diff options
Diffstat (limited to 'src/corelib/thread/qsemaphore.cpp')
| -rw-r--r-- | src/corelib/thread/qsemaphore.cpp | 39 |
1 files changed, 6 insertions, 33 deletions
diff --git a/src/corelib/thread/qsemaphore.cpp b/src/corelib/thread/qsemaphore.cpp index 74e0746f43..aa04fb10ff 100644 --- a/src/corelib/thread/qsemaphore.cpp +++ b/src/corelib/thread/qsemaphore.cpp @@ -39,8 +39,6 @@ ****************************************************************************/ #include "qsemaphore.h" - -#ifndef QT_NO_THREAD #include "qmutex.h" #include "qfutex_p.h" #include "qwaitcondition.h" @@ -487,11 +485,9 @@ bool QSemaphore::tryAcquire(int n, int timeout) QDeadlineTimer timer(timeout); QMutexLocker locker(&d->mutex); - qint64 remainingTime = timer.remainingTime(); - while (n > d->avail && remainingTime != 0) { - if (!d->cond.wait(locker.mutex(), remainingTime)) + while (n > d->avail && !timer.hasExpired()) { + if (!d->cond.wait(locker.mutex(), timer)) return false; - remainingTime = timer.remainingTime(); } if (n > d->avail) return false; @@ -519,10 +515,7 @@ bool QSemaphore::tryAcquire(int n, int timeout) You can use this to reliably release a semaphore to avoid dead-lock in the face of exceptions or early returns: - \code - // ... do something that may throw or return early - sem.release(); - \endcode + \snippet code/src_corelib_thread_qsemaphore.cpp 4 If an early return is taken or an exception is thrown before the \c{sem.release()} call is reached, the semaphore is not released, @@ -531,11 +524,7 @@ bool QSemaphore::tryAcquire(int n, int timeout) When using RAII instead: - \code - const QSemaphoreReleaser releaser(sem); - // ... do something that may throw or early return - // implicitly calls sem.release() here and at every other return in between - \endcode + \snippet code/src_corelib_thread_qsemaphore.cpp 5 this can no longer happen, because the compiler will make sure that the QSemaphoreReleaser destructor is always called, and therefore @@ -545,17 +534,7 @@ bool QSemaphore::tryAcquire(int n, int timeout) from functions to transfer responsibility for releasing a semaphore out of a function or a scope: - \code - { // some scope - QSemaphoreReleaser releaser; // does nothing - // ... - if (someCondition) { - releaser = QSemaphoreReleaser(sem); - // ... - } - // ... - } // conditionally calls sem.release(), depending on someCondition - \endcode + \snippet code/src_corelib_thread_qsemaphore.cpp 6 A QSemaphoreReleaser can be canceled by a call to cancel(). A canceled semaphore releaser will no longer call QSemaphore::release() in its @@ -639,14 +618,8 @@ bool QSemaphore::tryAcquire(int n, int timeout) To enable again, assign a new QSemaphoreReleaser: - \code - releaser.cancel(); // avoid releasing old semaphore() - releaser = QSemaphoreReleaser(sem, 42); - // now will call sem.release(42) when 'releaser' is destroyed - \endcode + \snippet code/src_corelib_thread_qsemaphore.cpp 7 */ QT_END_NAMESPACE - -#endif // QT_NO_THREAD |