diff options
Diffstat (limited to 'examples/qtconcurrent/wordcount/main.cpp')
| -rw-r--r-- | examples/qtconcurrent/wordcount/main.cpp | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/examples/qtconcurrent/wordcount/main.cpp b/examples/qtconcurrent/wordcount/main.cpp new file mode 100644 index 0000000..5008eaf --- /dev/null +++ b/examples/qtconcurrent/wordcount/main.cpp @@ -0,0 +1,167 @@ +/**************************************************************************** +** +** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies). +** Contact: Qt Software Information (qt-info@nokia.com) +** +** This file is part of the examples of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:LGPL$ +** No Commercial Usage +** This file contains pre-release code and may not be distributed. +** You may use this file in accordance with the terms and conditions +** contained in the either Technology Preview License Agreement or the +** Beta Release License Agreement. +** +** GNU Lesser General Public License Usage +** Alternatively, this file may be used under the terms of the GNU Lesser +** General Public License version 2.1 as published by the Free Software +** Foundation and appearing in the file LICENSE.LGPL included in the +** packaging of this file. Please review the following information to +** ensure the GNU Lesser General Public License version 2.1 requirements +** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html. +** +** In addition, as a special exception, Nokia gives you certain +** additional rights. These rights are described in the Nokia Qt LGPL +** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this +** package. +** +** GNU General Public License Usage +** Alternatively, this file may be used under the terms of the GNU +** General Public License version 3.0 as published by the Free Software +** Foundation and appearing in the file LICENSE.GPL included in the +** packaging of this file. Please review the following information to +** ensure the GNU General Public License version 3.0 requirements will be +** met: http://www.gnu.org/copyleft/gpl.html. +** +** If you are unsure which license is appropriate for your use, please +** contact the sales department at qt-sales@nokia.com. +** $QT_END_LICENSE$ +** +****************************************************************************/ + +#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 |