| <!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 `common/rusty_leveldb_sgx/src/table_block.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>table_block.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="../../rusty_leveldb/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="../../rusty_leveldb/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="kw">use </span><span class="kw">crate</span>::block::Block; |
| <span class="kw">use </span><span class="kw">crate</span>::blockhandle::BlockHandle; |
| <span class="kw">use </span><span class="kw">crate</span>::env::RandomAccess; |
| <span class="kw">use </span><span class="kw">crate</span>::error::{err, <span class="prelude-ty">Result</span>, StatusCode}; |
| <span class="kw">use </span><span class="kw">crate</span>::filter; |
| <span class="kw">use </span><span class="kw">crate</span>::filter_block::FilterBlockReader; |
| <span class="kw">use </span><span class="kw">crate</span>::log::unmask_crc; |
| <span class="kw">use </span><span class="kw">crate</span>::options::{<span class="self">self</span>, CompressionType, Options}; |
| <span class="kw">use </span><span class="kw">crate</span>::table_builder; |
| |
| <span class="kw">use </span>crc::crc32::{<span class="self">self</span>, Hasher32}; |
| <span class="kw">use </span>integer_encoding::FixedInt; |
| <span class="kw">use </span>snap::Decoder; |
| |
| <span class="doccomment">/// Reads the data for the specified block handle from a file. |
| </span><span class="kw">fn </span>read_bytes(f: <span class="kw-2">&</span><span class="kw">dyn </span>RandomAccess, location: <span class="kw-2">&</span>BlockHandle) -> <span class="prelude-ty">Result</span><Vec<u8>> { |
| <span class="kw">let </span><span class="kw-2">mut </span>buf = <span class="macro">vec!</span>[<span class="number">0</span>; location.size()]; |
| f.read_at(location.offset(), <span class="kw-2">&mut </span>buf).map(|<span class="kw">_</span>| buf) |
| } |
| |
| <span class="doccomment">/// Reads a serialized filter block from a file and returns a FilterBlockReader. |
| </span><span class="kw">pub fn </span>read_filter_block( |
| src: <span class="kw-2">&</span><span class="kw">dyn </span>RandomAccess, |
| location: <span class="kw-2">&</span>BlockHandle, |
| policy: filter::BoxedFilterPolicy, |
| ) -> <span class="prelude-ty">Result</span><FilterBlockReader> { |
| <span class="kw">if </span>location.size() == <span class="number">0 </span>{ |
| <span class="kw">return </span>err( |
| StatusCode::InvalidArgument, |
| <span class="string">"no filter block in empty location"</span>, |
| ); |
| } |
| <span class="kw">let </span>buf = read_bytes(src, location)<span class="question-mark">?</span>; |
| <span class="prelude-val">Ok</span>(FilterBlockReader::new_owned(policy, buf)) |
| } |
| |
| <span class="doccomment">/// Reads a table block from a random-access source. |
| /// A table block consists of [bytes..., compress (1B), checksum (4B)]; the handle only refers to |
| /// the location and length of [bytes...]. |
| </span><span class="kw">pub fn </span>read_table_block( |
| opt: Options, |
| f: <span class="kw-2">&</span><span class="kw">dyn </span>RandomAccess, |
| location: <span class="kw-2">&</span>BlockHandle, |
| ) -> <span class="prelude-ty">Result</span><Block> { |
| <span class="comment">// The block is denoted by offset and length in BlockHandle. A block in an encoded |
| // table is followed by 1B compression type and 4B checksum. |
| // The checksum refers to the compressed contents. |
| </span><span class="kw">let </span>buf = read_bytes(f, location)<span class="question-mark">?</span>; |
| <span class="kw">let </span>compress = read_bytes( |
| f, |
| <span class="kw-2">&</span>BlockHandle::new( |
| location.offset() + location.size(), |
| table_builder::TABLE_BLOCK_COMPRESS_LEN, |
| ), |
| )<span class="question-mark">?</span>; |
| <span class="kw">let </span>cksum = read_bytes( |
| f, |
| <span class="kw-2">&</span>BlockHandle::new( |
| location.offset() + location.size() + table_builder::TABLE_BLOCK_COMPRESS_LEN, |
| table_builder::TABLE_BLOCK_CKSUM_LEN, |
| ), |
| )<span class="question-mark">?</span>; |
| |
| <span class="kw">if </span>!verify_table_block(<span class="kw-2">&</span>buf, compress[<span class="number">0</span>], unmask_crc(u32::decode_fixed(<span class="kw-2">&</span>cksum))) { |
| <span class="kw">return </span>err( |
| StatusCode::Corruption, |
| <span class="kw-2">&</span><span class="macro">format!</span>( |
| <span class="string">"checksum verification failed for block at {}"</span>, |
| location.offset() |
| ), |
| ); |
| } |
| |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(ctype) = options::int_to_compressiontype(compress[<span class="number">0</span>] <span class="kw">as </span>u32) { |
| <span class="kw">match </span>ctype { |
| CompressionType::CompressionNone => <span class="prelude-val">Ok</span>(Block::new(opt, buf)), |
| CompressionType::CompressionSnappy => { |
| <span class="kw">let </span>decoded = Decoder::new().decompress_vec(<span class="kw-2">&</span>buf)<span class="question-mark">?</span>; |
| <span class="prelude-val">Ok</span>(Block::new(opt, decoded)) |
| } |
| } |
| } <span class="kw">else </span>{ |
| err(StatusCode::InvalidData, <span class="string">"invalid compression type"</span>) |
| } |
| } |
| |
| <span class="doccomment">/// Verify checksum of block |
| </span><span class="kw">fn </span>verify_table_block(data: <span class="kw-2">&</span>[u8], compression: u8, want: u32) -> bool { |
| <span class="kw">let </span><span class="kw-2">mut </span>digest = crc32::Digest::new(crc32::CASTAGNOLI); |
| digest.write(data); |
| digest.write(<span class="kw-2">&</span>[compression; <span class="number">1</span>]); |
| digest.sum32() == want |
| } |
| </code></pre></div> |
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