diff options
Diffstat (limited to 'src/corelib/thread/qmutex.cpp')
| -rw-r--r-- | src/corelib/thread/qmutex.cpp | 81 |
1 files changed, 61 insertions, 20 deletions
diff --git a/src/corelib/thread/qmutex.cpp b/src/corelib/thread/qmutex.cpp index fb15606ec0..ec6c711a4f 100644 --- a/src/corelib/thread/qmutex.cpp +++ b/src/corelib/thread/qmutex.cpp @@ -8,7 +8,6 @@ #include "qmutex.h" #include <qdebug.h> #include "qatomic.h" -#include "qelapsedtimer.h" #include "qfutex_p.h" #include "qthread.h" #include "qmutex_p.h" @@ -146,6 +145,23 @@ void QBasicMutex::destroyInternal(QMutexPrivate *d) \sa lock(), unlock() */ +/*! \fn bool QMutex::tryLock(QDeadlineTimer timer) + \since 6.6 + + Attempts to lock the mutex. This function returns \c true if the lock + was obtained; otherwise it returns \c false. If another thread has + locked the mutex, this function will wait until \a timer expires + for the mutex to become available. + + If the lock was obtained, the mutex must be unlocked with unlock() + before another thread can successfully lock it. + + Calling this function multiple times on the same mutex from the + same thread will cause a \e dead-lock. + + \sa lock(), unlock() +*/ + /*! \fn bool QMutex::tryLock() \overload @@ -279,6 +295,8 @@ QRecursiveMutex::~QRecursiveMutex() */ /*! + \fn QRecursiveMutex::tryLock(int timeout) + Attempts to lock the mutex. This function returns \c true if the lock was obtained; otherwise it returns \c false. If another thread has locked the mutex, this function will wait for at most \a timeout @@ -296,7 +314,24 @@ QRecursiveMutex::~QRecursiveMutex() \sa lock(), unlock() */ -bool QRecursiveMutex::tryLock(int timeout) QT_MUTEX_LOCK_NOEXCEPT + +/*! + \since 6.6 + + Attempts to lock the mutex. This function returns \c true if the lock + was obtained; otherwise it returns \c false. If another thread has + locked the mutex, this function will wait until \a timeout expires + for the mutex to become available. + + If the lock was obtained, the mutex must be unlocked with unlock() + before another thread can successfully lock it. + + Calling this function multiple times on the same mutex from the + same thread is allowed. + + \sa lock(), unlock() +*/ +bool QRecursiveMutex::tryLock(QDeadlineTimer timeout) QT_MUTEX_LOCK_NOEXCEPT { unsigned tsanFlags = QtTsan::MutexWriteReentrant | QtTsan::TryLock; QtTsan::mutexPreLock(this, tsanFlags); @@ -309,7 +344,7 @@ bool QRecursiveMutex::tryLock(int timeout) QT_MUTEX_LOCK_NOEXCEPT return true; } bool success = true; - if (timeout == -1) { + if (timeout.isForever()) { mutex.lock(); } else { success = mutex.tryLock(timeout); @@ -622,27 +657,38 @@ void QBasicMutex::lockInternal() QT_MUTEX_LOCK_NOEXCEPT /*! \internal helper for lock(int) */ +#if QT_VERSION < QT_VERSION_CHECK(7, 0, 0) bool QBasicMutex::lockInternal(int timeout) QT_MUTEX_LOCK_NOEXCEPT { if (timeout == 0) return false; + return lockInternal(QDeadlineTimer(timeout)); +} +#endif + +/*! + \internal helper for tryLock(QDeadlineTimer) + */ +bool QBasicMutex::lockInternal(QDeadlineTimer deadlineTimer) QT_MUTEX_LOCK_NOEXCEPT +{ + if (deadlineTimer.hasExpired()) + return false; + if (futexAvailable()) { - if (Q_UNLIKELY(timeout < 0)) { + if (Q_UNLIKELY(deadlineTimer.isForever())) { lockInternal(); return true; } - QDeadlineTimer deadlineTimer(timeout); // The mutex is already locked, set a bit indicating we're waiting. // Note we must set to dummyFutexValue because there could be other threads // also waiting. if (d_ptr.fetchAndStoreAcquire(dummyFutexValue()) == nullptr) return true; - qint64 remainingTime = deadlineTimer.remainingTimeNSecs(); - Q_FOREVER { - if (!futexWait(d_ptr, dummyFutexValue(), remainingTime)) + for (;;) { + if (!futexWait(d_ptr, dummyFutexValue(), deadlineTimer)) return false; // We got woken up, so must try to acquire the mutex. We must set @@ -651,9 +697,7 @@ bool QBasicMutex::lockInternal(int timeout) QT_MUTEX_LOCK_NOEXCEPT if (d_ptr.fetchAndStoreAcquire(dummyFutexValue()) == nullptr) return true; - // calculate the remaining time - remainingTime = deadlineTimer.remainingTimeNSecs(); - if (remainingTime <= 0) + if (deadlineTimer.hasExpired()) return false; } } @@ -665,7 +709,7 @@ bool QBasicMutex::lockInternal(int timeout) QT_MUTEX_LOCK_NOEXCEPT continue; if (copy == dummyLocked()) { - if (timeout == 0) + if (deadlineTimer.hasExpired()) return false; // The mutex is locked but does not have a QMutexPrivate yet. // we need to allocate a QMutexPrivate @@ -680,7 +724,7 @@ bool QBasicMutex::lockInternal(int timeout) QT_MUTEX_LOCK_NOEXCEPT } QMutexPrivate *d = static_cast<QMutexPrivate *>(copy); - if (timeout == 0 && !d->possiblyUnlocked.loadRelaxed()) + if (deadlineTimer.hasExpired() && !d->possiblyUnlocked.loadRelaxed()) return false; // At this point we have a pointer to a QMutexPrivate. But the other thread @@ -733,7 +777,7 @@ bool QBasicMutex::lockInternal(int timeout) QT_MUTEX_LOCK_NOEXCEPT continue; } - if (d->wait(timeout)) { + if (d->wait(deadlineTimer)) { // reset the possiblyUnlocked flag if needed (and deref its corresponding reference) if (d->possiblyUnlocked.loadRelaxed() && d->possiblyUnlocked.testAndSetRelaxed(true, false)) d->deref(); @@ -742,8 +786,7 @@ bool QBasicMutex::lockInternal(int timeout) QT_MUTEX_LOCK_NOEXCEPT Q_ASSERT(d == d_ptr.loadRelaxed()); return true; } else { - Q_ASSERT(timeout >= 0); - //timeout + // timed out d->derefWaiters(1); //There may be a race in which the mutex is unlocked right after we timed out, // and before we deref the waiters, so maybe the mutex is actually unlocked. @@ -865,12 +908,10 @@ void QMutexPrivate::derefWaiters(int value) noexcept QT_END_NAMESPACE -#if defined(Q_OS_LINUX) && defined(QT_ALWAYS_USE_FUTEX) +#if defined(QT_ALWAYS_USE_FUTEX) // nothing -#elif defined(Q_OS_MAC) +#elif defined(Q_OS_DARWIN) # include "qmutex_mac.cpp" -#elif defined(Q_OS_WIN) -# include "qmutex_win.cpp" #else # include "qmutex_unix.cpp" #endif |