QReadLocker

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

Synopsis

Functions

• def __enter__ ()

• def __exit__ (arg__1, arg__2, arg__3)

• def readWriteLock ()

• def relock ()

• def unlock ()

Detailed Description

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:

lock = QReadWriteLock()

def readData():
    locker = QReadLocker(lock)
    # ...
    return data

It is equivalent to the following code:

lock = QReadWriteLock()

def 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 QReadWriteLock

class PySide2.QtCore.QReadLocker(readWriteLock)

param readWriteLock:

PySide2.QtCore.QReadWriteLock

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

lockForRead()

PySide2.QtCore.QReadLocker.__enter__()

PySide2.QtCore.QReadLocker.__exit__(arg__1, arg__2, arg__3)

Parameters:

• arg__1 – object

• arg__2 – object

• arg__3 – object

PySide2.QtCore.QReadLocker.readWriteLock()

Return type:

PySide2.QtCore.QReadWriteLock

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

PySide2.QtCore.QReadLocker.relock()

Relocks an unlocked lock.

See also

unlock()

PySide2.QtCore.QReadLocker.unlock()

Unlocks the lock associated with this locker.

See also

unlock()