function may not return errors of kind <code>WouldBlock</code> or
<code>Interrupted</code>. Implementations must convert <code>WouldBlock</code> into
<code>Poll::Pending</code> and either internally retry or convert
<code>Interrupted</code> into another error kind.</p>
</div></details></div><h2 id="foreign-impls" class="section-header">Implementations on Foreign Types<a href="#foreign-impls" class="anchor">§</a></h2><details class="toggle implementors-toggle"><summary><section id="impl-AsyncSeek-for-Pin%3CP%3E" class="impl"><a class="src rightside" href="../src/futures_io/lib.rs.html#495-507">Source</a><a href="#impl-AsyncSeek-for-Pin%3CP%3E" class="anchor">§</a><h3 class="code-header">impl&lt;P&gt; <a class="trait" href="trait.AsyncSeek.html" title="trait futures_io::AsyncSeek">AsyncSeek</a> for <a class="struct" href="https://doc.rust-lang.org/1.84.0/core/pin/struct.Pin.html" title="struct core::pin::Pin">Pin</a>&lt;P&gt;<div class="where">where
P: <a class="trait" href="https://doc.rust-lang.org/1.84.0/core/ops/deref/trait.DerefMut.html" title="trait core::ops::deref::DerefMut">DerefMut</a> + <a class="trait" href="https://doc.rust-lang.org/1.84.0/core/marker/trait.Unpin.html" title="trait core::marker::Unpin">Unpin</a>,
P::<a class="associatedtype" href="https://doc.rust-lang.org/1.84.0/core/ops/deref/trait.Deref.html#associatedtype.Target" title="type core::ops::deref::Deref::Target">Target</a>: <a class="trait" href="trait.AsyncSeek.html" title="trait futures_io::AsyncSeek">AsyncSeek</a>,</div></h3></section></summary><div class="impl-items"><section id="method.poll_seek" class="method trait-impl"><a class="src rightside" href="../src/futures_io/lib.rs.html#500-506">Source</a><a href="#method.poll_seek" class="anchor">§</a><h4 class="code-header">fn <a href="#tymethod.poll_seek" class="fn">poll_seek</a>(
self: <a class="struct" href="https://doc.rust-lang.org/1.84.0/core/pin/struct.Pin.html" title="struct core::pin::Pin">Pin</a>&lt;&amp;mut Self&gt;,
cx: &amp;mut <a class="struct" href="https://doc.rust-lang.org/1.84.0/core/task/wake/struct.Context.html" title="struct core::task::wake::Context">Context</a>&lt;'_&gt;,
pos: <a class="enum" href="https://doc.rust-lang.org/1.84.0/std/io/enum.SeekFrom.html" title="enum std::io::SeekFrom">SeekFrom</a>,
) -&gt; <a class="enum" href="https://doc.rust-lang.org/1.84.0/core/task/poll/enum.Poll.html" title="enum core::task::poll::Poll">Poll</a>&lt;<a class="type" href="https://doc.rust-lang.org/1.84.0/std/io/error/type.Result.html" title="type std::io::error::Result">Result</a>&lt;<a class="primitive" href="https://doc.rust-lang.org/1.84.0/std/primitive.u64.html">u64</a>&gt;&gt;</h4></section></div></details><details class="toggle implementors-toggle"><summary><section id="impl-AsyncSeek-for-%26mut+T" class="impl"><a class="src rightside" href="../src/futures_io/lib.rs.html#491-493">Source</a><a href="#impl-AsyncSeek-for-%26mut+T" class="anchor">§</a><h3 class="code-header">impl&lt;T: ?<a class="trait" href="https://doc.rust-lang.org/1.84.0/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a> + <a class="trait" href="trait.AsyncSeek.html" title="trait futures_io::AsyncSeek">AsyncSeek</a> + <a class="trait" href="https://doc.rust-lang.org/1.84.0/core/marker/trait.Unpin.html" title="trait core::marker::Unpin">Unpin</a>&gt; <a class="trait" href="trait.AsyncSeek.html" title="trait futures_io::AsyncSeek">AsyncSeek</a> for <a class="primitive" href="https://doc.rust-lang.org/1.84.0/std/primitive.reference.html">&amp;mut T</a></h3></section></summary><div class="impl-items"><section id="method.poll_seek-1" class="method trait-impl"><a class="src rightside" href="../src/futures_io/lib.rs.html#492">Source</a><a href="#method.poll_seek-1" class="anchor">§</a><h4 class="code-header">fn <a href="#tymethod.poll_seek" class="fn">poll_seek</a>(
self: <a class="struct" href="https://doc.rust-lang.org/1.84.0/core/pin/struct.Pin.html" title="struct core::pin::Pin">Pin</a>&lt;&amp;mut Self&gt;,
cx: &amp;mut <a class="struct" href="https://doc.rust-lang.org/1.84.0/core/task/wake/struct.Context.html" title="struct core::task::wake::Context">Context</a>&lt;'_&gt;,
pos: <a class="enum" href="https://doc.rust-lang.org/1.84.0/std/io/enum.SeekFrom.html" title="enum std::io::SeekFrom">SeekFrom</a>,
) -&gt; <a class="enum" href="https://doc.rust-lang.org/1.84.0/core/task/poll/enum.Poll.html" title="enum core::task::poll::Poll">Poll</a>&lt;<a class="type" href="https://doc.rust-lang.org/1.84.0/std/io/error/type.Result.html" title="type std::io::error::Result">Result</a>&lt;<a class="primitive" href="https://doc.rust-lang.org/1.84.0/std/primitive.u64.html">u64</a>&gt;&gt;</h4></section></div></details><details class="toggle implementors-toggle"><summary><section id="impl-AsyncSeek-for-Box%3CT%3E" class="impl"><a class="src rightside" href="../src/futures_io/lib.rs.html#487-489">Source</a><a href="#impl-AsyncSeek-for-Box%3CT%3E" class="anchor">§</a><h3 class="code-header">impl&lt;T: ?<a class="trait" href="https://doc.rust-lang.org/1.84.0/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a> + <a class="trait" href="trait.AsyncSeek.html" title="trait futures_io::AsyncSeek">AsyncSeek</a> + <a class="trait" href="https://doc.rust-lang.org/1.84.0/core/marker/trait.Unpin.html" title="trait core::marker::Unpin">Unpin</a>&gt; <a class="trait" href="trait.AsyncSeek.html" title="trait futures_io::AsyncSeek">AsyncSeek</a> for <a class="struct" href="https://doc.rust-lang.org/1.84.0/alloc/boxed/struct.Box.html" title="struct alloc::boxed::Box">Box</a>&lt;T&gt;</h3></section></summary><div class="impl-items"><section id="method.poll_seek-2" class="method trait-impl"><a class="src rightside" href="../src/futures_io/lib.rs.html#488">Source</a><a href="#method.poll_seek-2" class="anchor">§</a><h4 class="code-header">fn <a href="#tymethod.poll_seek" class="fn">poll_seek</a>(
self: <a class="struct" href="https://doc.rust-lang.org/1.84.0/core/pin/struct.Pin.html" title="struct core::pin::Pin">Pin</a>&lt;&amp;mut Self&gt;,
cx: &amp;mut <a class="struct" href="https://doc.rust-lang.org/1.84.0/core/task/wake/struct.Context.html" title="struct core::task::wake::Context">Context</a>&lt;'_&gt;,
pos: <a class="enum" href="https://doc.rust-lang.org/1.84.0/std/io/enum.SeekFrom.html" title="enum std::io::SeekFrom">SeekFrom</a>,
) -&gt; <a class="enum" href="https://doc.rust-lang.org/1.84.0/core/task/poll/enum.Poll.html" title="enum core::task::poll::Poll">Poll</a>&lt;<a class="type" href="https://doc.rust-lang.org/1.84.0/std/io/error/type.Result.html" title="type std::io::error::Result">Result</a>&lt;<a class="primitive" href="https://doc.rust-lang.org/1.84.0/std/primitive.u64.html">u64</a>&gt;&gt;</h4></section></div></details><h2 id="implementors" class="section-header">Implementors<a href="#implementors" class="anchor">§</a></h2><div id="implementors-list"></div><script src="../trait.impl/futures_io/if_std/trait.AsyncSeek.js" data-ignore-extern-crates="alloc,core" async></script></section></div></main></body></html>