| 1 | // Copyright (C) 2016 The Qt Company Ltd. |
|---|---|
| 2 | // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only |
| 3 | |
| 4 | #include "qtconcurrentiteratekernel.h" |
| 5 | |
| 6 | #include <qdeadlinetimer.h> |
| 7 | #include "private/qfunctions_p.h" |
| 8 | |
| 9 | |
| 10 | #if !defined(QT_NO_CONCURRENT) || defined(Q_QDOC) |
| 11 | |
| 12 | QT_BEGIN_NAMESPACE |
| 13 | |
| 14 | enum { |
| 15 | TargetRatio = 100 |
| 16 | }; |
| 17 | |
| 18 | static qint64 getticks() |
| 19 | { |
| 20 | return QDeadlineTimer::current(timerType: Qt::PreciseTimer).deadlineNSecs(); |
| 21 | } |
| 22 | |
| 23 | static double elapsed(qint64 after, qint64 before) |
| 24 | { |
| 25 | return double(after - before); |
| 26 | } |
| 27 | |
| 28 | namespace QtConcurrent { |
| 29 | |
| 30 | /*! |
| 31 | \class QtConcurrent::Median |
| 32 | \inmodule QtConcurrent |
| 33 | \internal |
| 34 | */ |
| 35 | |
| 36 | /*! |
| 37 | \class QtConcurrent::BlockSizeManager |
| 38 | \inmodule QtConcurrent |
| 39 | \internal |
| 40 | */ |
| 41 | |
| 42 | /*! |
| 43 | \class QtConcurrent::ResultReporter |
| 44 | \inmodule QtConcurrent |
| 45 | \internal |
| 46 | */ |
| 47 | |
| 48 | /*! \fn bool QtConcurrent::selectIteration(std::bidirectional_iterator_tag) |
| 49 | \internal |
| 50 | */ |
| 51 | |
| 52 | /*! \fn bool QtConcurrent::selectIteration(std::forward_iterator_tag) |
| 53 | \internal |
| 54 | */ |
| 55 | |
| 56 | /*! \fn bool QtConcurrent::selectIteration(std::random_access_iterator_tag) |
| 57 | \internal |
| 58 | */ |
| 59 | |
| 60 | /*! |
| 61 | \class QtConcurrent::IterateKernel |
| 62 | \inmodule QtConcurrent |
| 63 | \internal |
| 64 | */ |
| 65 | |
| 66 | /*! \internal |
| 67 | |
| 68 | */ |
| 69 | BlockSizeManager::BlockSizeManager(QThreadPool *pool, int iterationCount) |
| 70 | : maxBlockSize(iterationCount / (pool->maxThreadCount() * 2)), |
| 71 | beforeUser(0), afterUser(0), |
| 72 | m_blockSize(1) |
| 73 | { } |
| 74 | |
| 75 | // Records the time before user code. |
| 76 | void BlockSizeManager::timeBeforeUser() |
| 77 | { |
| 78 | if (blockSizeMaxed()) |
| 79 | return; |
| 80 | |
| 81 | beforeUser = getticks(); |
| 82 | controlPartElapsed.addValue(value: elapsed(after: beforeUser, before: afterUser)); |
| 83 | } |
| 84 | |
| 85 | // Records the time after user code and adjust the block size if we are spending |
| 86 | // to much time in the for control code compared with the user code. |
| 87 | void BlockSizeManager::timeAfterUser() |
| 88 | { |
| 89 | if (blockSizeMaxed()) |
| 90 | return; |
| 91 | |
| 92 | afterUser = getticks(); |
| 93 | userPartElapsed.addValue(value: elapsed(after: afterUser, before: beforeUser)); |
| 94 | |
| 95 | if (controlPartElapsed.isMedianValid() == false) |
| 96 | return; |
| 97 | |
| 98 | if (controlPartElapsed.median() * int(TargetRatio) < userPartElapsed.median()) |
| 99 | return; |
| 100 | |
| 101 | m_blockSize = qMin(a: m_blockSize * 2, b: maxBlockSize); |
| 102 | |
| 103 | #ifdef QTCONCURRENT_FOR_DEBUG |
| 104 | qDebug() << QThread::currentThread() << "adjusting block size"<< controlPartElapsed.median() << userPartElapsed.median() << m_blockSize; |
| 105 | #endif |
| 106 | |
| 107 | // Reset the medians after adjusting the block size so we get |
| 108 | // new measurements with the new block size. |
| 109 | controlPartElapsed.reset(); |
| 110 | userPartElapsed.reset(); |
| 111 | } |
| 112 | |
| 113 | int BlockSizeManager::blockSize() |
| 114 | { |
| 115 | return m_blockSize; |
| 116 | } |
| 117 | |
| 118 | } // namespace QtConcurrent |
| 119 | |
| 120 | QT_END_NAMESPACE |
| 121 | |
| 122 | #endif // QT_NO_CONCURRENT |
| 123 |