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/****************************************************************************
**
** Copyright (C) 2015 The Qt Company Ltd.
** Contact: http://www.qt.io/licensing/
**
** 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 The Qt Company Ltd 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>
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;
}
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