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Diffstat (limited to 'src/concurrent/qtconcurrentiteratekernel.cpp')
| -rw-r--r-- | src/concurrent/qtconcurrentiteratekernel.cpp | 194 |
1 files changed, 194 insertions, 0 deletions
diff --git a/src/concurrent/qtconcurrentiteratekernel.cpp b/src/concurrent/qtconcurrentiteratekernel.cpp new file mode 100644 index 0000000000..b695805135 --- /dev/null +++ b/src/concurrent/qtconcurrentiteratekernel.cpp @@ -0,0 +1,194 @@ +/**************************************************************************** +** +** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies). +** Contact: http://www.qt-project.org/ +** +** This file is part of the QtCore module of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:LGPL$ +** GNU Lesser General Public License Usage +** 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. +** +** GNU General Public License Usage +** Alternatively, this file may be used under the terms of the GNU General +** Public License version 3.0 as published by the Free Software Foundation +** and appearing in the file LICENSE.GPL included in the packaging of this +** file. Please review the following information to ensure the GNU General +** Public License version 3.0 requirements will be met: +** http://www.gnu.org/copyleft/gpl.html. +** +** Other Usage +** Alternatively, this file may be used in accordance with the terms and +** conditions contained in a signed written agreement between you and Nokia. +** +** +** +** +** +** +** $QT_END_LICENSE$ +** +****************************************************************************/ + +#include "qtconcurrentiteratekernel.h" + +#if defined(Q_OS_MAC) +#include <mach/mach.h> +#include <mach/mach_time.h> +#include <unistd.h> +#elif defined(Q_OS_UNIX) +#if defined(Q_OS_HURD) +#include <sys/time.h> +#endif +#include <time.h> +#include <unistd.h> +#elif defined(Q_OS_WIN) +#include <qt_windows.h> +#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 + + // no clock_gettime(), fall back to wall time + struct timeval tv; + gettimeofday(&tv, 0); + return (tv.tv_sec * 1000000) + tv.tv_usec; +#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 |