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+/****************************************************************************
+**
+** 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