203 lines
6.8 KiB
C++
203 lines
6.8 KiB
C++
/****************************************************************************
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**
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** Copyright (C) 2017 Intel Corporation.
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** Contact: https://www.qt.io/licensing/
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**
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** This file is part of the QtCore module of the Qt Toolkit.
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**
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** $QT_BEGIN_LICENSE:LGPL$
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** Commercial License Usage
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** Licensees holding valid commercial Qt licenses may use this file in
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** accordance with the commercial license agreement provided with the
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** Software or, alternatively, in accordance with the terms contained in
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** a written agreement between you and The Qt Company. For licensing terms
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** and conditions see https://www.qt.io/terms-conditions. For further
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** information use the contact form at https://www.qt.io/contact-us.
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**
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** GNU Lesser General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU Lesser
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** General Public License version 3 as published by the Free Software
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** Foundation and appearing in the file LICENSE.LGPL3 included in the
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** packaging of this file. Please review the following information to
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** ensure the GNU Lesser General Public License version 3 requirements
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** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
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**
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** GNU General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU
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** General Public License version 2.0 or (at your option) the GNU General
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** Public license version 3 or any later version approved by the KDE Free
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** Qt Foundation. The licenses are as published by the Free Software
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** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
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** included in the packaging of this file. Please review the following
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** information to ensure the GNU General Public License requirements will
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** be met: https://www.gnu.org/licenses/gpl-2.0.html and
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** https://www.gnu.org/licenses/gpl-3.0.html.
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**
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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#ifndef QFUTEX_P_H
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#define QFUTEX_P_H
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//
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// W A R N I N G
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// -------------
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//
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// This file is not part of the Qt API. It exists purely as an
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// implementation detail. This header file may change from version to
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// version without notice, or even be removed.
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//
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// We mean it.
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//
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#include <qglobal.h>
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#if (__has_feature(thread_sanitizer) || defined(__SANITIZE_THREAD__)) && __has_include(<sanitizer/tsan_interface.h>)
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# include <sanitizer/tsan_interface.h>
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inline void _q_tsan_acquire(void *addr, void *addr2 = nullptr)
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{
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// A futex call ensures total ordering on the futex words
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// (in either success or failure of the call). Instruct TSAN accordingly,
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// as TSAN does not understand the futex(2) syscall (or equivalent).
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__tsan_acquire(addr);
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if (addr2)
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__tsan_acquire(addr2);
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}
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inline void _q_tsan_release(void *addr, void *addr2 = nullptr)
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{
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if (addr2)
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__tsan_release(addr2);
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__tsan_release(addr);
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}
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#else
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inline void _q_tsan_acquire(void *, void * = nullptr) {}
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inline void _q_tsan_release(void *, void * = nullptr) {}
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#endif // building for TSAN and __has_include(<sanitizer/tsan_interface.h>)
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QT_BEGIN_NAMESPACE
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namespace QtDummyFutex {
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constexpr inline bool futexAvailable() { return false; }
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template <typename Atomic>
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inline bool futexWait(Atomic &, typename Atomic::Type, int = 0)
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{ Q_UNREACHABLE(); return false; }
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template <typename Atomic> inline void futexWakeOne(Atomic &)
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{ Q_UNREACHABLE(); }
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template <typename Atomic> inline void futexWakeAll(Atomic &)
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{ Q_UNREACHABLE(); }
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}
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QT_END_NAMESPACE
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#if defined(Q_OS_LINUX) && !defined(QT_LINUXBASE)
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// use Linux mutexes everywhere except for LSB builds
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# include <sys/syscall.h>
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# include <errno.h>
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# include <limits.h>
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# include <unistd.h>
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# include <asm/unistd.h>
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# include <linux/futex.h>
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# define QT_ALWAYS_USE_FUTEX
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// if not defined in linux/futex.h
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# define FUTEX_PRIVATE_FLAG 128 // added in v2.6.22
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QT_BEGIN_NAMESPACE
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namespace QtLinuxFutex {
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constexpr inline bool futexAvailable() { return true; }
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inline int _q_futex(int *addr, int op, int val, quintptr val2 = 0,
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int *addr2 = nullptr, int val3 = 0) noexcept
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{
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_q_tsan_release(addr, addr2);
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// we use __NR_futex because some libcs (like Android's bionic) don't
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// provide SYS_futex etc.
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int result = syscall(__NR_futex, addr, op | FUTEX_PRIVATE_FLAG, val, val2, addr2, val3);
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_q_tsan_acquire(addr, addr2);
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return result;
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}
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template <typename T> int *addr(T *ptr)
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{
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int *int_addr = reinterpret_cast<int *>(ptr);
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#if Q_BYTE_ORDER == Q_BIG_ENDIAN
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if (sizeof(T) > sizeof(int))
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int_addr++; //We want a pointer to the least significant half
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#endif
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return int_addr;
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}
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template <typename Atomic>
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inline void futexWait(Atomic &futex, typename Atomic::Type expectedValue)
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{
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_q_futex(addr(&futex), FUTEX_WAIT, qintptr(expectedValue));
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}
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template <typename Atomic>
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inline bool futexWait(Atomic &futex, typename Atomic::Type expectedValue, qint64 nstimeout)
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{
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struct timespec ts;
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ts.tv_sec = nstimeout / 1000 / 1000 / 1000;
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ts.tv_nsec = nstimeout % (1000 * 1000 * 1000);
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int r = _q_futex(addr(&futex), FUTEX_WAIT, qintptr(expectedValue), quintptr(&ts));
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return r == 0 || errno != ETIMEDOUT;
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}
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template <typename Atomic> inline void futexWakeOne(Atomic &futex)
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{
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_q_futex(addr(&futex), FUTEX_WAKE, 1);
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}
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template <typename Atomic> inline void futexWakeAll(Atomic &futex)
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{
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_q_futex(addr(&futex), FUTEX_WAKE, INT_MAX);
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}
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template <typename Atomic> inline
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void futexWakeOp(Atomic &futex1, int wake1, int wake2, Atomic &futex2, quint32 op)
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{
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_q_futex(addr(&futex1), FUTEX_WAKE_OP, wake1, wake2, addr(&futex2), op);
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}
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}
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namespace QtFutex = QtLinuxFutex;
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QT_END_NAMESPACE
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#elif defined(Q_OS_WIN)
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# include <qt_windows.h>
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QT_BEGIN_NAMESPACE
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namespace QtWindowsFutex {
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#define QT_ALWAYS_USE_FUTEX
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constexpr inline bool futexAvailable() { return true; }
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template <typename Atomic>
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inline void futexWait(Atomic &futex, typename Atomic::Type expectedValue)
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{
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_q_tsan_release(&futex);
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WaitOnAddress(&futex, &expectedValue, sizeof(expectedValue), INFINITE);
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_q_tsan_acquire(&futex);
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}
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template <typename Atomic>
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inline bool futexWait(Atomic &futex, typename Atomic::Type expectedValue, qint64 nstimeout)
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{
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BOOL r = WaitOnAddress(&futex, &expectedValue, sizeof(expectedValue), DWORD(nstimeout / 1000 / 1000));
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return r || GetLastError() != ERROR_TIMEOUT;
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}
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template <typename Atomic> inline void futexWakeAll(Atomic &futex)
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{
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WakeByAddressAll(&futex);
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}
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template <typename Atomic> inline void futexWakeOne(Atomic &futex)
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{
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WakeByAddressSingle(&futex);
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}
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}
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namespace QtFutex = QtWindowsFutex;
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QT_END_NAMESPACE
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#else
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QT_BEGIN_NAMESPACE
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namespace QtFutex = QtDummyFutex;
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QT_END_NAMESPACE
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#endif
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#endif // QFUTEX_P_H
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