| <!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/tower-0.4.13/src/util/boxed/layer.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>layer.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="../../../../tower/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="../../../../tower/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> |
| <span id="2">2</span> |
| <span id="3">3</span> |
| <span id="4">4</span> |
| <span id="5">5</span> |
| <span id="6">6</span> |
| <span id="7">7</span> |
| <span id="8">8</span> |
| <span id="9">9</span> |
| <span id="10">10</span> |
| <span id="11">11</span> |
| <span id="12">12</span> |
| <span id="13">13</span> |
| <span id="14">14</span> |
| <span id="15">15</span> |
| <span id="16">16</span> |
| <span id="17">17</span> |
| <span id="18">18</span> |
| <span id="19">19</span> |
| <span id="20">20</span> |
| <span id="21">21</span> |
| <span id="22">22</span> |
| <span id="23">23</span> |
| <span id="24">24</span> |
| <span id="25">25</span> |
| <span id="26">26</span> |
| <span id="27">27</span> |
| <span id="28">28</span> |
| <span id="29">29</span> |
| <span id="30">30</span> |
| <span id="31">31</span> |
| <span id="32">32</span> |
| <span id="33">33</span> |
| <span id="34">34</span> |
| <span id="35">35</span> |
| <span id="36">36</span> |
| <span id="37">37</span> |
| <span id="38">38</span> |
| <span id="39">39</span> |
| <span id="40">40</span> |
| <span id="41">41</span> |
| <span id="42">42</span> |
| <span id="43">43</span> |
| <span id="44">44</span> |
| <span id="45">45</span> |
| <span id="46">46</span> |
| <span id="47">47</span> |
| <span id="48">48</span> |
| <span id="49">49</span> |
| <span id="50">50</span> |
| <span id="51">51</span> |
| <span id="52">52</span> |
| <span id="53">53</span> |
| <span id="54">54</span> |
| <span id="55">55</span> |
| <span id="56">56</span> |
| <span id="57">57</span> |
| <span id="58">58</span> |
| <span id="59">59</span> |
| <span id="60">60</span> |
| <span id="61">61</span> |
| <span id="62">62</span> |
| <span id="63">63</span> |
| <span id="64">64</span> |
| <span id="65">65</span> |
| <span id="66">66</span> |
| <span id="67">67</span> |
| <span id="68">68</span> |
| <span id="69">69</span> |
| <span id="70">70</span> |
| <span id="71">71</span> |
| <span id="72">72</span> |
| <span id="73">73</span> |
| <span id="74">74</span> |
| <span id="75">75</span> |
| <span id="76">76</span> |
| <span id="77">77</span> |
| <span id="78">78</span> |
| <span id="79">79</span> |
| <span id="80">80</span> |
| <span id="81">81</span> |
| <span id="82">82</span> |
| <span id="83">83</span> |
| <span id="84">84</span> |
| <span id="85">85</span> |
| <span id="86">86</span> |
| <span id="87">87</span> |
| <span id="88">88</span> |
| <span id="89">89</span> |
| <span id="90">90</span> |
| <span id="91">91</span> |
| <span id="92">92</span> |
| <span id="93">93</span> |
| <span id="94">94</span> |
| <span id="95">95</span> |
| <span id="96">96</span> |
| <span id="97">97</span> |
| </pre><pre class="rust"><code><span class="kw">use </span><span class="kw">crate</span>::util::BoxService; |
| <span class="kw">use </span>std::{fmt, sync::Arc}; |
| <span class="kw">use </span>tower_layer::{layer_fn, Layer}; |
| <span class="kw">use </span>tower_service::Service; |
| |
| <span class="doccomment">/// A boxed [`Layer`] trait object. |
| /// |
| /// [`BoxLayer`] turns a layer into a trait object, allowing both the [`Layer`] itself |
| /// and the output [`Service`] to be dynamic, while having consistent types. |
| /// |
| /// This [`Layer`] produces [`BoxService`] instances erasing the type of the |
| /// [`Service`] produced by the wrapped [`Layer`]. |
| /// |
| /// # Example |
| /// |
| /// `BoxLayer` can, for example, be useful to create layers dynamically that otherwise wouldn't have |
| /// the same types. In this example, we include a [`Timeout`] layer |
| /// only if an environment variable is set. We can use `BoxLayer` |
| /// to return a consistent type regardless of runtime configuration: |
| /// |
| /// ``` |
| /// use std::time::Duration; |
| /// use tower::{Service, ServiceBuilder, BoxError, util::BoxLayer}; |
| /// |
| /// fn common_layer<S, T>() -> BoxLayer<S, T, S::Response, BoxError> |
| /// where |
| /// S: Service<T> + Send + 'static, |
| /// S::Future: Send + 'static, |
| /// S::Error: Into<BoxError> + 'static, |
| /// { |
| /// let builder = ServiceBuilder::new() |
| /// .concurrency_limit(100); |
| /// |
| /// if std::env::var("SET_TIMEOUT").is_ok() { |
| /// let layer = builder |
| /// .timeout(Duration::from_secs(30)) |
| /// .into_inner(); |
| /// |
| /// BoxLayer::new(layer) |
| /// } else { |
| /// let layer = builder |
| /// .map_err(Into::into) |
| /// .into_inner(); |
| /// |
| /// BoxLayer::new(layer) |
| /// } |
| /// } |
| /// ``` |
| /// |
| /// [`Layer`]: tower_layer::Layer |
| /// [`Service`]: tower_service::Service |
| /// [`BoxService`]: super::BoxService |
| /// [`Timeout`]: crate::timeout |
| </span><span class="kw">pub struct </span>BoxLayer<In, T, U, E> { |
| boxed: Arc<<span class="kw">dyn </span>Layer<In, Service = BoxService<T, U, E>> + Send + Sync + <span class="lifetime">'static</span>>, |
| } |
| |
| <span class="kw">impl</span><In, T, U, E> BoxLayer<In, T, U, E> { |
| <span class="doccomment">/// Create a new [`BoxLayer`]. |
| </span><span class="kw">pub fn </span>new<L>(inner_layer: L) -> <span class="self">Self |
| </span><span class="kw">where |
| </span>L: Layer<In> + Send + Sync + <span class="lifetime">'static</span>, |
| L::Service: Service<T, Response = U, Error = E> + Send + <span class="lifetime">'static</span>, |
| <L::Service <span class="kw">as </span>Service<T>>::Future: Send + <span class="lifetime">'static</span>, |
| { |
| <span class="kw">let </span>layer = layer_fn(<span class="kw">move </span>|inner: In| { |
| <span class="kw">let </span>out = inner_layer.layer(inner); |
| BoxService::new(out) |
| }); |
| |
| <span class="self">Self </span>{ |
| boxed: Arc::new(layer), |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><In, T, U, E> Layer<In> <span class="kw">for </span>BoxLayer<In, T, U, E> { |
| <span class="kw">type </span>Service = BoxService<T, U, E>; |
| |
| <span class="kw">fn </span>layer(<span class="kw-2">&</span><span class="self">self</span>, inner: In) -> <span class="self">Self</span>::Service { |
| <span class="self">self</span>.boxed.layer(inner) |
| } |
| } |
| |
| <span class="kw">impl</span><In, T, U, E> Clone <span class="kw">for </span>BoxLayer<In, T, U, E> { |
| <span class="kw">fn </span>clone(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="self">Self </span>{ |
| <span class="self">Self </span>{ |
| boxed: Arc::clone(<span class="kw-2">&</span><span class="self">self</span>.boxed), |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><In, T, U, E> fmt::Debug <span class="kw">for </span>BoxLayer<In, T, U, E> { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, fmt: <span class="kw-2">&mut </span>fmt::Formatter) -> fmt::Result { |
| fmt.debug_struct(<span class="string">"BoxLayer"</span>).finish() |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../../../" data-current-crate="tower" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
