Subgroup: Read

Class: QgsReadWriteLocker

class qgis.core.QgsReadWriteLocker(lock: QReadWriteLock, mode: QgsReadWriteLocker.Mode)

Bases: sip.wrapper

Create a new QgsReadWriteLocker for lock and initialize in mode.

QgsReadWriteLocker(QgsReadWriteLocker)

The QgsReadWriteLocker class is a convenience class that simplifies locking and unlocking QReadWriteLocks.

Locking and unlocking a QReadWriteLocks in complex functions and statements or in exception handling code is error-prone and difficult to debug. QgsReadWriteLocker can be used in such situations to ensure that the state of the lock is always well-defined.

QgsReadWriteLocker should be created within a function where a QReadWriteLock needs to be locked. The lock may be locked when QgsReadWriteLocker is created or when changeMode is called. You can unlock and relock the lock with unlock() and changeMode(). If locked, the lock will be unlocked when the QgsReadWriteLocker is destroyed.

New in version 3.4: Methods

changeMode Change the mode of the lock to mode.
unlock Unlocks the lock.

Signals

Attributes

Read
Unlocked
Write
class Mode

Bases: int

Read = 0
Unlocked = 2
Write = 1
changeMode(self, mode: QgsReadWriteLocker.Mode)

Change the mode of the lock to mode. The lock will be unlocked and relocked as required.

unlock(self)

Unlocks the lock. Equivalent to doing changeMode( QgsReadWriteLocker.Unlock );