QWriteLocker Class

The QWriteLocker class is a convenience class that simplifies locking and unlocking read-write locks for write access. More...

Header:	#include <QWriteLocker>
qmake:	QT += core

List of all members, including inherited members

Note: All functions in this class are thread-safe.

Public Functions

	QWriteLocker(QReadWriteLock *lock)
	~QWriteLocker()
QReadWriteLock *	readWriteLock() const
void	relock()
void	unlock()

Detailed Description

The QWriteLocker class is a convenience class that simplifies locking and unlocking read-write locks for write access.

The purpose of QWriteLocker (and QReadLocker) is to simplify QReadWriteLock locking and unlocking. Locking and unlocking statements or in exception handling code is error-prone and difficult to debug. QWriteLocker can be used in such situations to ensure that the state of the lock is always well-defined.

Here's an example that uses QWriteLocker to lock and unlock a read-write lock for writing:


  QReadWriteLock lock;

  void writeData(const QByteArray &data)
  {
      QWriteLocker locker(&lock);
      ...
  }

It is equivalent to the following code:


  QReadWriteLock lock;

  void writeData(const QByteArray &data)
  {
      lock.lockForWrite();
      ...
      lock.unlock();
  }

The QMutexLocker documentation shows examples where the use of a locker object greatly simplifies programming.

See also QReadLocker and QReadWriteLock.

Member Function Documentation

QWriteLocker::QWriteLocker(QReadWriteLock **lock*)

Constructs a QWriteLocker and locks lock for writing. The lock will be unlocked when the QWriteLocker is destroyed. If lock is zero, QWriteLocker does nothing.

See also QReadWriteLock::lockForWrite().

QWriteLocker::~QWriteLocker()

Destroys the QWriteLocker and unlocks the lock that was passed to the constructor.

See also QReadWriteLock::unlock().

QReadWriteLock *QWriteLocker::readWriteLock() const

Returns a pointer to the read-write lock that was passed to the constructor.

void QWriteLocker::relock()

Relocks an unlocked lock.

See also unlock().

void QWriteLocker::unlock()

Unlocks the lock associated with this locker.