1 | /****************************************************************************
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2 | **
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3 | ** Copyright (C) 2010 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 QtCore module of the Qt Toolkit.
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8 | **
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9 | ** $QT_BEGIN_LICENSE:LGPL$
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10 | ** Commercial Usage
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11 | ** Licensees holding valid Qt Commercial licenses may use this file in
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12 | ** accordance with the Qt Commercial License Agreement provided with the
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13 | ** Software or, alternatively, in accordance with the terms contained in
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14 | ** a written agreement between you and Nokia.
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15 | **
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16 | ** GNU Lesser General Public License Usage
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17 | ** Alternatively, this file may be used under the terms of the GNU Lesser
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18 | ** General Public License version 2.1 as published by the Free Software
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19 | ** Foundation and appearing in the file LICENSE.LGPL included in the
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20 | ** packaging of this file. Please review the following information to
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21 | ** ensure the GNU Lesser General Public License version 2.1 requirements
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22 | ** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
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23 | **
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24 | ** In addition, as a special exception, Nokia gives you certain additional
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25 | ** rights. These rights are described in the Nokia Qt LGPL Exception
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26 | ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
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27 | **
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28 | ** GNU General Public License Usage
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29 | ** Alternatively, this file may be used under the terms of the GNU
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30 | ** General Public License version 3.0 as published by the Free Software
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31 | ** Foundation and appearing in the file LICENSE.GPL included in the
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32 | ** packaging of this file. Please review the following information to
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33 | ** ensure the GNU General Public License version 3.0 requirements will be
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34 | ** met: http://www.gnu.org/copyleft/gpl.html.
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35 | **
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36 | ** If you have questions regarding the use of this file, please contact
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37 | ** Nokia at [email protected].
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38 | ** $QT_END_LICENSE$
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39 | **
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40 | ****************************************************************************/
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41 |
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42 | #ifndef QTCONCURRENT_ITERATEKERNEL_H
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43 | #define QTCONCURRENT_ITERATEKERNEL_H
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44 |
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45 | #include <QtCore/qglobal.h>
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46 |
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47 | #ifndef QT_NO_CONCURRENT
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48 |
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49 | #include <QtCore/qatomic.h>
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50 | #include <QtCore/qtconcurrentmedian.h>
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51 | #include <QtCore/qtconcurrentthreadengine.h>
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52 |
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53 | #ifndef QT_NO_STL
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54 | # include <iterator>
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55 | #endif
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56 |
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57 | QT_BEGIN_HEADER
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58 | QT_BEGIN_NAMESPACE
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59 |
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60 | QT_MODULE(Core)
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61 |
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62 | #ifndef qdoc
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63 |
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64 | namespace QtConcurrent {
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65 |
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66 | #ifndef QT_NO_STL
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67 | using std::advance;
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68 | #else
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69 | template <typename It, typename T>
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70 | void advance(It &it, T value)
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71 | {
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72 | it+=value;
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73 | }
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74 | #endif
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75 |
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76 | /*
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77 | The BlockSizeManager class manages how many iterations a thread should
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78 | reserve and process at a time. This is done by measuring the time spent
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79 | in the user code versus the control part code, and then increasing
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80 | the block size if the ratio between them is to small. The block size
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81 | management is done on the basis of the median of several timing measuremens,
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82 | and it is done induvidualy for each thread.
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83 | */
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84 | class Q_CORE_EXPORT BlockSizeManager
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85 | {
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86 | public:
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87 | BlockSizeManager(int iterationCount);
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88 | void timeBeforeUser();
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89 | void timeAfterUser();
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90 | int blockSize();
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91 | private:
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92 | inline bool blockSizeMaxed()
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93 | {
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94 | return (m_blockSize >= maxBlockSize);
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95 | }
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96 |
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97 | const int maxBlockSize;
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98 | qint64 beforeUser;
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99 | qint64 afterUser;
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100 | Median<double> controlPartElapsed;
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101 | Median<double> userPartElapsed;
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102 | int m_blockSize;
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103 | };
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104 |
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105 | template <typename T>
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106 | class ResultReporter
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107 | {
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108 | public:
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109 | ResultReporter(ThreadEngine<T> *_threadEngine)
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110 | :threadEngine(_threadEngine)
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111 | {
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112 |
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113 | }
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114 |
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115 | void reserveSpace(int resultCount)
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116 | {
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117 | currentResultCount = resultCount;
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118 | vector.resize(qMax(resultCount, vector.count()));
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119 | }
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120 |
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121 | void reportResults(int begin)
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122 | {
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123 | const int useVectorThreshold = 4; // Tunable parameter.
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124 | if (currentResultCount > useVectorThreshold) {
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125 | vector.resize(currentResultCount);
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126 | threadEngine->reportResults(vector, begin);
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127 | } else {
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128 | for (int i = 0; i < currentResultCount; ++i)
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129 | threadEngine->reportResult(&vector.at(i), begin + i);
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130 | }
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131 | }
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132 |
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133 | inline T * getPointer()
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134 | {
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135 | return vector.data();
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136 | }
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137 |
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138 | int currentResultCount;
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139 | ThreadEngine<T> *threadEngine;
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140 | QVector<T> vector;
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141 | };
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142 |
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143 | template <>
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144 | class ResultReporter<void>
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145 | {
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146 | public:
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147 | inline ResultReporter(ThreadEngine<void> *) { }
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148 | inline void reserveSpace(int) { };
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149 | inline void reportResults(int) { };
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150 | inline void * getPointer() { return 0; }
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151 | };
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