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60 lines
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HTML
<!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="Read bytes asynchronously."><title>AsyncBufRead 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>BufRead</a></h2><h3><a href="#required-methods">Required Methods</a></h3><ul class="block"><li><a href="#tymethod.consume" title="consume">consume</a></li><li><a href="#tymethod.poll_fill_buf" title="poll_fill_buf">poll_fill_buf</a></li></ul><h3><a href="#foreign-impls">Implementations on Foreign Types</a></h3><ul class="block"><li><a href="#impl-AsyncBufRead-for-%26%5Bu8%5D" title="&[u8]">&[u8]</a></li><li><a href="#impl-AsyncBufRead-for-%26mut+T" title="&mut T">&mut T</a></li><li><a href="#impl-AsyncBufRead-for-Box%3CT%3E" title="Box<T>">Box<T></a></li><li><a href="#impl-AsyncBufRead-for-Pin%3CP%3E" title="Pin<P>">Pin<P></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">AsyncBufRead</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#254-301">Source</a> </span></div><pre class="rust item-decl"><code>pub trait AsyncBufRead: <a class="trait" href="trait.AsyncRead.html" title="trait futures_io::AsyncRead">AsyncRead</a> {
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// Required methods
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fn <a href="#tymethod.poll_fill_buf" class="fn">poll_fill_buf</a>(
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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><&mut Self>,
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cx: &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><'_>,
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) -> <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><<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><&[<a class="primitive" href="https://doc.rust-lang.org/1.84.0/std/primitive.u8.html">u8</a>]>>;
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<span class="item-spacer"></span> fn <a href="#tymethod.consume" class="fn">consume</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><&mut Self>, amt: <a class="primitive" href="https://doc.rust-lang.org/1.84.0/std/primitive.usize.html">usize</a>);
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}</code></pre><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Read bytes asynchronously.</p>
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<p>This trait is analogous to the <code>std::io::BufRead</code> trait, but integrates
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with the asynchronous task system. In particular, the <code>poll_fill_buf</code>
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method, unlike <code>BufRead::fill_buf</code>, will automatically queue the current task
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for wakeup and return if data is not yet available, rather than blocking
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the calling thread.</p>
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</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_fill_buf" class="method"><a class="src rightside" href="../src/futures_io/lib.rs.html#283">Source</a><h4 class="code-header">fn <a href="#tymethod.poll_fill_buf" class="fn">poll_fill_buf</a>(
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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><&mut Self>,
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cx: &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><'_>,
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) -> <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><<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><&[<a class="primitive" href="https://doc.rust-lang.org/1.84.0/std/primitive.u8.html">u8</a>]>></h4></section></summary><div class="docblock"><p>Attempt to return the contents of the internal buffer, filling it with more data
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from the inner reader if it is empty.</p>
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<p>On success, returns <code>Poll::Ready(Ok(buf))</code>.</p>
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<p>If no data is available for reading, the method returns
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<code>Poll::Pending</code> and arranges for the current task (via
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<code>cx.waker().wake_by_ref()</code>) to receive a notification when the object becomes
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readable or is closed.</p>
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<p>This function is a lower-level call. It needs to be paired with the
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<a href="trait.AsyncBufRead.html#tymethod.consume" title="method futures_io::AsyncBufRead::consume"><code>consume</code></a> method to function properly. When calling this
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method, none of the contents will be “read” in the sense that later
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calling <a href="trait.AsyncRead.html#tymethod.poll_read" title="method futures_io::AsyncRead::poll_read"><code>poll_read</code></a> may return the same contents. As such, <a href="trait.AsyncBufRead.html#tymethod.consume" title="method futures_io::AsyncBufRead::consume"><code>consume</code></a> must
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be called with the number of bytes that are consumed from this buffer to
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ensure that the bytes are never returned twice.</p>
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<p>An empty buffer returned indicates that the stream has reached EOF.</p>
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<h5 id="implementation"><a class="doc-anchor" href="#implementation">§</a>Implementation</h5>
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<p>This function may not return errors of kind <code>WouldBlock</code> or
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<code>Interrupted</code>. Implementations must convert <code>WouldBlock</code> into
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<code>Poll::Pending</code> and either internally retry or convert
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<code>Interrupted</code> into another error kind.</p>
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</div></details><details class="toggle method-toggle" open><summary><section id="tymethod.consume" class="method"><a class="src rightside" href="../src/futures_io/lib.rs.html#300">Source</a><h4 class="code-header">fn <a href="#tymethod.consume" class="fn">consume</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><&mut Self>, amt: <a class="primitive" href="https://doc.rust-lang.org/1.84.0/std/primitive.usize.html">usize</a>)</h4></section></summary><div class="docblock"><p>Tells this buffer that <code>amt</code> bytes have been consumed from the buffer,
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so they should no longer be returned in calls to <a href="trait.AsyncRead.html#tymethod.poll_read" title="method futures_io::AsyncRead::poll_read"><code>poll_read</code></a>.</p>
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<p>This function is a lower-level call. It needs to be paired with the
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<a href="trait.AsyncBufRead.html#tymethod.poll_fill_buf" title="method futures_io::AsyncBufRead::poll_fill_buf"><code>poll_fill_buf</code></a> method to function properly. This function does
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not perform any I/O, it simply informs this object that some amount of
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its buffer, returned from <a href="trait.AsyncBufRead.html#tymethod.poll_fill_buf" title="method futures_io::AsyncBufRead::poll_fill_buf"><code>poll_fill_buf</code></a>, has been consumed and should
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no longer be returned. As such, this function may do odd things if
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<a href="trait.AsyncBufRead.html#tymethod.poll_fill_buf" title="method futures_io::AsyncBufRead::poll_fill_buf"><code>poll_fill_buf</code></a> isn’t called before calling it.</p>
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<p>The <code>amt</code> must be <code><=</code> the number of bytes in the buffer returned by
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<a href="trait.AsyncBufRead.html#tymethod.poll_fill_buf" title="method futures_io::AsyncBufRead::poll_fill_buf"><code>poll_fill_buf</code></a>.</p>
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</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-AsyncBufRead-for-%26%5Bu8%5D" class="impl"><a class="src rightside" href="../src/futures_io/lib.rs.html#555-557">Source</a><a href="#impl-AsyncBufRead-for-%26%5Bu8%5D" class="anchor">§</a><h3 class="code-header">impl <a class="trait" href="trait.AsyncBufRead.html" title="trait futures_io::AsyncBufRead">AsyncBufRead</a> for &[<a class="primitive" href="https://doc.rust-lang.org/1.84.0/std/primitive.u8.html">u8</a>]</h3></section></summary><div class="impl-items"><section id="method.poll_fill_buf" class="method trait-impl"><a class="src rightside" href="../src/futures_io/lib.rs.html#556">Source</a><a href="#method.poll_fill_buf" class="anchor">§</a><h4 class="code-header">fn <a href="#tymethod.poll_fill_buf" class="fn">poll_fill_buf</a>(
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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><&mut Self>,
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_: &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><'_>,
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) -> <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><<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><&[<a class="primitive" href="https://doc.rust-lang.org/1.84.0/std/primitive.u8.html">u8</a>]>></h4></section><section id="method.consume" class="method trait-impl"><a class="src rightside" href="../src/futures_io/lib.rs.html#556">Source</a><a href="#method.consume" class="anchor">§</a><h4 class="code-header">fn <a href="#tymethod.consume" class="fn">consume</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><&mut Self>, amt: <a class="primitive" href="https://doc.rust-lang.org/1.84.0/std/primitive.usize.html">usize</a>)</h4></section></div></details><details class="toggle implementors-toggle"><summary><section id="impl-AsyncBufRead-for-Pin%3CP%3E" class="impl"><a class="src rightside" href="../src/futures_io/lib.rs.html#529-541">Source</a><a href="#impl-AsyncBufRead-for-Pin%3CP%3E" class="anchor">§</a><h3 class="code-header">impl<P> <a class="trait" href="trait.AsyncBufRead.html" title="trait futures_io::AsyncBufRead">AsyncBufRead</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><P><div class="where">where
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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>,
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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.AsyncBufRead.html" title="trait futures_io::AsyncBufRead">AsyncBufRead</a>,</div></h3></section></summary><div class="impl-items"><section id="method.poll_fill_buf-1" class="method trait-impl"><a class="src rightside" href="../src/futures_io/lib.rs.html#534-536">Source</a><a href="#method.poll_fill_buf-1" class="anchor">§</a><h4 class="code-header">fn <a href="#tymethod.poll_fill_buf" class="fn">poll_fill_buf</a>(
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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><&mut Self>,
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cx: &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><'_>,
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) -> <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><<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><&[<a class="primitive" href="https://doc.rust-lang.org/1.84.0/std/primitive.u8.html">u8</a>]>></h4></section><section id="method.consume-1" class="method trait-impl"><a class="src rightside" href="../src/futures_io/lib.rs.html#538-540">Source</a><a href="#method.consume-1" class="anchor">§</a><h4 class="code-header">fn <a href="#tymethod.consume" class="fn">consume</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><&mut Self>, amt: <a class="primitive" href="https://doc.rust-lang.org/1.84.0/std/primitive.usize.html">usize</a>)</h4></section></div></details><details class="toggle implementors-toggle"><summary><section id="impl-AsyncBufRead-for-%26mut+T" class="impl"><a class="src rightside" href="../src/futures_io/lib.rs.html#525-527">Source</a><a href="#impl-AsyncBufRead-for-%26mut+T" class="anchor">§</a><h3 class="code-header">impl<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.AsyncBufRead.html" title="trait futures_io::AsyncBufRead">AsyncBufRead</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>> <a class="trait" href="trait.AsyncBufRead.html" title="trait futures_io::AsyncBufRead">AsyncBufRead</a> for <a class="primitive" href="https://doc.rust-lang.org/1.84.0/std/primitive.reference.html">&mut T</a></h3></section></summary><div class="impl-items"><section id="method.poll_fill_buf-2" class="method trait-impl"><a class="src rightside" href="../src/futures_io/lib.rs.html#526">Source</a><a href="#method.poll_fill_buf-2" class="anchor">§</a><h4 class="code-header">fn <a href="#tymethod.poll_fill_buf" class="fn">poll_fill_buf</a>(
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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><&mut Self>,
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cx: &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><'_>,
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) -> <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><<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><&[<a class="primitive" href="https://doc.rust-lang.org/1.84.0/std/primitive.u8.html">u8</a>]>></h4></section><section id="method.consume-2" class="method trait-impl"><a class="src rightside" href="../src/futures_io/lib.rs.html#526">Source</a><a href="#method.consume-2" class="anchor">§</a><h4 class="code-header">fn <a href="#tymethod.consume" class="fn">consume</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><&mut Self>, amt: <a class="primitive" href="https://doc.rust-lang.org/1.84.0/std/primitive.usize.html">usize</a>)</h4></section></div></details><details class="toggle implementors-toggle"><summary><section id="impl-AsyncBufRead-for-Box%3CT%3E" class="impl"><a class="src rightside" href="../src/futures_io/lib.rs.html#521-523">Source</a><a href="#impl-AsyncBufRead-for-Box%3CT%3E" class="anchor">§</a><h3 class="code-header">impl<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.AsyncBufRead.html" title="trait futures_io::AsyncBufRead">AsyncBufRead</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>> <a class="trait" href="trait.AsyncBufRead.html" title="trait futures_io::AsyncBufRead">AsyncBufRead</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><T></h3></section></summary><div class="impl-items"><section id="method.poll_fill_buf-3" class="method trait-impl"><a class="src rightside" href="../src/futures_io/lib.rs.html#522">Source</a><a href="#method.poll_fill_buf-3" class="anchor">§</a><h4 class="code-header">fn <a href="#tymethod.poll_fill_buf" class="fn">poll_fill_buf</a>(
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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><&mut Self>,
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cx: &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><'_>,
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) -> <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><<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><&[<a class="primitive" href="https://doc.rust-lang.org/1.84.0/std/primitive.u8.html">u8</a>]>></h4></section><section id="method.consume-3" class="method trait-impl"><a class="src rightside" href="../src/futures_io/lib.rs.html#522">Source</a><a href="#method.consume-3" class="anchor">§</a><h4 class="code-header">fn <a href="#tymethod.consume" class="fn">consume</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><&mut Self>, amt: <a class="primitive" href="https://doc.rust-lang.org/1.84.0/std/primitive.usize.html">usize</a>)</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.AsyncBufRead.js" data-ignore-extern-crates="alloc,core,std" async></script></section></div></main></body></html> |