summaryrefslogtreecommitdiffstats
path: root/doc/src/snippets/qelapsedtimer/main.cpp
blob: 9d0421f1be26df889439256107420af43a7d4340 (plain)
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
/****************************************************************************
**
** 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 QtNetwork module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the Technology Preview License Agreement accompanying
** this package.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights.  These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
**
**
**
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
#include <QtCore>

void slowOperation1()
{
    static char buf[256];
    for (int i = 0; i < (1<<20); ++i)
        buf[i % sizeof buf] = i;
}

void slowOperation2(int) { slowOperation1(); }

void startExample()
{
//![0]
    QElapsedTimer timer;
    timer.start();

    slowOperation1();

    qDebug() << "The slow operation took" << timer.elapsed() << "milliseconds";
//![0]
}

//![1]
void executeSlowOperations(int timeout)
{
    QElapsedTimer timer;
    timer.start();
    slowOperation1();

    int remainingTime = timeout - timer.elapsed();
    if (remainingTime > 0)
        slowOperation2(remainingTime);
}
//![1]

//![2]
void executeOperationsForTime(int ms)
{
    QElapsedTimer timer;
    timer.start();

    while (!timer.hasExpired(ms))
        slowOperation1();
}
//![2]

int restartExample()
{
//![3]
    QElapsedTimer timer;

    int count = 1;
    timer.start();
    do {
        count *= 2;
        slowOperation2(count);
    } while (timer.restart() < 250);

    return count;
//![3]
}

int main(int argc, char **argv)
{
    QCoreApplication app(argc, argv);

    startExample();
    restartExample();
    executeSlowOperations(5);
    executeOperationsForTime(5);
}