| <!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/load/completion.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>completion.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> |
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| </pre><pre class="rust"><code><span class="doccomment">//! Application-specific request completion semantics. |
| |
| </span><span class="kw">use </span>futures_core::ready; |
| <span class="kw">use </span>pin_project_lite::pin_project; |
| <span class="kw">use </span>std::{ |
| future::Future, |
| pin::Pin, |
| task::{Context, Poll}, |
| }; |
| |
| <span class="doccomment">/// Attaches `H`-typed completion tracker to `V` typed values. |
| /// |
| /// Handles (of type `H`) are intended to be RAII guards that primarily implement [`Drop`] and update |
| /// load metric state as they are dropped. This trait allows implementors to "forward" the handle |
| /// to later parts of the request-handling pipeline, so that the handle is only dropped when the |
| /// request has truly completed. |
| /// |
| /// This utility allows load metrics to have a protocol-agnostic means to track streams past their |
| /// initial response future. For example, if `V` represents an HTTP response type, an |
| /// implementation could add `H`-typed handles to each response's extensions to detect when all the |
| /// response's extensions have been dropped. |
| /// |
| /// A base `impl<H, V> TrackCompletion<H, V> for CompleteOnResponse` is provided to drop the handle |
| /// once the response future is resolved. This is appropriate when a response is discrete and |
| /// cannot comprise multiple messages. |
| /// |
| /// In many cases, the `Output` type is simply `V`. However, [`TrackCompletion`] may alter the type |
| /// in order to instrument it appropriately. For example, an HTTP [`TrackCompletion`] may modify |
| /// the body type: so a [`TrackCompletion`] that takes values of type |
| /// [`http::Response<A>`][response] may output values of type [`http::Response<B>`][response]. |
| /// |
| /// [response]: https://docs.rs/http/latest/http/response/struct.Response.html |
| </span><span class="kw">pub trait </span>TrackCompletion<H, V>: Clone { |
| <span class="doccomment">/// The instrumented value type. |
| </span><span class="kw">type </span>Output; |
| |
| <span class="doccomment">/// Attaches a `H`-typed handle to a `V`-typed value. |
| </span><span class="kw">fn </span>track_completion(<span class="kw-2">&</span><span class="self">self</span>, handle: H, value: V) -> <span class="self">Self</span>::Output; |
| } |
| |
| <span class="doccomment">/// A [`TrackCompletion`] implementation that considers the request completed when the response |
| /// future is resolved. |
| </span><span class="attribute">#[derive(Clone, Copy, Debug, Default)] |
| #[non_exhaustive] |
| </span><span class="kw">pub struct </span>CompleteOnResponse; |
| |
| <span class="macro">pin_project! </span>{ |
| <span class="doccomment">/// Attaches a `C`-typed completion tracker to the result of an `F`-typed [`Future`]. |
| </span><span class="attribute">#[derive(Debug)] |
| </span><span class="kw">pub struct </span>TrackCompletionFuture<F, C, H> { |
| <span class="attribute">#[pin] |
| </span>future: F, |
| handle: <span class="prelude-ty">Option</span><H>, |
| completion: C, |
| } |
| } |
| |
| <span class="comment">// ===== impl InstrumentFuture ===== |
| |
| </span><span class="kw">impl</span><F, C, H> TrackCompletionFuture<F, C, H> { |
| <span class="doccomment">/// Wraps a future, propagating the tracker into its value if successful. |
| </span><span class="kw">pub fn </span>new(completion: C, handle: H, future: F) -> <span class="self">Self </span>{ |
| TrackCompletionFuture { |
| future, |
| completion, |
| handle: <span class="prelude-val">Some</span>(handle), |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><F, C, H, T, E> Future <span class="kw">for </span>TrackCompletionFuture<F, C, H> |
| <span class="kw">where |
| </span>F: Future<Output = <span class="prelude-ty">Result</span><T, E>>, |
| C: TrackCompletion<H, T>, |
| { |
| <span class="kw">type </span>Output = <span class="prelude-ty">Result</span><C::Output, E>; |
| |
| <span class="kw">fn </span>poll(<span class="self">self</span>: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>, cx: <span class="kw-2">&mut </span>Context<<span class="lifetime">'_</span>>) -> Poll<<span class="self">Self</span>::Output> { |
| <span class="kw">let </span>this = <span class="self">self</span>.project(); |
| <span class="kw">let </span>rsp = <span class="macro">ready!</span>(this.future.poll(cx))<span class="question-mark">?</span>; |
| <span class="kw">let </span>h = this.handle.take().expect(<span class="string">"handle"</span>); |
| Poll::Ready(<span class="prelude-val">Ok</span>(this.completion.track_completion(h, rsp))) |
| } |
| } |
| |
| <span class="comment">// ===== CompleteOnResponse ===== |
| |
| </span><span class="kw">impl</span><H, V> TrackCompletion<H, V> <span class="kw">for </span>CompleteOnResponse { |
| <span class="kw">type </span>Output = V; |
| |
| <span class="kw">fn </span>track_completion(<span class="kw-2">&</span><span class="self">self</span>, handle: H, value: V) -> V { |
| drop(handle); |
| value |
| } |
| } |
| </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> |
