| <!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/jpeg-decoder-0.1.22/src/worker/multithreaded.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>multithreaded.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="../../../jpeg_decoder/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="../../../jpeg_decoder/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="doccomment">//! This module implements per-component parallelism. |
| //! It should be possible to implement per-row parallelism as well, |
| //! which should also boost performance of grayscale images |
| //! and allow scaling to more cores. |
| //! However, that would be more complex, so we use this as a starting point. |
| |
| </span><span class="kw">use </span>decoder::MAX_COMPONENTS; |
| <span class="kw">use </span>error::Result; |
| <span class="kw">use </span>std::{mem, sync::mpsc::{<span class="self">self</span>, Sender}}; |
| <span class="kw">use </span>std::thread; |
| <span class="kw">use super</span>::{RowData, Worker}; |
| <span class="kw">use </span><span class="kw">super</span>::immediate::ImmediateWorker; |
| |
| <span class="kw">enum </span>WorkerMsg { |
| Start(RowData), |
| AppendRow(Vec<i16>), |
| GetResult(Sender<Vec<u8>>), |
| } |
| <span class="kw">pub struct </span>MultiThreadedWorker { |
| senders: [<span class="prelude-ty">Option</span><Sender<WorkerMsg>>; MAX_COMPONENTS] |
| } |
| |
| <span class="kw">impl </span>Worker <span class="kw">for </span>MultiThreadedWorker { |
| <span class="kw">fn </span>new() -> <span class="prelude-ty">Result</span><<span class="self">Self</span>> { |
| <span class="prelude-val">Ok</span>(MultiThreadedWorker { |
| senders: [<span class="prelude-val">None</span>, <span class="prelude-val">None</span>, <span class="prelude-val">None</span>, <span class="prelude-val">None</span>] |
| }) |
| } |
| <span class="kw">fn </span>start(<span class="kw-2">&mut </span><span class="self">self</span>, row_data: RowData) -> <span class="prelude-ty">Result</span><()> { |
| <span class="comment">// if there is no worker thread for this component yet, start one |
| </span><span class="kw">let </span>component = row_data.index; |
| <span class="kw">if let </span><span class="prelude-val">None </span>= <span class="self">self</span>.senders[component] { |
| <span class="kw">let </span>sender = spawn_worker_thread(component)<span class="question-mark">?</span>; |
| <span class="self">self</span>.senders[component] = <span class="prelude-val">Some</span>(sender); |
| } |
| <span class="comment">// we do the "take out value and put it back in once we're done" dance here |
| // and in all other message-passing methods because there's not that many rows |
| // and this should be cheaper than spawning MAX_COMPONENTS many threads up front |
| </span><span class="kw">let </span>sender = mem::replace(<span class="kw-2">&mut </span><span class="self">self</span>.senders[component], <span class="prelude-val">None</span>).unwrap(); |
| sender.send(WorkerMsg::Start(row_data)).expect(<span class="string">"jpeg-decoder worker thread error"</span>); |
| <span class="self">self</span>.senders[component] = <span class="prelude-val">Some</span>(sender); |
| <span class="prelude-val">Ok</span>(()) |
| } |
| <span class="kw">fn </span>append_row(<span class="kw-2">&mut </span><span class="self">self</span>, row: (usize, Vec<i16>)) -> <span class="prelude-ty">Result</span><()> { |
| <span class="kw">let </span>component = row.<span class="number">0</span>; |
| <span class="kw">let </span>sender = mem::replace(<span class="kw-2">&mut </span><span class="self">self</span>.senders[component], <span class="prelude-val">None</span>).unwrap(); |
| sender.send(WorkerMsg::AppendRow(row.<span class="number">1</span>)).expect(<span class="string">"jpeg-decoder worker thread error"</span>); |
| <span class="self">self</span>.senders[component] = <span class="prelude-val">Some</span>(sender); |
| <span class="prelude-val">Ok</span>(()) |
| } |
| <span class="kw">fn </span>get_result(<span class="kw-2">&mut </span><span class="self">self</span>, index: usize) -> <span class="prelude-ty">Result</span><Vec<u8>> { |
| <span class="kw">let </span>(tx, rx) = mpsc::channel(); |
| <span class="kw">let </span>sender = mem::replace(<span class="kw-2">&mut </span><span class="self">self</span>.senders[index], <span class="prelude-val">None</span>).unwrap(); |
| sender.send(WorkerMsg::GetResult(tx)).expect(<span class="string">"jpeg-decoder worker thread error"</span>); |
| <span class="prelude-val">Ok</span>(rx.recv().expect(<span class="string">"jpeg-decoder worker thread error"</span>)) |
| } |
| } |
| |
| <span class="kw">fn </span>spawn_worker_thread(component: usize) -> <span class="prelude-ty">Result</span><Sender<WorkerMsg>> { |
| <span class="kw">let </span>thread_builder = thread::Builder::new().name(<span class="macro">format!</span>(<span class="string">"worker thread for component {}"</span>, component)); |
| <span class="kw">let </span>(tx, rx) = mpsc::channel(); |
| |
| thread_builder.spawn(<span class="kw">move </span>|| { |
| <span class="kw">let </span><span class="kw-2">mut </span>worker = ImmediateWorker::new_immediate(); |
| |
| <span class="kw">while let </span><span class="prelude-val">Ok</span>(message) = rx.recv() { |
| <span class="kw">match </span>message { |
| WorkerMsg::Start(<span class="kw-2">mut </span>data) => { |
| <span class="comment">// we always set component index to 0 for worker threads |
| // because they only ever handle one per thread and we don't want them |
| // to attempt to access nonexistent components |
| </span>data.index = <span class="number">0</span>; |
| worker.start_immediate(data); |
| }, |
| WorkerMsg::AppendRow(row) => { |
| worker.append_row_immediate((<span class="number">0</span>, row)); |
| }, |
| WorkerMsg::GetResult(chan) => { |
| <span class="kw">let _ </span>= chan.send(worker.get_result_immediate(<span class="number">0</span>)); |
| <span class="kw">break</span>; |
| }, |
| } |
| } |
| })<span class="question-mark">?</span>; |
| |
| <span class="prelude-val">Ok</span>(tx) |
| }</code></pre></div> |
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