In no particular order:
* Clean up #includes.
* Document what is protected by the mutex.
* Use explicit, nullptr.
* Use lock managers, not manual calls to lock/unlock.
* Unlock the mutex before notifying the condition variables.
* Condition variables are always meant to be used in a while loop, and
never with a plain if, because of spurious wakeups.
* Don't lock a mutex just to protect a plain integer. We have atomics
for that use case.
* Remove an unneeded signal, therefore also the need of using
Q_OBJECT and the inclusion of the moc-generated file.
Pick-to: 5.15 6.2 6.4
Fixes: QTBUG-108860
Change-Id: I2afc77955b95de8aa5fb88048cd9feb217f83b4f
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
3a449bbb69