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多线程安全的变量模板

51自学网 2015-08-30 http://www.wanshiok.com
  多线程的变量同步问题,一直是困扰广大VC程序员的一大难题,其主要表现是在多线程模式下,线程间共享变量的存取不再安全,程序员无法确保变量的值在存取时是否准确可信,对此,微软给出的解决方案是使用临界区对象加以保护。但是,临界区对象使用太过于繁琐,需要不断地加锁和解锁,很容易搞忘,引起新的Bug。

  这里,东楼给出多线程安全的变量模板,由此模板,可派生绝大多数变量类型,实现线程间各种变量的安全互访。本模板已经重载了几乎全部运算符,大家可以很方便地使用++、――、+=、-=等操作,方便编程使用。

#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_

  大家只需要把这段代码放入Mvar.h文件,在stdafx.h中include这个头文件,即可在程序中自由使用变量。以上仅仅是东楼根据自己的需要,派生的几个常用类型,大家也可以尝试派生新的类型使用。

  注意,当派生的变量需要取得其中的值时,必须使用.Get()成员函数,这是唯一一点不如普通变量方便的地方。

  下面给出一个控制例子,大家可以参考:

#includen “mvar.h”
class CMyClass
{
public:
  CMyClass();
  ~ CMyClass();
protected:
  static UINT MyThread(LPVOID pParam);  //线程函数
  MBOOL m_bThreadContinue;        //线程循环标志
  MUINT m_nThreadCount;          //线程计数器
};

CMyClass::CMyClass()
{
  m_bThreadContinue=TRUE;
  m_nThreadCount=0;
  int i;
  //开启100个线程
  for(i=0;i<100;i++)
  {
    m_nThreadCount++;        //一定要在开启线程前累加线程计数器
    AfxBeginThread(MyThread,this);  //开启线程,以本对象指针为参数
}
}
CMyClass::~CMyClass()
{
  m_bThreadContinue=FALSE;    //通知线程关闭
  while(m_nThreadCount!=0) {}   //等待所有线程退出
  //此时退出,线程已经全部安全退出!!!
}
UINT CMyClass::MyThread(LPVOID pParam)
{
  CMyClass* pThis=(CMyClass*)pParam;  //得到本对象指针
  while(pThis->m_bThreadContinue)
  {
    //循环体
    Sleep(100);
}
pThis->m_nThreadCount --;//线程计数器减1
return 0;
}

 

 

 
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