QMutexLocker Class

template <typename MutexT> class QMutexLocker

The QMutexLocker class is a convenience class that simplifies locking and unlocking mutexes. More…

Header	`#include <QMutexLocker>`
CMake	`target_link_libraries(app PRIVATE Nt::Core)`
Module	Nt Core C++ Classes

List of all members, including inherited members

Public Functions

	QMutexLocker(MutexT *mtx)
	QMutexLocker(QMutexLocker &&o)
QMutexLocker &	operator=(QMutexLocker &&o)
void	swap(QMutexLocker &other)
	~QMutexLocker()
void	unlock()
void	relock()
MutexT *	mutex() const
bool	isLocked() const

Detailed Description

A QMutexLocker locks the mutex it is given when it is constructed and unlocks it when it is destroyed, so the mutex is released on every path out of a scope, including exceptions and early returns:

QMutex mutex;

int complexFunction(int flag)
{
    QMutexLocker locker(&mutex);
    if (flag < 0)
        return 0;
    return flag * 2;
}

The class works with any type that provides lock() and unlock(), such as QMutex and QRecursiveMutex. A QMutexLocker can be moved but not copied.

See also QMutex, QRecursiveMutex, QReadLocker and QWriteLocker.

Differences from Qt

A null pointer is accepted and results in a locker that never locks anything. The locker works with any type that has lock() and unlock(), not only the Nt mutex classes.

Member Function Documentation

[explicit] QMutexLocker::QMutexLocker(MutexT **mtx*)

Constructs a QMutexLocker and locks mtx. The mutex is unlocked when the locker is destroyed. If mtx is nullptr, the locker does nothing.

See also unlock().

QMutexLocker::QMutexLocker(QMutexLocker &&o)

Move-constructs a locker from o, taking over the mutex and its locked state. o no longer refers to a mutex afterwards.

QMutexLocker::~QMutexLocker()

Destroys the locker and unlocks the mutex if it is currently locked by this locker.

bool QMutexLocker::isLocked() const

Returns true if this locker currently holds the mutex; otherwise returns false.

See also unlock() and relock().

MutexT * QMutexLocker::mutex() const

Returns the mutex this locker operates on, or nullptr if there is none.

QMutexLocker & QMutexLocker::operator=(QMutexLocker &&o)

Move-assigns o to this locker. The mutex this locker held is unlocked first; then the locker takes over the mutex and locked state of o, which no longer refers to a mutex.

void QMutexLocker::relock()

Relocks the mutex after it was unlocked with unlock(). Does nothing if the mutex is already locked by this locker.