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线程同步
线程同步: 一:相互排斥同步 1.原子訪问是windows仅仅有的线程同步 InterlockedExchange 改变值 InterlockedIncrement ++ InterlockedDecrement -- InterlockedExchangeAdd += 实现旋转锁:锁一段代码 void CThreadOurDlg::OnBnClickedButton1() { AfxBeginThread(&CThreadOurDlg::ThreadA,this); AfxBeginThread(&CThreadOurDlg::ThreadB,this); } long int g_x=0; BOOL flag=FALSE; long int a=100; long int b=200; UINT _cdecl CThreadOurDlg::ThreadA(LPVOID lpvoid) { while(InterlockedExchange((LONG*)&flag,TRUE)==TRUE) Sleep(0); a=a+b; TRACE("--------------------------------\n"); TRACE("%d\n",a); TRACE("--------------------------------\n"); InterlockedExchange((LONG*)&flag,FALSE); return 0; } UINT _cdecl CThreadOurDlg::ThreadB(LPVOID lpvoid) { while(InterlockedExchange((LONG*)&flag,TRUE)==TRUE) Sleep(0); a=a+b; TRACE("++++++++++++++++++++++++++++++++\n"); TRACE("%d\n",a); TRACE("++++++++++++++++++++++++++++++++\n"); InterlockedExchange((LONG*)&flag,FALSE); return 0; } 旋转锁实现卖票: long nTicket = 1000; BOOL nFlag=FALSE; UINT _cdecl CThreadOurDlg::ThreadFun(LPVOID lpvoid) { int i=(int)lpvoid; while(1) { if(nTicket<=0) { break; } if(nTicket>0) { //------------------------------------------------------------枷锁---------------------------------------- while(InterlockedExchange((LONG*)&nFlag,TRUE)==TRUE) Sleep(0); CString str; str.Format(_T("第%d窗体卖出第%d张票"),i,nTicket); TRACE("第%d窗体卖出第%d张票\n",i,nTicket); InterlockedDecrement(&nTicket); //---------------------------------------------------------解锁---------------------------------------------- InterlockedExchange((LONG*)&nFlag,FALSE); } Sleep(20); } TRACE("第%d窗体没有票了\n",i); return 0; } void CThreadOurDlg::OnBnClickedButton2() { //创建10个工作者线程 for(int i=0;i<10;i++) { AfxBeginThread(&CThreadOurDlg::ThreadFun,(LPVOID)i); } } 2.临界区 2.1 Windows的函数 CRITICAL_SECTION cs; ::InitializeCriticalSection(&cs);初始化临界区 ::InitializeCriticalSectionAndSpinCount(&cs,4000);包括旋转锁 ::DeleteCriticalSection(&cs);销毁 ::TryEnterCriticalSection尝试进入临界区 ::EnterCriticalSection(&((CThreadOurDlg*)AfxGetApp()->m_pMainWnd)->cs);进入 ::LeaveCriticalSection(&((CThreadOurDlg*)AfxGetApp()->m_pMainWnd)->cs);退出 2.2 MFC的函数 CCriticalSection o_cs; o_cs.Lock(); o_cs.Unlock(); 3.相互排斥量 内核模式 有系统管理 3.1 MFC的类 void CThreadOurDlg::OnBnClickedButton2() { //创建10个工作者线程 for(int i=0;i<10;i++) { AfxBeginThread(&CThreadOurDlg::ThreadFun,(LPVOID)i); } //释放相互排斥量 ::ReleaseMutex(mx.m_hObject); } UINT _cdecl CThreadOurDlg::ThreadFun(LPVOID lpvoid) { int i=(int)lpvoid; while(1) { if(nTicket<=0) { break; } //----------------------------------等待相互排斥量信号------------------------------------ ::WaitForSingleObject(((CThreadOurDlg*)AfxGetApp()->m_pMainWnd)->mx.m_hObject,INFINITE); if(nTicket>0) { CString str; str.Format(_T("第%d窗体卖出第%d张票"),i,nTicket); TRACE("第%d窗体卖出第%d张票\n",i,nTicket); ((CThreadOurDlg*)AfxGetApp()->m_pMainWnd)->m_listBox.AddString(str); InterlockedDecrement(&nTicket); } //释放相互排斥量 ::ReleaseMutex(((CThreadOurDlg*)AfxGetApp()->m_pMainWnd)->mx.m_hObject); Sleep(20); } TRACE("第%d窗体没有票了\n",i); return 0; } 3.2 HANDLE m_hMutex ; //创建一个相互排斥量 m_hMutex=CreateMutex(NULL,FALSE,NULL); CloseHandle(m_hMutex); m_hMutex=NULL; 4.事件 三个进度条一起跑 4.1MFC类 CEvent cc(FALSE,TRUE);人工 4.2Windows HANDLE m_hEvent; ::WaitForSingleObject(m_hEvent,INFINITE); 5.信号量 5.1Windows HANDLE m_hSingle; m_hSingle = ::CreateSemaphore(NULL,0/*初始值有几个信号*/,3/*最多能释放几个信号*/,NULL); ::RealeaseSemaphore(m_hSingle,3/*一次释放多少个*/,NULL/*上一次释放多少个*/); 5.2MFC CSemaphore
线程同步
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