QReadLocker

Synopsis

Functions

• def __enter__ ()
• def __exit__ (arg__1, arg__2, arg__3)
• def readWriteLock ()
• def relock ()
• def unlock ()

Detailed Description

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

The purpose of PySide.QtCore.QReadLocker (and PySide.QtCore.QWriteLocker ) is to simplify PySide.QtCore.QReadWriteLock locking and unlocking. Locking and unlocking statements or in exception handling code is error-prone and difficult to debug. PySide.QtCore.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 PySide.QtCore.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 PySide.QtCore.QMutexLocker documentation shows examples where the use of a locker object greatly simplifies programming.

See also

PySide.QtCore.QWriteLocker PySide.QtCore.QReadWriteLock

class PySide.QtCore.QReadLocker(readWriteLock)

Parameters:readWriteLock – PySide.QtCore.QReadWriteLock

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

See also

QReadWriteLock.lockForRead()

PySide.QtCore.QReadLocker.__enter__()

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

Parameters:

• arg__1 – PyObject
• arg__2 – PyObject
• arg__3 – PyObject

PySide.QtCore.QReadLocker.readWriteLock()

Return type:PySide.QtCore.QReadWriteLock

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

PySide.QtCore.QReadLocker.relock()

Relocks an unlocked lock.

See also

PySide.QtCore.QReadLocker.unlock()

PySide.QtCore.QReadLocker.unlock()

Unlocks the lock associated with this locker.

See also

QReadWriteLock.unlock()