rust
/
rust-course
mirror of https://github.com/sunface/rust-course
5
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity
You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
Branches Tags
${ item.name }
Create tag ${ searchTerm }
Create branch ${ searchTerm }
from 'gh-pages'
${ noResults }
rust-course/logs/log.html

449 lines
70 KiB
Raw Permalink Normal View History Unescape

deploy
1 month ago
<!DOCTYPE HTML>
<html lang="zh-CN" class="light" dir="ltr">
<head>
<!-- Book generated using mdBook -->
<meta charset="UTF-8">
<title>日志门面 log - Rust语言圣经(Rust Course)</title>
<!-- Custom HTML head -->
<meta name="description" content="">
<meta name="viewport" content="width=device-width, initial-scale=1">
<meta name="theme-color" content="#ffffff">
<link rel="icon" href="../favicon.svg">
<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 rel="stylesheet" href="../fonts/fonts.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 -->
<link rel="stylesheet" href="../theme/style.css">
</head>
<body class="sidebar-visible no-js">
<div id="body-container">
<!-- Provide site root to javascript -->
<script>
var path_to_root = "../";
var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "navy" : "light";
</script>
<!-- Work around some values being stored in localStorage wrapped in quotes -->
<script>
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>
var theme;
try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
if (theme === null || theme === undefined) { theme = default_theme; }
var html = document.querySelector('html');
html.classList.remove('light')
html.classList.add(theme);
var body = document.querySelector('body');
body.classList.remove('no-js')
body.classList.add('js');
</script>
<input type="checkbox" id="sidebar-toggle-anchor" class="hidden">
<!-- Hide / unhide sidebar before it is displayed -->
<script>
var body = document.querySelector('body');
var sidebar = null;
var sidebar_toggle = document.getElementById("sidebar-toggle-anchor");
if (document.body.clientWidth >= 1080) {
try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { }
sidebar = sidebar || 'visible';
} else {
sidebar = 'hidden';
}
sidebar_toggle.checked = sidebar === 'visible';
body.classList.remove('sidebar-visible');
body.classList.add("sidebar-" + sidebar);
</script>
<nav id="sidebar" class="sidebar" aria-label="Table of contents">
<div class="sidebar-scrollbox">
<ol class="chapter"><li class="chapter-item affix "><a href="../about-book.html">关于本书</a></li><li class="chapter-item affix "><a href="../into-rust.html">进入 Rust 编程世界</a></li><li class="chapter-item affix "><a href="../first-try/sth-you-should-not-do.html">避免从入门到放弃</a></li><li class="chapter-item affix "><a href="../community.html">社区和锈书</a></li><li class="spacer"></li><li class="chapter-item affix "><a href="../some-thoughts.html">Xobserve: 一切皆可观测</a></li><li class="chapter-item affix "><a href="../beat-ai.html">BeatAI: 工程师 AI 入门圣经</a></li><li class="chapter-item affix "><li class="part-title">Rust 语言基础学习</li><li class="spacer"></li><li class="chapter-item "><a href="../first-try/intro.html"><strong aria-hidden="true">1.</strong> 寻找牛刀，以便小试</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../first-try/installation.html"><strong aria-hidden="true">1.1.</strong> 安装 Rust 环境</a></li><li class="chapter-item "><a href="../first-try/editor.html"><strong aria-hidden="true">1.2.</strong> 墙推 VSCode!</a></li><li class="chapter-item "><a href="../first-try/cargo.html"><strong aria-hidden="true">1.3.</strong> 认识 Cargo</a></li><li class="chapter-item "><a href="../first-try/hello-world.html"><strong aria-hidden="true">1.4.</strong> 不仅仅是 Hello world</a></li><li class="chapter-item "><a href="../first-try/slowly-downloading.html"><strong aria-hidden="true">1.5.</strong> 下载依赖太慢了？</a></li></ol></li><li class="chapter-item "><a href="../basic/intro.html"><strong aria-hidden="true">2.</strong> Rust 基础入门</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../basic/variable.html"><strong aria-hidden="true">2.1.</strong> 变量绑定与解构</a></li><li class="chapter-item "><a href="../basic/base-type/index.html"><strong aria-hidden="true">2.2.</strong> 基本类型</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../basic/base-type/numbers.html"><strong aria-hidden="true">2.2.1.</strong> 数值类型</a></li><li class="chapter-item "><a href="../basic/base-type/char-bool.html"><strong aria-hidden="true">2.2.2.</strong> 字符、布尔、单元类型</a></li><li class="chapter-item "><a href="../basic/base-type/statement-expression.html"><strong aria-hidden="true">2.2.3.</strong> 语句与表达式</a></li><li class="chapter-item "><a href="../basic/base-type/function.html"><strong aria-hidden="true">2.2.4.</strong> 函数</a></li></ol></li><li class="chapter-item "><a href="../basic/ownership/index.html"><strong aria-hidden="true">2.3.</strong> 所有权和借用</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../basic/ownership/ownership.html"><strong aria-hidden="true">2.3.1.</strong> 所有权</a></li><li class="chapter-item "><a href="../basic/ownership/borrowing.html"><strong aria-hidden="true">2.3.2.</strong> 引用与借用</a></li></ol></li><li class="chapter-item "><a href="../basic/compound-type/intro.html"><strong aria-hidden="true">2.4.</strong> 复合类型</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../basic/compound-type/string-slice.html"><strong aria-hidden="true">2.4.1.</strong> 字符串与切片</a></li><li class="chapter-item "><a href="../basic/compound-type/tuple.html"><strong aria-hidden="true">2.4.2.</strong> 元组</a></li><li class="chapter-item "><a href="../basic/compound-type/struct.html"><strong aria-hidden="true">2.4.3.</strong> 结构体</a></li><li class="chapter-item "><a href="../basic/compound-type/enum.html"><strong aria-hidden="true">2.4.4.</strong> 枚举</a></li><li class="chapter-item "><a href="../basic/compound-type/array.html"><strong aria-hidden="true">2.4.5.</strong> 数组</a></li></ol></li><li class="chapter-item "><a href="../basic/flow-control.html"><strong a
</div>
<div id="sidebar-resize-handle" class="sidebar-resize-handle">
<div class="sidebar-resize-indicator"></div>
</div>
</nav>
<!-- Track and set sidebar scroll position -->
<script>
var sidebarScrollbox = document.querySelector('#sidebar .sidebar-scrollbox');
sidebarScrollbox.addEventListener('click', function(e) {
if (e.target.tagName === 'A') {
sessionStorage.setItem('sidebar-scroll', sidebarScrollbox.scrollTop);
}
}, { passive: true });
var sidebarScrollTop = sessionStorage.getItem('sidebar-scroll');
sessionStorage.removeItem('sidebar-scroll');
if (sidebarScrollTop) {
// preserve sidebar scroll position when navigating via links within sidebar
sidebarScrollbox.scrollTop = sidebarScrollTop;
} else {
// scroll sidebar to current active section when navigating via "next/previous chapter" buttons
var activeSection = document.querySelector('#sidebar .active');
if (activeSection) {
activeSection.scrollIntoView({ block: 'center' });
}
}
</script>
<div id="page-wrapper" class="page-wrapper">
<div class="page">
<div id="menu-bar-hover-placeholder"></div>
<div id="menu-bar" class="menu-bar sticky">
<div class="left-buttons">
<label id="sidebar-toggle" class="icon-button" for="sidebar-toggle-anchor" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar">
<i class="fa fa-bars"></i>
</label>
<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</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">Rust语言圣经(Rust Course)</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/sunface/rust-course" title="Git repository" aria-label="Git repository">
<i id="git-repository-button" class="fa fa-github"></i>
</a>
<a href="https://github.com/sunface/rust-course/edit/main/src/logs/log.md" title="Suggest an edit" aria-label="Suggest an edit">
<i id="git-edit-button" class="fa fa-edit"></i>
</a>
</div>
</div>
<div id="search-wrapper" class="hidden">
<form id="searchbar-outer" class="searchbar-outer">
<input type="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>
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">
<!-- Page table of contents -->
<div class="sidetoc"><nav class="pagetoc"></nav></div>
<main>
<h1 id="日志门面-log"><a class="header" href="#日志门面-log">日志门面 log</a></h1>
<p>就如同 slf4j 是 Java 的日志门面库，<a href="https://github.com/rust-lang/log">log</a> 也是 Rust 的日志门面库( 这不是我自己编的，官方用语: logging facade )，它目前由官方积极维护，因此大家可以放心使用。</p>
<p>使用方式很简单，只要在 <code>Cargo.toml</code> 中引入即可：</p>
<pre><code class="language-toml">[dependencies]
log = &quot;0.4&quot;
</code></pre>
<blockquote>
<p>日志门面不是说排场很大的意思，而是指相应的日志 API 已成为事实上的标准，会被其它日志框架所使用。通过这种统一的门面，开发者就可以不必再拘泥于日志框架的选择，未来大不了再换一个日志框架就是</p>
</blockquote>
<p>既然是门面，<code>log</code> 自然定义了一套统一的日志特征和 API，将日志的操作进行了抽象。</p>
<h2 id="log-特征"><a class="header" href="#log-特征">Log 特征</a></h2>
<p>例如，它定义了一个 <code>Log</code> 特征：</p>
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>pub trait Log: Sync + Send {
fn enabled(&amp;self, metadata: &amp;Metadata&lt;'_&gt;) -&gt; bool;
fn log(&amp;self, record: &amp;Record&lt;'_&gt;);
fn flush(&amp;self);
}
<span class="boring">}</span></code></pre></pre>
<ul>
<li><code>enabled</code> 用于判断某条带有元数据的日志是否能被记录，它对于 <code>log_enabled!</code> 宏特别有用</li>
<li><code>log</code> 会记录 <code>record</code> 所代表的日志</li>
<li><code>flush</code> 会将缓存中的日志数据刷到输出中，例如标准输出或者文件中</li>
</ul>
<h2 id="日志宏"><a class="header" href="#日志宏">日志宏</a></h2>
<p><code>log</code> 还为我们提供了一整套标准的宏，用于方便地记录日志。看到 <code>trace!</code>、<code>debug!</code>、<code>info!</code>、<code>warn!</code>、<code>error!</code>，大家是否感觉眼熟呢？是的，它们跟上一章节提到的日志级别几乎一模一样，唯一的区别就是这里乱入了一个 <code>trace!</code>，它比 <code>debug!</code> 的日志级别还要低，记录的信息还要详细。可以说，你如果想巨细无遗地了解某个流程的所有踪迹，它就是不二之选。</p>
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>use log::{info, trace, warn};
pub fn shave_the_yak(yak: &amp;mut Yak) {
trace!(&quot;Commencing yak shaving&quot;);
loop {
match find_a_razor() {
Ok(razor) =&gt; {
info!(&quot;Razor located: {}&quot;, razor);
yak.shave(razor);
break;
}
Err(err) =&gt; {
warn!(&quot;Unable to locate a razor: {}, retrying&quot;, err);
}
}
}
}
<span class="boring">}</span></code></pre></pre>
<p>上面的例子使用 <code>trace!</code> 记录了一条可有可无的信息：准备开始剃须，然后开始寻找剃须刀，找到后就用 <code>info!</code> 记录一条可能事后也没人看的信息：找到剃须刀；没找到的话，就记录一条 <code>warn!</code> 信息，这条信息就有一定价值了，不仅告诉我们没找到的原因，还记录了发生的次数，有助于事后定位问题。</p>
<p>可以看出，这里使用日志级别的方式和我们上一章节所述基本相符。</p>
<p>除了以上常用的，<code>log</code> 还提供了 <code>log!</code> 和 <code>log_enabled!</code> 宏，后者用于确定一条消息在当前模块中，对于给定的日志级别是否能够被记录</p>
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>use log::Level::Debug;
use log::{debug, log_enabled};
// 判断能否记录 Debug 消息
if log_enabled!(Debug) {
let data = expensive_call();
// 下面的日志记录较为昂贵，因此我们先在前面判断了是否能够记录，能，才继续这里的逻辑
debug!(&quot;expensive debug data: {} {}&quot;, data.x, data.y);
}
if log_enabled!(target: &quot;Global&quot;, Debug) {
let data = expensive_call();
debug!(target: &quot;Global&quot;, &quot;expensive debug data: {} {}&quot;, data.x, data.y);
}
<span class="boring">}</span></code></pre></pre>
<p>而 <code>log!</code> 宏就简单的多，它是一个通用的日志记录方式，因此需要我们手动指定日志级别：</p>
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>use log::{log, Level};
let data = (42, &quot;Forty-two&quot;);
let private_data = &quot;private&quot;;
log!(Level::Error, &quot;Received errors: {}, {}&quot;, data.0, data.1);
log!(target: &quot;app_events&quot;, Level::Warn, &quot;App warning: {}, {}, {}&quot;,
data.0, data.1, private_data);
<span class="boring">}</span></code></pre></pre>
<h2 id="日志输出在哪里"><a class="header" href="#日志输出在哪里">日志输出在哪里？</a></h2>
<p>我不知道有没有同学尝试运行过上面的代码，但是我知道，就算你们运行了，也看不到任何输出。</p>
<p>为什么？原因很简单，<code>log</code> 仅仅是日志门面库，<strong>它并不具备完整的日志库功能！</strong>，因此你无法在控制台中看到任何日志输出，这种情况下，说实话，远不如一个 <code>println!</code> 有用！</p>
<p>但是别急，让我们看看该如何让 <code>log</code> 有用起来。</p>
<h2 id="使用具体的日志库"><a class="header" href="#使用具体的日志库">使用具体的日志库</a></h2>
<p><code>log</code> 包这么设计，其实是有很多好处的。</p>
<h3 id="rust-库的开发者"><a class="header" href="#rust-库的开发者">Rust 库的开发者</a></h3>
<p>最直接的好处就是，如果你是一个 Rust 库开发者，那你自己或库的用户肯定都不希望这个库绑定任何具体的日志库，否则用户想使用 <code>log1</code> 来记录日志，你的库却使用了 <code>log2</code>，这就存在很多问题了！</p>
<p>因此，<strong>作为库的开发者，你只要在库中使用门面库即可</strong>，将具体的日志库交给用户去选择和绑定。</p>
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>use log::{info, trace, warn};
pub fn deal_with_something() {
// 开始处理
// 记录一些日志
trace!(&quot;a trace log&quot;);
info!(&quot;a info long: {}&quot;, &quot;abc&quot;);
warn!(&quot;a warning log: {}, retrying&quot;, err);
// 结束处理
}
<span class="boring">}</span></code></pre></pre>
<h3 id="应用开发者"><a class="header" href="#应用开发者">应用开发者</a></h3>
<p>如果是应用开发者，那你的应用运行起来，却看不到任何日志输出，这种场景想想都捉急。此时就需要去选择一个具体的日志库了。</p>
<p>目前来说，已经有了不少日志库实现，官方也<a href="https://github.com/rust-lang/log#in-executables">推荐了一些</a>
，大家可以根据自己的需求来选择，不过 <a href="https://docs.rs/env_logger/*/env_logger/">env_logger</a> 是一个相当不错的选择。</p>
<p><code>log</code> 还提供了 <a href="https://docs.rs/log/0.4.8/log/fn.set_logger.html">set_logger</a> 函数用于设置日志库，<a href="https://docs.rs/log/0.4.8/log/fn.set_max_level.html">set_max_level</a> 用于设置最大日志级别，但是如果你选了具体的日志库，它往往会提供更高级的 API，无需我们手动调用这两个函数，例如下面的 <code>env_logger</code> 就是如此。</p>
<h4 id="env_logger"><a class="header" href="#env_logger">env_logger</a></h4>
<p>修改 <code>Cargo.toml</code> , 添加以下内容:</p>
<pre><code class="language-toml"># in Cargo.toml
[dependencies]
log = &quot;0.4.0&quot;
env_logger = &quot;0.9&quot;
</code></pre>
<p>在 <code>src/main.rs</code> 中添加如下代码：</p>
<pre><pre class="playground"><code class="language-rust edition2021">use log::{debug, error, log_enabled, info, Level};
fn main() {
// 注意，env_logger 必须尽可能早的初始化
env_logger::init();
debug!(&quot;this is a debug {}&quot;, &quot;message&quot;);
error!(&quot;this is printed by default&quot;);
if log_enabled!(Level::Info) {
let x = 3 * 4; // expensive computation
info!(&quot;the answer was: {}&quot;, x);
}
}</code></pre></pre>
<p>在运行程序时，可以通过环境变量来设定日志级别:</p>
<pre><code class="language-shell">$ RUST_LOG=error ./main
[2017-11-09T02:12:24Z ERROR main] this is printed by default
</code></pre>
<p>我们还可以为单独一个模块指定日志级别:</p>
<pre><code class="language-shell">$ RUST_LOG=main=info ./main
[2017-11-09T02:12:24Z ERROR main] this is printed by default
[2017-11-09T02:12:24Z INFO main] the answer was: 12
</code></pre>
<p>还能为某个模块开启所有日志级别：</p>
<pre><code class="language-shell">$ RUST_LOG=main ./main
[2017-11-09T02:12:24Z DEBUG main] this is a debug message
[2017-11-09T02:12:24Z ERROR main] this is printed by default
[2017-11-09T02:12:24Z INFO main] the answer was: 12
</code></pre>
<p>需要注意的是，如果文件名包含 <code>-</code>，你需要将其替换成下划线来使用，原因是 Rust 的模块和包名不支持使用 <code>-</code>。</p>
<pre><code class="language-shell">$ RUST_LOG=my_app ./my-app
[2017-11-09T02:12:24Z DEBUG my_app] this is a debug message
[2017-11-09T02:12:24Z ERROR my_app] this is printed by default
[2017-11-09T02:12:24Z INFO my_app] the answer was: 12
</code></pre>
<p>默认情况下，<code>env_logger</code> 会输出到标准错误 <code>stderr</code>，如果你想要输出到标准输出 <code>stdout</code>，可以使用 <code>Builder</code> 来改变日志对象( target ):</p>
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>use std::env;
use env_logger::{Builder, Target};
let mut builder = Builder::from_default_env();
builder.target(Target::Stdout);
builder.init();
<span class="boring">}</span></code></pre></pre>
<p>默认</p>
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span> if cfg!(debug_assertions) {
eprintln!(&quot;debug: {:?} -&gt; {:?}&quot;,
record, fields);
}
<span class="boring">}</span></code></pre></pre>
<h3 id="日志库开发者"><a class="header" href="#日志库开发者">日志库开发者</a></h3>
<p>对于这类开发者而言，自然要实现自己的 <code>Log</code> 特征咯:</p>
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>use log::{Record, Level, Metadata};
struct SimpleLogger;
impl log::Log for SimpleLogger {
fn enabled(&amp;self, metadata: &amp;Metadata) -&gt; bool {
metadata.level() &lt;= Level::Info
}
fn log(&amp;self, record: &amp;Record) {
if self.enabled(record.metadata()) {
println!(&quot;{} - {}&quot;, record.level(), record.args());
}
}
fn flush(&amp;self) {}
}
<span class="boring">}</span></code></pre></pre>
<p>除此之外，我们还需要像 <code>env_logger</code> 一样包装下 <code>set_logger</code> 和 <code>set_max_level</code>:</p>
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>use log::{SetLoggerError, LevelFilter};
static LOGGER: SimpleLogger = SimpleLogger;
pub fn init() -&gt; Result&lt;(), SetLoggerError&gt; {
log::set_logger(&amp;LOGGER)
.map(|()| log::set_max_level(LevelFilter::Info))
}
<span class="boring">}</span></code></pre></pre>
<h2 id="更多示例"><a class="header" href="#更多示例">更多示例</a></h2>
<p>关于 <code>log</code> 门面库和具体的日志库还有更多的使用方式，详情请参见锈书的<a href="https://rusty.course.rs/devtools/log.html">开发者工具</a>一章。</p>
<div id="giscus-container"></div>
</main>
<nav class="nav-wrapper" aria-label="Page navigation">
<!-- Mobile navigation buttons -->
<a rel="prev" href="../logs/about-log.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
<i class="fa fa-angle-left"></i>
</a>
<a rel="next prefetch" href="../logs/tracing.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
<i class="fa fa-angle-right"></i>
</a>
<div style="clear: both"></div>
</nav>
</div>
</div>
<nav class="nav-wide-wrapper" aria-label="Page navigation">
<a rel="prev" href="../logs/about-log.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
<i class="fa fa-angle-left"></i>
</a>
<a rel="next prefetch" href="../logs/tracing.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
<i class="fa fa-angle-right"></i>
</a>
</nav>
</div>
<script>
window.playground_copyable = true;
</script>
<script src="../ace.js"></script>
<script src="../editor.js"></script>
<script src="../mode-rust.js"></script>
<script src="../theme-dawn.js"></script>
<script src="../theme-tomorrow_night.js"></script>
<script src="../elasticlunr.min.js"></script>
<script src="../mark.min.js"></script>
<script src="../searcher.js"></script>
<script src="../clipboard.min.js"></script>
<script src="../highlight.js"></script>
<script src="../book.js"></script>
<script type="text/javascript" charset="utf-8">
var pagePath = "logs/log.md"
</script>
<!-- Custom JS scripts -->
<script src="../assets/custom.js"></script>
<script src="../assets/bigPicture.js"></script>
</div>
</body>
</html>