| <!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/git/checkouts/tokio-377c595163f99a10/dfe252d/tokio/src/util/rc_cell.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>rc_cell.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="../../../tokio/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="../../../tokio/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> |
| </pre><pre class="rust"><code><span class="kw">use </span><span class="kw">crate</span>::loom::cell::UnsafeCell; |
| |
| <span class="kw">use </span>std::rc::Rc; |
| |
| <span class="doccomment">/// This is exactly like `Cell<Option<Rc<T>>>`, except that it provides a `get` |
| /// method even though `Rc` is not `Copy`. |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">struct </span>RcCell<T> { |
| inner: UnsafeCell<<span class="prelude-ty">Option</span><Rc<T>>>, |
| } |
| |
| <span class="kw">impl</span><T> RcCell<T> { |
| <span class="attribute">#[cfg(not(all(loom, test)))] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">const fn </span>new() -> <span class="self">Self </span>{ |
| <span class="self">Self </span>{ |
| inner: UnsafeCell::new(<span class="prelude-val">None</span>), |
| } |
| } |
| |
| <span class="comment">// The UnsafeCell in loom does not have a const `new` fn. |
| </span><span class="attribute">#[cfg(all(loom, test))] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>new() -> <span class="self">Self </span>{ |
| <span class="self">Self </span>{ |
| inner: UnsafeCell::new(<span class="prelude-val">None</span>), |
| } |
| } |
| |
| <span class="doccomment">/// Safety: This method may not be called recursively. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">unsafe fn </span>with_inner<F, R>(<span class="kw-2">&</span><span class="self">self</span>, f: F) -> R |
| <span class="kw">where |
| </span>F: FnOnce(<span class="kw-2">&mut </span><span class="prelude-ty">Option</span><Rc<T>>) -> R, |
| { |
| <span class="comment">// safety: This type is not Sync, so concurrent calls of this method |
| // cannot happen. Furthermore, the caller guarantees that the method is |
| // not called recursively. Finally, this is the only place that can |
| // create mutable references to the inner Rc. This ensures that any |
| // mutable references created here are exclusive. |
| </span><span class="self">self</span>.inner.with_mut(|ptr| f(<span class="kw-2">&mut *</span>ptr)) |
| } |
| |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>get(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="prelude-ty">Option</span><Rc<T>> { |
| <span class="comment">// safety: The `Rc::clone` method will not call any unknown user-code, |
| // so it will not result in a recursive call to `with_inner`. |
| </span><span class="kw">unsafe </span>{ <span class="self">self</span>.with_inner(|rc| rc.clone()) } |
| } |
| |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>replace(<span class="kw-2">&</span><span class="self">self</span>, val: <span class="prelude-ty">Option</span><Rc<T>>) -> <span class="prelude-ty">Option</span><Rc<T>> { |
| <span class="comment">// safety: No destructors or other unknown user-code will run inside the |
| // `with_inner` call, so no recursive call to `with_inner` can happen. |
| </span><span class="kw">unsafe </span>{ <span class="self">self</span>.with_inner(|rc| std::mem::replace(rc, val)) } |
| } |
| |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>set(<span class="kw-2">&</span><span class="self">self</span>, val: <span class="prelude-ty">Option</span><Rc<T>>) { |
| <span class="kw">let </span>old = <span class="self">self</span>.replace(val); |
| drop(old); |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../../" data-current-crate="tokio" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |