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/****************************************************************************
**
** Copyright (C) 2010 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.
**
** $QT_BEGIN_LICENSE:LGPL$
** 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 Technology Preview License Agreement accompanying
** this package.
**
** 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 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@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
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