| <!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="Creates a future which represents a collection of the outputs of the futures given."><meta name="keywords" content="rust, rustlang, rust-lang, join_all"><title>join_all in futures::future - Rust</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin 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class="sidebar-menu-toggle">☰</button><a class="sidebar-logo" href="../../futures/index.html"><div class="logo-container"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></div></a><h2></h2></nav><nav class="sidebar"><a class="sidebar-logo" href="../../futures/index.html"><div class="logo-container"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></div></a><div class="sidebar-elems"><h2><a href="index.html">In futures::future</a></h2></div></nav><main><div class="width-limiter"><nav class="sub"><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="main-heading"><h1 class="fqn">Function <a href="../index.html">futures</a>::<wbr><a href="index.html">future</a>::<wbr><a class="fn" href="#">join_all</a><button id="copy-path" onclick="copy_path(this)" title="Copy item path to clipboard"><img src="../../clipboard.svg" width="19" height="18" alt="Copy item path"></button></h1><span class="out-of-band"><a class="srclink" href="../../src/futures_util/future/join_all.rs.html#102-105">source</a> · <a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class="inner">−</span>]</a></span></div><div class="item-decl"><pre class="rust fn"><code>pub fn join_all<I>(iter: I) -> <a class="struct" href="struct.JoinAll.html" title="struct futures::future::JoinAll">JoinAll</a><<I as <a class="trait" href="https://doc.rust-lang.org/nightly/core/iter/traits/collect/trait.IntoIterator.html" title="trait core::iter::traits::collect::IntoIterator">IntoIterator</a>>::<a class="associatedtype" href="https://doc.rust-lang.org/nightly/core/iter/traits/collect/trait.IntoIterator.html#associatedtype.Item" title="type core::iter::traits::collect::IntoIterator::Item">Item</a>><span class="notable-traits"><span class="notable-traits-tooltip">ⓘ<span class="notable-traits-tooltiptext"><span class="docblock"><span class="notable">Notable traits for <a class="struct" href="struct.JoinAll.html" title="struct futures::future::JoinAll">JoinAll</a><F></span><code class="content"><span class="where fmt-newline">impl<F> <a class="trait" href="trait.Future.html" title="trait futures::future::Future">Future</a> for <a class="struct" href="struct.JoinAll.html" title="struct futures::future::JoinAll">JoinAll</a><F><span class="where fmt-newline">where<br> F: <a class="trait" href="trait.Future.html" title="trait futures::future::Future">Future</a>,</span></span><span class="where fmt-newline"> type <a href="trait.Future.html#associatedtype.Output" class="associatedtype">Output</a> = <a class="struct" href="https://doc.rust-lang.org/nightly/alloc/vec/struct.Vec.html" title="struct alloc::vec::Vec">Vec</a><<F as <a class="trait" href="trait.Future.html" title="trait futures::future::Future">Future</a>>::<a class="associatedtype" href="trait.Future.html#associatedtype.Output" title="type futures::future::Future::Output">Output</a>, <a class="struct" href="https://doc.rust-lang.org/nightly/alloc/alloc/struct.Global.html" title="struct alloc::alloc::Global">Global</a>>;</span></code></span></span></span></span><span class="where fmt-newline">where<br> I: <a class="trait" href="https://doc.rust-lang.org/nightly/core/iter/traits/collect/trait.IntoIterator.html" title="trait core::iter::traits::collect::IntoIterator">IntoIterator</a>,<br> <I as <a class="trait" href="https://doc.rust-lang.org/nightly/core/iter/traits/collect/trait.IntoIterator.html" title="trait core::iter::traits::collect::IntoIterator">IntoIterator</a>>::<a class="associatedtype" href="https://doc.rust-lang.org/nightly/core/iter/traits/collect/trait.IntoIterator.html#associatedtype.Item" title="type core::iter::traits::collect::IntoIterator::Item">Item</a>: <a class="trait" href="trait.Future.html" title="trait futures::future::Future">Future</a>,</span></code></pre></div><details class="rustdoc-toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Creates a future which represents a collection of the outputs of the futures |
| given.</p> |
| <p>The returned future will drive execution for all of its underlying futures, |
| collecting the results into a destination <code>Vec<T></code> in the same order as they |
| were provided.</p> |
| <p>This function is only available when the <code>std</code> or <code>alloc</code> feature of this |
| library is activated, and it is activated by default.</p> |
| <h2 id="see-also"><a href="#see-also">See Also</a></h2> |
| <p><code>join_all</code> will switch to the more powerful <a href="../stream/struct.FuturesOrdered.html" title="FuturesOrdered"><code>FuturesOrdered</code></a> for performance |
| reasons if the number of futures is large. You may want to look into using it or |
| it’s counterpart <a href="../stream/struct.FuturesUnordered.html" title="crate::stream::FuturesUnordered"><code>FuturesUnordered</code></a> directly.</p> |
| <p>Some examples for additional functionality provided by these are:</p> |
| <ul> |
| <li> |
| <p>Adding new futures to the set even after it has been started.</p> |
| </li> |
| <li> |
| <p>Only polling the specific futures that have been woken. In cases where |
| you have a lot of futures this will result in much more efficient polling.</p> |
| </li> |
| </ul> |
| <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>futures::future::join_all; |
| |
| <span class="kw">async fn </span>foo(i: u32) -> u32 { i } |
| |
| <span class="kw">let </span>futures = <span class="macro">vec!</span>[foo(<span class="number">1</span>), foo(<span class="number">2</span>), foo(<span class="number">3</span>)]; |
| |
| <span class="macro">assert_eq!</span>(join_all(futures).<span class="kw">await</span>, [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>]);</code></pre></div> |
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