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QReadLocker Class Reference
^{[QtCore module]}

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

 #include <QReadLocker>

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

• List of all members, including inherited members

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()
 {
     locker.lockForRead();
     ...
     locker.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.

See also QReadWriteLock::unlock().