读者写者问题实现操作系统课程设计 第5页
wait_for_mutex=WaitForSingleObject(h_Mutex,-1); //等待互斥信号，保证对readcount的访问、
//修改互斥
readcount++; //读者数目加一
if (readcount==1)
EnterCriticalSection(&RP_Write);//禁止写者进入
ReleaseMutex(h_Mutex);//释放互斥对象，允许下个读者继续读：
//读文件
cout<<"读者线程 "<<m_Threadhao<<" 开始读文件."<<endl;
Sleep(m_ThreadRunTime);
//退出线程
cout<<"读者线程 "<<m_Threadhao<<" 完成读文件."<<endl;
wait_for_mutex=WaitForSingleObject(h_Mutex,-1); //等待互斥信号，保证对readcount的访问、修改互斥
readcount--; //读者数目减少
if (readcount==0)
LeaveCriticalSection(&RP_Write); //如果所有读者读完，唤醒写者
ReleaseMutex(h_Mutex);//释放互斥信号
}
//读者优先-----写者线程
void R_WriterThread(void *p)
{
DWORD m_delay; //延迟时间
DWORD m_ThreadRunTime; //读文件持续时间
int m_Threadhao; //线程序号
//从参数中获得信息
m_Threadhao=((ThreadInfo *)(p))->Threadhao;
m_delay=(DWORD)(((ThreadInfo *)(p))->ThreadStartTime*100);
m_ThreadRunTime=(DWORD)(((ThreadInfo *)(p))->ThreadRunTime*100);
Sleep(m_delay); //延迟等待
cout<<"写者线程 "<<m_Threadhao<<" 发出写请求."<<endl;
EnterCriticalSection(&RP_Write);//禁止下一位写者进入
//写文件
cout<<"写者线程 "<<m_Threadhao<<" 开始写文件."<<endl;
Sleep(m_ThreadRunTime);
//退出线程
cout<<"写者线程 "<<m_Threadhao<<" 完成写文件."<<endl;
LeaveCriticalSection(&RP_Write); //如果所有读者读完，唤醒写者
}
//写者优先处理函数
void WriterFun(char* file)
{
DWORD n_thread=0; //线程数目
DWORD thread_ID; //线程ID
DWORD wait_for_all; //等待所有线程结束
//互斥对象
HANDLE h_Mutex1, h_Mutex2, h_Mutex3;
h_Mutex1 = CreateMutex(NULL, FALSE, "mutex_for_writecount");
h_Mutex2 = CreateMutex(NULL, FALSE, "mutex_for_readcount");
h_Mutex3 = CreateMutex(NULL, FALSE, "mutex_for_read");
//线程对象数组
HANDLE h_Thread[64];
ThreadInfo thread_info[64];
readcount=0; //初始化readcount
InitializeCriticalSection(&cs_Write); //初始化临界区
InitializeCriticalSection(&cs_Read);
ifstream inFile;
inFile.open(file); //打开文件
cout<<"写者优先:\n"<<endl;
while (inFile)
{//读入每一个读者、写者的信息 inFile>>thread_info[n_thread].Threadhao
>>thread_info[n_thread].ThreadClass
>>thread_info[n_thread].ThreadStartTime
>>thread_info[n_thread].ThreadRunTime;
if(-1 == inFile.get())
break;
n_thread++;//线程数加一
}
for (int i=0;i<(int)(n_thread);i++)
{
if (thread_info[i].ThreadClass=='r')
//创建读者线程
h_Thread[i]=CreateThread(NULL,0,\
(LPTHREAD_START_ROUTINE)(W_ReaderThread),\
&thread_info[i],0,&thread_ID);
else
//创建写者线程
h_Thread[i]=CreateThread(NULL,0,\
(LPTHREAD_START_ROUTINE)(W_WriterThread),\
&thread_info[i],0,&thread_ID);
}
//等待所有线程结束
wait_for_all=WaitForMultipleObjects(n_thread,h_Thread,TRUE,-1);
cout<<"所有的读者和写者线程完成操作."<<endl;
}
//写者优先-----写者线程
void W_WriterThread(void *p)
{
//互斥变量
HANDLE h_Mutex1;
h_Mutex1 = OpenMutex(MUTEX_ALL_ACCESS,FALSE,"mutex_for_writecount")
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