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// Copyright (C) 2017 Intel Corporation.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
#ifndef QFUTEX_P_H
#define QFUTEX_P_H
//
// W A R N I N G
// -------------
//
// This file is not part of the Qt API. It exists purely as an
// implementation detail. This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
//
#include <private/qglobal_p.h>
#include <QtCore/qtsan_impl.h>
QT_BEGIN_NAMESPACE
namespace QtDummyFutex {
constexpr inline bool futexAvailable() { return false; }
template <typename Atomic>
inline bool futexWait(Atomic &, typename Atomic::Type, int = 0)
{ Q_UNREACHABLE(); return false; }
template <typename Atomic> inline void futexWakeOne(Atomic &)
{ Q_UNREACHABLE(); }
template <typename Atomic> inline void futexWakeAll(Atomic &)
{ Q_UNREACHABLE(); }
}
QT_END_NAMESPACE
#if defined(Q_OS_LINUX) && !defined(QT_LINUXBASE)
// use Linux mutexes everywhere except for LSB builds
# include <sys/syscall.h>
# include <errno.h>
# include <limits.h>
# include <unistd.h>
# include <asm/unistd.h>
# include <linux/futex.h>
# define QT_ALWAYS_USE_FUTEX
// if not defined in linux/futex.h
# define FUTEX_PRIVATE_FLAG 128 // added in v2.6.22
// RISC-V does not supply __NR_futex
# ifndef __NR_futex
# define __NR_futex __NR_futex_time64
# endif
QT_BEGIN_NAMESPACE
namespace QtLinuxFutex {
constexpr inline bool futexAvailable() { return true; }
inline int _q_futex(int *addr, int op, int val, quintptr val2 = 0,
int *addr2 = nullptr, int val3 = 0) noexcept
{
QtTsan::futexRelease(addr, addr2);
// we use __NR_futex because some libcs (like Android's bionic) don't
// provide SYS_futex etc.
int result = syscall(__NR_futex, addr, op | FUTEX_PRIVATE_FLAG, val, val2, addr2, val3);
QtTsan::futexAcquire(addr, addr2);
return result;
}
template <typename T> int *addr(T *ptr)
{
int *int_addr = reinterpret_cast<int *>(ptr);
#if Q_BYTE_ORDER == Q_BIG_ENDIAN
if (sizeof(T) > sizeof(int))
int_addr++; //We want a pointer to the least significant half
#endif
return int_addr;
}
template <typename Atomic>
inline void futexWait(Atomic &futex, typename Atomic::Type expectedValue)
{
_q_futex(addr(&futex), FUTEX_WAIT, qintptr(expectedValue));
}
template <typename Atomic>
inline bool futexWait(Atomic &futex, typename Atomic::Type expectedValue, qint64 nstimeout)
{
struct timespec ts;
ts.tv_sec = nstimeout / 1000 / 1000 / 1000;
ts.tv_nsec = nstimeout % (1000 * 1000 * 1000);
int r = _q_futex(addr(&futex), FUTEX_WAIT, qintptr(expectedValue), quintptr(&ts));
return r == 0 || errno != ETIMEDOUT;
}
template <typename Atomic> inline void futexWakeOne(Atomic &futex)
{
_q_futex(addr(&futex), FUTEX_WAKE, 1);
}
template <typename Atomic> inline void futexWakeAll(Atomic &futex)
{
_q_futex(addr(&futex), FUTEX_WAKE, INT_MAX);
}
template <typename Atomic> inline
void futexWakeOp(Atomic &futex1, int wake1, int wake2, Atomic &futex2, quint32 op)
{
_q_futex(addr(&futex1), FUTEX_WAKE_OP, wake1, wake2, addr(&futex2), op);
}
}
namespace QtFutex = QtLinuxFutex;
QT_END_NAMESPACE
#elif defined(Q_OS_WIN)
# include <qt_windows.h>
QT_BEGIN_NAMESPACE
namespace QtWindowsFutex {
#define QT_ALWAYS_USE_FUTEX
constexpr inline bool futexAvailable() { return true; }
template <typename Atomic>
inline void futexWait(Atomic &futex, typename Atomic::Type expectedValue)
{
QtTsan::futexRelease(&futex);
WaitOnAddress(&futex, &expectedValue, sizeof(expectedValue), INFINITE);
QtTsan::futexAcquire(&futex);
}
template <typename Atomic>
inline bool futexWait(Atomic &futex, typename Atomic::Type expectedValue, qint64 nstimeout)
{
BOOL r = WaitOnAddress(&futex, &expectedValue, sizeof(expectedValue), DWORD(nstimeout / 1000 / 1000));
return r || GetLastError() != ERROR_TIMEOUT;
}
template <typename Atomic> inline void futexWakeAll(Atomic &futex)
{
WakeByAddressAll(&futex);
}
template <typename Atomic> inline void futexWakeOne(Atomic &futex)
{
WakeByAddressSingle(&futex);
}
}
namespace QtFutex = QtWindowsFutex;
QT_END_NAMESPACE
#else
QT_BEGIN_NAMESPACE
namespace QtFutex = QtDummyFutex;
QT_END_NAMESPACE
#endif
#endif // QFUTEX_P_H
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