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/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or (at your option) the GNU General
** Public license version 3 or any later version approved by the KDE Free
** Qt Foundation. The licenses are as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-2.0.html and
** https://www.gnu.org/licenses/gpl-3.0.html.
**
** $QT_END_LICENSE$
**
****************************************************************************/
#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 QBasicAtomicInt sUseThreadCpuTime = Q_BASIC_ATOMIC_INITIALIZER(-2);
int useThreadCpuTime = sUseThreadCpuTime.load();
if (useThreadCpuTime == -2) {
// sysconf() will return either -1L or _POSIX_VERSION
// (don't care about sysconf's exact return value)
useThreadCpuTime = sysconf(_SC_THREAD_CPUTIME) == -1L ? -1 : 0 ;
sUseThreadCpuTime.store(useThreadCpuTime); // might happen multiple times, but doesn't matter
}
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
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