1 | /****************************************************************************
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2 | **
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3 | ** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
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4 | ** All rights reserved.
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5 | ** Contact: Nokia Corporation ([email protected])
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6 | **
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7 | ** This file is part of the examples of the Qt Toolkit.
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8 | **
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9 | ** $QT_BEGIN_LICENSE:BSD$
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10 | ** You may use this file under the terms of the BSD license as follows:
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11 | **
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12 | ** "Redistribution and use in source and binary forms, with or without
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13 | ** modification, are permitted provided that the following conditions are
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14 | ** met:
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15 | ** * Redistributions of source code must retain the above copyright
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16 | ** notice, this list of conditions and the following disclaimer.
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17 | ** * Redistributions in binary form must reproduce the above copyright
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18 | ** notice, this list of conditions and the following disclaimer in
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19 | ** the documentation and/or other materials provided with the
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20 | ** distribution.
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21 | ** * Neither the name of Nokia Corporation and its Subsidiary(-ies) nor
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22 | ** the names of its contributors may be used to endorse or promote
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23 | ** products derived from this software without specific prior written
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24 | ** permission.
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25 | **
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26 | ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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27 | ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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28 | ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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29 | ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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30 | ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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31 | ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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32 | ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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33 | ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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34 | ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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35 | ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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36 | ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
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37 | ** $QT_END_LICENSE$
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38 | **
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39 | ****************************************************************************/
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40 |
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41 | #include <QList>
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42 | #include <QMap>
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43 | #include <QTextStream>
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44 | #include <QString>
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45 | #include <QStringList>
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46 | #include <QDir>
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47 | #include <QTime>
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48 | #include <QApplication>
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49 | #include <QDebug>
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50 |
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51 | #include <qtconcurrentmap.h>
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52 |
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53 | #ifndef QT_NO_CONCURRENT
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54 |
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55 | using namespace QtConcurrent;
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56 |
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57 | /*
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58 | Utility function that recursivily searches for files.
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59 | */
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60 | QStringList findFiles(const QString &startDir, QStringList filters)
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61 | {
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62 | QStringList names;
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63 | QDir dir(startDir);
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64 |
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65 | foreach (QString file, dir.entryList(filters, QDir::Files))
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66 | names += startDir + "/" + file;
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67 |
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68 | foreach (QString subdir, dir.entryList(QDir::AllDirs | QDir::NoDotAndDotDot))
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69 | names += findFiles(startDir + "/" + subdir, filters);
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70 | return names;
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71 | }
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72 |
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73 | typedef QMap<QString, int> WordCount;
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74 |
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75 | /*
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76 | Single threaded word counter function.
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77 | */
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78 | WordCount singleThreadedWordCount(QStringList files)
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79 | {
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80 | WordCount wordCount;
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81 | foreach (QString file, files) {
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82 | QFile f(file);
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83 | f.open(QIODevice::ReadOnly);
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84 | QTextStream textStream(&f);
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85 | while (textStream.atEnd() == false)
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86 | foreach(QString word, textStream.readLine().split(" "))
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87 | wordCount[word] += 1;
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88 |
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89 | }
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90 | return wordCount;
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91 | }
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92 |
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93 |
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94 | // countWords counts the words in a single file. This function is
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95 | // called in parallel by several threads and must be thread
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96 | // safe.
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97 | WordCount countWords(const QString &file)
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98 | {
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99 | QFile f(file);
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100 | f.open(QIODevice::ReadOnly);
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101 | QTextStream textStream(&f);
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102 | WordCount wordCount;
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103 |
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104 | while (textStream.atEnd() == false)
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105 | foreach (QString word, textStream.readLine().split(" "))
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106 | wordCount[word] += 1;
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107 |
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108 | return wordCount;
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109 | }
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110 |
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111 | // reduce adds the results from map to the final
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112 | // result. This functor will only be called by one thread
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113 | // at a time.
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114 | void reduce(WordCount &result, const WordCount &w)
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115 | {
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116 | QMapIterator<QString, int> i(w);
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117 | while (i.hasNext()) {
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118 | i.next();
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119 | result[i.key()] += i.value();
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120 | }
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121 | }
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122 |
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123 | int main(int argc, char** argv)
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124 | {
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125 | QApplication app(argc, argv);
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126 | qDebug() << "finding files...";
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127 | QStringList files = findFiles("../../", QStringList() << "*.cpp" << "*.h");
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128 | qDebug() << files.count() << "files";
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129 |
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130 | qDebug() << "warmup";
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131 | {
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132 | QTime time;
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133 | time.start();
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134 | WordCount total = singleThreadedWordCount(files);
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135 | }
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136 |
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137 | qDebug() << "warmup done";
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138 |
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139 | int singleThreadTime = 0;
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140 | {
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141 | QTime time;
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142 | time.start();
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143 | WordCount total = singleThreadedWordCount(files);
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144 | singleThreadTime = time.elapsed();
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145 | qDebug() << "single thread" << singleThreadTime;
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146 | }
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147 |
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148 | int mapReduceTime = 0;
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149 | {
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150 | QTime time;
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151 | time.start();
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152 | WordCount total = mappedReduced(files, countWords, reduce);
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153 | mapReduceTime = time.elapsed();
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154 | qDebug() << "MapReduce" << mapReduceTime;
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155 | }
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156 | qDebug() << "MapReduce speedup x" << ((double)singleThreadTime - (double)mapReduceTime) / (double)mapReduceTime + 1;
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157 | }
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158 |
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159 | #else
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160 |
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161 | int main()
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162 | {
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163 | qDebug() << "Qt Concurrent is not yet supported on this platform";
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164 | }
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165 |
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166 | #endif
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