| <!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/tokio-1.28.2/src/io/util/vec_with_initialized.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>vec_with_initialized.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> |
| <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> |
| <span id="98">98</span> |
| <span id="99">99</span> |
| <span id="100">100</span> |
| <span id="101">101</span> |
| <span id="102">102</span> |
| <span id="103">103</span> |
| <span id="104">104</span> |
| <span id="105">105</span> |
| <span id="106">106</span> |
| <span id="107">107</span> |
| <span id="108">108</span> |
| <span id="109">109</span> |
| <span id="110">110</span> |
| <span id="111">111</span> |
| <span id="112">112</span> |
| <span id="113">113</span> |
| <span id="114">114</span> |
| <span id="115">115</span> |
| <span id="116">116</span> |
| <span id="117">117</span> |
| <span id="118">118</span> |
| <span id="119">119</span> |
| <span id="120">120</span> |
| <span id="121">121</span> |
| <span id="122">122</span> |
| <span id="123">123</span> |
| <span id="124">124</span> |
| <span id="125">125</span> |
| <span id="126">126</span> |
| <span id="127">127</span> |
| <span id="128">128</span> |
| <span id="129">129</span> |
| <span id="130">130</span> |
| <span id="131">131</span> |
| <span id="132">132</span> |
| <span id="133">133</span> |
| <span id="134">134</span> |
| <span id="135">135</span> |
| <span id="136">136</span> |
| <span id="137">137</span> |
| <span id="138">138</span> |
| <span id="139">139</span> |
| <span id="140">140</span> |
| <span id="141">141</span> |
| <span id="142">142</span> |
| </pre><pre class="rust"><code><span class="kw">use </span><span class="kw">crate</span>::io::ReadBuf; |
| <span class="kw">use </span>std::mem::MaybeUninit; |
| |
| <span class="doccomment">/// Something that looks like a `Vec<u8>`. |
| /// |
| /// # Safety |
| /// |
| /// The implementor must guarantee that the vector returned by the |
| /// `as_mut` and `as_mut` methods do not change from one call to |
| /// another. |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">unsafe trait </span>VecU8: AsRef<Vec<u8>> + AsMut<Vec<u8>> {} |
| |
| <span class="kw">unsafe impl </span>VecU8 <span class="kw">for </span>Vec<u8> {} |
| <span class="kw">unsafe impl </span>VecU8 <span class="kw">for </span><span class="kw-2">&mut </span>Vec<u8> {} |
| |
| <span class="doccomment">/// This struct wraps a `Vec<u8>` or `&mut Vec<u8>`, combining it with a |
| /// `num_initialized`, which keeps track of the number of initialized bytes |
| /// in the unused capacity. |
| /// |
| /// The purpose of this struct is to remember how many bytes were initialized |
| /// through a `ReadBuf` from call to call. |
| /// |
| /// This struct has the safety invariant that the first `num_initialized` of the |
| /// vector's allocation must be initialized at any time. |
| </span><span class="attribute">#[derive(Debug)] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">struct </span>VecWithInitialized<V> { |
| vec: V, |
| <span class="comment">// The number of initialized bytes in the vector. |
| // Always between `vec.len()` and `vec.capacity()`. |
| </span>num_initialized: usize, |
| starting_capacity: usize, |
| } |
| |
| <span class="kw">impl </span>VecWithInitialized<Vec<u8>> { |
| <span class="attribute">#[cfg(feature = <span class="string">"io-util"</span>)] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>take(<span class="kw-2">&mut </span><span class="self">self</span>) -> Vec<u8> { |
| <span class="self">self</span>.num_initialized = <span class="number">0</span>; |
| std::mem::take(<span class="kw-2">&mut </span><span class="self">self</span>.vec) |
| } |
| } |
| |
| <span class="kw">impl</span><V> VecWithInitialized<V> |
| <span class="kw">where |
| </span>V: VecU8, |
| { |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>new(<span class="kw-2">mut </span>vec: V) -> <span class="self">Self </span>{ |
| <span class="comment">// SAFETY: The safety invariants of vector guarantee that the bytes up |
| // to its length are initialized. |
| </span><span class="self">Self </span>{ |
| num_initialized: vec.as_mut().len(), |
| starting_capacity: vec.as_ref().capacity(), |
| vec, |
| } |
| } |
| |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>reserve(<span class="kw-2">&mut </span><span class="self">self</span>, num_bytes: usize) { |
| <span class="kw">let </span>vec = <span class="self">self</span>.vec.as_mut(); |
| <span class="kw">if </span>vec.capacity() - vec.len() >= num_bytes { |
| <span class="kw">return</span>; |
| } |
| <span class="comment">// SAFETY: Setting num_initialized to `vec.len()` is correct as |
| // `reserve` does not change the length of the vector. |
| </span><span class="self">self</span>.num_initialized = vec.len(); |
| vec.reserve(num_bytes); |
| } |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"io-util"</span>)] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>is_empty(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="self">self</span>.vec.as_ref().is_empty() |
| } |
| |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>get_read_buf<<span class="lifetime">'a</span>>(<span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span><span class="self">self</span>) -> ReadBuf<<span class="lifetime">'a</span>> { |
| <span class="kw">let </span>num_initialized = <span class="self">self</span>.num_initialized; |
| |
| <span class="comment">// SAFETY: Creating the slice is safe because of the safety invariants |
| // on Vec<u8>. The safety invariants of `ReadBuf` will further guarantee |
| // that no bytes in the slice are de-initialized. |
| </span><span class="kw">let </span>vec = <span class="self">self</span>.vec.as_mut(); |
| <span class="kw">let </span>len = vec.len(); |
| <span class="kw">let </span>cap = vec.capacity(); |
| <span class="kw">let </span>ptr = vec.as_mut_ptr().cast::<MaybeUninit<u8>>(); |
| <span class="kw">let </span>slice = <span class="kw">unsafe </span>{ std::slice::from_raw_parts_mut::<<span class="lifetime">'a</span>, MaybeUninit<u8>>(ptr, cap) }; |
| |
| <span class="comment">// SAFETY: This is safe because the safety invariants of |
| // VecWithInitialized say that the first num_initialized bytes must be |
| // initialized. |
| </span><span class="kw">let </span><span class="kw-2">mut </span>read_buf = ReadBuf::uninit(slice); |
| <span class="kw">unsafe </span>{ |
| read_buf.assume_init(num_initialized); |
| } |
| read_buf.set_filled(len); |
| |
| read_buf |
| } |
| |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>apply_read_buf(<span class="kw-2">&mut </span><span class="self">self</span>, parts: ReadBufParts) { |
| <span class="kw">let </span>vec = <span class="self">self</span>.vec.as_mut(); |
| <span class="macro">assert_eq!</span>(vec.as_ptr(), parts.ptr); |
| |
| <span class="comment">// SAFETY: |
| // The ReadBufParts really does point inside `self.vec` due to the above |
| // check, and the safety invariants of `ReadBuf` guarantee that the |
| // first `parts.initialized` bytes of `self.vec` really have been |
| // initialized. Additionally, `ReadBuf` guarantees that `parts.len` is |
| // at most `parts.initialized`, so the first `parts.len` bytes are also |
| // initialized. |
| // |
| // Note that this relies on the fact that `V` is either `Vec<u8>` or |
| // `&mut Vec<u8>`, so the vector returned by `self.vec.as_mut()` cannot |
| // change from call to call. |
| </span><span class="kw">unsafe </span>{ |
| <span class="self">self</span>.num_initialized = parts.initialized; |
| vec.set_len(parts.len); |
| } |
| } |
| |
| <span class="comment">// Returns a boolean telling the caller to try reading into a small local buffer first if true. |
| // Doing so would avoid overallocating when vec is filled to capacity and we reached EOF. |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>try_small_read_first(<span class="kw-2">&</span><span class="self">self</span>, num_bytes: usize) -> bool { |
| <span class="kw">let </span>vec = <span class="self">self</span>.vec.as_ref(); |
| vec.capacity() - vec.len() < num_bytes |
| && <span class="self">self</span>.starting_capacity == vec.capacity() |
| && <span class="self">self</span>.starting_capacity >= num_bytes |
| } |
| } |
| |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">struct </span>ReadBufParts { |
| <span class="comment">// Pointer is only used to check that the ReadBuf actually came from the |
| // right VecWithInitialized. |
| </span>ptr: <span class="kw-2">*const </span>u8, |
| len: usize, |
| initialized: usize, |
| } |
| |
| <span class="comment">// This is needed to release the borrow on `VecWithInitialized<V>`. |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>into_read_buf_parts(rb: ReadBuf<<span class="lifetime">'_</span>>) -> ReadBufParts { |
| ReadBufParts { |
| ptr: rb.filled().as_ptr(), |
| len: rb.filled().len(), |
| initialized: rb.initialized().len(), |
| } |
| } |
| </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> |
