| <!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 `crates/intern/src/symbol.rs`."><title>symbol.rs - source</title><script>if(window.location.protocol!=="file:")document.head.insertAdjacentHTML("beforeend","SourceSerif4-Regular-6b053e98.ttf.woff2,FiraSans-Italic-81dc35de.woff2,FiraSans-Regular-0fe48ade.woff2,FiraSans-MediumItalic-ccf7e434.woff2,FiraSans-Medium-e1aa3f0a.woff2,SourceCodePro-Regular-8badfe75.ttf.woff2,SourceCodePro-Semibold-aa29a496.ttf.woff2".split(",").map(f=>`<link rel="preload" as="font" type="font/woff2"href="../../static.files/${f}">`).join(""))</script><link rel="stylesheet" href="../../static.files/normalize-9960930a.css"><link rel="stylesheet" href="../../static.files/rustdoc-77263533.css"><meta name="rustdoc-vars" data-root-path="../../" data-static-root-path="../../static.files/" data-current-crate="intern" data-themes="" data-resource-suffix="" data-rustdoc-version="1.94.0 (4a4ef493e 2026-03-02)" data-channel="1.94.0" data-search-js="search-9e2438ea.js" data-stringdex-js="stringdex-b897f86f.js" data-settings-js="settings-c38705f0.js" ><script src="../../static.files/storage-e2aeef58.js"></script><script defer src="../../static.files/src-script-813739b1.js"></script><script defer src="../../src-files.js"></script><script defer src="../../static.files/main-7bab91a1.js"></script><noscript><link rel="stylesheet" href="../../static.files/noscript-ffcac47a.css"></noscript><link rel="alternate icon" type="image/png" href="../../static.files/favicon-32x32-eab170b8.png"><link rel="icon" type="image/svg+xml" href="../../static.files/favicon-044be391.svg"></head><body class="rustdoc src"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="src-sidebar-title"><h2>Files</h2></div></nav><div class="sidebar-resizer" title="Drag to resize sidebar"></div><main><section id="main-content" class="content"><div class="main-heading"><h1><div class="sub-heading">intern/</div>symbol.rs</h1><rustdoc-toolbar></rustdoc-toolbar></div><div class="example-wrap digits-3"><pre class="rust"><code><a href=#1 id=1 data-nosnippet>1</a><span class="doccomment">//! Attempt at flexible symbol interning, allowing to intern and free strings at runtime while also |
| <a href=#2 id=2 data-nosnippet>2</a>//! supporting compile time declaration of symbols that will never be freed. |
| <a href=#3 id=3 data-nosnippet>3</a> |
| <a href=#4 id=4 data-nosnippet>4</a></span><span class="kw">use </span>std::{ |
| <a href=#5 id=5 data-nosnippet>5</a> fmt, |
| <a href=#6 id=6 data-nosnippet>6</a> hash::{BuildHasher, BuildHasherDefault, Hash}, |
| <a href=#7 id=7 data-nosnippet>7</a> mem::{<span class="self">self</span>, ManuallyDrop}, |
| <a href=#8 id=8 data-nosnippet>8</a> ptr::NonNull, |
| <a href=#9 id=9 data-nosnippet>9</a> sync::OnceLock, |
| <a href=#10 id=10 data-nosnippet>10</a>}; |
| <a href=#11 id=11 data-nosnippet>11</a> |
| <a href=#12 id=12 data-nosnippet>12</a><span class="kw">use </span>dashmap::{DashMap, SharedValue}; |
| <a href=#13 id=13 data-nosnippet>13</a><span class="kw">use </span>hashbrown::raw::RawTable; |
| <a href=#14 id=14 data-nosnippet>14</a><span class="kw">use </span>rustc_hash::FxHasher; |
| <a href=#15 id=15 data-nosnippet>15</a><span class="kw">use </span>triomphe::Arc; |
| <a href=#16 id=16 data-nosnippet>16</a> |
| <a href=#17 id=17 data-nosnippet>17</a><span class="kw">pub mod </span>symbols; |
| <a href=#18 id=18 data-nosnippet>18</a> |
| <a href=#19 id=19 data-nosnippet>19</a><span class="comment">// some asserts for layout compatibility |
| <a href=#20 id=20 data-nosnippet>20</a></span><span class="kw">const _</span>: () = <span class="macro">assert!</span>(size_of::<Box<str>>() == size_of::<<span class="kw-2">&</span>str>()); |
| <a href=#21 id=21 data-nosnippet>21</a><span class="kw">const _</span>: () = <span class="macro">assert!</span>(align_of::<Box<str>>() == align_of::<<span class="kw-2">&</span>str>()); |
| <a href=#22 id=22 data-nosnippet>22</a> |
| <a href=#23 id=23 data-nosnippet>23</a><span class="kw">const _</span>: () = <span class="macro">assert!</span>(size_of::<Arc<Box<str>>>() == size_of::<&&str>()); |
| <a href=#24 id=24 data-nosnippet>24</a><span class="kw">const _</span>: () = <span class="macro">assert!</span>(align_of::<Arc<Box<str>>>() == align_of::<&&str>()); |
| <a href=#25 id=25 data-nosnippet>25</a> |
| <a href=#26 id=26 data-nosnippet>26</a><span class="kw">const _</span>: () = <span class="macro">assert!</span>(size_of::<<span class="kw-2">*const *const </span>str>() == size_of::<TaggedArcPtr>()); |
| <a href=#27 id=27 data-nosnippet>27</a><span class="kw">const _</span>: () = <span class="macro">assert!</span>(align_of::<<span class="kw-2">*const *const </span>str>() == align_of::<TaggedArcPtr>()); |
| <a href=#28 id=28 data-nosnippet>28</a> |
| <a href=#29 id=29 data-nosnippet>29</a><span class="kw">const _</span>: () = <span class="macro">assert!</span>(size_of::<Arc<Box<str>>>() == size_of::<TaggedArcPtr>()); |
| <a href=#30 id=30 data-nosnippet>30</a><span class="kw">const _</span>: () = <span class="macro">assert!</span>(align_of::<Arc<Box<str>>>() == align_of::<TaggedArcPtr>()); |
| <a href=#31 id=31 data-nosnippet>31</a> |
| <a href=#32 id=32 data-nosnippet>32</a><span class="doccomment">/// A pointer that points to a pointer to a `str`, it may be backed as a `&'static &'static str` or |
| <a href=#33 id=33 data-nosnippet>33</a>/// `Arc<Box<str>>` but its size is that of a thin pointer. The active variant is encoded as a tag |
| <a href=#34 id=34 data-nosnippet>34</a>/// in the LSB of the alignment niche. |
| <a href=#35 id=35 data-nosnippet>35</a></span><span class="comment">// Note, Ideally this would encode a `ThinArc<str>` and `ThinRef<str>`/`ThinConstPtr<str>` instead of the double indirection. |
| <a href=#36 id=36 data-nosnippet>36</a></span><span class="attr">#[derive(PartialEq, Eq, Hash, Copy, Clone, Debug)] |
| <a href=#37 id=37 data-nosnippet>37</a></span><span class="kw">struct </span>TaggedArcPtr { |
| <a href=#38 id=38 data-nosnippet>38</a> packed: NonNull<<span class="kw-2">*const </span>str>, |
| <a href=#39 id=39 data-nosnippet>39</a>} |
| <a href=#40 id=40 data-nosnippet>40</a> |
| <a href=#41 id=41 data-nosnippet>41</a><span class="kw">unsafe impl </span>Send <span class="kw">for </span>TaggedArcPtr {} |
| <a href=#42 id=42 data-nosnippet>42</a><span class="kw">unsafe impl </span>Sync <span class="kw">for </span>TaggedArcPtr {} |
| <a href=#43 id=43 data-nosnippet>43</a> |
| <a href=#44 id=44 data-nosnippet>44</a><span class="kw">impl </span>TaggedArcPtr { |
| <a href=#45 id=45 data-nosnippet>45</a> <span class="kw">const </span>BOOL_BITS: usize = <span class="bool-val">true </span><span class="kw">as </span>usize; |
| <a href=#46 id=46 data-nosnippet>46</a> |
| <a href=#47 id=47 data-nosnippet>47</a> <span class="kw">const fn </span>non_arc(r: <span class="kw-2">&</span><span class="lifetime">'static </span><span class="kw-2">&</span><span class="lifetime">'static </span>str) -> <span class="self">Self </span>{ |
| <a href=#48 id=48 data-nosnippet>48</a> <span class="macro">assert!</span>(align_of::<<span class="kw-2">&</span><span class="lifetime">'static </span><span class="kw-2">&</span><span class="lifetime">'static </span>str>().trailing_zeros() <span class="kw">as </span>usize > <span class="self">Self</span>::BOOL_BITS); |
| <a href=#49 id=49 data-nosnippet>49</a> <span class="comment">// SAFETY: The pointer is non-null as it is derived from a reference |
| <a href=#50 id=50 data-nosnippet>50</a> // Ideally we would call out to `pack_arc` but for a `false` tag, unfortunately the |
| <a href=#51 id=51 data-nosnippet>51</a> // packing stuff requires reading out the pointer to an integer which is not supported |
| <a href=#52 id=52 data-nosnippet>52</a> // in const contexts, so here we make use of the fact that for the non-arc version the |
| <a href=#53 id=53 data-nosnippet>53</a> // tag is false (0) and thus does not need touching the actual pointer value.ext) |
| <a href=#54 id=54 data-nosnippet>54</a> |
| <a href=#55 id=55 data-nosnippet>55</a> </span><span class="kw">let </span>packed = |
| <a href=#56 id=56 data-nosnippet>56</a> <span class="kw">unsafe </span>{ NonNull::new_unchecked((r <span class="kw">as </span><span class="kw-2">*const &</span>str).cast::<<span class="kw-2">*const </span>str>().cast_mut()) }; |
| <a href=#57 id=57 data-nosnippet>57</a> <span class="self">Self </span>{ packed } |
| <a href=#58 id=58 data-nosnippet>58</a> } |
| <a href=#59 id=59 data-nosnippet>59</a> |
| <a href=#60 id=60 data-nosnippet>60</a> <span class="kw">fn </span>arc(arc: Arc<Box<str>>) -> <span class="self">Self </span>{ |
| <a href=#61 id=61 data-nosnippet>61</a> <span class="macro">assert!</span>(align_of::<<span class="kw-2">&</span><span class="lifetime">'static </span><span class="kw-2">&</span><span class="lifetime">'static </span>str>().trailing_zeros() <span class="kw">as </span>usize > <span class="self">Self</span>::BOOL_BITS); |
| <a href=#62 id=62 data-nosnippet>62</a> <span class="self">Self </span>{ |
| <a href=#63 id=63 data-nosnippet>63</a> packed: <span class="self">Self</span>::pack_arc( |
| <a href=#64 id=64 data-nosnippet>64</a> <span class="comment">// Safety: `Arc::into_raw` always returns a non null pointer |
| <a href=#65 id=65 data-nosnippet>65</a> </span><span class="kw">unsafe </span>{ NonNull::new_unchecked(Arc::into_raw(arc).cast_mut().cast()) }, |
| <a href=#66 id=66 data-nosnippet>66</a> ), |
| <a href=#67 id=67 data-nosnippet>67</a> } |
| <a href=#68 id=68 data-nosnippet>68</a> } |
| <a href=#69 id=69 data-nosnippet>69</a> |
| <a href=#70 id=70 data-nosnippet>70</a> <span class="doccomment">/// Retrieves the tag. |
| <a href=#71 id=71 data-nosnippet>71</a> /// |
| <a href=#72 id=72 data-nosnippet>72</a> /// # Safety |
| <a href=#73 id=73 data-nosnippet>73</a> /// |
| <a href=#74 id=74 data-nosnippet>74</a> /// You can only drop the `Arc` if the instance is dropped. |
| <a href=#75 id=75 data-nosnippet>75</a> </span><span class="attr">#[inline] |
| <a href=#76 id=76 data-nosnippet>76</a> </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">unsafe fn </span>try_as_arc_owned(<span class="self">self</span>) -> <span class="prelude-ty">Option</span><ManuallyDrop<Arc<Box<str>>>> { |
| <a href=#77 id=77 data-nosnippet>77</a> <span class="comment">// Unpack the tag from the alignment niche |
| <a href=#78 id=78 data-nosnippet>78</a> </span><span class="kw">let </span>tag = <span class="self">self</span>.packed.as_ptr().addr() & <span class="self">Self</span>::BOOL_BITS; |
| <a href=#79 id=79 data-nosnippet>79</a> <span class="kw">if </span><span class="macro">tag !</span>= <span class="number">0 </span>{ |
| <a href=#80 id=80 data-nosnippet>80</a> <span class="comment">// Safety: We checked that the tag is non-zero -> true, so we are pointing to the data offset of an `Arc` |
| <a href=#81 id=81 data-nosnippet>81</a> </span><span class="prelude-val">Some</span>(ManuallyDrop::new(<span class="kw">unsafe </span>{ |
| <a href=#82 id=82 data-nosnippet>82</a> Arc::from_raw(<span class="self">self</span>.pointer().as_ptr().cast::<Box<str>>()) |
| <a href=#83 id=83 data-nosnippet>83</a> })) |
| <a href=#84 id=84 data-nosnippet>84</a> } <span class="kw">else </span>{ |
| <a href=#85 id=85 data-nosnippet>85</a> <span class="prelude-val">None |
| <a href=#86 id=86 data-nosnippet>86</a> </span>} |
| <a href=#87 id=87 data-nosnippet>87</a> } |
| <a href=#88 id=88 data-nosnippet>88</a> |
| <a href=#89 id=89 data-nosnippet>89</a> <span class="attr">#[inline] |
| <a href=#90 id=90 data-nosnippet>90</a> </span><span class="kw">fn </span>pack_arc(ptr: NonNull<<span class="kw-2">*const </span>str>) -> NonNull<<span class="kw-2">*const </span>str> { |
| <a href=#91 id=91 data-nosnippet>91</a> <span class="kw">let </span>packed_tag = <span class="bool-val">true </span><span class="kw">as </span>usize; |
| <a href=#92 id=92 data-nosnippet>92</a> |
| <a href=#93 id=93 data-nosnippet>93</a> <span class="kw">unsafe </span>{ |
| <a href=#94 id=94 data-nosnippet>94</a> <span class="comment">// Safety: The pointer is derived from a non-null and bit-oring it with true (1) will |
| <a href=#95 id=95 data-nosnippet>95</a> // not make it null. |
| <a href=#96 id=96 data-nosnippet>96</a> </span>NonNull::new_unchecked(ptr.as_ptr().map_addr(|addr| addr | packed_tag)) |
| <a href=#97 id=97 data-nosnippet>97</a> } |
| <a href=#98 id=98 data-nosnippet>98</a> } |
| <a href=#99 id=99 data-nosnippet>99</a> |
| <a href=#100 id=100 data-nosnippet>100</a> <span class="attr">#[inline] |
| <a href=#101 id=101 data-nosnippet>101</a> </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>pointer(<span class="self">self</span>) -> NonNull<<span class="kw-2">*const </span>str> { |
| <a href=#102 id=102 data-nosnippet>102</a> <span class="comment">// SAFETY: The resulting pointer is guaranteed to be NonNull as we only modify the niche bytes |
| <a href=#103 id=103 data-nosnippet>103</a> </span><span class="kw">unsafe </span>{ |
| <a href=#104 id=104 data-nosnippet>104</a> NonNull::new_unchecked(<span class="self">self</span>.packed.as_ptr().map_addr(|addr| addr & !<span class="self">Self</span>::BOOL_BITS)) |
| <a href=#105 id=105 data-nosnippet>105</a> } |
| <a href=#106 id=106 data-nosnippet>106</a> } |
| <a href=#107 id=107 data-nosnippet>107</a> |
| <a href=#108 id=108 data-nosnippet>108</a> <span class="attr">#[inline] |
| <a href=#109 id=109 data-nosnippet>109</a> </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>as_str(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span>str { |
| <a href=#110 id=110 data-nosnippet>110</a> <span class="comment">// SAFETY: We always point to a pointer to a str no matter what variant is active |
| <a href=#111 id=111 data-nosnippet>111</a> </span><span class="kw">unsafe </span>{ <span class="kw-2">*</span><span class="self">self</span>.pointer().as_ptr().cast::<<span class="kw-2">&</span>str>() } |
| <a href=#112 id=112 data-nosnippet>112</a> } |
| <a href=#113 id=113 data-nosnippet>113</a>} |
| <a href=#114 id=114 data-nosnippet>114</a> |
| <a href=#115 id=115 data-nosnippet>115</a><span class="attr">#[derive(PartialEq, Eq, Hash)] |
| <a href=#116 id=116 data-nosnippet>116</a></span><span class="kw">pub struct </span>Symbol { |
| <a href=#117 id=117 data-nosnippet>117</a> repr: TaggedArcPtr, |
| <a href=#118 id=118 data-nosnippet>118</a>} |
| <a href=#119 id=119 data-nosnippet>119</a> |
| <a href=#120 id=120 data-nosnippet>120</a><span class="kw">impl </span>fmt::Debug <span class="kw">for </span>Symbol { |
| <a href=#121 id=121 data-nosnippet>121</a> <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| <a href=#122 id=122 data-nosnippet>122</a> <span class="self">self</span>.as_str().fmt(f) |
| <a href=#123 id=123 data-nosnippet>123</a> } |
| <a href=#124 id=124 data-nosnippet>124</a>} |
| <a href=#125 id=125 data-nosnippet>125</a> |
| <a href=#126 id=126 data-nosnippet>126</a><span class="kw">const _</span>: () = <span class="macro">assert!</span>(size_of::<Symbol>() == size_of::<NonNull<()>>()); |
| <a href=#127 id=127 data-nosnippet>127</a><span class="kw">const _</span>: () = <span class="macro">assert!</span>(align_of::<Symbol>() == align_of::<NonNull<()>>()); |
| <a href=#128 id=128 data-nosnippet>128</a> |
| <a href=#129 id=129 data-nosnippet>129</a><span class="kw">type </span>Map = DashMap<Symbol, (), BuildHasherDefault<FxHasher>>; |
| <a href=#130 id=130 data-nosnippet>130</a><span class="kw">static </span>MAP: OnceLock<Map> = OnceLock::new(); |
| <a href=#131 id=131 data-nosnippet>131</a> |
| <a href=#132 id=132 data-nosnippet>132</a><span class="kw">impl </span>Symbol { |
| <a href=#133 id=133 data-nosnippet>133</a> <span class="kw">pub fn </span>intern(s: <span class="kw-2">&</span>str) -> <span class="self">Self </span>{ |
| <a href=#134 id=134 data-nosnippet>134</a> <span class="kw">let </span>storage = MAP.get_or_init(symbols::prefill); |
| <a href=#135 id=135 data-nosnippet>135</a> <span class="kw">let </span>(<span class="kw-2">mut </span>shard, hash) = <span class="self">Self</span>::select_shard(storage, s); |
| <a href=#136 id=136 data-nosnippet>136</a> <span class="comment">// Atomically, |
| <a href=#137 id=137 data-nosnippet>137</a> // - check if `obj` is already in the map |
| <a href=#138 id=138 data-nosnippet>138</a> // - if so, copy out its entry, conditionally bumping the backing Arc and return it |
| <a href=#139 id=139 data-nosnippet>139</a> // - if not, put it into a box and then into an Arc, insert it, bump the ref-count and return the copy |
| <a href=#140 id=140 data-nosnippet>140</a> // This needs to be atomic (locking the shard) to avoid races with other thread, which could |
| <a href=#141 id=141 data-nosnippet>141</a> // insert the same object between us looking it up and inserting it. |
| <a href=#142 id=142 data-nosnippet>142</a> </span><span class="kw">let </span>bucket = <span class="kw">match </span>shard.find_or_find_insert_slot( |
| <a href=#143 id=143 data-nosnippet>143</a> hash, |
| <a href=#144 id=144 data-nosnippet>144</a> |(other, <span class="kw">_</span>)| other.as_str() == s, |
| <a href=#145 id=145 data-nosnippet>145</a> |(x, <span class="kw">_</span>)| <span class="self">Self</span>::hash(storage, x.as_str()), |
| <a href=#146 id=146 data-nosnippet>146</a> ) { |
| <a href=#147 id=147 data-nosnippet>147</a> <span class="prelude-val">Ok</span>(bucket) => bucket, |
| <a href=#148 id=148 data-nosnippet>148</a> <span class="comment">// SAFETY: The slot came from `find_or_find_insert_slot()`, and the table wasn't modified since then. |
| <a href=#149 id=149 data-nosnippet>149</a> </span><span class="prelude-val">Err</span>(insert_slot) => <span class="kw">unsafe </span>{ |
| <a href=#150 id=150 data-nosnippet>150</a> shard.insert_in_slot( |
| <a href=#151 id=151 data-nosnippet>151</a> hash, |
| <a href=#152 id=152 data-nosnippet>152</a> insert_slot, |
| <a href=#153 id=153 data-nosnippet>153</a> ( |
| <a href=#154 id=154 data-nosnippet>154</a> Symbol { repr: TaggedArcPtr::arc(Arc::new(Box::<str>::from(s))) }, |
| <a href=#155 id=155 data-nosnippet>155</a> SharedValue::new(()), |
| <a href=#156 id=156 data-nosnippet>156</a> ), |
| <a href=#157 id=157 data-nosnippet>157</a> ) |
| <a href=#158 id=158 data-nosnippet>158</a> }, |
| <a href=#159 id=159 data-nosnippet>159</a> }; |
| <a href=#160 id=160 data-nosnippet>160</a> <span class="comment">// SAFETY: We just retrieved/inserted this bucket. |
| <a href=#161 id=161 data-nosnippet>161</a> </span><span class="kw">unsafe </span>{ bucket.as_ref().<span class="number">0</span>.clone() } |
| <a href=#162 id=162 data-nosnippet>162</a> } |
| <a href=#163 id=163 data-nosnippet>163</a> |
| <a href=#164 id=164 data-nosnippet>164</a> <span class="kw">pub fn </span>integer(i: usize) -> <span class="self">Self </span>{ |
| <a href=#165 id=165 data-nosnippet>165</a> <span class="kw">match </span>i { |
| <a href=#166 id=166 data-nosnippet>166</a> <span class="number">0 </span>=> symbols::INTEGER_0, |
| <a href=#167 id=167 data-nosnippet>167</a> <span class="number">1 </span>=> symbols::INTEGER_1, |
| <a href=#168 id=168 data-nosnippet>168</a> <span class="number">2 </span>=> symbols::INTEGER_2, |
| <a href=#169 id=169 data-nosnippet>169</a> <span class="number">3 </span>=> symbols::INTEGER_3, |
| <a href=#170 id=170 data-nosnippet>170</a> <span class="number">4 </span>=> symbols::INTEGER_4, |
| <a href=#171 id=171 data-nosnippet>171</a> <span class="number">5 </span>=> symbols::INTEGER_5, |
| <a href=#172 id=172 data-nosnippet>172</a> <span class="number">6 </span>=> symbols::INTEGER_6, |
| <a href=#173 id=173 data-nosnippet>173</a> <span class="number">7 </span>=> symbols::INTEGER_7, |
| <a href=#174 id=174 data-nosnippet>174</a> <span class="number">8 </span>=> symbols::INTEGER_8, |
| <a href=#175 id=175 data-nosnippet>175</a> <span class="number">9 </span>=> symbols::INTEGER_9, |
| <a href=#176 id=176 data-nosnippet>176</a> <span class="number">10 </span>=> symbols::INTEGER_10, |
| <a href=#177 id=177 data-nosnippet>177</a> <span class="number">11 </span>=> symbols::INTEGER_11, |
| <a href=#178 id=178 data-nosnippet>178</a> <span class="number">12 </span>=> symbols::INTEGER_12, |
| <a href=#179 id=179 data-nosnippet>179</a> <span class="number">13 </span>=> symbols::INTEGER_13, |
| <a href=#180 id=180 data-nosnippet>180</a> <span class="number">14 </span>=> symbols::INTEGER_14, |
| <a href=#181 id=181 data-nosnippet>181</a> <span class="number">15 </span>=> symbols::INTEGER_15, |
| <a href=#182 id=182 data-nosnippet>182</a> i => Symbol::intern(<span class="kw-2">&</span><span class="macro">format!</span>(<span class="string">"{i}"</span>)), |
| <a href=#183 id=183 data-nosnippet>183</a> } |
| <a href=#184 id=184 data-nosnippet>184</a> } |
| <a href=#185 id=185 data-nosnippet>185</a> |
| <a href=#186 id=186 data-nosnippet>186</a> <span class="kw">pub fn </span>empty() -> <span class="self">Self </span>{ |
| <a href=#187 id=187 data-nosnippet>187</a> symbols::__empty |
| <a href=#188 id=188 data-nosnippet>188</a> } |
| <a href=#189 id=189 data-nosnippet>189</a> |
| <a href=#190 id=190 data-nosnippet>190</a> <span class="attr">#[inline] |
| <a href=#191 id=191 data-nosnippet>191</a> </span><span class="kw">pub fn </span>as_str(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span>str { |
| <a href=#192 id=192 data-nosnippet>192</a> <span class="self">self</span>.repr.as_str() |
| <a href=#193 id=193 data-nosnippet>193</a> } |
| <a href=#194 id=194 data-nosnippet>194</a> |
| <a href=#195 id=195 data-nosnippet>195</a> <span class="attr">#[inline] |
| <a href=#196 id=196 data-nosnippet>196</a> </span><span class="kw">fn </span>select_shard( |
| <a href=#197 id=197 data-nosnippet>197</a> storage: <span class="kw-2">&</span><span class="lifetime">'static </span>Map, |
| <a href=#198 id=198 data-nosnippet>198</a> s: <span class="kw-2">&</span>str, |
| <a href=#199 id=199 data-nosnippet>199</a> ) -> (dashmap::RwLockWriteGuard<<span class="lifetime">'static</span>, RawTable<(Symbol, SharedValue<()>)>>, u64) { |
| <a href=#200 id=200 data-nosnippet>200</a> <span class="kw">let </span>hash = <span class="self">Self</span>::hash(storage, s); |
| <a href=#201 id=201 data-nosnippet>201</a> <span class="kw">let </span>shard_idx = storage.determine_shard(hash <span class="kw">as </span>usize); |
| <a href=#202 id=202 data-nosnippet>202</a> <span class="kw">let </span>shard = <span class="kw-2">&</span>storage.shards()[shard_idx]; |
| <a href=#203 id=203 data-nosnippet>203</a> (shard.write(), hash) |
| <a href=#204 id=204 data-nosnippet>204</a> } |
| <a href=#205 id=205 data-nosnippet>205</a> |
| <a href=#206 id=206 data-nosnippet>206</a> <span class="attr">#[inline] |
| <a href=#207 id=207 data-nosnippet>207</a> </span><span class="kw">fn </span>hash(storage: <span class="kw-2">&</span><span class="lifetime">'static </span>Map, s: <span class="kw-2">&</span>str) -> u64 { |
| <a href=#208 id=208 data-nosnippet>208</a> storage.hasher().hash_one(s) |
| <a href=#209 id=209 data-nosnippet>209</a> } |
| <a href=#210 id=210 data-nosnippet>210</a> |
| <a href=#211 id=211 data-nosnippet>211</a> <span class="attr">#[cold] |
| <a href=#212 id=212 data-nosnippet>212</a> </span><span class="kw">fn </span>drop_slow(arc: <span class="kw-2">&</span>Arc<Box<str>>) { |
| <a href=#213 id=213 data-nosnippet>213</a> <span class="kw">let </span>storage = MAP.get_or_init(symbols::prefill); |
| <a href=#214 id=214 data-nosnippet>214</a> <span class="kw">let </span>(<span class="kw-2">mut </span>shard, hash) = <span class="self">Self</span>::select_shard(storage, arc); |
| <a href=#215 id=215 data-nosnippet>215</a> |
| <a href=#216 id=216 data-nosnippet>216</a> <span class="kw">match </span>Arc::count(arc) { |
| <a href=#217 id=217 data-nosnippet>217</a> <span class="number">0 </span>| <span class="number">1 </span>=> <span class="macro">unreachable!</span>(), |
| <a href=#218 id=218 data-nosnippet>218</a> <span class="number">2 </span>=> (), |
| <a href=#219 id=219 data-nosnippet>219</a> <span class="kw">_ </span>=> { |
| <a href=#220 id=220 data-nosnippet>220</a> <span class="comment">// Another thread has interned another copy |
| <a href=#221 id=221 data-nosnippet>221</a> </span><span class="kw">return</span>; |
| <a href=#222 id=222 data-nosnippet>222</a> } |
| <a href=#223 id=223 data-nosnippet>223</a> } |
| <a href=#224 id=224 data-nosnippet>224</a> |
| <a href=#225 id=225 data-nosnippet>225</a> <span class="kw">let </span>s = <span class="kw-2">&***</span>arc; |
| <a href=#226 id=226 data-nosnippet>226</a> <span class="kw">let </span>(ptr, <span class="kw">_</span>) = shard.remove_entry(hash, |(x, <span class="kw">_</span>)| x.as_str() == s).unwrap(); |
| <a href=#227 id=227 data-nosnippet>227</a> <span class="kw">let </span>ptr = ManuallyDrop::new(ptr); |
| <a href=#228 id=228 data-nosnippet>228</a> <span class="comment">// SAFETY: We're dropping, we have ownership. |
| <a href=#229 id=229 data-nosnippet>229</a> </span>ManuallyDrop::into_inner(<span class="kw">unsafe </span>{ ptr.repr.try_as_arc_owned().unwrap() }); |
| <a href=#230 id=230 data-nosnippet>230</a> <span class="macro">debug_assert_eq!</span>(Arc::count(arc), <span class="number">1</span>); |
| <a href=#231 id=231 data-nosnippet>231</a> |
| <a href=#232 id=232 data-nosnippet>232</a> <span class="comment">// Shrink the backing storage if the shard is less than 50% occupied. |
| <a href=#233 id=233 data-nosnippet>233</a> </span><span class="kw">if </span>shard.len() * <span class="number">2 </span>< shard.capacity() { |
| <a href=#234 id=234 data-nosnippet>234</a> <span class="kw">let </span>len = shard.len(); |
| <a href=#235 id=235 data-nosnippet>235</a> shard.shrink_to(len, |(x, <span class="kw">_</span>)| <span class="self">Self</span>::hash(storage, x.as_str())); |
| <a href=#236 id=236 data-nosnippet>236</a> } |
| <a href=#237 id=237 data-nosnippet>237</a> } |
| <a href=#238 id=238 data-nosnippet>238</a>} |
| <a href=#239 id=239 data-nosnippet>239</a> |
| <a href=#240 id=240 data-nosnippet>240</a><span class="kw">impl </span>Drop <span class="kw">for </span>Symbol { |
| <a href=#241 id=241 data-nosnippet>241</a> <span class="attr">#[inline] |
| <a href=#242 id=242 data-nosnippet>242</a> </span><span class="kw">fn </span>drop(<span class="kw-2">&mut </span><span class="self">self</span>) { |
| <a href=#243 id=243 data-nosnippet>243</a> <span class="comment">// SAFETY: We're dropping, we have ownership. |
| <a href=#244 id=244 data-nosnippet>244</a> </span><span class="kw">let </span><span class="prelude-val">Some</span>(arc) = (<span class="kw">unsafe </span>{ <span class="self">self</span>.repr.try_as_arc_owned() }) <span class="kw">else </span>{ |
| <a href=#245 id=245 data-nosnippet>245</a> <span class="kw">return</span>; |
| <a href=#246 id=246 data-nosnippet>246</a> }; |
| <a href=#247 id=247 data-nosnippet>247</a> <span class="comment">// When the last `Ref` is dropped, remove the object from the global map. |
| <a href=#248 id=248 data-nosnippet>248</a> </span><span class="kw">if </span>Arc::count(<span class="kw-2">&</span>arc) == <span class="number">2 </span>{ |
| <a href=#249 id=249 data-nosnippet>249</a> <span class="comment">// Only `self` and the global map point to the object. |
| <a href=#250 id=250 data-nosnippet>250</a> |
| <a href=#251 id=251 data-nosnippet>251</a> </span><span class="self">Self</span>::drop_slow(<span class="kw-2">&</span>arc); |
| <a href=#252 id=252 data-nosnippet>252</a> } |
| <a href=#253 id=253 data-nosnippet>253</a> <span class="comment">// decrement the ref count |
| <a href=#254 id=254 data-nosnippet>254</a> </span>ManuallyDrop::into_inner(arc); |
| <a href=#255 id=255 data-nosnippet>255</a> } |
| <a href=#256 id=256 data-nosnippet>256</a>} |
| <a href=#257 id=257 data-nosnippet>257</a> |
| <a href=#258 id=258 data-nosnippet>258</a><span class="kw">impl </span>Clone <span class="kw">for </span>Symbol { |
| <a href=#259 id=259 data-nosnippet>259</a> <span class="kw">fn </span>clone(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="self">Self </span>{ |
| <a href=#260 id=260 data-nosnippet>260</a> <span class="self">Self </span>{ repr: increase_arc_refcount(<span class="self">self</span>.repr) } |
| <a href=#261 id=261 data-nosnippet>261</a> } |
| <a href=#262 id=262 data-nosnippet>262</a>} |
| <a href=#263 id=263 data-nosnippet>263</a> |
| <a href=#264 id=264 data-nosnippet>264</a><span class="kw">fn </span>increase_arc_refcount(repr: TaggedArcPtr) -> TaggedArcPtr { |
| <a href=#265 id=265 data-nosnippet>265</a> <span class="comment">// SAFETY: We're not dropping the `Arc`. |
| <a href=#266 id=266 data-nosnippet>266</a> </span><span class="kw">let </span><span class="prelude-val">Some</span>(arc) = (<span class="kw">unsafe </span>{ repr.try_as_arc_owned() }) <span class="kw">else </span>{ |
| <a href=#267 id=267 data-nosnippet>267</a> <span class="kw">return </span>repr; |
| <a href=#268 id=268 data-nosnippet>268</a> }; |
| <a href=#269 id=269 data-nosnippet>269</a> <span class="comment">// increase the ref count |
| <a href=#270 id=270 data-nosnippet>270</a> </span>mem::forget(Arc::clone(<span class="kw-2">&</span>arc)); |
| <a href=#271 id=271 data-nosnippet>271</a> repr |
| <a href=#272 id=272 data-nosnippet>272</a>} |
| <a href=#273 id=273 data-nosnippet>273</a> |
| <a href=#274 id=274 data-nosnippet>274</a><span class="kw">impl </span>fmt::Display <span class="kw">for </span>Symbol { |
| <a href=#275 id=275 data-nosnippet>275</a> <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| <a href=#276 id=276 data-nosnippet>276</a> <span class="self">self</span>.as_str().fmt(f) |
| <a href=#277 id=277 data-nosnippet>277</a> } |
| <a href=#278 id=278 data-nosnippet>278</a>} |
| <a href=#279 id=279 data-nosnippet>279</a> |
| <a href=#280 id=280 data-nosnippet>280</a><span class="attr">#[cfg(test)] |
| <a href=#281 id=281 data-nosnippet>281</a></span><span class="kw">mod </span>tests { |
| <a href=#282 id=282 data-nosnippet>282</a> <span class="kw">use </span>super::<span class="kw-2">*</span>; |
| <a href=#283 id=283 data-nosnippet>283</a> |
| <a href=#284 id=284 data-nosnippet>284</a> <span class="attr">#[test] |
| <a href=#285 id=285 data-nosnippet>285</a> </span><span class="kw">fn </span>smoke_test() { |
| <a href=#286 id=286 data-nosnippet>286</a> Symbol::intern(<span class="string">"isize"</span>); |
| <a href=#287 id=287 data-nosnippet>287</a> <span class="kw">let </span>base_len = MAP.get().unwrap().len(); |
| <a href=#288 id=288 data-nosnippet>288</a> <span class="kw">let </span>hello = Symbol::intern(<span class="string">"hello"</span>); |
| <a href=#289 id=289 data-nosnippet>289</a> <span class="kw">let </span>world = Symbol::intern(<span class="string">"world"</span>); |
| <a href=#290 id=290 data-nosnippet>290</a> <span class="kw">let </span>more_worlds = world.clone(); |
| <a href=#291 id=291 data-nosnippet>291</a> <span class="kw">let </span>bang = Symbol::intern(<span class="string">"!"</span>); |
| <a href=#292 id=292 data-nosnippet>292</a> <span class="kw">let </span>q = Symbol::intern(<span class="string">"?"</span>); |
| <a href=#293 id=293 data-nosnippet>293</a> <span class="macro">assert_eq!</span>(MAP.get().unwrap().len(), base_len + <span class="number">4</span>); |
| <a href=#294 id=294 data-nosnippet>294</a> <span class="kw">let </span>bang2 = Symbol::intern(<span class="string">"!"</span>); |
| <a href=#295 id=295 data-nosnippet>295</a> <span class="macro">assert_eq!</span>(MAP.get().unwrap().len(), base_len + <span class="number">4</span>); |
| <a href=#296 id=296 data-nosnippet>296</a> drop(bang2); |
| <a href=#297 id=297 data-nosnippet>297</a> <span class="macro">assert_eq!</span>(MAP.get().unwrap().len(), base_len + <span class="number">4</span>); |
| <a href=#298 id=298 data-nosnippet>298</a> drop(q); |
| <a href=#299 id=299 data-nosnippet>299</a> <span class="macro">assert_eq!</span>(MAP.get().unwrap().len(), base_len + <span class="number">3</span>); |
| <a href=#300 id=300 data-nosnippet>300</a> <span class="kw">let </span>default = Symbol::intern(<span class="string">"default"</span>); |
| <a href=#301 id=301 data-nosnippet>301</a> <span class="kw">let </span>many_worlds = world.clone(); |
| <a href=#302 id=302 data-nosnippet>302</a> <span class="macro">assert_eq!</span>(MAP.get().unwrap().len(), base_len + <span class="number">3</span>); |
| <a href=#303 id=303 data-nosnippet>303</a> <span class="macro">assert_eq!</span>( |
| <a href=#304 id=304 data-nosnippet>304</a> <span class="string">"hello default world!"</span>, |
| <a href=#305 id=305 data-nosnippet>305</a> <span class="macro">format!</span>(<span class="string">"{} {} {}{}"</span>, hello.as_str(), default.as_str(), world.as_str(), bang.as_str()) |
| <a href=#306 id=306 data-nosnippet>306</a> ); |
| <a href=#307 id=307 data-nosnippet>307</a> drop(default); |
| <a href=#308 id=308 data-nosnippet>308</a> <span class="macro">assert_eq!</span>( |
| <a href=#309 id=309 data-nosnippet>309</a> <span class="string">"hello world!"</span>, |
| <a href=#310 id=310 data-nosnippet>310</a> <span class="macro">format!</span>(<span class="string">"{} {}{}"</span>, hello.as_str(), world.as_str(), bang.as_str()) |
| <a href=#311 id=311 data-nosnippet>311</a> ); |
| <a href=#312 id=312 data-nosnippet>312</a> drop(many_worlds); |
| <a href=#313 id=313 data-nosnippet>313</a> drop(more_worlds); |
| <a href=#314 id=314 data-nosnippet>314</a> drop(hello); |
| <a href=#315 id=315 data-nosnippet>315</a> drop(world); |
| <a href=#316 id=316 data-nosnippet>316</a> drop(bang); |
| <a href=#317 id=317 data-nosnippet>317</a> <span class="macro">assert_eq!</span>(MAP.get().unwrap().len(), base_len); |
| <a href=#318 id=318 data-nosnippet>318</a> } |
| <a href=#319 id=319 data-nosnippet>319</a>} |
| </code></pre></div></section></main></body></html> |
