/**************************************************************************** ** ** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies). ** Contact: Nokia Corporation (qt-info@nokia.com) ** ** This file is part of the QtCore 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 "qtconcurrentiteratekernel.h" #if defined(Q_OS_MAC) #include #include #include #elif defined(Q_OS_UNIX) #include #include #elif defined(Q_OS_WIN) #include #endif #include "private/qfunctions_p.h" #ifndef QT_NO_CONCURRENT QT_BEGIN_NAMESPACE enum { TargetRatio = 100, MedianSize = 7 }; #if defined(Q_OS_MAC) static qint64 getticks() { return mach_absolute_time(); } #elif defined(Q_OS_UNIX) static qint64 getticks() { #if defined(_POSIX_TIMERS) && (_POSIX_TIMERS > 0) clockid_t clockId; #ifndef _POSIX_THREAD_CPUTIME clockId = CLOCK_REALTIME; #elif (_POSIX_THREAD_CPUTIME-0 <= 0) // if we don't have CLOCK_THREAD_CPUTIME_ID, we have to just use elapsed realtime instead clockId = CLOCK_REALTIME; # if (_POSIX_THREAD_CPUTIME-0 == 0) // detect availablility of CLOCK_THREAD_CPUTIME_ID static long useThreadCpuTime = -2; if (useThreadCpuTime == -2) { // sysconf() will return either -1 or _POSIX_VERSION (don't care about thread races here) useThreadCpuTime = sysconf(_SC_THREAD_CPUTIME); } if (useThreadCpuTime != -1) clockId = CLOCK_THREAD_CPUTIME_ID; # endif #else clockId = CLOCK_THREAD_CPUTIME_ID; #endif struct timespec ts; if (clock_gettime(clockId, &ts) == -1) return 0; return (ts.tv_sec * 1000000000) + ts.tv_nsec; #else #ifdef Q_OS_SYMBIAN return clock(); #else // no clock_gettime(), fall back to wall time struct timeval tv; gettimeofday(&tv, 0); return (tv.tv_sec * 1000000) + tv.tv_usec; #endif #endif } #elif defined(Q_OS_WIN) static qint64 getticks() { LARGE_INTEGER x; if (!QueryPerformanceCounter(&x)) return 0; return x.QuadPart; } #endif static double elapsed(qint64 after, qint64 before) { return double(after - before); } namespace QtConcurrent { /*! \internal */ BlockSizeManager::BlockSizeManager(int iterationCount) : maxBlockSize(iterationCount / (QThreadPool::globalInstance()->maxThreadCount() * 2)), beforeUser(0), afterUser(0), controlPartElapsed(MedianSize), userPartElapsed(MedianSize), m_blockSize(1) { } // Records the time before user code. void BlockSizeManager::timeBeforeUser() { if (blockSizeMaxed()) return; beforeUser = getticks(); controlPartElapsed.addValue(elapsed(beforeUser, afterUser)); } // Records the time after user code and adjust the block size if we are spending // to much time in the for control code compared with the user code. void BlockSizeManager::timeAfterUser() { if (blockSizeMaxed()) return; afterUser = getticks(); userPartElapsed.addValue(elapsed(afterUser, beforeUser)); if (controlPartElapsed.isMedianValid() == false) return; if (controlPartElapsed.median() * TargetRatio < userPartElapsed.median()) return; m_blockSize = qMin(m_blockSize * 2, maxBlockSize); #ifdef QTCONCURRENT_FOR_DEBUG qDebug() << QThread::currentThread() << "adjusting block size" << controlPartElapsed.median() << userPartElapsed.median() << m_blockSize; #endif // Reset the medians after adjusting the block size so we get // new measurements with the new block size. controlPartElapsed.reset(); userPartElapsed.reset(); } int BlockSizeManager::blockSize() { return m_blockSize; } } // namespace QtConcurrent QT_END_NAMESPACE #endif // QT_NO_CONCURRENT