source: trunk/examples/qtconcurrent/wordcount/main.cpp@ 1028

Last change on this file since 1028 was 846, checked in by Dmitry A. Kuminov, 14 years ago

trunk: Merged in qt 4.7.2 sources from branches/vendor/nokia/qt.

File size: 5.0 KB
Line 
1/****************************************************************************
2**
3** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
4** All rights reserved.
5** Contact: Nokia Corporation ([email protected])
6**
7** This file is part of the examples of the Qt Toolkit.
8**
9** $QT_BEGIN_LICENSE:BSD$
10** You may use this file under the terms of the BSD license as follows:
11**
12** "Redistribution and use in source and binary forms, with or without
13** modification, are permitted provided that the following conditions are
14** met:
15** * Redistributions of source code must retain the above copyright
16** notice, this list of conditions and the following disclaimer.
17** * Redistributions in binary form must reproduce the above copyright
18** notice, this list of conditions and the following disclaimer in
19** the documentation and/or other materials provided with the
20** distribution.
21** * Neither the name of Nokia Corporation and its Subsidiary(-ies) nor
22** the names of its contributors may be used to endorse or promote
23** products derived from this software without specific prior written
24** permission.
25**
26** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
27** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
28** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
29** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
30** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
31** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
32** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
33** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
34** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
35** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
36** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
37** $QT_END_LICENSE$
38**
39****************************************************************************/
40
41#include <QList>
42#include <QMap>
43#include <QTextStream>
44#include <QString>
45#include <QStringList>
46#include <QDir>
47#include <QTime>
48#include <QApplication>
49#include <QDebug>
50
51#include <qtconcurrentmap.h>
52
53#ifndef QT_NO_CONCURRENT
54
55using namespace QtConcurrent;
56
57/*
58 Utility function that recursivily searches for files.
59*/
60QStringList findFiles(const QString &startDir, QStringList filters)
61{
62 QStringList names;
63 QDir dir(startDir);
64
65 foreach (QString file, dir.entryList(filters, QDir::Files))
66 names += startDir + "/" + file;
67
68 foreach (QString subdir, dir.entryList(QDir::AllDirs | QDir::NoDotAndDotDot))
69 names += findFiles(startDir + "/" + subdir, filters);
70 return names;
71}
72
73typedef QMap<QString, int> WordCount;
74
75/*
76 Single threaded word counter function.
77*/
78WordCount singleThreadedWordCount(QStringList files)
79{
80 WordCount wordCount;
81 foreach (QString file, files) {
82 QFile f(file);
83 f.open(QIODevice::ReadOnly);
84 QTextStream textStream(&f);
85 while (textStream.atEnd() == false)
86 foreach(QString word, textStream.readLine().split(" "))
87 wordCount[word] += 1;
88
89 }
90 return wordCount;
91}
92
93
94// countWords counts the words in a single file. This function is
95// called in parallel by several threads and must be thread
96// safe.
97WordCount countWords(const QString &file)
98{
99 QFile f(file);
100 f.open(QIODevice::ReadOnly);
101 QTextStream textStream(&f);
102 WordCount wordCount;
103
104 while (textStream.atEnd() == false)
105 foreach (QString word, textStream.readLine().split(" "))
106 wordCount[word] += 1;
107
108 return wordCount;
109}
110
111// reduce adds the results from map to the final
112// result. This functor will only be called by one thread
113// at a time.
114void reduce(WordCount &result, const WordCount &w)
115{
116 QMapIterator<QString, int> i(w);
117 while (i.hasNext()) {
118 i.next();
119 result[i.key()] += i.value();
120 }
121}
122
123int main(int argc, char** argv)
124{
125 QApplication app(argc, argv);
126 qDebug() << "finding files...";
127 QStringList files = findFiles("../../", QStringList() << "*.cpp" << "*.h");
128 qDebug() << files.count() << "files";
129
130 qDebug() << "warmup";
131 {
132 QTime time;
133 time.start();
134 WordCount total = singleThreadedWordCount(files);
135 }
136
137 qDebug() << "warmup done";
138
139 int singleThreadTime = 0;
140 {
141 QTime time;
142 time.start();
143 WordCount total = singleThreadedWordCount(files);
144 singleThreadTime = time.elapsed();
145 qDebug() << "single thread" << singleThreadTime;
146 }
147
148 int mapReduceTime = 0;
149 {
150 QTime time;
151 time.start();
152 WordCount total = mappedReduced(files, countWords, reduce);
153 mapReduceTime = time.elapsed();
154 qDebug() << "MapReduce" << mapReduceTime;
155 }
156 qDebug() << "MapReduce speedup x" << ((double)singleThreadTime - (double)mapReduceTime) / (double)mapReduceTime + 1;
157}
158
159#else
160
161int main()
162{
163 qDebug() << "Qt Concurrent is not yet supported on this platform";
164}
165
166#endif
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