The QRecursiveMutex class provides access serialization between threads. More...
| Header: | #include <QRecursiveMutex> |
| CMake: | find_package(Qt6 REQUIRED COMPONENTS Core) target_link_libraries(mytarget PRIVATE Qt6::Core) |
| qmake: | QT += core |
| Since: | Qt 5.14 |
Note: All functions in this class are thread-safe.
| QRecursiveMutex() | |
| ~QRecursiveMutex() | |
| void | lock() |
| bool | tryLock(int timeout = 0) |
| bool | try_lock() |
| bool | try_lock_for(std::chrono::duration<Rep, Period> duration) |
| bool | try_lock_until(std::chrono::time_point<Clock, Duration> timePoint) |
| void | unlock() |
The QRecursiveMutex class is a mutex, like QMutex, with which it is API-compatible. It differs from QMutex by accepting lock() calls from the same thread any number of times. QMutex would deadlock in this situation.
QRecursiveMutex is much more expensive to construct and operate on, so use a plain QMutex whenever you can. Sometimes, one public function, however, calls another public function, and they both need to lock the same mutex. In this case, you have two options:
See also QMutex, QMutexLocker, QReadWriteLock, QSemaphore, and QWaitCondition.
Constructs a new recursive mutex. The mutex is created in an unlocked state.
Destroys the mutex.
Warning: Destroying a locked mutex may result in undefined behavior.
Locks the mutex. If another thread has locked the mutex then this call will block until that thread has unlocked it.
Calling this function multiple times on the same mutex from the same thread is allowed.
See also unlock().
Attempts to lock the mutex. This function returns true if the lock was obtained; otherwise it returns false. If another thread has locked the mutex, this function will wait for at most
timeout milliseconds for the mutex to become available.
Note: Passing a negative number as the timeout is equivalent to calling lock(), i.e. this function will wait forever until mutex can be locked if timeout is negative.
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.
[since 5.8] bool QRecursiveMutex::try_lock()Attempts to lock the mutex. This function returns true if the lock was obtained; otherwise it returns false.
This function is provided for compatibility with the Standard Library concept Lockable. It is equivalent to tryLock().
This function was introduced in Qt 5.8.
[since 5.8] template <typename Rep, typename Period> bool QRecursiveMutex::try_lock_for(std::chrono::duration<Rep, Period> duration)Attempts to lock the mutex. This function returns true if the lock was obtained; otherwise it returns false. If another thread has locked the mutex, this function will wait for at least
duration for the mutex to become available.
Note: Passing a negative duration as the duration is equivalent to calling try_lock(). This behavior differs from tryLock().
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.
This function was introduced in Qt 5.8.
[since 5.8] template <typename Clock, typename Duration> bool QRecursiveMutex::try_lock_until(std::chrono::time_point<Clock, Duration> timePoint)Attempts to lock the mutex. This function returns true if the lock was obtained; otherwise it returns false. If another thread has locked the mutex, this function will wait at least until
timePoint for the mutex to become available.
Note: Passing a timePoint which has already passed is equivalent to calling try_lock(). This behavior differs from tryLock().
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.
This function was introduced in Qt 5.8.
Unlocks the mutex. Attempting to unlock a mutex in a different thread to the one that locked it results in an error. Unlocking a mutex that is not locked results in undefined behavior.
See also lock().
