CODEWITHSUNDEEP
multithreadingmfccritical-section
mapples
mapples

Reputation: 23

How to use CriticalSection - MFC?

I' am working on a small example and am a bit of curious using criticalsection in my example. What I'am doing is,I have a CStringArray(which has 10 elements added to it).I want to copy these 10 elements(string) to another CStringArray(am doing this to understand threading and Critical section),I have created 2 threads,Thread1 will copy the first 5 element to another CStringArray and Thread2 will copy the rest.Here two CStringArray are being used,I know only 1 thread can access it at a time.I wanted to know how this can be solved by using criticalsection or any other method.

void CThreadingEx4Dlg::OnBnClickedOk()
{
    // TODO: Add your control notification handler code here
    thread1 = AfxBeginThread((AFX_THREADPROC)MyThreadFunction1,this);
    thread2 = AfxBeginThread((AFX_THREADPROC)MyThreadFunction2,this);
}
UINT MyThreadFunction1(LPARAM lparam)
{
    CThreadingEx4Dlg* pthis = (CThreadingEx4Dlg*)lparam;

    pthis->MyFunction(0,5);
    return 0;
}
UINT MyThreadFunction2(LPARAM lparam)
{
    CThreadingEx4Dlg* pthis = (CThreadingEx4Dlg*)lparam;
    pthis->MyFunction(6,10);
    return 0;
}

void CThreadingEx4Dlg::MyFunction(int minCount,int maxCount)
{
    for(int i=minCount;i<=maxCount;i++)
    {
        CString temp;
        temp = myArray.GetAt(i);
        myShiftArray.Add(temp);
    }
}

Upvotes: 2

Views: 5077

Answers (2)

Vigdis
Vigdis

Reputation: 21

Consider using CSingleLock so that the constructor takes care of the locking and the destructor automatically takes care of the unlocking

void CThreadingEx4Dlg::MyFunction(int minCount,int maxCount)
{
    CSingleLock myLock(&m_CriticalSection, TRUE);

    // do work here.

    // The critical section will be unlocked when myLock goes out of scope
}

Upvotes: 1

Slauma
Slauma

Reputation: 177163

The way I'd use a CriticalSection is:

  • Declare a member variable in your CThreadingEx4Dlg class:

    CCriticalSection m_CriticalSection;

  • Enclose your not thread safe code in a Lock-Unlock block of this CriticalSection:

    void CThreadingEx4Dlg::MyFunction(int minCount,int maxCount)
{
    m_CriticalSection.Lock();
    for(int i=minCount;i<=maxCount;i++)
        myShiftArray.Add(myArray.GetAt(i));
    m_CriticalSection.Unlock();
}

Upvotes: 2

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