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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="Receiving-half of the `broadcast` channel."><title>Receiver in tokio::sync::broadcast - Rust</title><script>if(window.location.protocol!=="file:")document.head.insertAdjacentHTML("beforeend","SourceSerif4-Regular-6b053e98.ttf.woff2,FiraSans-Italic-81dc35de.woff2,FiraSans-Regular-0fe48ade.woff2,FiraSans-MediumItalic-ccf7e434.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"href="../../../static.files/${f}">`).join(""))</script><link rel="stylesheet" href="../../../static.files/normalize-9960930a.css"><link rel="stylesheet" href="../../../static.files/rustdoc-ca0dd0c4.css"><meta name="rustdoc-vars" data-root-path="../../../" data-static-root-path="../../../static.files/" data-current-crate="tokio" data-themes="" data-resource-suffix="" data-rustdoc-version="1.93.1 (01f6ddf75 2026-02-11) (Arch Linux rust 1:1.93.1-1)" data-channel="1.93.1" data-search-js="search-9e2438ea.js" data-stringdex-js="stringdex-a3946164.js" data-settings-js="settings-c38705f0.js" ><script src="../../../static.files/storage-e2aeef58.js"></script><script defer src="sidebar-items.js"></script><script defer src="../../../static.files/main-a410ff4d.js"></script><noscript><link rel="stylesheet" href="../../../static.files/noscript-263c88ec.css"></noscript><link rel="alternate icon" type="image/png" href="../../../static.files/favicon-32x32-eab170b8.png"><link rel="icon" type="image/svg+xml" href="../../../static.files/favicon-044be391.svg"></head><body class="rustdoc struct"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><rustdoc-topbar><h2><a href="#">Receiver</a></h2></rustdoc-topbar><nav class="sidebar"><div class="sidebar-crate"><h2><a href="../../../tokio/index.html">tokio</a><span class="version">1.49.0</span></h2></div><div class="sidebar-elems"><section id="rustdoc-toc"><h2 class="location"><a href="#">Receiver</a></h2><h3><a href="#">Sections</a></h3><ul class="block top-toc"><li><a href="#examples" title="Examples">Examples</a></li></ul><h3><a href="#implementations">Methods</a></h3><ul class="block method"><li><a href="#method.blocking_recv" title="blocking_recv">blocking_recv</a></li><li><a href="#method.is_closed" title="is_closed">is_closed</a></li><li><a href="#method.is_empty" title="is_empty">is_empty</a></li><li><a href="#method.len" title="len">len</a></li><li><a href="#method.recv" title="recv">recv</a></li><li><a href="#method.resubscribe" title="resubscribe">resubscribe</a></li><li><a href="#method.same_channel" title="same_channel">same_channel</a></li><li><a href="#method.sender_strong_count" title="sender_strong_count">sender_strong_count</a></li><li><a href="#method.sender_weak_count" title="sender_weak_count">sender_weak_count</a></li><li><a href="#method.try_recv" title="try_recv">try_recv</a></li></ul><h3><a href="#trait-implementations">Trait Implementations</a></h3><ul class="block trait-implementation"><li><a href="#impl-Debug-for-Receiver%3CT%3E" title="Debug">Debug</a></li><li><a href="#impl-Drop-for-Receiver%3CT%3E" title="Drop">Drop</a></li></ul><h3><a href="#synthetic-implementations">Auto Trait Implementations</a></h3><ul class="block synthetic-implementation"><li><a href="#impl-RefUnwindSafe-for-Receiver%3CT%3E" title="!RefUnwindSafe">!RefUnwindSafe</a></li><li><a href="#impl-UnwindSafe-for-Receiver%3CT%3E" title="!UnwindSafe">!UnwindSafe</a></li><li><a href="#impl-Freeze-for-Receiver%3CT%3E" title="Freeze">Freeze</a></li><li><a href="#impl-Send-for-Receiver%3CT%3E" title="Send">Send</a></li><li><a href="#impl-Sync-for-Receiver%3CT%3E" title="Sync">Sync</a></li><li><a href="#impl-Unpin-for-Receiver%3CT%3E" title="Unpin">Unpin</a></li></ul><h3><a href="#blanket-implementations">Blanket Implementations</a></h3><ul class="block blanket-implementation"><li><a href="#impl-Any-for-T" title="Any">Any</a></li><li><a href="#impl-Borrow%3CT%3E-for-T" title="Borrow<T>">Borrow<T></a></li><li><a href="#impl-BorrowMut%3CT%3E-for-T" title="BorrowMut<T>">BorrowMut<T></a></li><li><a href="#impl-From%3CT%3E-for-T" title="From<T>">From<T></a></li><li><a href="#impl-Into%3CU%3E-for-T" title="Into<U>">Into<U></a></li><li><a href="#impl-TryFrom%3CU%3E-for-T" title="TryFrom<U>">TryFrom<U></a></li><li><a href="#impl-TryInto%3CU%3E-for-T" title="TryInto<U>">TryInto<U></a></li></ul></section><div id="rustdoc-modnav"><h2><a href="index.html">In tokio::<wbr>sync::<wbr>broadcast</a></h2></div></div></nav><div class="sidebar-resizer" title="Drag to resize sidebar"></div><main><div class="width-limiter"><section id="main-content" class="content"><div class="main-heading"><div class="rustdoc-breadcrumbs"><a href="../../index.html">tokio</a>::<wbr><a href="../index.html">sync</a>::<wbr><a href="index.html">broadcast</a></div><h1>Struct <span class="struct">Receiver</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/tokio/sync/broadcast.rs.html#239-245">Source</a> </span></div><pre class="rust item-decl"><code>pub struct Receiver<T> { <span class="comment">/* private fields */</span> }</code></pre><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Receiving-half of the <a href="index.html" title="mod tokio::sync::broadcast"><code>broadcast</code></a> channel.</p>
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<p>Must not be used concurrently. Messages may be retrieved using
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<a href="struct.Receiver.html#method.recv" title="method tokio::sync::broadcast::Receiver::recv"><code>recv</code></a>.</p>
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<p>To turn this receiver into a <code>Stream</code>, you can use the <a href="https://docs.rs/tokio-stream/0.1/tokio_stream/wrappers/struct.BroadcastStream.html"><code>BroadcastStream</code></a>
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wrapper.</p>
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<h2 id="examples"><a class="doc-anchor" href="#examples">§</a>Examples</h2>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>tokio::sync::broadcast;
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<span class="kw">let </span>(tx, <span class="kw-2">mut </span>rx1) = broadcast::channel(<span class="number">16</span>);
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<span class="kw">let </span><span class="kw-2">mut </span>rx2 = tx.subscribe();
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tokio::spawn(<span class="kw">async move </span>{
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<span class="macro">assert_eq!</span>(rx1.recv().<span class="kw">await</span>.unwrap(), <span class="number">10</span>);
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<span class="macro">assert_eq!</span>(rx1.recv().<span class="kw">await</span>.unwrap(), <span class="number">20</span>);
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});
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tokio::spawn(<span class="kw">async move </span>{
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<span class="macro">assert_eq!</span>(rx2.recv().<span class="kw">await</span>.unwrap(), <span class="number">10</span>);
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<span class="macro">assert_eq!</span>(rx2.recv().<span class="kw">await</span>.unwrap(), <span class="number">20</span>);
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});
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tx.send(<span class="number">10</span>).unwrap();
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tx.send(<span class="number">20</span>).unwrap();</code></pre></div></div></details><h2 id="implementations" class="section-header">Implementations<a href="#implementations" class="anchor">§</a></h2><div id="implementations-list"><details class="toggle implementors-toggle" open><summary><section id="impl-Receiver%3CT%3E" class="impl"><a class="src rightside" href="../../../src/tokio/sync/broadcast.rs.html#1131-1365">Source</a><a href="#impl-Receiver%3CT%3E" class="anchor">§</a><h3 class="code-header">impl<T> <a class="struct" href="struct.Receiver.html" title="struct tokio::sync::broadcast::Receiver">Receiver</a><T></h3></section></summary><div class="impl-items"><details class="toggle method-toggle" open><summary><section id="method.len" class="method"><a class="src rightside" href="../../../src/tokio/sync/broadcast.rs.html#1165-1168">Source</a><h4 class="code-header">pub fn <a href="#method.len" class="fn">len</a>(&self) -> <a class="primitive" href="https://doc.rust-lang.org/1.93.1/std/primitive.usize.html">usize</a></h4></section></summary><div class="docblock"><p>Returns the number of messages that were sent into the channel and that
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this <a href="struct.Receiver.html" title="struct tokio::sync::broadcast::Receiver"><code>Receiver</code></a> has yet to receive.</p>
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<p>If the returned value from <code>len</code> is larger than the next largest power of 2
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of the capacity of the channel any call to <a href="struct.Receiver.html#method.recv" title="method tokio::sync::broadcast::Receiver::recv"><code>recv</code></a> will return an
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<code>Err(RecvError::Lagged)</code> and any call to <a href="struct.Receiver.html#method.try_recv" title="method tokio::sync::broadcast::Receiver::try_recv"><code>try_recv</code></a> will return an
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<code>Err(TryRecvError::Lagged)</code>, e.g. if the capacity of the channel is 10,
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<a href="struct.Receiver.html#method.recv" title="method tokio::sync::broadcast::Receiver::recv"><code>recv</code></a> will start to return <code>Err(RecvError::Lagged)</code> once <code>len</code> returns
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values larger than 16.</p>
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<h5 id="examples-1"><a class="doc-anchor" href="#examples-1">§</a>Examples</h5>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>tokio::sync::broadcast;
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<span class="kw">let </span>(tx, <span class="kw-2">mut </span>rx1) = broadcast::channel(<span class="number">16</span>);
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tx.send(<span class="number">10</span>).unwrap();
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tx.send(<span class="number">20</span>).unwrap();
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<span class="macro">assert_eq!</span>(rx1.len(), <span class="number">2</span>);
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<span class="macro">assert_eq!</span>(rx1.recv().<span class="kw">await</span>.unwrap(), <span class="number">10</span>);
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<span class="macro">assert_eq!</span>(rx1.len(), <span class="number">1</span>);
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<span class="macro">assert_eq!</span>(rx1.recv().<span class="kw">await</span>.unwrap(), <span class="number">20</span>);
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<span class="macro">assert_eq!</span>(rx1.len(), <span class="number">0</span>);</code></pre></div></div></details><details class="toggle method-toggle" open><summary><section id="method.is_empty" class="method"><a class="src rightside" href="../../../src/tokio/sync/broadcast.rs.html#1195-1197">Source</a><h4 class="code-header">pub fn <a href="#method.is_empty" class="fn">is_empty</a>(&self) -> <a class="primitive" href="https://doc.rust-lang.org/1.93.1/std/primitive.bool.html">bool</a></h4></section></summary><div class="docblock"><p>Returns true if there aren’t any messages in the channel that the <a href="struct.Receiver.html" title="struct tokio::sync::broadcast::Receiver"><code>Receiver</code></a>
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has yet to receive.</p>
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<h5 id="examples-2"><a class="doc-anchor" href="#examples-2">§</a>Examples</h5>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>tokio::sync::broadcast;
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<span class="kw">let </span>(tx, <span class="kw-2">mut </span>rx1) = broadcast::channel(<span class="number">16</span>);
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<span class="macro">assert!</span>(rx1.is_empty());
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tx.send(<span class="number">10</span>).unwrap();
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tx.send(<span class="number">20</span>).unwrap();
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<span class="macro">assert!</span>(!rx1.is_empty());
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<span class="macro">assert_eq!</span>(rx1.recv().<span class="kw">await</span>.unwrap(), <span class="number">10</span>);
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<span class="macro">assert_eq!</span>(rx1.recv().<span class="kw">await</span>.unwrap(), <span class="number">20</span>);
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<span class="macro">assert!</span>(rx1.is_empty());</code></pre></div></div></details><details class="toggle method-toggle" open><summary><section id="method.same_channel" class="method"><a class="src rightside" href="../../../src/tokio/sync/broadcast.rs.html#1218-1220">Source</a><h4 class="code-header">pub fn <a href="#method.same_channel" class="fn">same_channel</a>(&self, other: &Self) -> <a class="primitive" href="https://doc.rust-lang.org/1.93.1/std/primitive.bool.html">bool</a></h4></section></summary><div class="docblock"><p>Returns <code>true</code> if receivers belong to the same channel.</p>
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<h5 id="examples-3"><a class="doc-anchor" href="#examples-3">§</a>Examples</h5>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>tokio::sync::broadcast;
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<span class="kw">let </span>(tx, rx) = broadcast::channel::<()>(<span class="number">16</span>);
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<span class="kw">let </span>rx2 = tx.subscribe();
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<span class="macro">assert!</span>(rx.same_channel(<span class="kw-2">&</span>rx2));
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<span class="kw">let </span>(_tx3, rx3) = broadcast::channel::<()>(<span class="number">16</span>);
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<span class="macro">assert!</span>(!rx3.same_channel(<span class="kw-2">&</span>rx2));</code></pre></div></div></details><details class="toggle method-toggle" open><summary><section id="method.sender_strong_count" class="method"><a class="src rightside" href="../../../src/tokio/sync/broadcast.rs.html#1331-1333">Source</a><h4 class="code-header">pub fn <a href="#method.sender_strong_count" class="fn">sender_strong_count</a>(&self) -> <a class="primitive" href="https://doc.rust-lang.org/1.93.1/std/primitive.usize.html">usize</a></h4></section></summary><div class="docblock"><p>Returns the number of <a href="struct.Sender.html" title="struct tokio::sync::broadcast::Sender"><code>Sender</code></a> handles.</p>
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</div></details><details class="toggle method-toggle" open><summary><section id="method.sender_weak_count" class="method"><a class="src rightside" href="../../../src/tokio/sync/broadcast.rs.html#1336-1338">Source</a><h4 class="code-header">pub fn <a href="#method.sender_weak_count" class="fn">sender_weak_count</a>(&self) -> <a class="primitive" href="https://doc.rust-lang.org/1.93.1/std/primitive.usize.html">usize</a></h4></section></summary><div class="docblock"><p>Returns the number of <a href="struct.WeakSender.html" title="struct tokio::sync::broadcast::WeakSender"><code>WeakSender</code></a> handles.</p>
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</div></details><details class="toggle method-toggle" open><summary><section id="method.is_closed" class="method"><a class="src rightside" href="../../../src/tokio/sync/broadcast.rs.html#1361-1364">Source</a><h4 class="code-header">pub fn <a href="#method.is_closed" class="fn">is_closed</a>(&self) -> <a class="primitive" href="https://doc.rust-lang.org/1.93.1/std/primitive.bool.html">bool</a></h4></section></summary><div class="docblock"><p>Checks if a channel is closed.</p>
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<p>This method returns <code>true</code> if the channel has been closed. The channel is closed
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when all <a href="struct.Sender.html" title="struct tokio::sync::broadcast::Sender"><code>Sender</code></a> have been dropped.</p>
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<h5 id="examples-4"><a class="doc-anchor" href="#examples-4">§</a>Examples</h5>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>tokio::sync::broadcast;
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<span class="kw">let </span>(tx, rx) = broadcast::channel::<()>(<span class="number">10</span>);
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<span class="macro">assert!</span>(!rx.is_closed());
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drop(tx);
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<span class="macro">assert!</span>(rx.is_closed());</code></pre></div></div></details></div></details><details class="toggle implementors-toggle" open><summary><section id="impl-Receiver%3CT%3E-1" class="impl"><a class="src rightside" href="../../../src/tokio/sync/broadcast.rs.html#1367-1546">Source</a><a href="#impl-Receiver%3CT%3E-1" class="anchor">§</a><h3 class="code-header">impl<T: <a class="trait" href="https://doc.rust-lang.org/1.93.1/core/clone/trait.Clone.html" title="trait core::clone::Clone">Clone</a>> <a class="struct" href="struct.Receiver.html" title="struct tokio::sync::broadcast::Receiver">Receiver</a><T></h3></section></summary><div class="impl-items"><details class="toggle method-toggle" open><summary><section id="method.resubscribe" class="method"><a class="src rightside" href="../../../src/tokio/sync/broadcast.rs.html#1391-1394">Source</a><h4 class="code-header">pub fn <a href="#method.resubscribe" class="fn">resubscribe</a>(&self) -> Self</h4></section></summary><div class="docblock"><p>Re-subscribes to the channel starting from the current tail element.</p>
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<p>This <a href="struct.Receiver.html" title="struct tokio::sync::broadcast::Receiver"><code>Receiver</code></a> handle will receive a clone of all values sent
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<strong>after</strong> it has resubscribed. This will not include elements that are
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in the queue of the current receiver. Consider the following example.</p>
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<h5 id="examples-5"><a class="doc-anchor" href="#examples-5">§</a>Examples</h5>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>tokio::sync::broadcast;
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<span class="kw">let </span>(tx, <span class="kw-2">mut </span>rx) = broadcast::channel(<span class="number">2</span>);
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tx.send(<span class="number">1</span>).unwrap();
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<span class="kw">let </span><span class="kw-2">mut </span>rx2 = rx.resubscribe();
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tx.send(<span class="number">2</span>).unwrap();
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<span class="macro">assert_eq!</span>(rx2.recv().<span class="kw">await</span>.unwrap(), <span class="number">2</span>);
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<span class="macro">assert_eq!</span>(rx.recv().<span class="kw">await</span>.unwrap(), <span class="number">1</span>);</code></pre></div></div></details><details class="toggle method-toggle" open><summary><section id="method.recv" class="method"><a class="src rightside" href="../../../src/tokio/sync/broadcast.rs.html#1467-1469">Source</a><h4 class="code-header">pub async fn <a href="#method.recv" class="fn">recv</a>(&mut self) -> <a class="enum" href="https://doc.rust-lang.org/1.93.1/core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, <a class="enum" href="error/enum.RecvError.html" title="enum tokio::sync::broadcast::error::RecvError">RecvError</a>></h4></section></summary><div class="docblock"><p>Receives the next value for this receiver.</p>
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<p>Each <a href="struct.Receiver.html" title="struct tokio::sync::broadcast::Receiver"><code>Receiver</code></a> handle will receive a clone of all values sent
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<strong>after</strong> it has subscribed.</p>
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<p><code>Err(RecvError::Closed)</code> is returned when all <code>Sender</code> halves have
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dropped, indicating that no further values can be sent on the channel.</p>
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<p>If the <a href="struct.Receiver.html" title="struct tokio::sync::broadcast::Receiver"><code>Receiver</code></a> handle falls behind, once the channel is full, newly
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sent values will overwrite old values. At this point, a call to <a href="struct.Receiver.html#method.recv" title="method tokio::sync::broadcast::Receiver::recv"><code>recv</code></a>
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will return with <code>Err(RecvError::Lagged)</code> and the <a href="struct.Receiver.html" title="struct tokio::sync::broadcast::Receiver"><code>Receiver</code></a>’s
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internal cursor is updated to point to the oldest value still held by
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the channel. A subsequent call to <a href="struct.Receiver.html#method.recv" title="method tokio::sync::broadcast::Receiver::recv"><code>recv</code></a> will return this value
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<strong>unless</strong> it has been since overwritten.</p>
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<h5 id="cancel-safety"><a class="doc-anchor" href="#cancel-safety">§</a>Cancel safety</h5>
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<p>This method is cancel safe. If <code>recv</code> is used as the event in a
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<a href="../../macro.select.html" title="macro tokio::select"><code>tokio::select!</code></a> statement and some other branch
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completes first, it is guaranteed that no messages were received on this
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channel.</p>
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<h5 id="examples-6"><a class="doc-anchor" href="#examples-6">§</a>Examples</h5>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>tokio::sync::broadcast;
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<span class="kw">let </span>(tx, <span class="kw-2">mut </span>rx1) = broadcast::channel(<span class="number">16</span>);
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<span class="kw">let </span><span class="kw-2">mut </span>rx2 = tx.subscribe();
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tokio::spawn(<span class="kw">async move </span>{
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<span class="macro">assert_eq!</span>(rx1.recv().<span class="kw">await</span>.unwrap(), <span class="number">10</span>);
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<span class="macro">assert_eq!</span>(rx1.recv().<span class="kw">await</span>.unwrap(), <span class="number">20</span>);
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});
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tokio::spawn(<span class="kw">async move </span>{
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<span class="macro">assert_eq!</span>(rx2.recv().<span class="kw">await</span>.unwrap(), <span class="number">10</span>);
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<span class="macro">assert_eq!</span>(rx2.recv().<span class="kw">await</span>.unwrap(), <span class="number">20</span>);
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});
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tx.send(<span class="number">10</span>).unwrap();
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tx.send(<span class="number">20</span>).unwrap();</code></pre></div>
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<p>Handling lag</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>tokio::sync::broadcast;
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<span class="kw">let </span>(tx, <span class="kw-2">mut </span>rx) = broadcast::channel(<span class="number">2</span>);
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tx.send(<span class="number">10</span>).unwrap();
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tx.send(<span class="number">20</span>).unwrap();
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tx.send(<span class="number">30</span>).unwrap();
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<span class="comment">// The receiver lagged behind
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</span><span class="macro">assert!</span>(rx.recv().<span class="kw">await</span>.is_err());
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<span class="comment">// At this point, we can abort or continue with lost messages
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</span><span class="macro">assert_eq!</span>(<span class="number">20</span>, rx.recv().<span class="kw">await</span>.unwrap());
|
||
<span class="macro">assert_eq!</span>(<span class="number">30</span>, rx.recv().<span class="kw">await</span>.unwrap());</code></pre></div></div></details><details class="toggle method-toggle" open><summary><section id="method.try_recv" class="method"><a class="src rightside" href="../../../src/tokio/sync/broadcast.rs.html#1511-1514">Source</a><h4 class="code-header">pub fn <a href="#method.try_recv" class="fn">try_recv</a>(&mut self) -> <a class="enum" href="https://doc.rust-lang.org/1.93.1/core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, <a class="enum" href="error/enum.TryRecvError.html" title="enum tokio::sync::broadcast::error::TryRecvError">TryRecvError</a>></h4></section></summary><div class="docblock"><p>Attempts to return a pending value on this receiver without awaiting.</p>
|
||
<p>This is useful for a flavor of “optimistic check” before deciding to
|
||
await on a receiver.</p>
|
||
<p>Compared with <a href="struct.Receiver.html#method.recv" title="method tokio::sync::broadcast::Receiver::recv"><code>recv</code></a>, this function has three failure cases instead of two
|
||
(one for closed, one for an empty buffer, one for a lagging receiver).</p>
|
||
<p><code>Err(TryRecvError::Closed)</code> is returned when all <code>Sender</code> halves have
|
||
dropped, indicating that no further values can be sent on the channel.</p>
|
||
<p>If the <a href="struct.Receiver.html" title="struct tokio::sync::broadcast::Receiver"><code>Receiver</code></a> handle falls behind, once the channel is full, newly
|
||
sent values will overwrite old values. At this point, a call to <a href="struct.Receiver.html#method.recv" title="method tokio::sync::broadcast::Receiver::recv"><code>recv</code></a>
|
||
will return with <code>Err(TryRecvError::Lagged)</code> and the <a href="struct.Receiver.html" title="struct tokio::sync::broadcast::Receiver"><code>Receiver</code></a>’s
|
||
internal cursor is updated to point to the oldest value still held by
|
||
the channel. A subsequent call to <a href="struct.Receiver.html#method.try_recv" title="method tokio::sync::broadcast::Receiver::try_recv"><code>try_recv</code></a> will return this value
|
||
<strong>unless</strong> it has been since overwritten. If there are no values to
|
||
receive, <code>Err(TryRecvError::Empty)</code> is returned.</p>
|
||
<h5 id="examples-7"><a class="doc-anchor" href="#examples-7">§</a>Examples</h5>
|
||
<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>tokio::sync::broadcast;
|
||
|
||
<span class="kw">let </span>(tx, <span class="kw-2">mut </span>rx) = broadcast::channel(<span class="number">16</span>);
|
||
|
||
<span class="macro">assert!</span>(rx.try_recv().is_err());
|
||
|
||
tx.send(<span class="number">10</span>).unwrap();
|
||
|
||
<span class="kw">let </span>value = rx.try_recv().unwrap();
|
||
<span class="macro">assert_eq!</span>(<span class="number">10</span>, value);</code></pre></div></div></details><details class="toggle method-toggle" open><summary><section id="method.blocking_recv" class="method"><a class="src rightside" href="../../../src/tokio/sync/broadcast.rs.html#1543-1545">Source</a><h4 class="code-header">pub fn <a href="#method.blocking_recv" class="fn">blocking_recv</a>(&mut self) -> <a class="enum" href="https://doc.rust-lang.org/1.93.1/core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, <a class="enum" href="error/enum.RecvError.html" title="enum tokio::sync::broadcast::error::RecvError">RecvError</a>></h4></section></summary><div class="docblock"><p>Blocking receive to call outside of asynchronous contexts.</p>
|
||
<h5 id="panics"><a class="doc-anchor" href="#panics">§</a>Panics</h5>
|
||
<p>This function panics if called within an asynchronous execution
|
||
context.</p>
|
||
<h5 id="examples-8"><a class="doc-anchor" href="#examples-8">§</a>Examples</h5>
|
||
<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>std::thread;
|
||
<span class="kw">use </span>tokio::sync::broadcast;
|
||
|
||
<span class="attr">#[tokio::main]
|
||
</span><span class="kw">async fn </span>main() {
|
||
<span class="kw">let </span>(tx, <span class="kw-2">mut </span>rx) = broadcast::channel(<span class="number">16</span>);
|
||
|
||
<span class="kw">let </span>sync_code = thread::spawn(<span class="kw">move </span>|| {
|
||
<span class="macro">assert_eq!</span>(rx.blocking_recv(), <span class="prelude-val">Ok</span>(<span class="number">10</span>));
|
||
});
|
||
|
||
<span class="kw">let _ </span>= tx.send(<span class="number">10</span>);
|
||
sync_code.join().unwrap();
|
||
}</code></pre></div></div></details></div></details></div><h2 id="trait-implementations" class="section-header">Trait Implementations<a href="#trait-implementations" class="anchor">§</a></h2><div id="trait-implementations-list"><details class="toggle implementors-toggle" open><summary><section id="impl-Debug-for-Receiver%3CT%3E" class="impl"><a class="src rightside" href="../../../src/tokio/sync/broadcast.rs.html#1697-1701">Source</a><a href="#impl-Debug-for-Receiver%3CT%3E" class="anchor">§</a><h3 class="code-header">impl<T> <a class="trait" href="https://doc.rust-lang.org/1.93.1/core/fmt/trait.Debug.html" title="trait core::fmt::Debug">Debug</a> for <a class="struct" href="struct.Receiver.html" title="struct tokio::sync::broadcast::Receiver">Receiver</a><T></h3></section></summary><div class="impl-items"><details class="toggle method-toggle" open><summary><section id="method.fmt" class="method trait-impl"><a class="src rightside" href="../../../src/tokio/sync/broadcast.rs.html#1698-1700">Source</a><a href="#method.fmt" class="anchor">§</a><h4 class="code-header">fn <a href="https://doc.rust-lang.org/1.93.1/core/fmt/trait.Debug.html#tymethod.fmt" class="fn">fmt</a>(&self, fmt: &mut <a class="struct" href="https://doc.rust-lang.org/1.93.1/core/fmt/struct.Formatter.html" title="struct core::fmt::Formatter">Formatter</a><'_>) -> <a class="type" href="https://doc.rust-lang.org/1.93.1/core/fmt/type.Result.html" title="type core::fmt::Result">Result</a></h4></section></summary><div class='docblock'>Formats the value using the given formatter. <a href="https://doc.rust-lang.org/1.93.1/core/fmt/trait.Debug.html#tymethod.fmt">Read more</a></div></details></div></details><details class="toggle implementors-toggle" open><summary><section id="impl-Drop-for-Receiver%3CT%3E" class="impl"><a class="src rightside" href="../../../src/tokio/sync/broadcast.rs.html#1548-1575">Source</a><a href="#impl-Drop-for-Receiver%3CT%3E" class="anchor">§</a><h3 class="code-header">impl<T> <a class="trait" href="https://doc.rust-lang.org/1.93.1/core/ops/drop/trait.Drop.html" title="trait core::ops::drop::Drop">Drop</a> for <a class="struct" href="struct.Receiver.html" title="struct tokio::sync::broadcast::Receiver">Receiver</a><T></h3></section></summary><div class="impl-items"><details class="toggle method-toggle" open><summary><section id="method.drop" class="method trait-impl"><a class="src rightside" href="../../../src/tokio/sync/broadcast.rs.html#1549-1574">Source</a><a href="#method.drop" class="anchor">§</a><h4 class="code-header">fn <a href="https://doc.rust-lang.org/1.93.1/core/ops/drop/trait.Drop.html#tymethod.drop" class="fn">drop</a>(&mut self)</h4></section></summary><div class='docblock'>Executes the destructor for this type. <a href="https://doc.rust-lang.org/1.93.1/core/ops/drop/trait.Drop.html#tymethod.drop">Read more</a></div></details></div></details></div><h2 id="synthetic-implementations" class="section-header">Auto Trait Implementations<a href="#synthetic-implementations" class="anchor">§</a></h2><div id="synthetic-implementations-list"><section id="impl-Freeze-for-Receiver%3CT%3E" class="impl"><a href="#impl-Freeze-for-Receiver%3CT%3E" class="anchor">§</a><h3 class="code-header">impl<T> <a class="trait" href="https://doc.rust-lang.org/1.93.1/core/marker/trait.Freeze.html" title="trait core::marker::Freeze">Freeze</a> for <a class="struct" href="struct.Receiver.html" title="struct tokio::sync::broadcast::Receiver">Receiver</a><T></h3></section><section id="impl-RefUnwindSafe-for-Receiver%3CT%3E" class="impl"><a href="#impl-RefUnwindSafe-for-Receiver%3CT%3E" class="anchor">§</a><h3 class="code-header">impl<T> !<a class="trait" href="https://doc.rust-lang.org/1.93.1/core/panic/unwind_safe/trait.RefUnwindSafe.html" title="trait core::panic::unwind_safe::RefUnwindSafe">RefUnwindSafe</a> for <a class="struct" href="struct.Receiver.html" title="struct tokio::sync::broadcast::Receiver">Receiver</a><T></h3></section><section id="impl-Send-for-Receiver%3CT%3E" class="impl"><a href="#impl-Send-for-Receiver%3CT%3E" class="anchor">§</a><h3 class="code-header">impl<T> <a class="trait" href="https://doc.rust-lang.org/1.93.1/core/marker/trait.Send.html" title="trait core::marker::Send">Send</a> for <a class="struct" href="struct.Receiver.html" title="struct tokio::sync::broadcast::Receiver">Receiver</a><T><div class="where">where
|
||
T: <a class="trait" href="https://doc.rust-lang.org/1.93.1/core/marker/trait.Send.html" title="trait core::marker::Send">Send</a>,</div></h3></section><section id="impl-Sync-for-Receiver%3CT%3E" class="impl"><a href="#impl-Sync-for-Receiver%3CT%3E" class="anchor">§</a><h3 class="code-header">impl<T> <a class="trait" href="https://doc.rust-lang.org/1.93.1/core/marker/trait.Sync.html" title="trait core::marker::Sync">Sync</a> for <a class="struct" href="struct.Receiver.html" title="struct tokio::sync::broadcast::Receiver">Receiver</a><T><div class="where">where
|
||
T: <a class="trait" href="https://doc.rust-lang.org/1.93.1/core/marker/trait.Send.html" title="trait core::marker::Send">Send</a>,</div></h3></section><section id="impl-Unpin-for-Receiver%3CT%3E" class="impl"><a href="#impl-Unpin-for-Receiver%3CT%3E" class="anchor">§</a><h3 class="code-header">impl<T> <a class="trait" href="https://doc.rust-lang.org/1.93.1/core/marker/trait.Unpin.html" title="trait core::marker::Unpin">Unpin</a> for <a class="struct" href="struct.Receiver.html" title="struct tokio::sync::broadcast::Receiver">Receiver</a><T></h3></section><section id="impl-UnwindSafe-for-Receiver%3CT%3E" class="impl"><a href="#impl-UnwindSafe-for-Receiver%3CT%3E" class="anchor">§</a><h3 class="code-header">impl<T> !<a class="trait" href="https://doc.rust-lang.org/1.93.1/core/panic/unwind_safe/trait.UnwindSafe.html" title="trait core::panic::unwind_safe::UnwindSafe">UnwindSafe</a> for <a class="struct" href="struct.Receiver.html" title="struct tokio::sync::broadcast::Receiver">Receiver</a><T></h3></section></div><h2 id="blanket-implementations" class="section-header">Blanket Implementations<a href="#blanket-implementations" class="anchor">§</a></h2><div id="blanket-implementations-list"><details class="toggle implementors-toggle"><summary><section id="impl-Any-for-T" class="impl"><a class="src rightside" href="https://doc.rust-lang.org/1.93.1/src/core/any.rs.html#138">Source</a><a href="#impl-Any-for-T" class="anchor">§</a><h3 class="code-header">impl<T> <a class="trait" href="https://doc.rust-lang.org/1.93.1/core/any/trait.Any.html" title="trait core::any::Any">Any</a> for T<div class="where">where
|
||
T: 'static + ?<a class="trait" href="https://doc.rust-lang.org/1.93.1/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>,</div></h3></section></summary><div class="impl-items"><details class="toggle method-toggle" open><summary><section id="method.type_id" class="method trait-impl"><a class="src rightside" href="https://doc.rust-lang.org/1.93.1/src/core/any.rs.html#139">Source</a><a href="#method.type_id" class="anchor">§</a><h4 class="code-header">fn <a href="https://doc.rust-lang.org/1.93.1/core/any/trait.Any.html#tymethod.type_id" class="fn">type_id</a>(&self) -> <a class="struct" href="https://doc.rust-lang.org/1.93.1/core/any/struct.TypeId.html" title="struct core::any::TypeId">TypeId</a></h4></section></summary><div class='docblock'>Gets the <code>TypeId</code> of <code>self</code>. <a href="https://doc.rust-lang.org/1.93.1/core/any/trait.Any.html#tymethod.type_id">Read more</a></div></details></div></details><details class="toggle implementors-toggle"><summary><section id="impl-Borrow%3CT%3E-for-T" class="impl"><a class="src rightside" href="https://doc.rust-lang.org/1.93.1/src/core/borrow.rs.html#212">Source</a><a href="#impl-Borrow%3CT%3E-for-T" class="anchor">§</a><h3 class="code-header">impl<T> <a class="trait" href="https://doc.rust-lang.org/1.93.1/core/borrow/trait.Borrow.html" title="trait core::borrow::Borrow">Borrow</a><T> for T<div class="where">where
|
||
T: ?<a class="trait" href="https://doc.rust-lang.org/1.93.1/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>,</div></h3></section></summary><div class="impl-items"><details class="toggle method-toggle" open><summary><section id="method.borrow" class="method trait-impl"><a class="src rightside" href="https://doc.rust-lang.org/1.93.1/src/core/borrow.rs.html#214">Source</a><a href="#method.borrow" class="anchor">§</a><h4 class="code-header">fn <a href="https://doc.rust-lang.org/1.93.1/core/borrow/trait.Borrow.html#tymethod.borrow" class="fn">borrow</a>(&self) -> <a class="primitive" href="https://doc.rust-lang.org/1.93.1/std/primitive.reference.html">&T</a></h4></section></summary><div class='docblock'>Immutably borrows from an owned value. <a href="https://doc.rust-lang.org/1.93.1/core/borrow/trait.Borrow.html#tymethod.borrow">Read more</a></div></details></div></details><details class="toggle implementors-toggle"><summary><section id="impl-BorrowMut%3CT%3E-for-T" class="impl"><a class="src rightside" href="https://doc.rust-lang.org/1.93.1/src/core/borrow.rs.html#221">Source</a><a href="#impl-BorrowMut%3CT%3E-for-T" class="anchor">§</a><h3 class="code-header">impl<T> <a class="trait" href="https://doc.rust-lang.org/1.93.1/core/borrow/trait.BorrowMut.html" title="trait core::borrow::BorrowMut">BorrowMut</a><T> for T<div class="where">where
|
||
T: ?<a class="trait" href="https://doc.rust-lang.org/1.93.1/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>,</div></h3></section></summary><div class="impl-items"><details class="toggle method-toggle" open><summary><section id="method.borrow_mut" class="method trait-impl"><a class="src rightside" href="https://doc.rust-lang.org/1.93.1/src/core/borrow.rs.html#222">Source</a><a href="#method.borrow_mut" class="anchor">§</a><h4 class="code-header">fn <a href="https://doc.rust-lang.org/1.93.1/core/borrow/trait.BorrowMut.html#tymethod.borrow_mut" class="fn">borrow_mut</a>(&mut self) -> <a class="primitive" href="https://doc.rust-lang.org/1.93.1/std/primitive.reference.html">&mut T</a></h4></section></summary><div class='docblock'>Mutably borrows from an owned value. <a href="https://doc.rust-lang.org/1.93.1/core/borrow/trait.BorrowMut.html#tymethod.borrow_mut">Read more</a></div></details></div></details><details class="toggle implementors-toggle"><summary><section id="impl-From%3CT%3E-for-T" class="impl"><a class="src rightside" href="https://doc.rust-lang.org/1.93.1/src/core/convert/mod.rs.html#785">Source</a><a href="#impl-From%3CT%3E-for-T" class="anchor">§</a><h3 class="code-header">impl<T> <a class="trait" href="https://doc.rust-lang.org/1.93.1/core/convert/trait.From.html" title="trait core::convert::From">From</a><T> for T</h3></section></summary><div class="impl-items"><details class="toggle method-toggle" open><summary><section id="method.from" class="method trait-impl"><a class="src rightside" href="https://doc.rust-lang.org/1.93.1/src/core/convert/mod.rs.html#788">Source</a><a href="#method.from" class="anchor">§</a><h4 class="code-header">fn <a href="https://doc.rust-lang.org/1.93.1/core/convert/trait.From.html#tymethod.from" class="fn">from</a>(t: T) -> T</h4></section></summary><div class="docblock"><p>Returns the argument unchanged.</p>
|
||
</div></details></div></details><details class="toggle implementors-toggle"><summary><section id="impl-Into%3CU%3E-for-T" class="impl"><a class="src rightside" href="https://doc.rust-lang.org/1.93.1/src/core/convert/mod.rs.html#767-769">Source</a><a href="#impl-Into%3CU%3E-for-T" class="anchor">§</a><h3 class="code-header">impl<T, U> <a class="trait" href="https://doc.rust-lang.org/1.93.1/core/convert/trait.Into.html" title="trait core::convert::Into">Into</a><U> for T<div class="where">where
|
||
U: <a class="trait" href="https://doc.rust-lang.org/1.93.1/core/convert/trait.From.html" title="trait core::convert::From">From</a><T>,</div></h3></section></summary><div class="impl-items"><details class="toggle method-toggle" open><summary><section id="method.into" class="method trait-impl"><a class="src rightside" href="https://doc.rust-lang.org/1.93.1/src/core/convert/mod.rs.html#777">Source</a><a href="#method.into" class="anchor">§</a><h4 class="code-header">fn <a href="https://doc.rust-lang.org/1.93.1/core/convert/trait.Into.html#tymethod.into" class="fn">into</a>(self) -> U</h4></section></summary><div class="docblock"><p>Calls <code>U::from(self)</code>.</p>
|
||
<p>That is, this conversion is whatever the implementation of
|
||
<code><a href="https://doc.rust-lang.org/1.93.1/core/convert/trait.From.html" title="trait core::convert::From">From</a><T> for U</code> chooses to do.</p>
|
||
</div></details></div></details><details class="toggle implementors-toggle"><summary><section id="impl-TryFrom%3CU%3E-for-T" class="impl"><a class="src rightside" href="https://doc.rust-lang.org/1.93.1/src/core/convert/mod.rs.html#827-829">Source</a><a href="#impl-TryFrom%3CU%3E-for-T" class="anchor">§</a><h3 class="code-header">impl<T, U> <a class="trait" href="https://doc.rust-lang.org/1.93.1/core/convert/trait.TryFrom.html" title="trait core::convert::TryFrom">TryFrom</a><U> for T<div class="where">where
|
||
U: <a class="trait" href="https://doc.rust-lang.org/1.93.1/core/convert/trait.Into.html" title="trait core::convert::Into">Into</a><T>,</div></h3></section></summary><div class="impl-items"><details class="toggle" open><summary><section id="associatedtype.Error-1" class="associatedtype trait-impl"><a class="src rightside" href="https://doc.rust-lang.org/1.93.1/src/core/convert/mod.rs.html#831">Source</a><a href="#associatedtype.Error-1" class="anchor">§</a><h4 class="code-header">type <a href="https://doc.rust-lang.org/1.93.1/core/convert/trait.TryFrom.html#associatedtype.Error" class="associatedtype">Error</a> = <a class="enum" href="https://doc.rust-lang.org/1.93.1/core/convert/enum.Infallible.html" title="enum core::convert::Infallible">Infallible</a></h4></section></summary><div class='docblock'>The type returned in the event of a conversion error.</div></details><details class="toggle method-toggle" open><summary><section id="method.try_from" class="method trait-impl"><a class="src rightside" href="https://doc.rust-lang.org/1.93.1/src/core/convert/mod.rs.html#834">Source</a><a href="#method.try_from" class="anchor">§</a><h4 class="code-header">fn <a href="https://doc.rust-lang.org/1.93.1/core/convert/trait.TryFrom.html#tymethod.try_from" class="fn">try_from</a>(value: U) -> <a class="enum" href="https://doc.rust-lang.org/1.93.1/core/result/enum.Result.html" title="enum core::result::Result">Result</a><T, <T as <a class="trait" href="https://doc.rust-lang.org/1.93.1/core/convert/trait.TryFrom.html" title="trait core::convert::TryFrom">TryFrom</a><U>>::<a class="associatedtype" href="https://doc.rust-lang.org/1.93.1/core/convert/trait.TryFrom.html#associatedtype.Error" title="type core::convert::TryFrom::Error">Error</a>></h4></section></summary><div class='docblock'>Performs the conversion.</div></details></div></details><details class="toggle implementors-toggle"><summary><section id="impl-TryInto%3CU%3E-for-T" class="impl"><a class="src rightside" href="https://doc.rust-lang.org/1.93.1/src/core/convert/mod.rs.html#811-813">Source</a><a href="#impl-TryInto%3CU%3E-for-T" class="anchor">§</a><h3 class="code-header">impl<T, U> <a class="trait" href="https://doc.rust-lang.org/1.93.1/core/convert/trait.TryInto.html" title="trait core::convert::TryInto">TryInto</a><U> for T<div class="where">where
|
||
U: <a class="trait" href="https://doc.rust-lang.org/1.93.1/core/convert/trait.TryFrom.html" title="trait core::convert::TryFrom">TryFrom</a><T>,</div></h3></section></summary><div class="impl-items"><details class="toggle" open><summary><section id="associatedtype.Error" class="associatedtype trait-impl"><a class="src rightside" href="https://doc.rust-lang.org/1.93.1/src/core/convert/mod.rs.html#815">Source</a><a href="#associatedtype.Error" class="anchor">§</a><h4 class="code-header">type <a href="https://doc.rust-lang.org/1.93.1/core/convert/trait.TryInto.html#associatedtype.Error" class="associatedtype">Error</a> = <U as <a class="trait" href="https://doc.rust-lang.org/1.93.1/core/convert/trait.TryFrom.html" title="trait core::convert::TryFrom">TryFrom</a><T>>::<a class="associatedtype" href="https://doc.rust-lang.org/1.93.1/core/convert/trait.TryFrom.html#associatedtype.Error" title="type core::convert::TryFrom::Error">Error</a></h4></section></summary><div class='docblock'>The type returned in the event of a conversion error.</div></details><details class="toggle method-toggle" open><summary><section id="method.try_into" class="method trait-impl"><a class="src rightside" href="https://doc.rust-lang.org/1.93.1/src/core/convert/mod.rs.html#818">Source</a><a href="#method.try_into" class="anchor">§</a><h4 class="code-header">fn <a href="https://doc.rust-lang.org/1.93.1/core/convert/trait.TryInto.html#tymethod.try_into" class="fn">try_into</a>(self) -> <a class="enum" href="https://doc.rust-lang.org/1.93.1/core/result/enum.Result.html" title="enum core::result::Result">Result</a><U, <U as <a class="trait" href="https://doc.rust-lang.org/1.93.1/core/convert/trait.TryFrom.html" title="trait core::convert::TryFrom">TryFrom</a><T>>::<a class="associatedtype" href="https://doc.rust-lang.org/1.93.1/core/convert/trait.TryFrom.html#associatedtype.Error" title="type core::convert::TryFrom::Error">Error</a>></h4></section></summary><div class='docblock'>Performs the conversion.</div></details></div></details></div></section></div></main></body></html> |