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1 /**************************************************************************** |
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2 ** |
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3 ** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies). |
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4 ** All rights reserved. |
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5 ** Contact: Nokia Corporation (qt-info@nokia.com) |
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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 ** No Commercial Usage |
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11 ** This file contains pre-release code and may not be distributed. |
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12 ** You may use this file in accordance with the terms and conditions |
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13 ** contained in the Technology Preview License Agreement accompanying |
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14 ** this package. |
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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 ** If you have questions regarding the use of this file, please contact |
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29 ** Nokia at qt-info@nokia.com. |
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30 ** |
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31 ** |
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32 ** |
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33 ** |
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34 ** |
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35 ** |
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36 ** |
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37 ** |
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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 #include "qtconcurrentiteratekernel.h" |
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43 |
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44 #if defined(Q_OS_MAC) |
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45 #include <mach/mach.h> |
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46 #include <mach/mach_time.h> |
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47 #include <unistd.h> |
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48 #elif defined(Q_OS_UNIX) |
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49 #include <time.h> |
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50 #include <unistd.h> |
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51 #elif defined(Q_OS_WIN) |
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52 #include <qt_windows.h> |
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53 #endif |
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54 |
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55 #include "private/qfunctions_p.h" |
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56 |
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57 |
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58 #ifndef QT_NO_CONCURRENT |
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59 |
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60 QT_BEGIN_NAMESPACE |
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61 |
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62 enum { |
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63 TargetRatio = 100, |
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64 MedianSize = 7 |
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65 }; |
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66 |
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67 #if defined(Q_OS_MAC) |
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68 |
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69 static qint64 getticks() |
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70 { |
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71 return mach_absolute_time(); |
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72 } |
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73 |
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74 #elif defined(Q_OS_UNIX) |
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75 |
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76 |
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77 static qint64 getticks() |
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78 { |
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79 #if defined(_POSIX_TIMERS) && (_POSIX_TIMERS > 0) |
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80 clockid_t clockId; |
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81 |
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82 #ifndef _POSIX_THREAD_CPUTIME |
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83 clockId = CLOCK_REALTIME; |
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84 #elif (_POSIX_THREAD_CPUTIME-0 <= 0) |
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85 // if we don't have CLOCK_THREAD_CPUTIME_ID, we have to just use elapsed realtime instead |
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86 clockId = CLOCK_REALTIME; |
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87 |
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88 # if (_POSIX_THREAD_CPUTIME-0 == 0) |
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89 // detect availablility of CLOCK_THREAD_CPUTIME_ID |
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90 static long useThreadCpuTime = -2; |
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91 if (useThreadCpuTime == -2) { |
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92 // sysconf() will return either -1 or _POSIX_VERSION (don't care about thread races here) |
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93 useThreadCpuTime = sysconf(_SC_THREAD_CPUTIME); |
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94 } |
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95 if (useThreadCpuTime != -1) |
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96 clockId = CLOCK_THREAD_CPUTIME_ID; |
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97 # endif |
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98 #else |
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99 clockId = CLOCK_THREAD_CPUTIME_ID; |
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100 #endif |
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101 |
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102 struct timespec ts; |
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103 if (clock_gettime(clockId, &ts) == -1) |
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104 return 0; |
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105 return (ts.tv_sec * 1000000000) + ts.tv_nsec; |
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106 #else |
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107 |
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108 #ifdef Q_OS_SYMBIAN |
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109 return clock(); |
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110 #else |
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111 // no clock_gettime(), fall back to wall time |
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112 struct timeval tv; |
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113 gettimeofday(&tv, 0); |
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114 return (tv.tv_sec * 1000000) + tv.tv_usec; |
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115 #endif |
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116 |
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117 #endif |
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118 } |
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119 |
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120 #elif defined(Q_OS_WIN) |
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121 |
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122 static qint64 getticks() |
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123 { |
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124 LARGE_INTEGER x; |
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125 if (!QueryPerformanceCounter(&x)) |
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126 return 0; |
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127 return x.QuadPart; |
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128 } |
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129 |
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130 #endif |
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131 |
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132 static double elapsed(qint64 after, qint64 before) |
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133 { |
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134 return double(after - before); |
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135 } |
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136 |
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137 namespace QtConcurrent { |
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138 |
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139 /*! \internal |
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140 |
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141 */ |
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142 BlockSizeManager::BlockSizeManager(int iterationCount) |
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143 : maxBlockSize(iterationCount / (QThreadPool::globalInstance()->maxThreadCount() * 2)), |
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144 beforeUser(0), afterUser(0), |
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145 controlPartElapsed(MedianSize), userPartElapsed(MedianSize), |
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146 m_blockSize(1) |
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147 { } |
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148 |
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149 // Records the time before user code. |
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150 void BlockSizeManager::timeBeforeUser() |
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151 { |
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152 if (blockSizeMaxed()) |
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153 return; |
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154 |
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155 beforeUser = getticks(); |
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156 controlPartElapsed.addValue(elapsed(beforeUser, afterUser)); |
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157 } |
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158 |
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159 // Records the time after user code and adjust the block size if we are spending |
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160 // to much time in the for control code compared with the user code. |
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161 void BlockSizeManager::timeAfterUser() |
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162 { |
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163 if (blockSizeMaxed()) |
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164 return; |
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165 |
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166 afterUser = getticks(); |
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167 userPartElapsed.addValue(elapsed(afterUser, beforeUser)); |
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168 |
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169 if (controlPartElapsed.isMedianValid() == false) |
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170 return; |
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171 |
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172 if (controlPartElapsed.median() * TargetRatio < userPartElapsed.median()) |
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173 return; |
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174 |
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175 m_blockSize = qMin(m_blockSize * 2, maxBlockSize); |
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176 |
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177 #ifdef QTCONCURRENT_FOR_DEBUG |
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178 qDebug() << QThread::currentThread() << "adjusting block size" << controlPartElapsed.median() << userPartElapsed.median() << m_blockSize; |
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179 #endif |
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180 |
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181 // Reset the medians after adjusting the block size so we get |
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182 // new measurements with the new block size. |
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183 controlPartElapsed.reset(); |
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184 userPartElapsed.reset(); |
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185 } |
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186 |
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187 int BlockSizeManager::blockSize() |
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188 { |
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189 return m_blockSize; |
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190 } |
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191 |
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192 } // namespace QtConcurrent |
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193 |
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194 QT_END_NAMESPACE |
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195 |
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196 #endif // QT_NO_CONCURRENT |