QReadLocker Class

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

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

List of all members, including inherited members

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

Public Functions

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

Detailed Description

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

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

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


  QReadWriteLock lock;

  QByteArray readData()
  {
      QReadLocker locker(&lock);
      ...
      return data;
  }

It is equivalent to the following code:


  QReadWriteLock lock;

  QByteArray readData()
  {
      lock.lockForRead();
      ...
      lock.unlock();
      return data;
  }

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

See also QWriteLocker and QReadWriteLock.

Member Function Documentation

QReadLocker::QReadLocker(QReadWriteLock **lock*)

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

See also QReadWriteLock::lockForRead().

QReadLocker::~QReadLocker()

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

See also QReadWriteLock::unlock().

QReadWriteLock *QReadLocker::readWriteLock() const

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

void QReadLocker::relock()

Relocks an unlocked lock.

See also unlock().

void QReadLocker::unlock()

Unlocks the lock associated with this locker.