48 lines
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48 lines
7.8 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 thread pool for isolating blocking I/O in async programs."><title>blocking - 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="blocking" 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="../crates.js"></script><script defer src="../static.files/main-5f194d8c.js"></script><noscript><link rel="stylesheet" href="../static.files/noscript-893ab5e7.css"></noscript><link rel="icon" href="https://raw.githubusercontent.com/smol-rs/smol/master/assets/images/logo_fullsize_transparent.png"></head><body class="rustdoc mod crate"><!--[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><a class="logo-container" href="../blocking/index.html"><img src="https://raw.githubusercontent.com/smol-rs/smol/master/assets/images/logo_fullsize_transparent.png" alt=""></a></nav><nav class="sidebar"><div class="sidebar-crate"><a class="logo-container" href="../blocking/index.html"><img src="https://raw.githubusercontent.com/smol-rs/smol/master/assets/images/logo_fullsize_transparent.png" alt="logo"></a><h2><a href="../blocking/index.html">blocking</a><span class="version">1.6.1</span></h2></div><div class="sidebar-elems"><ul class="block"><li><a id="all-types" href="all.html">All Items</a></li></ul><section id="rustdoc-toc"><h3><a href="#">Sections</a></h3><ul class="block top-toc"><li><a href="#examples" title="Examples">Examples</a></li></ul><h3><a href="#reexports">Crate Items</a></h3><ul class="block"><li><a href="#reexports" title="Re-exports">Re-exports</a></li><li><a href="#structs" title="Structs">Structs</a></li><li><a href="#functions" title="Functions">Functions</a></li></ul></section><div id="rustdoc-modnav"></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"><h1>Crate <span>blocking</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/blocking/lib.rs.html#1-1025">Source</a> </span></div><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>A thread pool for isolating blocking I/O in async programs.</p>
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<p>Sometimes there’s no way to avoid blocking I/O. Consider files or stdin, which have weak async
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support on modern operating systems. While <a href="https://en.wikipedia.org/wiki/Input/output_completion_port">IOCP</a>, <a href="http://man7.org/linux/man-pages/man2/io_submit.2.html">AIO</a>, and <a href="https://lwn.net/Articles/776703">io_uring</a> are possible
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solutions, they’re not always available or ideal.</p>
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<p>Since blocking is not allowed inside futures, we must move blocking I/O onto a special thread
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pool provided by this crate. The pool dynamically spawns and stops threads depending on the
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current number of running I/O jobs.</p>
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<p>Note that there is a limit on the number of active threads. Once that limit is hit, a running
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job has to finish before others get a chance to run. When a thread is idle, it waits for the
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next job or shuts down after a certain timeout.</p>
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<p>The default number of threads (set to 500) can be altered by setting BLOCKING_MAX_THREADS environment
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variable with value between 1 and 10000.</p>
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<h2 id="examples"><a class="doc-anchor" href="#examples">§</a>Examples</h2>
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<p>Read the contents of a file:</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>blocking::unblock;
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<span class="kw">use </span>std::fs;
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<span class="kw">let </span>contents = unblock(|| fs::read_to_string(<span class="string">"file.txt"</span>)).<span class="kw">await</span><span class="question-mark">?</span>;
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<span class="macro">println!</span>(<span class="string">"{}"</span>, contents);</code></pre></div>
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<p>Read a file and pipe its contents to stdout:</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>blocking::{unblock, Unblock};
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<span class="kw">use </span>futures_lite::io;
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<span class="kw">use </span>std::fs::File;
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<span class="kw">let </span>input = unblock(|| File::open(<span class="string">"file.txt"</span>)).<span class="kw">await</span><span class="question-mark">?</span>;
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<span class="kw">let </span>input = Unblock::new(input);
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<span class="kw">let </span><span class="kw-2">mut </span>output = Unblock::new(std::io::stdout());
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io::copy(input, <span class="kw-2">&mut </span>output).<span class="kw">await</span><span class="question-mark">?</span>;</code></pre></div>
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<p>Iterate over the contents of a directory:</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>blocking::Unblock;
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<span class="kw">use </span>futures_lite::prelude::<span class="kw-2">*</span>;
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<span class="kw">use </span>std::fs;
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<span class="kw">let </span><span class="kw-2">mut </span>dir = Unblock::new(fs::read_dir(<span class="string">"."</span>)<span class="question-mark">?</span>);
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<span class="kw">while let </span><span class="prelude-val">Some</span>(item) = dir.next().<span class="kw">await </span>{
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<span class="macro">println!</span>(<span class="string">"{}"</span>, item<span class="question-mark">?</span>.file_name().to_string_lossy());
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}</code></pre></div>
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<p>Spawn a process:</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>blocking::unblock;
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<span class="kw">use </span>std::process::Command;
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<span class="kw">let </span>out = unblock(|| Command::new(<span class="string">"dir"</span>).output()).<span class="kw">await</span><span class="question-mark">?</span>;</code></pre></div>
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</div></details><h2 id="reexports" class="section-header">Re-exports<a href="#reexports" class="anchor">§</a></h2><ul class="item-table"><li><div class="item-name" id="reexport.Task"><code>pub use async_task::<a class="struct" href="../async_task/task/struct.Task.html" title="struct async_task::task::Task">Task</a>;</code></div></li></ul><h2 id="structs" class="section-header">Structs<a href="#structs" class="anchor">§</a></h2><ul class="item-table"><li><div class="item-name"><a class="struct" href="struct.Unblock.html" title="struct blocking::Unblock">Unblock</a></div><div class="desc docblock-short">Runs blocking I/O on a thread pool.</div></li></ul><h2 id="functions" class="section-header">Functions<a href="#functions" class="anchor">§</a></h2><ul class="item-table"><li><div class="item-name"><a class="fn" href="fn.unblock.html" title="fn blocking::unblock">unblock</a></div><div class="desc docblock-short">Runs blocking code on a thread pool.</div></li></ul></section></div></main></body></html> |