On Friday, 23 August 2019 10:31:20 CEST Mutz, Marc via Development wrote: > On 2019-05-29 12:53, Mutz, Marc via Development wrote: > > === QWaitCondition -> std::condition_variable(_any) === > > > > Plumbing that std::condition_variable can do better. > > So, I've looked at QWaitCondition because I had a need to call wait() > with a QBasicMutex instead of a QMutex, and that doesn't exist, yet. I > was surprised about what I saw, so I have to ask: > > Do I understand it correctly that the implementation of QWaitCondition > has _another_ mutex inside?! So, two mutexes? The one users pass in and > then the one that QWaitCondition uses internally, because it's > pthread_cond and that needs pthread_mutex? > > If that's the case, shouldn't we run, not walk, to replace our internal > uses with std::mutex + std::condition_variable to have only one mutex? > https://code.woboq.org/gcc/libstdc++-v3/include/std/ condition_variable.html#std::_V2::condition_variable_any::_M_mutex
The std::conditional_variable has the same problem QWaitCondition has. No mutex is passed on construction or to the wake methods, so a second mutex is needed to protect waking/notifying. There is no other way with that API design. 'Allan _______________________________________________ Development mailing list Development@qt-project.org https://lists.qt-project.org/listinfo/development
