287 lines
15 KiB
HTML
287 lines
15 KiB
HTML
<!DOCTYPE HTML>
|
|
<html lang="en" class="sidebar-visible no-js">
|
|
<head>
|
|
<!-- Book generated using mdBook -->
|
|
<meta charset="UTF-8">
|
|
<title>Introduction - Futures Explained in 200 Lines of Rust</title>
|
|
|
|
|
|
<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
|
|
<meta name="description" content="This book aims to explain Futures in Rust using an example driven approach.">
|
|
<meta name="viewport" content="width=device-width, initial-scale=1">
|
|
<meta name="theme-color" content="#ffffff" />
|
|
|
|
<link rel="shortcut icon" href="favicon.png">
|
|
<link rel="stylesheet" href="css/variables.css">
|
|
<link rel="stylesheet" href="css/general.css">
|
|
<link rel="stylesheet" href="css/chrome.css">
|
|
<link rel="stylesheet" href="css/print.css" media="print">
|
|
|
|
<!-- Fonts -->
|
|
<link rel="stylesheet" href="FontAwesome/css/font-awesome.css">
|
|
<link href="https://fonts.googleapis.com/css?family=Open+Sans:300italic,400italic,600italic,700italic,800italic,400,300,600,700,800" rel="stylesheet" type="text/css">
|
|
<link href="https://fonts.googleapis.com/css?family=Source+Code+Pro:500" rel="stylesheet" type="text/css">
|
|
|
|
<!-- Highlight.js Stylesheets -->
|
|
<link rel="stylesheet" href="highlight.css">
|
|
<link rel="stylesheet" href="tomorrow-night.css">
|
|
<link rel="stylesheet" href="ayu-highlight.css">
|
|
|
|
<!-- Custom theme stylesheets -->
|
|
|
|
|
|
|
|
</head>
|
|
<body class="light">
|
|
<!-- Provide site root to javascript -->
|
|
<script type="text/javascript">
|
|
var path_to_root = "";
|
|
var default_theme = "light";
|
|
</script>
|
|
|
|
<!-- Work around some values being stored in localStorage wrapped in quotes -->
|
|
<script type="text/javascript">
|
|
try {
|
|
var theme = localStorage.getItem('mdbook-theme');
|
|
var sidebar = localStorage.getItem('mdbook-sidebar');
|
|
|
|
if (theme.startsWith('"') && theme.endsWith('"')) {
|
|
localStorage.setItem('mdbook-theme', theme.slice(1, theme.length - 1));
|
|
}
|
|
|
|
if (sidebar.startsWith('"') && sidebar.endsWith('"')) {
|
|
localStorage.setItem('mdbook-sidebar', sidebar.slice(1, sidebar.length - 1));
|
|
}
|
|
} catch (e) { }
|
|
</script>
|
|
|
|
<!-- Set the theme before any content is loaded, prevents flash -->
|
|
<script type="text/javascript">
|
|
var theme;
|
|
try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
|
|
if (theme === null || theme === undefined) { theme = default_theme; }
|
|
document.body.className = theme;
|
|
document.querySelector('html').className = theme + ' js';
|
|
</script>
|
|
|
|
<!-- Hide / unhide sidebar before it is displayed -->
|
|
<script type="text/javascript">
|
|
var html = document.querySelector('html');
|
|
var sidebar = 'hidden';
|
|
if (document.body.clientWidth >= 1080) {
|
|
try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { }
|
|
sidebar = sidebar || 'visible';
|
|
}
|
|
html.classList.remove('sidebar-visible');
|
|
html.classList.add("sidebar-" + sidebar);
|
|
</script>
|
|
|
|
<nav id="sidebar" class="sidebar" aria-label="Table of contents">
|
|
<div class="sidebar-scrollbox">
|
|
<ol class="chapter"><li class="affix"><a href="introduction.html">Introduction</a></li><li><a href="0_background_information.html"><strong aria-hidden="true">1.</strong> Background information</a></li><li><a href="1_futures_in_rust.html"><strong aria-hidden="true">2.</strong> Futures in Rust</a></li><li><a href="2_waker_context.html"><strong aria-hidden="true">3.</strong> Waker and Context</a></li><li><a href="3_generators_pin.html"><strong aria-hidden="true">4.</strong> Generators</a></li><li><a href="4_pin.html"><strong aria-hidden="true">5.</strong> Pin</a></li><li><a href="6_future_example.html"><strong aria-hidden="true">6.</strong> Implementing Futures</a></li><li><a href="8_finished_example.html"><strong aria-hidden="true">7.</strong> Finished example (editable)</a></li><li class="affix"><a href="conclusion.html">Conclusion and exercises</a></li></ol>
|
|
</div>
|
|
<div id="sidebar-resize-handle" class="sidebar-resize-handle"></div>
|
|
</nav>
|
|
|
|
<div id="page-wrapper" class="page-wrapper">
|
|
|
|
<div class="page">
|
|
|
|
<div id="menu-bar" class="menu-bar">
|
|
<div id="menu-bar-sticky-container">
|
|
<div class="left-buttons">
|
|
<button id="sidebar-toggle" class="icon-button" type="button" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar">
|
|
<i class="fa fa-bars"></i>
|
|
</button>
|
|
<button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list">
|
|
<i class="fa fa-paint-brush"></i>
|
|
</button>
|
|
<ul id="theme-list" class="theme-popup" aria-label="Themes" role="menu">
|
|
<li role="none"><button role="menuitem" class="theme" id="light">Light (default)</button></li>
|
|
<li role="none"><button role="menuitem" class="theme" id="rust">Rust</button></li>
|
|
<li role="none"><button role="menuitem" class="theme" id="coal">Coal</button></li>
|
|
<li role="none"><button role="menuitem" class="theme" id="navy">Navy</button></li>
|
|
<li role="none"><button role="menuitem" class="theme" id="ayu">Ayu</button></li>
|
|
</ul>
|
|
|
|
<button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
|
|
<i class="fa fa-search"></i>
|
|
</button>
|
|
|
|
</div>
|
|
|
|
<h1 class="menu-title">Futures Explained in 200 Lines of Rust</h1>
|
|
|
|
<div class="right-buttons">
|
|
<a href="print.html" title="Print this book" aria-label="Print this book">
|
|
<i id="print-button" class="fa fa-print"></i>
|
|
</a>
|
|
|
|
<a href="https://github.com/cfsamson/books-futures-explained" title="Git repository" aria-label="Git repository">
|
|
<i id="git-repository-button" class="fa fa-github"></i>
|
|
</a>
|
|
|
|
</div>
|
|
</div>
|
|
</div>
|
|
|
|
|
|
<div id="search-wrapper" class="hidden">
|
|
<form id="searchbar-outer" class="searchbar-outer">
|
|
<input type="search" name="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header">
|
|
</form>
|
|
<div id="searchresults-outer" class="searchresults-outer hidden">
|
|
<div id="searchresults-header" class="searchresults-header"></div>
|
|
<ul id="searchresults">
|
|
</ul>
|
|
</div>
|
|
</div>
|
|
|
|
|
|
<!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM -->
|
|
<script type="text/javascript">
|
|
document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible');
|
|
document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible');
|
|
Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) {
|
|
link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1);
|
|
});
|
|
</script>
|
|
|
|
<div id="content" class="content">
|
|
<main>
|
|
<h1><a class="header" href="#futures-explained-in-200-lines-of-rust" id="futures-explained-in-200-lines-of-rust">Futures Explained in 200 Lines of Rust</a></h1>
|
|
<p>This book aims to explain <code>Futures</code> in Rust using an example driven approach,
|
|
exploring why they're designed the way they are, and how they work. We'll also
|
|
take a look at some of the alternatives we have when dealing with concurrency
|
|
in programming.</p>
|
|
<p>Going into the level of detail I do in this book is not needed to use futures
|
|
or async/await in Rust. It's for the curious out there that want to know <em>how</em>
|
|
it all works.</p>
|
|
<h2><a class="header" href="#what-this-book-covers" id="what-this-book-covers">What this book covers</a></h2>
|
|
<p>This book will try to explain everything you might wonder about up until the
|
|
topic of different types of executors and runtimes. We'll just implement a very
|
|
simple runtime in this book introducing some concepts but it's enough to get
|
|
started.</p>
|
|
<p><a href="https://github.com/stjepang">Stjepan Glavina</a> has made an excellent series of
|
|
articles about async runtimes and executors, and if the rumors are right there
|
|
is more to come from him in the near future.</p>
|
|
<p>The way you should go about it is to read this book first, then continue
|
|
reading the <a href="https://stjepang.github.io/">articles from stejpang</a> to learn more
|
|
about runtimes and how they work, especially:</p>
|
|
<ol>
|
|
<li><a href="https://stjepang.github.io/2020/01/25/build-your-own-block-on.html">Build your own block_on()</a></li>
|
|
<li><a href="https://stjepang.github.io/2020/01/31/build-your-own-executor.html">Build your own executor</a></li>
|
|
</ol>
|
|
<p>I've limited myself to a 200 line main example (hence the title) to limit the
|
|
scope and introduce an example that can easily be explored further.</p>
|
|
<p>However, there is a lot to digest and it's not what I would call easy, but we'll
|
|
take everything step by step so get a cup of tea and relax. </p>
|
|
<p>I hope you enjoy the ride.</p>
|
|
<blockquote>
|
|
<p>This book is developed in the open, and contributions are welcome. You'll find
|
|
<a href="https://github.com/cfsamson/books-futures-explained">the repository for the book itself here</a>. The final example which
|
|
you can clone, fork or copy <a href="https://github.com/cfsamson/examples-futures">can be found here</a>. Any suggestions
|
|
or improvements can be filed as a PR or in the issue tracker for the book.</p>
|
|
<p>As always, all kinds of feedback is welcome.</p>
|
|
</blockquote>
|
|
<h2><a class="header" href="#reader-exercises-and-further-reading" id="reader-exercises-and-further-reading">Reader exercises and further reading</a></h2>
|
|
<p>In the last <a href="conclusion.html">chapter</a> I've taken the liberty to suggest some
|
|
small exercises if you want to explore a little further.</p>
|
|
<p>This book is also the fourth book I have written about concurrent programming
|
|
in Rust. If you like it, you might want to check out the others as well:</p>
|
|
<ul>
|
|
<li><a href="https://cfsamson.gitbook.io/green-threads-explained-in-200-lines-of-rust/">Green Threads Explained in 200 lines of rust</a></li>
|
|
<li><a href="https://cfsamson.github.io/book-exploring-async-basics/">The Node Experiment - Exploring Async Basics with Rust</a></li>
|
|
<li><a href="https://cfsamsonbooks.gitbook.io/epoll-kqueue-iocp-explained/">Epoll, Kqueue and IOCP Explained with Rust</a></li>
|
|
</ul>
|
|
<h2><a class="header" href="#credits-and-thanks" id="credits-and-thanks">Credits and thanks</a></h2>
|
|
<p>I'll like to take the chance of thanking the people behind <code>mio</code>, <code>tokio</code>,
|
|
<code>async_std</code>, <code>Futures</code>, <code>libc</code>, <code>crossbeam</code> and many other libraries which so
|
|
much is built upon.</p>
|
|
<p>A special thanks to <a href="https://github.com/jonhoo">Johnhoo</a> who was kind enough to
|
|
give me some feedback on an early draft of this book. He has not read the
|
|
finished product and has in no way endorsed it, but a thanks is definitely due.</p>
|
|
|
|
</main>
|
|
|
|
<nav class="nav-wrapper" aria-label="Page navigation">
|
|
<!-- Mobile navigation buttons -->
|
|
|
|
|
|
|
|
|
|
<div style="clear: both"></div>
|
|
</nav>
|
|
</div>
|
|
</div>
|
|
|
|
<nav class="nav-wide-wrapper" aria-label="Page navigation">
|
|
|
|
|
|
|
|
</nav>
|
|
|
|
</div>
|
|
|
|
|
|
<!-- Livereload script (if served using the cli tool) -->
|
|
<script type="text/javascript">
|
|
var socket = new WebSocket("ws://localhost:3001");
|
|
socket.onmessage = function (event) {
|
|
if (event.data === "reload") {
|
|
socket.close();
|
|
location.reload(true); // force reload from server (not from cache)
|
|
}
|
|
};
|
|
|
|
window.onbeforeunload = function() {
|
|
socket.close();
|
|
}
|
|
</script>
|
|
|
|
|
|
|
|
<!-- Google Analytics Tag -->
|
|
<script type="text/javascript">
|
|
var localAddrs = ["localhost", "127.0.0.1", ""];
|
|
|
|
// make sure we don't activate google analytics if the developer is
|
|
// inspecting the book locally...
|
|
if (localAddrs.indexOf(document.location.hostname) === -1) {
|
|
(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
|
|
(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
|
|
m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
|
|
})(window,document,'script','https://www.google-analytics.com/analytics.js','ga');
|
|
|
|
ga('create', 'UA-157536992-1', 'auto');
|
|
ga('send', 'pageview');
|
|
}
|
|
</script>
|
|
|
|
|
|
|
|
<script src="ace.js" type="text/javascript" charset="utf-8"></script>
|
|
<script src="editor.js" type="text/javascript" charset="utf-8"></script>
|
|
<script src="mode-rust.js" type="text/javascript" charset="utf-8"></script>
|
|
<script src="theme-dawn.js" type="text/javascript" charset="utf-8"></script>
|
|
<script src="theme-tomorrow_night.js" type="text/javascript" charset="utf-8"></script>
|
|
|
|
|
|
|
|
<script src="elasticlunr.min.js" type="text/javascript" charset="utf-8"></script>
|
|
<script src="mark.min.js" type="text/javascript" charset="utf-8"></script>
|
|
<script src="searcher.js" type="text/javascript" charset="utf-8"></script>
|
|
|
|
|
|
<script src="clipboard.min.js" type="text/javascript" charset="utf-8"></script>
|
|
<script src="highlight.js" type="text/javascript" charset="utf-8"></script>
|
|
<script src="book.js" type="text/javascript" charset="utf-8"></script>
|
|
|
|
<!-- Custom JS scripts -->
|
|
|
|
|
|
|
|
|
|
</body>
|
|
</html>
|