轉自：http://blog.csdn.net/tonyxiaohome/archive/2010/01/03/5124521.aspx
作者：肖舸
多線程的變量同步問題，一直是困擾廣大VC程序員的一大難題，其主要表現是在多線程模式下，線程間共享變量的存取不再安全，程序員無法確保變量的值在存取時是否準確可信，對此，微軟給出的解決方案是使用臨界區對象加以保護。但是，臨界區對象使用太過於繁瑣，需要不斷地加鎖和解鎖，很容易搞忘，引起新的Bug。
這裏，東樓給出多線程安全的變量模板，由此模板，可派生絕大多數變量類型，實現線程間各種變量的安全互訪。本模板已經重載了幾乎全部運算符，大家可以很方便地使用＋＋、――、＋＝、－＝等操作，方便編程使用。
#ifndef _XiaoGeMVarTempleteHasBeenDefined_
#define _XiaoGeMVarTempleteHasBeenDefined_
#include <Afxmt.h>
template <class MVAR_TYPE>
class MVAR
{
public:
MVAR()
{
m_pBegin=new char[sizeof(MVAR_TYPE)];
memset(m_pBegin,0,sizeof(MVAR_TYPE));
}
~MVAR(){delete[] m_pBegin;}
int GetLength(){return sizeof(MVAR_TYPE);}
MVAR_TYPE Set(MVAR_TYPE& value)
{
m_csLockHandle.Lock();
memcpy(m_pBegin,(char*)&value,sizeof(MVAR_TYPE));
m_csLockHandle.Unlock();
return value;
}
MVAR_TYPE Get()
{
MVAR_TYPE myValue;
m_csLockHandle.Lock();
memcpy((char*)&myValue,m_pBegin,sizeof(MVAR_TYPE));
m_csLockHandle.Unlock();
return myValue;
}
MVAR_TYPE operator=(MVAR_TYPE value)
{
MVAR_TYPE myValue;
m_csLockHandle.Lock();
myValue=value;
memcpy(m_pBegin,(char*)&myValue,sizeof(MVAR_TYPE));
m_csLockHandle.Unlock();
return myValue;
}
MVAR_TYPE operator~()
{
MVAR_TYPE myValue;
m_csLockHandle.Lock();
memcpy((char*)&myValue,m_pBegin,sizeof(MVAR_TYPE));
myValue=~myValue;
m_csLockHandle.Unlock();
return myValue;
}
MVAR_TYPE operator++(int)
{
MVAR_TYPE myValue;
m_csLockHandle.Lock();
memcpy((char*)&myValue,m_pBegin,sizeof(MVAR_TYPE));
myValue++;
memcpy(m_pBegin,(char*)&myValue,sizeof(MVAR_TYPE));
m_csLockHandle.Unlock();
return myValue;
}
MVAR_TYPE operator++()
{
MVAR_TYPE myValue;
m_csLockHandle.Lock();
memcpy((char*)&myValue,m_pBegin,sizeof(MVAR_TYPE));
myValue++;
memcpy(m_pBegin,(char*)&myValue,sizeof(MVAR_TYPE));
m_csLockHandle.Unlock();
return myValue;
}
MVAR_TYPE operator--(int)
{
MVAR_TYPE myValue;
m_csLockHandle.Lock();
memcpy((char*)&myValue,m_pBegin,sizeof(MVAR_TYPE));
myValue--;
memcpy(m_pBegin,(char*)&myValue,sizeof(MVAR_TYPE));
m_csLockHandle.Unlock();
return myValue;
}
MVAR_TYPE operator--()
{
MVAR_TYPE myValue;
m_csLockHandle.Lock();
memcpy((char*)&myValue,m_pBegin,sizeof(MVAR_TYPE));
myValue--;
memcpy(m_pBegin,(char*)&myValue,sizeof(MVAR_TYPE));
m_csLockHandle.Unlock();
return myValue;
}
MVAR_TYPE operator+(MVAR_TYPE value)
{
MVAR_TYPE myValue;
m_csLockHandle.Lock();
memcpy((char*)&myValue,m_pBegin,sizeof(MVAR_TYPE));
myValue+=value;
m_csLockHandle.Unlock();
return myValue;
}
MVAR_TYPE operator-(MVAR_TYPE value)
{
MVAR_TYPE myValue;
m_csLockHandle.Lock();
memcpy((char*)&myValue,m_pBegin,sizeof(MVAR_TYPE));
myValue-=value;
m_csLockHandle.Unlock();
return myValue;
}
MVAR_TYPE operator*(MVAR_TYPE value)
{
MVAR_TYPE myValue;
m_csLockHandle.Lock();
memcpy((char*)&myValue,m_pBegin,sizeof(MVAR_TYPE));
myValue*=value;
m_csLockHandle.Unlock();
return myValue;
}
MVAR_TYPE operator/(MVAR_TYPE value)
{
MVAR_TYPE myValue;
m_csLockHandle.Lock();
memcpy((char*)&myValue,m_pBegin,sizeof(MVAR_TYPE));
myValue/=value;
m_csLockHandle.Unlock();
return myValue;
}
MVAR_TYPE operator&(MVAR_TYPE value)
{
MVAR_TYPE myValue;
m_csLockHandle.Lock();
memcpy((char*)&myValue,m_pBegin,sizeof(MVAR_TYPE));
myValue&=value;
m_csLockHandle.Unlock();
return myValue;
}
MVAR_TYPE operator|(MVAR_TYPE value)
{
MVAR_TYPE myValue;
m_csLockHandle.Lock();
memcpy((char*)&myValue,m_pBegin,sizeof(MVAR_TYPE));
myValue|=value;
m_csLockHandle.Unlock();
return myValue;
}
MVAR_TYPE operator^(MVAR_TYPE value)
{
MVAR_TYPE myValue;
m_csLockHandle.Lock();
memcpy((char*)&myValue,m_pBegin,sizeof(MVAR_TYPE));
myValue^=value;
m_csLockHandle.Unlock();
return myValue;
}
MVAR_TYPE operator+=(MVAR_TYPE value)
{
MVAR_TYPE myValue;
m_csLockHandle.Lock();
memcpy((char*)&myValue,m_pBegin,sizeof(MVAR_TYPE));
myValue+=value;
memcpy(m_pBegin,(char*)&myValue,sizeof(MVAR_TYPE));
m_csLockHandle.Unlock();
return myValue;
}
MVAR_TYPE operator-=(MVAR_TYPE value)
{
MVAR_TYPE myValue;
m_csLockHandle.Lock();
memcpy((char*)&myValue,m_pBegin,sizeof(MVAR_TYPE));
myValue-=value;
memcpy(m_pBegin,(char*)&myValue,sizeof(MVAR_TYPE));
m_csLockHandle.Unlock();
return myValue;
}
MVAR_TYPE operator*=(MVAR_TYPE value)
{
MVAR_TYPE myValue;
m_csLockHandle.Lock();
memcpy((char*)&myValue,m_pBegin,sizeof(MVAR_TYPE));
myValue*=value;
memcpy(m_pBegin,(char*)&myValue,sizeof(MVAR_TYPE));
m_csLockHandle.Unlock();
return myValue;
}
MVAR_TYPE operator/=(MVAR_TYPE value)
{
MVAR_TYPE myValue;
m_csLockHandle.Lock();
memcpy((char*)&myValue,m_pBegin,sizeof(MVAR_TYPE));
myValue/=value;
memcpy(m_pBegin,(char*)&myValue,sizeof(MVAR_TYPE));
m_csLockHandle.Unlock();
return myValue;
}
MVAR_TYPE operator&=(MVAR_TYPE value)
{
MVAR_TYPE myValue;
m_csLockHandle.Lock();
memcpy((char*)&myValue,m_pBegin,sizeof(MVAR_TYPE));
myValue&=value;
memcpy(m_pBegin,(char*)&myValue,sizeof(MVAR_TYPE));
m_csLockHandle.Unlock();
return myValue;
}
MVAR_TYPE operator|=(MVAR_TYPE value)
{
MVAR_TYPE myValue;
m_csLockHandle.Lock();
memcpy((char*)&myValue,m_pBegin,sizeof(MVAR_TYPE));
myValue|=value;
memcpy(m_pBegin,(char*)&myValue,sizeof(MVAR_TYPE));
m_csLockHandle.Unlock();
return myValue;
}
MVAR_TYPE operator^=(MVAR_TYPE value)
{
MVAR_TYPE myValue;
m_csLockHandle.Lock();
memcpy((char*)&myValue,m_pBegin,sizeof(MVAR_TYPE));
myValue^=value;
memcpy(m_pBegin,(char*)&myValue,sizeof(MVAR_TYPE));
m_csLockHandle.Unlock();
return myValue;
}
BOOL operator>(MVAR_TYPE value)
{
MVAR_TYPE myValue;
BOOL bRet;
m_csLockHandle.Lock();
memcpy((char*)&myValue,m_pBegin,sizeof(MVAR_TYPE));
bRet=(myValue>value);
m_csLockHandle.Unlock();
return bRet;
}
BOOL operator<(MVAR_TYPE value)
{
MVAR_TYPE myValue;
BOOL bRet;
m_csLockHandle.Lock();
memcpy((char*)&myValue,m_pBegin,sizeof(MVAR_TYPE));
bRet=(myValue<value);
m_csLockHandle.Unlock();
return bRet;
}
BOOL operator>=(MVAR_TYPE value)
{
MVAR_TYPE myValue;
BOOL bRet;
m_csLockHandle.Lock();
memcpy((char*)&myValue,m_pBegin,sizeof(MVAR_TYPE));
bRet=(myValue>=value);
m_csLockHandle.Unlock();
return bRet;
}
BOOL operator<=(MVAR_TYPE value)
{
MVAR_TYPE myValue;
BOOL bRet;
m_csLockHandle.Lock();
memcpy((char*)&myValue,m_pBegin,sizeof(MVAR_TYPE));
bRet=(myValue<=value);
m_csLockHandle.Unlock();
return bRet;
}
BOOL operator==(MVAR_TYPE value)
{
MVAR_TYPE myValue;
BOOL bRet;
m_csLockHandle.Lock();
memcpy((char*)&myValue,m_pBegin,sizeof(MVAR_TYPE));
bRet=(myValue==value);
m_csLockHandle.Unlock();
return bRet;
}
BOOL operator!=(MVAR_TYPE value)
{
MVAR_TYPE myValue;
BOOL bRet;
m_csLockHandle.Lock();
memcpy((char*)&myValue,m_pBegin,sizeof(MVAR_TYPE));
bRet=(myValue!=value);
m_csLockHandle.Unlock();
return bRet;
}
private:
char* m_pBegin;
CCriticalSection m_csLockHandle;
};
typedef MVAR<char> MCHAR;
typedef MVAR<unsigned char> MUCHAR;
typedef MVAR<short> MSHORT;
typedef MVAR<unsigned short> MUSHORT;
typedef MVAR<int> MINT;
typedef MVAR<unsigned int> MUINT;
typedef MVAR<long> MLONG;
typedef MVAR<unsigned long> MULONG;
typedef MVAR<float> MFLOAT;
typedef MVAR<double> MDOUBLE;
typedef MVAR<BOOL> MBOOL;
typedef MVAR<LPVOID> MLPVOID;
typedef MVAR<BYTE> MBYTE;
#endif //_XiaoGeMVarTempleteHasBeenDefined_
大家只需要把這段代碼放入Mvar.h文件，在stdafx.h中include這個頭文件，即可在程序中自由使用變量。以上僅僅是東樓根據自己的需要，派生的幾個常用類型，大家也可以嘗試派生新的類型使用。
注意，當派生的變量需要取得其中的值時，必須使用.Get()成員函數，這是唯一一點不如普通變量方便的地方。
下面給出一個控制例子，大家可以參考：
#includen “mvar.h”
class CMyClass
{
public:
CMyClass();
~ CMyClass();
protected:
static UINT MyThread(LPVOID pParam); //線程函數
MBOOL m_bThreadContinue; //線程循環標誌
MUINT m_nThreadCount; //線程計數器
};
CMyClass::CMyClass()
{
m_bThreadContinue=TRUE;
m_nThreadCount=0;
int i;
//開啓100個線程
for(i=0;i<100;i++)
{
m_nThreadCount++; //一定要在開啓線程前累加線程計數器
AfxBeginThread(MyThread,this); //開啓線程，以本對象指針爲參數
}
}
CMyClass::~CMyClass()
{
m_bThreadContinue=FALSE; //通知線程關閉
while(m_nThreadCount!=0) {} //等待所有線程退出
//此時退出，線程已經全部安全退出!!!
}
UINT CMyClass::MyThread(LPVOID pParam)
{
CMyClass* pThis=(CMyClass*)pParam; //得到本對象指針
while(pThis->m_bThreadContinue)
{
//循環體
Sleep(100);
}
pThis->m_nThreadCount --; //線程計數器減1
return 0;
}
如果有問題，歡迎大家提問，如果有Bug,也請大家及時向東樓提出。