一种多线程变量区域锁的实现方法

多线程变量区域锁类定义

//写锁定义
typedef boost::shared_mutex Lock;
typedef boost::unique_lock<Lock> WriteLock;
typedef boost::shared_lock<Lock> ReadLock;
// 区域互斥锁类定义
class CVariableLock
{
public:
    CVariableLock(Lock *lock, bool *lock_flag);
    ~CVariableLock(void);
public:
    bool GetLockStatus();//获取资源状态，1——可访问，0——不可访问
private:
    Lock *m_lock;
    bool *m_lock_flag;
    bool m_get_lock_flag;
};

// 区域互斥锁构造函数
CVariableLock::CVariableLock(Lock *lock, bool *lock_flag)
{
    m_get_lock_flag = false;
    if(lock){
        m_lock = lock;
    }
    else{
        m_lock = NULL;
    }
    if(lock_flag){
        m_lock_flag = lock_flag;
    }
    else{
        m_lock_flag = NULL;
    }
}
// 区域互斥锁析构函数
CVariableLock::~CVariableLock(void)
{
    if(!m_lock || !m_lock_flag){
        return;
    }
    if(m_get_lock_flag){//只有在获取锁成功情况下才重置变量
    WriteLock w_lock(*m_lock);
        *m_lock_flag = false;
    }
}
// 区域互斥锁锁状态成员函数
bool CVariableLock::GetLockStatus(){//获取资源状态，返回结果：1——可访问，0——不可访问
    if(!m_lock  || !m_lock_flag){
         return true;
    }
    bool lock_status = true;
    {
        {
            ReadLock w_lock(*m_lock);
            lock_status = *m_lock_flag;
        }
        int count = 50;
        while(lock_status){
            if(count <= 0){
                break;
            }
            {
                ReadLock w_lock(*m_lock);
                lock_status = *m_lock_flag;
            }
            count--;
            Sleep(10);//延时10ms
        }
    }

    bool result = ~(lock_status);
    if(result){//获取锁成功
        {
            WriteLock w_lock(*m_lock);
            lock_status = *m_lock_flag;//再次读取变量值
            if(lock_status){//已被其他线程锁定
                m_get_lock_flag = false;
                result = false;
            }
            else{
                m_get_lock_flag = true;
                *m_lock_flag = true;
            }
        }
    }
    else{//获取锁失败
        m_get_lock_flag = false;
    }
    return result;
}

变量区域锁工作流程图

使用示例

// 区域互斥锁使用示例
bool lock_flag = false;
Lock rw_lock;
void Fun1()
{
    CVariableLock lock(&lock_flag, &rw_lock);
    if(!lock.GetLockStatus()){//获取锁失败
        return;
    }
    //获取锁成功，锁定区域1
    ……
}
void Fun2()
{
    CVariableLock lock(&lock_flag, &rw_lock);
    if(!lock.GetLockStatus()){//获取锁失败
        return;
    }
    //获取锁成功，锁定区域2
    ……
}