| <!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/discover/mod.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>mod.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">//! Service discovery |
| //! |
| //! This module provides the [`Change`] enum, which indicates the arrival or departure of a service |
| //! from a collection of similar services. Most implementations should use the [`Discover`] trait |
| //! in their bounds to indicate that they can handle services coming and going. [`Discover`] itself |
| //! is primarily a convenience wrapper around [`TryStream<Ok = Change>`][`TryStream`]. |
| //! |
| //! Every discovered service is assigned an identifier that is distinct among the currently active |
| //! services. If that service later goes away, a [`Change::Remove`] is yielded with that service's |
| //! identifier. From that point forward, the identifier may be re-used. |
| //! |
| //! # Examples |
| //! |
| //! ```rust |
| //! use futures_util::{future::poll_fn, pin_mut}; |
| //! use tower::discover::{Change, Discover}; |
| //! async fn services_monitor<D: Discover>(services: D) { |
| //! pin_mut!(services); |
| //! while let Some(Ok(change)) = poll_fn(|cx| services.as_mut().poll_discover(cx)).await { |
| //! match change { |
| //! Change::Insert(key, svc) => { |
| //! // a new service with identifier `key` was discovered |
| //! # let _ = (key, svc); |
| //! } |
| //! Change::Remove(key) => { |
| //! // the service with identifier `key` has gone away |
| //! # let _ = (key); |
| //! } |
| //! } |
| //! } |
| //! } |
| //! ``` |
| //! |
| //! [`TryStream`]: https://docs.rs/futures/latest/futures/stream/trait.TryStream.html |
| |
| </span><span class="kw">mod </span>error; |
| <span class="kw">mod </span>list; |
| |
| <span class="kw">pub use </span><span class="self">self</span>::list::ServiceList; |
| |
| <span class="kw">use </span><span class="kw">crate</span>::sealed::Sealed; |
| <span class="kw">use </span>futures_core::TryStream; |
| <span class="kw">use </span>std::{ |
| pin::Pin, |
| task::{Context, Poll}, |
| }; |
| |
| <span class="doccomment">/// A dynamically changing set of related services. |
| /// |
| /// As new services arrive and old services are retired, |
| /// [`Change`]s are returned which provide unique identifiers |
| /// for the services. |
| /// |
| /// See the module documentation for more details. |
| </span><span class="kw">pub trait </span>Discover: Sealed<Change<(), ()>> { |
| <span class="doccomment">/// A unique identifier for each active service. |
| /// |
| /// An identifier can be re-used once a [`Change::Remove`] has been yielded for its service. |
| </span><span class="kw">type </span>Key: Eq; |
| |
| <span class="doccomment">/// The type of [`Service`] yielded by this [`Discover`]. |
| /// |
| /// [`Service`]: crate::Service |
| </span><span class="kw">type </span>Service; |
| |
| <span class="doccomment">/// Error produced during discovery |
| </span><span class="kw">type </span>Error; |
| |
| <span class="doccomment">/// Yields the next discovery change set. |
| </span><span class="kw">fn </span>poll_discover( |
| <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="prelude-ty">Option</span><<span class="prelude-ty">Result</span><Change<<span class="self">Self</span>::Key, <span class="self">Self</span>::Service>, <span class="self">Self</span>::Error>>>; |
| } |
| |
| <span class="kw">impl</span><K, S, E, D: <span class="question-mark">?</span>Sized> Sealed<Change<(), ()>> <span class="kw">for </span>D |
| <span class="kw">where |
| </span>D: TryStream<<span class="prelude-val">Ok </span>= Change<K, S>, Error = E>, |
| K: Eq, |
| { |
| } |
| |
| <span class="kw">impl</span><K, S, E, D: <span class="question-mark">?</span>Sized> Discover <span class="kw">for </span>D |
| <span class="kw">where |
| </span>D: TryStream<<span class="prelude-val">Ok </span>= Change<K, S>, Error = E>, |
| K: Eq, |
| { |
| <span class="kw">type </span>Key = K; |
| <span class="kw">type </span>Service = S; |
| <span class="kw">type </span>Error = E; |
| |
| <span class="kw">fn </span>poll_discover( |
| <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="prelude-ty">Option</span><<span class="prelude-ty">Result</span><D::Ok, D::Error>>> { |
| TryStream::try_poll_next(<span class="self">self</span>, cx) |
| } |
| } |
| |
| <span class="doccomment">/// A change in the service set. |
| </span><span class="attribute">#[derive(Debug)] |
| </span><span class="kw">pub enum </span>Change<K, V> { |
| <span class="doccomment">/// A new service identified by key `K` was identified. |
| </span>Insert(K, V), |
| <span class="doccomment">/// The service identified by key `K` disappeared. |
| </span>Remove(K), |
| } |
| </code></pre></div> |
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