Non-Reentrant Class Use In Multithreaded Program

[kshegunov]

@Crag_Hack said in Non-Reentrant Class Use In Multithreaded Program:

I can check the std::atomic_bool cancel variable in the CopyFIleEx progress callback function and if it is true then return PROGRESS_CANCEL. Can you think of another way to do this though?

This sounds like a decent plan to me.

[Crag_Hack]

Will this code maintain the atomicity of the cancel variable? And should I declare cancel volatile? I'm guessing std:atomic_bool will make that unncecessary...

class Worker : public QObject
{
    bool getStop() { return cancel; }
    volatile std::atomic_bool cancel;
...
DWORD Worker::copyProgress(LARGE_INTEGER totalSize, LARGE_INTEGER totalTransferred, LARGE_INTEGER, LARGE_INTEGER, DWORD, DWORD, HANDLE, HANDLE, LPVOID data)
{
    Worker *worker = static_cast<Worker *>(data);
    if (worker->getStop())
        return PROGRESS_CANCEL;

[kshegunov]

@Crag_Hack said in Non-Reentrant Class Use In Multithreaded Program:

Will this code maintain the atomicity of the cancel variable?

Yes, of course.

And should I declare cancel volatile?

No, no reason to do that. Forget volatile, especially if you're not intimately familiar with what it does. It's very special and here there is no a proper reason to use it.

I'm guessing std:atomic_bool will make that unncecessary...

That is correct. volatile means something quite different anyway, it doesn't provide atomicity at all.

[Crag_Hack]

Thanks! Almost time to go live!