mirror of
https://github.com/OMGeeky/google-apis-rs.git
synced 2026-02-23 15:49:49 +01:00
102 lines
12 KiB
HTML
102 lines
12 KiB
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="A one-shot channel is used for sending a single message between asynchronous tasks. The `channel` function is used to create a `Sender` and `Receiver` handle pair that form the channel."><title>tokio::sync::oneshot - Rust</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../static.files/SourceSerif4-Regular-46f98efaafac5295.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../static.files/FiraSans-Regular-018c141bf0843ffd.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../static.files/FiraSans-Medium-8f9a781e4970d388.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../static.files/SourceCodePro-Regular-562dcc5011b6de7d.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../static.files/SourceCodePro-Semibold-d899c5a5c4aeb14a.ttf.woff2"><link rel="stylesheet" href="../../../static.files/normalize-76eba96aa4d2e634.css"><link rel="stylesheet" href="../../../static.files/rustdoc-ac92e1bbe349e143.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="1.76.0 (07dca489a 2024-02-04)" data-channel="1.76.0" data-search-js="search-2b6ce74ff89ae146.js" data-settings-js="settings-4313503d2e1961c2.js" ><script src="../../../static.files/storage-f2adc0d6ca4d09fb.js"></script><script defer src="../sidebar-items.js"></script><script defer src="../../../static.files/main-305769736d49e732.js"></script><noscript><link rel="stylesheet" href="../../../static.files/noscript-feafe1bb7466e4bd.css"></noscript><link rel="alternate icon" type="image/png" href="../../../static.files/favicon-16x16-8b506e7a72182f1c.png"><link rel="alternate icon" type="image/png" href="../../../static.files/favicon-32x32-422f7d1d52889060.png"><link rel="icon" type="image/svg+xml" href="../../../static.files/favicon-2c020d218678b618.svg"></head><body class="rustdoc mod"><!--[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">☰</button></nav><nav class="sidebar"><div class="sidebar-crate"><h2><a href="../../../tokio/index.html">tokio</a><span class="version">1.33.0</span></h2></div><h2 class="location"><a href="#">Module oneshot</a></h2><div class="sidebar-elems"><section><ul class="block"><li><a href="#modules">Modules</a></li><li><a href="#structs">Structs</a></li><li><a href="#functions">Functions</a></li></ul></section><h2><a href="../index.html">In tokio::sync</a></h2></div></nav><div class="sidebar-resizer"></div>
|
||
<main><div class="width-limiter"><nav class="sub"><form class="search-form"><span></span><div id="sidebar-button" tabindex="-1"><a href="../../../tokio/all.html" title="show sidebar"></a></div><input class="search-input" name="search" aria-label="Run search in the documentation" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" tabindex="-1"><a href="../../../help.html" title="help">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../../static.files/wheel-7b819b6101059cd0.svg"></a></div></form></nav><section id="main-content" class="content"><div class="main-heading"><h1>Module <a href="../../index.html">tokio</a>::<wbr><a href="../index.html">sync</a>::<wbr><a class="mod" href="#">oneshot</a><button id="copy-path" title="Copy item path to clipboard"><img src="../../../static.files/clipboard-7571035ce49a181d.svg" width="19" height="18" alt="Copy item path"></button></h1><span class="out-of-band"><a class="src" href="../../../src/tokio/sync/oneshot.rs.html#1-1389">source</a> · <button id="toggle-all-docs" title="collapse all docs">[<span>−</span>]</button></span></div><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>A one-shot channel is used for sending a single message between
|
||
asynchronous tasks. The <a href="fn.channel.html" title="fn tokio::sync::oneshot::channel"><code>channel</code></a> function is used to create a
|
||
<a href="struct.Sender.html" title="struct tokio::sync::oneshot::Sender"><code>Sender</code></a> and <a href="struct.Receiver.html" title="struct tokio::sync::oneshot::Receiver"><code>Receiver</code></a> handle pair that form the channel.</p>
|
||
<p>The <code>Sender</code> handle is used by the producer to send the value.
|
||
The <code>Receiver</code> handle is used by the consumer to receive the value.</p>
|
||
<p>Each handle can be used on separate tasks.</p>
|
||
<p>Since the <code>send</code> method is not async, it can be used anywhere. This includes
|
||
sending between two runtimes, and using it from non-async code.</p>
|
||
<p>If the <a href="struct.Receiver.html" title="struct tokio::sync::oneshot::Receiver"><code>Receiver</code></a> is closed before receiving a message which has already
|
||
been sent, the message will remain in the channel until the receiver is
|
||
dropped, at which point the message will be dropped immediately.</p>
|
||
<h2 id="examples"><a href="#examples">Examples</a></h2>
|
||
<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>tokio::sync::oneshot;
|
||
|
||
<span class="attr">#[tokio::main]
|
||
</span><span class="kw">async fn </span>main() {
|
||
<span class="kw">let </span>(tx, rx) = oneshot::channel();
|
||
|
||
tokio::spawn(<span class="kw">async move </span>{
|
||
<span class="kw">if let </span><span class="prelude-val">Err</span>(<span class="kw">_</span>) = tx.send(<span class="number">3</span>) {
|
||
<span class="macro">println!</span>(<span class="string">"the receiver dropped"</span>);
|
||
}
|
||
});
|
||
|
||
<span class="kw">match </span>rx.<span class="kw">await </span>{
|
||
<span class="prelude-val">Ok</span>(v) => <span class="macro">println!</span>(<span class="string">"got = {:?}"</span>, v),
|
||
<span class="prelude-val">Err</span>(<span class="kw">_</span>) => <span class="macro">println!</span>(<span class="string">"the sender dropped"</span>),
|
||
}
|
||
}</code></pre></div>
|
||
<p>If the sender is dropped without sending, the receiver will fail with
|
||
<a href="error/struct.RecvError.html" title="struct tokio::sync::oneshot::error::RecvError"><code>error::RecvError</code></a>:</p>
|
||
|
||
<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>tokio::sync::oneshot;
|
||
|
||
<span class="attr">#[tokio::main]
|
||
</span><span class="kw">async fn </span>main() {
|
||
<span class="kw">let </span>(tx, rx) = oneshot::channel::<u32>();
|
||
|
||
tokio::spawn(<span class="kw">async move </span>{
|
||
drop(tx);
|
||
});
|
||
|
||
<span class="kw">match </span>rx.<span class="kw">await </span>{
|
||
<span class="prelude-val">Ok</span>(<span class="kw">_</span>) => <span class="macro">panic!</span>(<span class="string">"This doesn't happen"</span>),
|
||
<span class="prelude-val">Err</span>(<span class="kw">_</span>) => <span class="macro">println!</span>(<span class="string">"the sender dropped"</span>),
|
||
}
|
||
}</code></pre></div>
|
||
<p>To use a oneshot channel in a <code>tokio::select!</code> loop, add <code>&mut</code> in front of
|
||
the channel.</p>
|
||
|
||
<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>tokio::sync::oneshot;
|
||
<span class="kw">use </span>tokio::time::{interval, sleep, Duration};
|
||
|
||
<span class="attr">#[tokio::main]
|
||
</span><span class="kw">async fn </span>main() {
|
||
<span class="kw">let </span>(send, <span class="kw-2">mut </span>recv) = oneshot::channel();
|
||
<span class="kw">let </span><span class="kw-2">mut </span>interval = interval(Duration::from_millis(<span class="number">100</span>));
|
||
|
||
tokio::spawn(<span class="kw">async move </span>{
|
||
sleep(Duration::from_secs(<span class="number">1</span>)).<span class="kw">await</span>;
|
||
send.send(<span class="string">"shut down"</span>).unwrap();
|
||
});
|
||
|
||
<span class="kw">loop </span>{
|
||
<span class="macro">tokio::select! </span>{
|
||
<span class="kw">_ </span>= interval.tick() => <span class="macro">println!</span>(<span class="string">"Another 100ms"</span>),
|
||
msg = <span class="kw-2">&mut </span>recv => {
|
||
<span class="macro">println!</span>(<span class="string">"Got message: {}"</span>, msg.unwrap());
|
||
<span class="kw">break</span>;
|
||
}
|
||
}
|
||
}
|
||
}</code></pre></div>
|
||
<p>To use a <code>Sender</code> from a destructor, put it in an <a href="https://doc.rust-lang.org/1.76.0/core/option/enum.Option.html" title="enum core::option::Option"><code>Option</code></a> and call
|
||
<a href="https://doc.rust-lang.org/1.76.0/core/option/enum.Option.html#method.take" title="method core::option::Option::take"><code>Option::take</code></a>.</p>
|
||
|
||
<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>tokio::sync::oneshot;
|
||
|
||
<span class="kw">struct </span>SendOnDrop {
|
||
sender: <span class="prelude-ty">Option</span><oneshot::Sender<<span class="kw-2">&</span><span class="lifetime">'static </span>str>>,
|
||
}
|
||
<span class="kw">impl </span>Drop <span class="kw">for </span>SendOnDrop {
|
||
<span class="kw">fn </span>drop(<span class="kw-2">&mut </span><span class="self">self</span>) {
|
||
<span class="kw">if let </span><span class="prelude-val">Some</span>(sender) = <span class="self">self</span>.sender.take() {
|
||
<span class="comment">// Using `let _ =` to ignore send errors.
|
||
</span><span class="kw">let _ </span>= sender.send(<span class="string">"I got dropped!"</span>);
|
||
}
|
||
}
|
||
}
|
||
|
||
<span class="attr">#[tokio::main]
|
||
</span><span class="kw">async fn </span>main() {
|
||
<span class="kw">let </span>(send, recv) = oneshot::channel();
|
||
|
||
<span class="kw">let </span>send_on_drop = SendOnDrop { sender: <span class="prelude-val">Some</span>(send) };
|
||
drop(send_on_drop);
|
||
|
||
<span class="macro">assert_eq!</span>(recv.<span class="kw">await</span>, <span class="prelude-val">Ok</span>(<span class="string">"I got dropped!"</span>));
|
||
}</code></pre></div>
|
||
</div></details><h2 id="modules" class="section-header"><a href="#modules">Modules</a></h2><ul class="item-table"><li><div class="item-name"><a class="mod" href="error/index.html" title="mod tokio::sync::oneshot::error">error</a></div><div class="desc docblock-short">Oneshot error types.</div></li></ul><h2 id="structs" class="section-header"><a href="#structs">Structs</a></h2><ul class="item-table"><li><div class="item-name"><a class="struct" href="struct.Receiver.html" title="struct tokio::sync::oneshot::Receiver">Receiver</a></div><div class="desc docblock-short">Receives a value from the associated <a href="struct.Sender.html" title="struct tokio::sync::oneshot::Sender"><code>Sender</code></a>.</div></li><li><div class="item-name"><a class="struct" href="struct.Sender.html" title="struct tokio::sync::oneshot::Sender">Sender</a></div><div class="desc docblock-short">Sends a value to the associated <a href="struct.Receiver.html" title="struct tokio::sync::oneshot::Receiver"><code>Receiver</code></a>.</div></li></ul><h2 id="functions" class="section-header"><a href="#functions">Functions</a></h2><ul class="item-table"><li><div class="item-name"><a class="fn" href="fn.channel.html" title="fn tokio::sync::oneshot::channel">channel</a></div><div class="desc docblock-short">Creates a new one-shot channel for sending single values across asynchronous
|
||
tasks.</div></li></ul></section></div></main></body></html> |