| <!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="Extension trait allowing futures to be instrumented with a `tracing` `Subscriber`."><meta name="keywords" content="rust, rustlang, rust-lang, WithSubscriber"><title>WithSubscriber in tracing::instrument - 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 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="sidebar-items.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 trait"><!--[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">☰</button><a class="sidebar-logo" href="../../tracing/index.html"><div class="logo-container"><img src="https://raw.githubusercontent.com/tokio-rs/tracing/master/assets/logo-type.png" alt="logo"></div></a><h2></h2></nav><nav class="sidebar"><a class="sidebar-logo" href="../../tracing/index.html"><div class="logo-container"> |
| <img src="https://raw.githubusercontent.com/tokio-rs/tracing/master/assets/logo-type.png" alt="logo"></div></a><h2 class="location"><a href="#">WithSubscriber</a></h2><div class="sidebar-elems"><section><h3><a href="#provided-methods">Provided Methods</a></h3><ul class="block"><li><a href="#method.with_current_subscriber">with_current_subscriber</a></li><li><a href="#method.with_subscriber">with_subscriber</a></li></ul><h3><a href="#implementors">Implementors</a></h3></section><h2><a href="index.html">In tracing::instrument</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">Trait <a href="../index.html">tracing</a>::<wbr><a href="index.html">instrument</a>::<wbr><a class="trait" href="#">WithSubscriber</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/tracing/instrument.rs.html#129-227">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 trait"><code>pub trait WithSubscriber: <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a> { |
| fn <a href="#method.with_subscriber" class="fnname">with_subscriber</a><S>(self, subscriber: S) -> <a class="struct" href="struct.WithDispatch.html" title="struct tracing::instrument::WithDispatch">WithDispatch</a><Self><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.WithDispatch.html" title="struct tracing::instrument::WithDispatch">WithDispatch</a><T></span><code class="content"><span class="where fmt-newline">impl<T: <a class="trait" href="https://doc.rust-lang.org/nightly/core/future/future/trait.Future.html" title="trait core::future::future::Future">Future</a>> <a class="trait" href="https://doc.rust-lang.org/nightly/core/future/future/trait.Future.html" title="trait core::future::future::Future">Future</a> for <a class="struct" href="struct.WithDispatch.html" title="struct tracing::instrument::WithDispatch">WithDispatch</a><T></span><span class="where fmt-newline"> type <a href="https://doc.rust-lang.org/nightly/core/future/future/trait.Future.html#associatedtype.Output" class="associatedtype">Output</a> = T::<a class="associatedtype" href="https://doc.rust-lang.org/nightly/core/future/future/trait.Future.html#associatedtype.Output" title="type core::future::future::Future::Output">Output</a>;</span></code></span></span></span></span><br> <span class="where">where<br> S: <a class="trait" href="https://doc.rust-lang.org/nightly/core/convert/trait.Into.html" title="trait core::convert::Into">Into</a><<a class="struct" href="../struct.Dispatch.html" title="struct tracing::Dispatch">Dispatch</a>></span>, |
| { ... } |
| <span class="item-spacer"></span> fn <a href="#method.with_current_subscriber" class="fnname">with_current_subscriber</a>(self) -> <a class="struct" href="struct.WithDispatch.html" title="struct tracing::instrument::WithDispatch">WithDispatch</a><Self><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.WithDispatch.html" title="struct tracing::instrument::WithDispatch">WithDispatch</a><T></span><code class="content"><span class="where fmt-newline">impl<T: <a class="trait" href="https://doc.rust-lang.org/nightly/core/future/future/trait.Future.html" title="trait core::future::future::Future">Future</a>> <a class="trait" href="https://doc.rust-lang.org/nightly/core/future/future/trait.Future.html" title="trait core::future::future::Future">Future</a> for <a class="struct" href="struct.WithDispatch.html" title="struct tracing::instrument::WithDispatch">WithDispatch</a><T></span><span class="where fmt-newline"> type <a href="https://doc.rust-lang.org/nightly/core/future/future/trait.Future.html#associatedtype.Output" class="associatedtype">Output</a> = T::<a class="associatedtype" href="https://doc.rust-lang.org/nightly/core/future/future/trait.Future.html#associatedtype.Output" title="type core::future::future::Future::Output">Output</a>;</span></code></span></span></span></span> { ... } |
| }</code></pre></div><details class="rustdoc-toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Extension trait allowing futures to be instrumented with |
| a <code>tracing</code> <a href="../trait.Subscriber.html"><code>Subscriber</code></a>.</p> |
| </div></details><h2 id="provided-methods" class="small-section-header">Provided Methods<a href="#provided-methods" class="anchor"></a></h2><div class="methods"><details class="rustdoc-toggle method-toggle" open><summary><section id="method.with_subscriber" class="method has-srclink"><a class="srclink rightside" href="../../src/tracing/instrument.rs.html#169-177">source</a><h4 class="code-header">fn <a href="#method.with_subscriber" class="fnname">with_subscriber</a><S>(self, subscriber: S) -> <a class="struct" href="struct.WithDispatch.html" title="struct tracing::instrument::WithDispatch">WithDispatch</a><Self><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.WithDispatch.html" title="struct tracing::instrument::WithDispatch">WithDispatch</a><T></span><code class="content"><span class="where fmt-newline">impl<T: <a class="trait" href="https://doc.rust-lang.org/nightly/core/future/future/trait.Future.html" title="trait core::future::future::Future">Future</a>> <a class="trait" href="https://doc.rust-lang.org/nightly/core/future/future/trait.Future.html" title="trait core::future::future::Future">Future</a> for <a class="struct" href="struct.WithDispatch.html" title="struct tracing::instrument::WithDispatch">WithDispatch</a><T></span><span class="where fmt-newline"> type <a href="https://doc.rust-lang.org/nightly/core/future/future/trait.Future.html#associatedtype.Output" class="associatedtype">Output</a> = T::<a class="associatedtype" href="https://doc.rust-lang.org/nightly/core/future/future/trait.Future.html#associatedtype.Output" title="type core::future::future::Future::Output">Output</a>;</span></code></span></span></span></span><span class="where fmt-newline">where<br> S: <a class="trait" href="https://doc.rust-lang.org/nightly/core/convert/trait.Into.html" title="trait core::convert::Into">Into</a><<a class="struct" href="../struct.Dispatch.html" title="struct tracing::Dispatch">Dispatch</a>>,</span></h4></section></summary><div class="docblock"><p>Attaches the provided <a href="../trait.Subscriber.html"><code>Subscriber</code></a> to this type, returning a |
| <a href="struct.WithDispatch.html" title="WithDispatch"><code>WithDispatch</code></a> wrapper.</p> |
| <p>The attached <a href="../trait.Subscriber.html"><code>Subscriber</code></a> will be set as the <a href="../dispatcher/index.html#setting-the-default-subscriber">default</a> when the returned |
| <a href="https://doc.rust-lang.org/nightly/core/future/future/trait.Future.html"><code>Future</code></a> is polled.</p> |
| <h5 id="examples"><a href="#examples">Examples</a></h5> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>tracing::instrument::WithSubscriber; |
| |
| <span class="comment">// Set the default `Subscriber` |
| </span><span class="kw">let </span>_default = tracing::subscriber::set_default(MySubscriber::default()); |
| |
| <span class="macro">tracing::info!</span>(<span class="string">"this event will be recorded by the default `Subscriber`"</span>); |
| |
| <span class="comment">// Create a different `Subscriber` and attach it to a future. |
| </span><span class="kw">let </span>other_subscriber = MyOtherSubscriber::default(); |
| <span class="kw">let </span>future = <span class="kw">async </span>{ |
| <span class="macro">tracing::info!</span>(<span class="string">"this event will be recorded by the other `Subscriber`"</span>); |
| <span class="comment">// ... |
| </span>}; |
| |
| future |
| <span class="comment">// Attach the other `Subscriber` to the future before awaiting it |
| </span>.with_subscriber(other_subscriber) |
| .<span class="kw">await</span>; |
| |
| <span class="comment">// Once the future has completed, we return to the default `Subscriber`. |
| </span><span class="macro">tracing::info!</span>(<span class="string">"this event will be recorded by the default `Subscriber`"</span>);</code></pre></div> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.with_current_subscriber" class="method has-srclink"><a class="srclink rightside" href="../../src/tracing/instrument.rs.html#221-226">source</a><h4 class="code-header">fn <a href="#method.with_current_subscriber" class="fnname">with_current_subscriber</a>(self) -> <a class="struct" href="struct.WithDispatch.html" title="struct tracing::instrument::WithDispatch">WithDispatch</a><Self><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.WithDispatch.html" title="struct tracing::instrument::WithDispatch">WithDispatch</a><T></span><code class="content"><span class="where fmt-newline">impl<T: <a class="trait" href="https://doc.rust-lang.org/nightly/core/future/future/trait.Future.html" title="trait core::future::future::Future">Future</a>> <a class="trait" href="https://doc.rust-lang.org/nightly/core/future/future/trait.Future.html" title="trait core::future::future::Future">Future</a> for <a class="struct" href="struct.WithDispatch.html" title="struct tracing::instrument::WithDispatch">WithDispatch</a><T></span><span class="where fmt-newline"> type <a href="https://doc.rust-lang.org/nightly/core/future/future/trait.Future.html#associatedtype.Output" class="associatedtype">Output</a> = T::<a class="associatedtype" href="https://doc.rust-lang.org/nightly/core/future/future/trait.Future.html#associatedtype.Output" title="type core::future::future::Future::Output">Output</a>;</span></code></span></span></span></span></h4></section></summary><div class="docblock"><p>Attaches the current <a href="../dispatcher/index.html#setting-the-default-subscriber">default</a> <a href="../trait.Subscriber.html"><code>Subscriber</code></a> to this type, returning a |
| <a href="struct.WithDispatch.html" title="WithDispatch"><code>WithDispatch</code></a> wrapper.</p> |
| <p>The attached <code>Subscriber</code> will be set as the <a href="../dispatcher/index.html#setting-the-default-subscriber">default</a> when the returned |
| <a href="https://doc.rust-lang.org/nightly/core/future/future/trait.Future.html"><code>Future</code></a> is polled.</p> |
| <p>This can be used to propagate the current dispatcher context when |
| spawning a new future that may run on a different thread.</p> |
| <h5 id="examples-1"><a href="#examples-1">Examples</a></h5> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>tracing::instrument::WithSubscriber; |
| |
| <span class="comment">// Using `set_default` (rather than `set_global_default`) sets the |
| // default `Subscriber` for *this* thread only. |
| </span><span class="kw">let </span>_default = tracing::subscriber::set_default(MySubscriber::default()); |
| |
| <span class="kw">let </span>future = <span class="kw">async </span>{ |
| <span class="comment">// ... |
| </span>}; |
| |
| <span class="comment">// If a multi-threaded async runtime is in use, this spawned task may |
| // run on a different thread, in a different default `Subscriber`'s context. |
| </span>tokio::spawn(future); |
| |
| <span class="comment">// However, calling `with_current_subscriber` on the future before |
| // spawning it, ensures that the current thread's default `Subscriber` is |
| // propagated to the spawned task, regardless of where it executes: |
| </span>tokio::spawn(future.with_current_subscriber());</code></pre></div> |
| </div></details></div><h2 id="implementors" class="small-section-header">Implementors<a href="#implementors" class="anchor"></a></h2><div id="implementors-list"><section id="impl-WithSubscriber-for-T" class="impl has-srclink"><a class="srclink rightside" href="../../src/tracing/instrument.rs.html#334">source</a><a href="#impl-WithSubscriber-for-T" class="anchor"></a><h3 class="code-header">impl<T: <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>> <a class="trait" href="trait.WithSubscriber.html" title="trait tracing::instrument::WithSubscriber">WithSubscriber</a> for T</h3></section></div><script src="../../implementors/tracing/instrument/trait.WithSubscriber.js" async></script></section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="tracing" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
