Sophie: qt4-doc-4:4.6.3-0.2mdv2010.2 i586

qt4-doc-4.6.3-0.2mdv2010.2.i586.rpm

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<pre><span class="comment"> /****************************************************************************
 **
 ** 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.
 **
 ** $QT_BEGIN_LICENSE:LGPL$
 ** Commercial Usage
 ** Licensees holding valid Qt Commercial licenses may use this file in
 ** accordance with the Qt Commercial License Agreement provided with the
 ** Software or, alternatively, in accordance with the terms contained in
 ** a written agreement between you and Nokia.
 **
 ** GNU Lesser General Public License Usage
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 ** General Public License version 2.1 as published by the Free Software
 ** Foundation and appearing in the file LICENSE.LGPL included in the
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 #include &lt;QList&gt;
 #include &lt;QMap&gt;
 #include &lt;QTextStream&gt;
 #include &lt;QString&gt;
 #include &lt;QStringList&gt;
 #include &lt;QDir&gt;
 #include &lt;QTime&gt;
 #include &lt;QApplication&gt;
 #include &lt;QDebug&gt;

 #include &lt;qtconcurrentmap.h&gt;

 #ifndef QT_NO_CONCURRENT

 using namespace QtConcurrent;

<span class="comment"> /*
     Utility function that recursivily searches for files.
 */</span>
 QStringList findFiles(const QString &amp;startDir, QStringList filters)
 {
     QStringList names;
     QDir dir(startDir);

     foreach (QString file, dir.entryList(filters, QDir::Files))
         names += startDir + &quot;/&quot; + file;

     foreach (QString subdir, dir.entryList(QDir::AllDirs | QDir::NoDotAndDotDot))
         names += findFiles(startDir + &quot;/&quot; + subdir, filters);
     return names;
 }

 typedef QMap&lt;QString, int&gt; WordCount;

<span class="comment"> /*
     Single threaded word counter function.
 */</span>
 WordCount singleThreadedWordCount(QStringList files)
 {
     WordCount wordCount;
     foreach (QString file, files) {
         QFile f(file);
         f.open(QIODevice::ReadOnly);
         QTextStream textStream(&amp;f);
         while (textStream.atEnd() == false)
             foreach(QString word, textStream.readLine().split(&quot; &quot;))
                 wordCount[word] += 1;

     }
     return wordCount;
 }

<span class="comment"> // countWords counts the words in a single file. This function is</span>
<span class="comment"> // called in parallel by several threads and must be thread</span>
<span class="comment"> // safe.</span>
 WordCount countWords(const QString &amp;file)
 {
     QFile f(file);
     f.open(QIODevice::ReadOnly);
     QTextStream textStream(&amp;f);
     WordCount wordCount;

     while (textStream.atEnd() == false)
         foreach (QString word, textStream.readLine().split(&quot; &quot;))
             wordCount[word] += 1;

     return wordCount;
 }

<span class="comment"> // reduce adds the results from map to the final</span>
<span class="comment"> // result. This functor will only be called by one thread</span>
<span class="comment"> // at a time.</span>
 void reduce(WordCount &amp;result, const WordCount &amp;w)
 {
     QMapIterator&lt;QString, int&gt; i(w);
     while (i.hasNext()) {
         i.next();
         result[i.key()] += i.value();
     }
 }

 int main(int argc, char** argv)
 {
     QApplication app(argc, argv);
     qDebug() &lt;&lt; &quot;finding files...&quot;;
     QStringList files = findFiles(&quot;../../&quot;, QStringList() &lt;&lt; &quot;*.cpp&quot; &lt;&lt; &quot;*.h&quot;);
     qDebug() &lt;&lt; files.count() &lt;&lt; &quot;files&quot;;

     qDebug() &lt;&lt; &quot;warmup&quot;;
     {
         QTime time;
         time.start();
         WordCount total = singleThreadedWordCount(files);
     }

     qDebug() &lt;&lt; &quot;warmup done&quot;;

     int singleThreadTime = 0;
     {
         QTime time;
         time.start();
         WordCount total = singleThreadedWordCount(files);
         singleThreadTime = time.elapsed();
         qDebug() &lt;&lt; &quot;single thread&quot; &lt;&lt; singleThreadTime;
     }

     int mapReduceTime = 0;
     {
         QTime time;
         time.start();
         WordCount total = mappedReduced(files, countWords, reduce);
         mapReduceTime = time.elapsed();
         qDebug() &lt;&lt; &quot;MapReduce&quot; &lt;&lt; mapReduceTime;
     }
     qDebug() &lt;&lt; &quot;MapReduce speedup x&quot; &lt;&lt; ((double)singleThreadTime - (double)mapReduceTime) / (double)mapReduceTime + 1;
 }

 #else

 int main()
 {
         qDebug() &lt;&lt; &quot;Qt Concurrent is not yet supported on this platform&quot;;
 }

 #endif</pre>
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