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Diffstat (limited to 'examples/qtconcurrent/wordcount/main.cpp')
-rw-r--r-- | examples/qtconcurrent/wordcount/main.cpp | 166 |
1 files changed, 166 insertions, 0 deletions
diff --git a/examples/qtconcurrent/wordcount/main.cpp b/examples/qtconcurrent/wordcount/main.cpp new file mode 100644 index 0000000000..035207c410 --- /dev/null +++ b/examples/qtconcurrent/wordcount/main.cpp @@ -0,0 +1,166 @@ +/**************************************************************************** +** +** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies). +** All rights reserved. +** Contact: Nokia Corporation (qt-info@nokia.com) +** +** This file is part of the examples of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:BSD$ +** 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 Nokia Corporation and its Subsidiary(-ies) 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." +** $QT_END_LICENSE$ +** +****************************************************************************/ + +#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 |