| <!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/tantivy-65d0bbbddbbd5d02/433372d/src/postings/block_search.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>block_search.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="../../../tantivy/index.html"><div class="logo-container"> |
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| <img src="http://fulmicoton.com/tantivy-logo/tantivy-logo.png" 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="kw">use </span><span class="kw">crate</span>::postings::compression::COMPRESSION_BLOCK_SIZE; |
| |
| <span class="doccomment">/// Search the first index containing an element greater or equal to |
| /// the target. |
| /// |
| /// The results should be equivalent to |
| /// ```compile_fail |
| /// block[..] |
| </span><span class="comment">// .iter() |
| // .take_while(|&&val| val < target) |
| // .count() |
| </span><span class="doccomment">/// ``` |
| /// |
| /// the `start` argument is just used to hint that the response is |
| /// greater than beyond `start`. The implementation may or may not use |
| /// it for optimization. |
| /// |
| /// # Assumption |
| /// |
| /// - The block is sorted. Some elements may appear several times. This is the case at the |
| /// end of the last block for instance. |
| /// - The target is assumed smaller or equal to the last element of the block. |
| </span><span class="kw">pub fn </span>branchless_binary_search(arr: <span class="kw-2">&</span>[u32; COMPRESSION_BLOCK_SIZE], target: u32) -> usize { |
| <span class="kw">let </span><span class="kw-2">mut </span>start = <span class="number">0</span>; |
| <span class="kw">let </span><span class="kw-2">mut </span>len = arr.len(); |
| <span class="kw">for _ in </span><span class="number">0</span>..<span class="number">7 </span>{ |
| len /= <span class="number">2</span>; |
| <span class="kw">let </span>pivot = <span class="kw">unsafe </span>{ <span class="kw-2">*</span>arr.get_unchecked(start + len - <span class="number">1</span>) }; |
| <span class="kw">if </span>pivot < target { |
| start += len; |
| } |
| } |
| start |
| } |
| |
| <span class="attribute">#[cfg(test)] |
| </span><span class="kw">mod </span>tests { |
| <span class="kw">use </span>std::collections::HashSet; |
| |
| <span class="kw">use </span>proptest::prelude::<span class="kw-2">*</span>; |
| |
| <span class="kw">use </span><span class="kw">super</span>::branchless_binary_search; |
| <span class="kw">use </span><span class="kw">crate</span>::docset::TERMINATED; |
| <span class="kw">use </span><span class="kw">crate</span>::postings::compression::COMPRESSION_BLOCK_SIZE; |
| |
| <span class="kw">fn </span>search_in_block_trivial_but_slow(block: <span class="kw-2">&</span>[u32], target: u32) -> usize { |
| block.iter().take_while(|&&val| val < target).count() |
| } |
| |
| <span class="kw">fn </span>util_test_search_in_block(block: <span class="kw-2">&</span>[u32], target: u32) { |
| <span class="kw">let </span>cursor = search_in_block_trivial_but_slow(block, target); |
| <span class="macro">assert!</span>(cursor < COMPRESSION_BLOCK_SIZE); |
| <span class="macro">assert!</span>(block[cursor] >= target); |
| <span class="kw">if </span>cursor > <span class="number">0 </span>{ |
| <span class="macro">assert!</span>(block[cursor - <span class="number">1</span>] < target); |
| } |
| <span class="macro">assert_eq!</span>(block.len(), COMPRESSION_BLOCK_SIZE); |
| <span class="kw">let </span><span class="kw-2">mut </span>output_buffer = [TERMINATED; COMPRESSION_BLOCK_SIZE]; |
| output_buffer[..block.len()].copy_from_slice(block); |
| <span class="macro">assert_eq!</span>(branchless_binary_search(<span class="kw-2">&</span>output_buffer, target), cursor); |
| } |
| |
| <span class="kw">fn </span>util_test_search_in_block_all(block: <span class="kw-2">&</span>[u32]) { |
| <span class="kw">let </span><span class="kw-2">mut </span>targets = HashSet::new(); |
| targets.insert(<span class="number">0</span>); |
| <span class="kw">for </span><span class="kw-2">&</span>val <span class="kw">in </span>block { |
| <span class="kw">if </span>val > <span class="number">0 </span>{ |
| targets.insert(val - <span class="number">1</span>); |
| } |
| targets.insert(val); |
| } |
| <span class="kw">for </span>target <span class="kw">in </span>targets { |
| util_test_search_in_block(block, target); |
| } |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>test_search_in_branchless_binary_search() { |
| <span class="kw">let </span>v: Vec<u32> = (<span class="number">0</span>..COMPRESSION_BLOCK_SIZE).map(|i| i <span class="kw">as </span>u32 * <span class="number">2</span>).collect(); |
| util_test_search_in_block_all(<span class="kw-2">&</span>v[..]); |
| } |
| |
| <span class="kw">fn </span>monotonous_block() -> <span class="kw">impl </span>Strategy<Value = Vec<u32>> { |
| prop::collection::vec(<span class="number">0u32</span>..<span class="number">5u32</span>, COMPRESSION_BLOCK_SIZE).prop_map(|<span class="kw-2">mut </span>deltas| { |
| <span class="kw">let </span><span class="kw-2">mut </span>el = <span class="number">0</span>; |
| <span class="kw">for </span>i <span class="kw">in </span><span class="number">0</span>..COMPRESSION_BLOCK_SIZE { |
| el += deltas[i]; |
| deltas[i] = el; |
| } |
| deltas |
| }) |
| } |
| |
| <span class="macro">proptest! </span>{ |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>test_proptest_branchless_binary_search(block <span class="kw">in </span>monotonous_block()) { |
| util_test_search_in_block_all(<span class="kw-2">&</span>block[..]); |
| } |
| } |
| } |
| </code></pre></div> |
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