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#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