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/**************************************************************************** ** ** Copyright (C) 2007-2008 Trolltech ASA. All rights reserved. ** ** This file is part of the example classes of the Qt Toolkit. ** ** This file may be used under the terms of the GNU General Public ** License versions 2.0 or 3.0 as published by the Free Software ** Foundation and appearing in the files LICENSE.GPL2 and LICENSE.GPL3 ** included in the packaging of this file. Alternatively you may (at ** your option) use any later version of the GNU General Public ** License if such license has been publicly approved by Trolltech ASA ** (or its successors, if any) and the KDE Free Qt Foundation. In ** addition, as a special exception, Trolltech gives you certain ** additional rights. These rights are described in the Trolltech GPL ** Exception version 1.2, which can be found at ** http://www.trolltech.com/products/qt/gplexception/ and in the file ** GPL_EXCEPTION.txt in this package. ** ** Please review the following information to ensure GNU General ** Public Licensing requirements will be met: ** http://trolltech.com/products/qt/licenses/licensing/opensource/. If ** you are unsure which license is appropriate for your use, please ** review the following information: ** http://trolltech.com/products/qt/licenses/licensing/licensingoverview ** or contact the sales department at sales@trolltech.com. ** ** In addition, as a special exception, Trolltech, as the sole ** copyright holder for Qt Designer, grants users of the Qt/Eclipse ** Integration plug-in the right for the Qt/Eclipse Integration to ** link to functionality provided by Qt Designer and its related ** libraries. ** ** This file is provided "AS IS" with NO WARRANTY OF ANY KIND, ** INCLUDING THE WARRANTIES OF DESIGN, MERCHANTABILITY AND FITNESS FOR ** A PARTICULAR PURPOSE. Trolltech reserves all rights not expressly ** granted herein. ** ** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. ** ****************************************************************************/ #include <QList> #include <QMap> #include <QTextStream> #include <QString> #include <QStringList> #include <QDir> #include <QTime> #include <QApplication> #include <QDebug> #include <qtconcurrentmap.h> #ifndef QT_NO_CONCURRENT using namespace QtConcurrent; /* Utility function that recursivily searches for files. */ QStringList findFiles(const QString &startDir, QStringList filters) { QStringList names; QDir dir(startDir); foreach (QString file, dir.entryList(filters, QDir::Files)) names += startDir + "/" + file; foreach (QString subdir, dir.entryList(QDir::AllDirs | QDir::NoDotAndDotDot)) names += findFiles(startDir + "/" + subdir, filters); return names; } typedef QMap<QString, int> WordCount; /* Single threaded word counter function. */ WordCount singleThreadedWordCount(QStringList files) { WordCount wordCount; foreach (QString file, files) { QFile f(file); f.open(QIODevice::ReadOnly); QTextStream textStream(&f); while (textStream.atEnd() == false) foreach(QString word, textStream.readLine().split(" ")) wordCount[word] += 1; } return wordCount; } // countWords counts the words in a single file. This function is // called in parallel by several threads and must be thread // safe. WordCount countWords(const QString &file) { QFile f(file); f.open(QIODevice::ReadOnly); QTextStream textStream(&f); WordCount wordCount; while (textStream.atEnd() == false) foreach (QString word, textStream.readLine().split(" ")) wordCount[word] += 1; return wordCount; } // reduce adds the results from map to the final // result. This functor will only be called by one thread // at a time. void reduce(WordCount &result, const WordCount &w) { QMapIterator<QString, int> i(w); while (i.hasNext()) { i.next(); result[i.key()] += i.value(); } } int main(int argc, char** argv) { QApplication app(argc, argv); qDebug() << "finding files..."; QStringList files = findFiles("../../", QStringList() << "*.cpp" << "*.h"); qDebug() << files.count() << "files"; qDebug() << "warmup"; { QTime time; time.start(); WordCount total = singleThreadedWordCount(files); } qDebug() << "warmup done"; int singleThreadTime = 0; { QTime time; time.start(); WordCount total = singleThreadedWordCount(files); singleThreadTime = time.elapsed(); qDebug() << "single thread" << singleThreadTime; } int mapReduceTime = 0; { QTime time; time.start(); WordCount total = mappedReduced(files, countWords, reduce); mapReduceTime = time.elapsed(); qDebug() << "MapReduce" << mapReduceTime; } qDebug() << "MapReduce speedup x" << ((double)singleThreadTime - (double)mapReduceTime) / (double)mapReduceTime + 1; } #else int main() { qDebug() << "Qt Concurrent is not yet supported on this platform"; } #endif
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