| <!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="Source of the Rust file `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-util-0.3.28/src/future/join_all.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>join_all.rs - source</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 href="../../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../../normalize.css"><link rel="stylesheet" href="../../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../../ayu.css" disabled><link rel="stylesheet" href="../../../dark.css" disabled><link rel="stylesheet" href="../../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../../storage.js"></script><script defer src="../../../source-script.js"></script><script defer src="../../../source-files.js"></script><script defer src="../../../main.js"></script><noscript><link rel="stylesheet" href="../../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../../futures_util/index.html"><div class="logo-container"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../../futures_util/index.html"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></a><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="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| </pre><pre class="rust"><code><span class="doccomment">//! Definition of the `JoinAll` combinator, waiting for all of a list of futures |
| //! to finish. |
| |
| </span><span class="kw">use </span>alloc::boxed::Box; |
| <span class="kw">use </span>alloc::vec::Vec; |
| <span class="kw">use </span>core::fmt; |
| <span class="kw">use </span>core::future::Future; |
| <span class="kw">use </span>core::iter::FromIterator; |
| <span class="kw">use </span>core::mem; |
| <span class="kw">use </span>core::pin::Pin; |
| <span class="kw">use </span>core::task::{Context, Poll}; |
| |
| <span class="kw">use super</span>::{assert_future, MaybeDone}; |
| |
| <span class="attribute">#[cfg(not(futures_no_atomic_cas))] |
| </span><span class="kw">use </span><span class="kw">crate</span>::stream::{Collect, FuturesOrdered, StreamExt}; |
| |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>iter_pin_mut<T>(slice: Pin<<span class="kw-2">&mut </span>[T]>) -> <span class="kw">impl </span>Iterator<Item = Pin<<span class="kw-2">&mut </span>T>> { |
| <span class="comment">// Safety: `std` _could_ make this unsound if it were to decide Pin's |
| // invariants aren't required to transmit through slices. Otherwise this has |
| // the same safety as a normal field pin projection. |
| </span><span class="kw">unsafe </span>{ slice.get_unchecked_mut() }.iter_mut().map(|t| <span class="kw">unsafe </span>{ Pin::new_unchecked(t) }) |
| } |
| |
| <span class="attribute">#[must_use = <span class="string">"futures do nothing unless you `.await` or poll them"</span>] |
| </span><span class="doccomment">/// Future for the [`join_all`] function. |
| </span><span class="kw">pub struct </span>JoinAll<F> |
| <span class="kw">where |
| </span>F: Future, |
| { |
| kind: JoinAllKind<F>, |
| } |
| |
| <span class="attribute">#[cfg(not(futures_no_atomic_cas))] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">const </span>SMALL: usize = <span class="number">30</span>; |
| |
| <span class="kw">enum </span>JoinAllKind<F> |
| <span class="kw">where |
| </span>F: Future, |
| { |
| Small { |
| elems: Pin<Box<[MaybeDone<F>]>>, |
| }, |
| <span class="attribute">#[cfg(not(futures_no_atomic_cas))] |
| </span>Big { |
| fut: Collect<FuturesOrdered<F>, Vec<F::Output>>, |
| }, |
| } |
| |
| <span class="kw">impl</span><F> fmt::Debug <span class="kw">for </span>JoinAll<F> |
| <span class="kw">where |
| </span>F: Future + fmt::Debug, |
| F::Output: fmt::Debug, |
| { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| <span class="kw">match </span><span class="self">self</span>.kind { |
| JoinAllKind::Small { <span class="kw-2">ref </span>elems } => { |
| f.debug_struct(<span class="string">"JoinAll"</span>).field(<span class="string">"elems"</span>, elems).finish() |
| } |
| <span class="attribute">#[cfg(not(futures_no_atomic_cas))] |
| </span>JoinAllKind::Big { <span class="kw-2">ref </span>fut, .. } => fmt::Debug::fmt(fut, f), |
| } |
| } |
| } |
| |
| <span class="doccomment">/// Creates a future which represents a collection of the outputs of the futures |
| /// given. |
| /// |
| /// The returned future will drive execution for all of its underlying futures, |
| /// collecting the results into a destination `Vec<T>` in the same order as they |
| /// were provided. |
| /// |
| /// This function is only available when the `std` or `alloc` feature of this |
| /// library is activated, and it is activated by default. |
| /// |
| /// # See Also |
| /// |
| /// `join_all` will switch to the more powerful [`FuturesOrdered`] for performance |
| /// reasons if the number of futures is large. You may want to look into using it or |
| /// it's counterpart [`FuturesUnordered`][crate::stream::FuturesUnordered] directly. |
| /// |
| /// Some examples for additional functionality provided by these are: |
| /// |
| /// * Adding new futures to the set even after it has been started. |
| /// |
| /// * 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. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// # futures::executor::block_on(async { |
| /// use futures::future::join_all; |
| /// |
| /// async fn foo(i: u32) -> u32 { i } |
| /// |
| /// let futures = vec![foo(1), foo(2), foo(3)]; |
| /// |
| /// assert_eq!(join_all(futures).await, [1, 2, 3]); |
| /// # }); |
| /// ``` |
| </span><span class="kw">pub fn </span>join_all<I>(iter: I) -> JoinAll<I::Item> |
| <span class="kw">where |
| </span>I: IntoIterator, |
| I::Item: Future, |
| { |
| <span class="kw">let </span>iter = iter.into_iter(); |
| |
| <span class="attribute">#[cfg(futures_no_atomic_cas)] |
| </span>{ |
| <span class="kw">let </span>kind = |
| JoinAllKind::Small { elems: iter.map(MaybeDone::Future).collect::<Box<[<span class="kw">_</span>]>>().into() }; |
| |
| assert_future::<Vec<<I::Item <span class="kw">as </span>Future>::Output>, <span class="kw">_</span>>(JoinAll { kind }) |
| } |
| |
| <span class="attribute">#[cfg(not(futures_no_atomic_cas))] |
| </span>{ |
| <span class="kw">let </span>kind = <span class="kw">match </span>iter.size_hint().<span class="number">1 </span>{ |
| <span class="prelude-val">Some</span>(max) <span class="kw">if </span>max <= SMALL => JoinAllKind::Small { |
| elems: iter.map(MaybeDone::Future).collect::<Box<[<span class="kw">_</span>]>>().into(), |
| }, |
| <span class="kw">_ </span>=> JoinAllKind::Big { fut: iter.collect::<FuturesOrdered<<span class="kw">_</span>>>().collect() }, |
| }; |
| |
| assert_future::<Vec<<I::Item <span class="kw">as </span>Future>::Output>, <span class="kw">_</span>>(JoinAll { kind }) |
| } |
| } |
| |
| <span class="kw">impl</span><F> Future <span class="kw">for </span>JoinAll<F> |
| <span class="kw">where |
| </span>F: Future, |
| { |
| <span class="kw">type </span>Output = Vec<F::Output>; |
| |
| <span class="kw">fn </span>poll(<span class="kw-2">mut </span><span class="self">self</span>: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>, cx: <span class="kw-2">&mut </span>Context<<span class="lifetime">'_</span>>) -> Poll<<span class="self">Self</span>::Output> { |
| <span class="kw">match </span><span class="kw-2">&mut </span><span class="self">self</span>.kind { |
| JoinAllKind::Small { elems } => { |
| <span class="kw">let </span><span class="kw-2">mut </span>all_done = <span class="bool-val">true</span>; |
| |
| <span class="kw">for </span>elem <span class="kw">in </span>iter_pin_mut(elems.as_mut()) { |
| <span class="kw">if </span>elem.poll(cx).is_pending() { |
| all_done = <span class="bool-val">false</span>; |
| } |
| } |
| |
| <span class="kw">if </span>all_done { |
| <span class="kw">let </span><span class="kw-2">mut </span>elems = mem::replace(elems, Box::pin([])); |
| <span class="kw">let </span>result = |
| iter_pin_mut(elems.as_mut()).map(|e| e.take_output().unwrap()).collect(); |
| Poll::Ready(result) |
| } <span class="kw">else </span>{ |
| Poll::Pending |
| } |
| } |
| <span class="attribute">#[cfg(not(futures_no_atomic_cas))] |
| </span>JoinAllKind::Big { fut } => Pin::new(fut).poll(cx), |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><F: Future> FromIterator<F> <span class="kw">for </span>JoinAll<F> { |
| <span class="kw">fn </span>from_iter<T: IntoIterator<Item = F>>(iter: T) -> <span class="self">Self </span>{ |
| join_all(iter) |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../../" data-current-crate="futures_util" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
