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| |
| #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 <qglobal.h> |
| |
| QT_BEGIN_NAMESPACE |
| |
| namespace QtDummyFutex { |
| Q_DECL_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 |
| |
| # if __has_feature(thread_sanitizer) || defined(__SANITIZE_THREAD__) |
| # include <sanitizer/tsan_interface.h> |
| inline void _q_tsan_acquire(void *addr, void *addr2) |
| { |
| __tsan_acquire(addr); |
| if (addr2) |
| __tsan_acquire(addr2); |
| } |
| inline void _q_tsan_release(void *addr, void *addr2) |
| { |
| if (addr2) |
| __tsan_release(addr2); |
| __tsan_release(addr); |
| } |
| # else |
| inline void _q_tsan_acquire(void *, void *) {} |
| inline void _q_tsan_release(void *, void *) {} |
| # endif // __has_feature(thread_sanitizer) || defined(__SANITIZE_THREAD__) |
| |
| 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 |
| { |
| // A futex call ensures total ordering on the futex words |
| // (in either success or failure of the call). Instruct TSAN accordingly, |
| // as TSAN does not understand the futex(2) syscall. |
| _q_tsan_release(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); |
| |
| _q_tsan_acquire(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 |
| |
| #else |
| |
| QT_BEGIN_NAMESPACE |
| namespace QtFutex = QtDummyFutex; |
| QT_END_NAMESPACE |
| #endif |
| |
| #endif // QFUTEX_P_H |