<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html> <html lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>main.cpp Example File | Qt Concurrent 5.12.6</title> <link rel="stylesheet" type="text/css" href="style/offline-simple.css" /> <script type="text/javascript"> document.getElementsByTagName("link").item(0).setAttribute("href", "style/offline.css"); // loading style sheet breaks anchors that were jumped to before // so force jumping to anchor again setTimeout(function() { var anchor = location.hash; // need to jump to different anchor first (e.g. none) location.hash = "#"; setTimeout(function() { location.hash = anchor; }, 0); }, 0); </script> </head> <body> <div class="header" id="qtdocheader"> <div class="main"> <div class="main-rounded"> <div class="navigationbar"> <table><tr> <td >Qt 5.12</td><td ><a href="qtconcurrent-index.html">Qt Concurrent</a></td><td ><a href="qtconcurrent-wordcount-example.html">QtConcurrent Word Count Example</a></td><td >main.cpp Example File</td></tr></table><table class="buildversion"><tr> <td id="buildversion" width="100%" align="right"><a href="qtconcurrent-index.html">Qt 5.12.6 Reference Documentation</a></td> </tr></table> </div> </div> <div class="content"> <div class="line"> <div class="content mainContent"> <div class="sidebar"><div class="sidebar-content" id="sidebar-content"></div></div> <h1 class="title">main.cpp Example File</h1> <span class="subtitle">wordcount/main.cpp</span> <!-- $$$wordcount/main.cpp-description --> <div class="descr"> <a name="details"></a> <pre class="cpp"> <span class="comment">/**************************************************************************** ** ** Copyright (C) 2016 The Qt Company Ltd. ** Contact: https://www.qt.io/licensing/ ** ** This file is part of the examples of the Qt Toolkit. ** ** $QT_BEGIN_LICENSE:BSD$ ** Commercial License Usage ** Licensees holding valid commercial Qt licenses may use this file in ** accordance with the commercial license agreement provided with the ** Software or, alternatively, in accordance with the terms contained in ** a written agreement between you and The Qt Company. For licensing terms ** and conditions see https://www.qt.io/terms-conditions. For further ** information use the contact form at https://www.qt.io/contact-us. ** ** BSD License Usage ** Alternatively, you may use this file under the terms of the BSD license ** as follows: ** ** "Redistribution and use in source and binary forms, with or without ** modification, are permitted provided that the following conditions are ** met: ** * Redistributions of source code must retain the above copyright ** notice, this list of conditions and the following disclaimer. ** * Redistributions in binary form must reproduce the above copyright ** notice, this list of conditions and the following disclaimer in ** the documentation and/or other materials provided with the ** distribution. ** * Neither the name of The Qt Company Ltd nor the names of its ** contributors may be used to endorse or promote products derived ** from this software without specific prior written permission. ** ** ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE." ** ** $QT_END_LICENSE$ ** ****************************************************************************/</span> <span class="preprocessor">#include <QList></span> <span class="preprocessor">#include <QMap></span> <span class="preprocessor">#include <QTextStream></span> <span class="preprocessor">#include <QString></span> <span class="preprocessor">#include <QStringList></span> <span class="preprocessor">#include <QDir></span> <span class="preprocessor">#include <QTime></span> <span class="preprocessor">#include <QApplication></span> <span class="preprocessor">#include <QDebug></span> <span class="preprocessor">#include <qtconcurrentmap.h></span> <span class="keyword">using</span> <span class="keyword">namespace</span> <span class="type"><a href="qtconcurrent-module.html">QtConcurrent</a></span>; <span class="comment">/* Utility function that recursivily searches for files. */</span> <span class="type"><a href="../qtcore/qstringlist.html">QStringList</a></span> findFiles(<span class="keyword">const</span> <span class="type"><a href="../qtcore/qstring.html">QString</a></span> <span class="operator">&</span>startDir<span class="operator">,</span> <span class="keyword">const</span> <span class="type"><a href="../qtcore/qstringlist.html">QStringList</a></span> <span class="operator">&</span>filters) { <span class="type"><a href="../qtcore/qstringlist.html">QStringList</a></span> names; <span class="type"><a href="../qtcore/qdir.html">QDir</a></span> dir(startDir); <span class="keyword">const</span> <span class="keyword">auto</span> files <span class="operator">=</span> dir<span class="operator">.</span>entryList(filters<span class="operator">,</span> <span class="type"><a href="../qtcore/qdir.html">QDir</a></span><span class="operator">::</span>Files); <span class="keyword">for</span> (<span class="keyword">const</span> <span class="type"><a href="../qtcore/qstring.html">QString</a></span> <span class="operator">&</span>file : files) names <span class="operator">+</span><span class="operator">=</span> startDir <span class="operator">+</span> <span class="char">'/'</span> <span class="operator">+</span> file; <span class="keyword">const</span> <span class="keyword">auto</span> subdirs <span class="operator">=</span> dir<span class="operator">.</span>entryList(<span class="type"><a href="../qtcore/qdir.html">QDir</a></span><span class="operator">::</span>AllDirs <span class="operator">|</span> <span class="type"><a href="../qtcore/qdir.html">QDir</a></span><span class="operator">::</span>NoDotAndDotDot); <span class="keyword">for</span> (<span class="keyword">const</span> <span class="type"><a href="../qtcore/qstring.html">QString</a></span> <span class="operator">&</span>subdir : subdirs) names <span class="operator">+</span><span class="operator">=</span> findFiles(startDir <span class="operator">+</span> <span class="char">'/'</span> <span class="operator">+</span> subdir<span class="operator">,</span> filters); <span class="keyword">return</span> names; } <span class="keyword">typedef</span> <span class="type"><a href="../qtcore/qmap.html">QMap</a></span><span class="operator"><</span><span class="type"><a href="../qtcore/qstring.html">QString</a></span><span class="operator">,</span> <span class="type">int</span><span class="operator">></span> WordCount; <span class="comment">/* Single threaded word counter function. */</span> WordCount singleThreadedWordCount(<span class="keyword">const</span> <span class="type"><a href="../qtcore/qstringlist.html">QStringList</a></span> <span class="operator">&</span>files) { WordCount wordCount; <span class="keyword">for</span> (<span class="keyword">const</span> <span class="type"><a href="../qtcore/qstring.html">QString</a></span> <span class="operator">&</span>file : files) { <span class="type"><a href="../qtcore/qfile.html">QFile</a></span> f(file); f<span class="operator">.</span>open(<span class="type"><a href="../qtcore/qiodevice.html">QIODevice</a></span><span class="operator">::</span>ReadOnly); <span class="type"><a href="../qtcore/qtextstream.html">QTextStream</a></span> textStream(<span class="operator">&</span>f); <span class="keyword">while</span> (<span class="operator">!</span>textStream<span class="operator">.</span>atEnd()) { <span class="keyword">const</span> <span class="keyword">auto</span> words <span class="operator">=</span> textStream<span class="operator">.</span>readLine()<span class="operator">.</span>split(<span class="char">' '</span>); <span class="keyword">for</span> (<span class="keyword">const</span> <span class="type"><a href="../qtcore/qstring.html">QString</a></span> <span class="operator">&</span>word : words) wordCount<span class="operator">[</span>word<span class="operator">]</span> <span class="operator">+</span><span class="operator">=</span> <span class="number">1</span>; } } <span class="keyword">return</span> wordCount; } <span class="comment">// countWords counts the words in a single file. This function is</span> <span class="comment">// called in parallel by several threads and must be thread</span> <span class="comment">// safe.</span> WordCount countWords(<span class="keyword">const</span> <span class="type"><a href="../qtcore/qstring.html">QString</a></span> <span class="operator">&</span>file) { <span class="type"><a href="../qtcore/qfile.html">QFile</a></span> f(file); f<span class="operator">.</span>open(<span class="type"><a href="../qtcore/qiodevice.html">QIODevice</a></span><span class="operator">::</span>ReadOnly); <span class="type"><a href="../qtcore/qtextstream.html">QTextStream</a></span> textStream(<span class="operator">&</span>f); WordCount wordCount; <span class="keyword">while</span> (<span class="operator">!</span>textStream<span class="operator">.</span>atEnd()) { <span class="keyword">const</span> <span class="keyword">auto</span> words <span class="operator">=</span> textStream<span class="operator">.</span>readLine()<span class="operator">.</span>split(<span class="char">' '</span>); <span class="keyword">for</span> (<span class="keyword">const</span> <span class="type"><a href="../qtcore/qstring.html">QString</a></span> <span class="operator">&</span>word : words) wordCount<span class="operator">[</span>word<span class="operator">]</span> <span class="operator">+</span><span class="operator">=</span> <span class="number">1</span>; } <span class="keyword">return</span> wordCount; } <span class="comment">// reduce adds the results from map to the final</span> <span class="comment">// result. This functor will only be called by one thread</span> <span class="comment">// at a time.</span> <span class="type">void</span> reduce(WordCount <span class="operator">&</span>result<span class="operator">,</span> <span class="keyword">const</span> WordCount <span class="operator">&</span>w) { <span class="type"><a href="../qtcore/qmapiterator.html">QMapIterator</a></span><span class="operator"><</span><span class="type"><a href="../qtcore/qstring.html">QString</a></span><span class="operator">,</span> <span class="type">int</span><span class="operator">></span> i(w); <span class="keyword">while</span> (i<span class="operator">.</span>hasNext()) { i<span class="operator">.</span>next(); result<span class="operator">[</span>i<span class="operator">.</span>key()<span class="operator">]</span> <span class="operator">+</span><span class="operator">=</span> i<span class="operator">.</span>value(); } } <span class="type">int</span> main(<span class="type">int</span> argc<span class="operator">,</span> <span class="type">char</span><span class="operator">*</span><span class="operator">*</span> argv) { <span class="type">QApplication</span> app(argc<span class="operator">,</span> argv); <a href="../qtcore/qtglobal.html#qDebug">qDebug</a>() <span class="operator"><</span><span class="operator"><</span> <span class="string">"finding files..."</span>; <span class="type"><a href="../qtcore/qstringlist.html">QStringList</a></span> files <span class="operator">=</span> findFiles(<span class="string">"../../"</span><span class="operator">,</span> <span class="type"><a href="../qtcore/qstringlist.html">QStringList</a></span>() <span class="operator"><</span><span class="operator"><</span> <span class="string">"*.cpp"</span> <span class="operator"><</span><span class="operator"><</span> <span class="string">"*.h"</span>); <a href="../qtcore/qtglobal.html#qDebug">qDebug</a>() <span class="operator"><</span><span class="operator"><</span> files<span class="operator">.</span>count() <span class="operator"><</span><span class="operator"><</span> <span class="string">"files"</span>; <a href="../qtcore/qtglobal.html#qDebug">qDebug</a>() <span class="operator"><</span><span class="operator"><</span> <span class="string">"warmup"</span>; { WordCount total <span class="operator">=</span> singleThreadedWordCount(files); } <a href="../qtcore/qtglobal.html#qDebug">qDebug</a>() <span class="operator"><</span><span class="operator"><</span> <span class="string">"warmup done"</span>; <span class="type">int</span> singleThreadTime <span class="operator">=</span> <span class="number">0</span>; { <span class="type"><a href="../qtcore/qtime.html">QTime</a></span> time; time<span class="operator">.</span>start(); WordCount total <span class="operator">=</span> singleThreadedWordCount(files); singleThreadTime <span class="operator">=</span> time<span class="operator">.</span>elapsed(); <a href="../qtcore/qtglobal.html#qDebug">qDebug</a>() <span class="operator"><</span><span class="operator"><</span> <span class="string">"single thread"</span> <span class="operator"><</span><span class="operator"><</span> singleThreadTime; } <span class="type">int</span> mapReduceTime <span class="operator">=</span> <span class="number">0</span>; { <span class="type"><a href="../qtcore/qtime.html">QTime</a></span> time; time<span class="operator">.</span>start(); WordCount total <span class="operator">=</span> mappedReduced(files<span class="operator">,</span> countWords<span class="operator">,</span> reduce); mapReduceTime <span class="operator">=</span> time<span class="operator">.</span>elapsed(); <a href="../qtcore/qtglobal.html#qDebug">qDebug</a>() <span class="operator"><</span><span class="operator"><</span> <span class="string">"MapReduce"</span> <span class="operator"><</span><span class="operator"><</span> mapReduceTime; } <a href="../qtcore/qtglobal.html#qDebug">qDebug</a>() <span class="operator"><</span><span class="operator"><</span> <span class="string">"MapReduce speedup x"</span> <span class="operator"><</span><span class="operator"><</span> ((<span class="type">double</span>)singleThreadTime <span class="operator">-</span> (<span class="type">double</span>)mapReduceTime) <span class="operator">/</span> (<span class="type">double</span>)mapReduceTime <span class="operator">+</span> <span class="number">1</span>; } </pre> </div> <!-- @@@wordcount/main.cpp --> </div> </div> </div> </div> </div> <div class="footer"> <p> <acronym title="Copyright">©</acronym> 2019 The Qt Company Ltd. Documentation contributions included herein are the copyrights of their respective owners.<br/> The documentation provided herein is licensed under the terms of the <a href="http://www.gnu.org/licenses/fdl.html">GNU Free Documentation License version 1.3</a> as published by the Free Software Foundation.<br/> Qt and respective logos are trademarks of The Qt Company Ltd. in Finland and/or other countries worldwide. All other trademarks are property of their respective owners. </p> </div> </body> </html>