1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
|
/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** BSD License Usage
** Alternatively, 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 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 <QElapsedTimer>
#include <QApplication>
#include <QDebug>
#include <qtconcurrentmap.h>
using namespace QtConcurrent;
/*
Utility function that recursivily searches for files.
*/
QStringList findFiles(const QString &startDir, const QStringList &filters)
{
QStringList names;
QDir dir(startDir);
const auto files = dir.entryList(filters, QDir::Files);
for (const QString &file : files)
names += startDir + '/' + file;
const auto subdirs = dir.entryList(QDir::AllDirs | QDir::NoDotAndDotDot);
for (const QString &subdir : subdirs)
names += findFiles(startDir + '/' + subdir, filters);
return names;
}
typedef QMap<QString, int> WordCount;
/*
Single threaded word counter function.
*/
WordCount singleThreadedWordCount(const QStringList &files)
{
WordCount wordCount;
for (const QString &file : files) {
QFile f(file);
f.open(QIODevice::ReadOnly);
QTextStream textStream(&f);
while (!textStream.atEnd()) {
const auto words = textStream.readLine().split(' ');
for (const QString &word : words)
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()) {
const auto words = textStream.readLine().split(' ');
for (const QString &word : words)
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)
{
for (auto i = w.begin(), end = w.end(); i != end; ++i)
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";
{
WordCount total = singleThreadedWordCount(files);
}
qDebug() << "warmup done";
int singleThreadTime = 0;
{
QElapsedTimer timer;
timer.start();
WordCount total = singleThreadedWordCount(files);
singleThreadTime = timer.elapsed();
qDebug() << "single thread" << singleThreadTime;
}
int mapReduceTime = 0;
{
QElapsedTimer timer;
timer.start();
WordCount total = mappedReduced(files, countWords, reduce);
mapReduceTime = timer.elapsed();
qDebug() << "MapReduce" << mapReduceTime;
}
qDebug() << "MapReduce speedup x" << ((double)singleThreadTime - (double)mapReduceTime) / (double)mapReduceTime + 1;
}
|
