端口扫描器之[1]多线程互斥

如果没有CriticalSection的话，就有很大的机会出现相同的值。

#include <iostream>
#include <stdio.h>
#include <windows.h>
#include <string>

int nShareVar = 0;

CRITICAL_SECTION gcs;

class HalfLock
{
public:
    HalfLock(CRITICAL_SECTION *gcs)
    {
        m_pSection = gcs;
    }
    ~HalfLock()
    {
        if(m_IsNull == FALSE)
            ::LeaveCriticalSection(m_pSection);
    }
public:
    void Lock()
    {
        ::EnterCriticalSection(m_pSection);
        m_IsNull = FALSE;
    }
    void UnLock()
    {
        if(m_IsNull == FALSE)
        {
            ::LeaveCriticalSection(m_pSection);
            m_IsNull = TRUE;
        }
    }
private:
    CRITICAL_SECTION *m_pSection;
    BOOL             m_IsNull;
};


DWORD   WINAPI RecvThread(LPVOID lp)
{
    int num = *(DWORD*)lp;  // 得到线程函数
    char tempBuf[128];
    HalfLock lock(&gcs);
    while(nShareVar < 1000)
    {
        sprintf_s(tempBuf, "Thread %d :: nShareVar = %d\n", num, nShareVar);
        std::cout<<tempBuf;
        //EnterCriticalSection(&gcs);
        lock.Lock();
        nShareVar++;
        lock.UnLock();
        //LeaveCriticalSection(&gcs);
    }
    return 0;
}

int main(void)
{
    InitializeCriticalSection(&gcs);
    HANDLE  Threads[10];
    // Threads
    for(int i=0; i<10; i++)
    {
        Threads[i] = CreateThread(NULL, 0, RecvThread, &i, 0, NULL);
        Sleep(500);
    }
    WaitForMultipleObjects(10, Threads, TRUE, 50000);
    DeleteCriticalSection(&gcs);
    TerminateThread(Threads, 0);
    for(int i=0; i<10; i++)
    {
        CloseHandle(Threads[i]);
    }
    system("pause");
    return 1;
}