Revision control
++ // Copyright (C) 2016 The Qt Company Ltd.
++ // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
++ // Qt-Security score:significant reason:default
++
++ #include "qtconcurrentiteratekernel.h"
++
++ #include <qdeadlinetimer.h>
++ #include "private/qfunctions_p.h"
++
++
++ #if !defined(QT_NO_CONCURRENT) || defined(Q_QDOC)
++
++ QT_BEGIN_NAMESPACE
++
++ enum {
++ TargetRatio = 100
++ };
++
++ static qint64 getticks()
++ {
++ return QDeadlineTimer::current(Qt::PreciseTimer).deadlineNSecs();
++ }
++
++ static double elapsed(qint64 after, qint64 before)
++ {
++ return double(after - before);
++ }
++
++ namespace QtConcurrent {
++
++ /*!
++ \class QtConcurrent::Median
++ \inmodule QtConcurrent
++ \internal
++ */
++
++ /*!
++ \class QtConcurrent::BlockSizeManager
++ \inmodule QtConcurrent
++ \internal
++ */
++
++ /*!
++ \class QtConcurrent::ResultReporter
++ \inmodule QtConcurrent
++ \internal
++ */
++
++ /*! \fn bool QtConcurrent::selectIteration(std::bidirectional_iterator_tag)
++ \internal
++ */
++
++ /*! \fn bool QtConcurrent::selectIteration(std::forward_iterator_tag)
++ \internal
++ */
++
++ /*! \fn bool QtConcurrent::selectIteration(std::random_access_iterator_tag)
++ \internal
++ */
++
++ /*!
++ \class QtConcurrent::IterateKernel
++ \inmodule QtConcurrent
++ \internal
++ */
++
++ /*! \internal
++
++ */
++ BlockSizeManager::BlockSizeManager(QThreadPool *pool, int iterationCount)
++ : maxBlockSize(iterationCount / (std::max(pool->maxThreadCount(), 1) * 2)),
++ beforeUser(0), afterUser(0),
++ 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() * int(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