MFC(线程同步与异步套接字,孙鑫C++第十六讲札记整理)提问者： yaozhi3333 发布时间：2014-06-26 浏览：66 回复：0 悬赏：0.0希赛币 MFC(线程同步与异步套接字,孙鑫C++第十六讲笔记整理)
1.事件对象：来实现线程的同步。与互斥对象一样均属于内核对象。 当人工重置有信号时，所有线程均得到信号，所以不能设为人工重置。代码就不贴了，通过创建匿名的事件对象，也可以让一个程序只能运行一个实例。 2.关键代码段实现线程的同步：类似公用电话亭，只有当电话亭里面没人了，其它人才可以再进去打电话。用了4个函数，这种方法比较简单！但缺点是如果使用了多少关键代码码，容易赞成线程的死锁 3.线程死锁，用关键代码示例，用了两个临界区对象，实战中要注意避免这种错误！ 4.使用异步套接字编写网络聊天室 1)加载套接字库，进行版本协商，包含头文件，链接库文件，这次请示的是2.2版本！ 2）在类CChatDlg中增加一个成员变量m_socket,在析构函数中释放这个变量 3）利用WSASocket()创建套接字（数据报类型的UDP型的） 4）然后调用WSAAsyncSelect(m_socket,m_hWnd,UM_SOCK,FD_READ)为网络事件定义消息！此时如果发生FD_READ消息，系统会发送UM_SOCK消息给应用程序！程序并不会阻塞在这儿了！ 以上是在BOOL CChatDlg::OnInitDialog()完成 5）然后完成消息响应！ 头文件中：#define UM_SOCKWM_USER+1 afx_msg void OnSock(WPARAM,LPARAM); 源文件中： ON_MESSAGE(UM_SOCK,OnSock) 实现消息响应函数：void CChatDlg::OnSock(WPARAM wParam,LPARAM lParam) { switch(LOWORD(lParam)) { case FD_READ: WSABUF wsabuf; wsabuf.buf=new char[200]; wsabuf.len=200; DWORD dwRead; DWORD dwFlag=0; SOCKADDR_IN addrFrom; int len=sizeof(SOCKADDR); CString str; CString strTemp; HOSTENT *pHost; if(SOCKET_ERROR==WSARecvFrom(m_socket,&wsabuf,1,&dwRead,&dwFlag, (SOCKADDR*)&addrFrom,&len,NULL,NULL)) { MessageBox("接收数据失败！"); return; } pHost=gethostbyaddr((char*)&addrFrom.sin_addr.S_un.S_addr,4,AF_INET); //str.Format("%s说 :%s",inet_ntoa(addrFrom.sin_addr),wsabuf.buf); str.Format("%s说 :%s",pHost->h_name,wsabuf.buf); str+="\r\n"; GetDlgItemText(IDC_EDIT_RECV,strTemp); str+=strTemp; SetDlgItemText(IDC_EDIT_RECV,str); break; } } OK！ 6）完成数据发送的功能！ void CChatDlg::OnBtnSend() { // TOD Add your control notification handler code here DWORD dwIP; CString strSend; WSABUF wsabuf; DWORD dwSend; int len; CString strHostName; SOCKADDR_IN addrTo; HOSTENT* pHost; if(GetDlgItemText(IDC_EDIT_HOSTNAME,strHostName),strHostName=="") { ((CIPAddressCtrl*)GetDlgItem(IDC_IPADDRESS1))->GetAddress(dwIP); addrTo.sin_addr.S_un.S_addr=htonl(dwIP); } else { pHost=gethostbyname(strHostName); addrTo.sin_addr.S_un.S_addr=*((DWORD*)pHost->h_addr_list[0]); } addrTo.sin_family=AF_INET; addrTo.sin_port=htons(6000); GetDlgItemText(IDC_EDIT_SEND,strSend); len=strSend.GetLength(); wsabuf.buf=strSend.GetBuffer(len); wsabuf.len=len+1; SetDlgItemText(IDC_EDIT_SEND,""); if(SOCKET_ERROR==WSASendTo(m_socket,&wsabuf,1,&dwSend,0, (SOCKADDR*)&addrTo,sizeof(SOCKADDR),NULL,NULL)) { MessageBox("发送数据失败！"); return; } }7）完成将主机名转换为IP地址的功能，以前将IP地址转换为主机名的功能，单线程的聊天室创建完毕！性能并且非常出色！ 下面是一些具体的代码： #include<windows.h> #include<iostream.h> DWORD WINAPI ThreadProc1( LPVOID lpParameter ); DWORD WINAPI ThreadProc2( LPVOID lpParameter ); int tickes=100; HANDLE hEvent; int main() { HANDLE hThread1=CreateThread(NULL,0,ThreadProc1,NULL,0,NULL); HANDLE hThread2=CreateThread(NULL,0,ThreadProc2,NULL,0,NULL); hEvent=CreateEvent(NULL,FALSE,TRUE,NULL);//自动，有信号 CloseHandle(hThread1); CloseHandle(hThread2); Sleep(4000); return 0; } DWORD WINAPI ThreadProc1( LPVOID lpParameter // thread data ) { while(TRUE) { SetEvent(hEvent); WaitForSingleObject(hEvent,INFINITE); if(tickes>0) { cout$amp;<> //CreateEvent设置自定的，并且初始有信号 /*#include<windows.h> #include<iostream.h> DWORD WINAPI ThreadProc1( LPVOID lpParameter ); DWORD WINAPI ThreadProc2( LPVOID lpParameter ); int tickes=100; HANDLE hEvent; int main() { HANDLE hThread1=CreateThread(NULL,0,ThreadProc1,NULL,0,NULL); HANDLE hThread2=CreateThread(NULL,0,ThreadProc2,NULL,0,NULL); hEvent=CreateEvent(NULL,FALSE,TRUE,NULL);//自动，有信号 CloseHandle(hThread1); CloseHandle(hThread2); Sleep(4000); return 0; } DWORD WINAPI ThreadProc1( LPVOID lpParameter // thread data ) { while(TRUE) { WaitForSingleObject(hEvent,INFINITE); if(tickes>0) { cout$amp;<> //CreateEvent手动，一开始就无信号 /*#include<windows.h> #include<iostream.h> DWORD WINAPI ThreadProc1( LPVOID lpParameter ); DWORD WINAPI ThreadProc2( LPVOID lpParameter ); int tickes=100; HANDLE hEvent; int main() { HANDLE hThread1=CreateThread(NULL,0,ThreadProc1,NULL,0,NULL); HANDLE hThread2=CreateThread(NULL,0,ThreadProc2,NULL,0,NULL); hEvent=CreateEvent(NULL,TRUE,FALSE,NULL);//手动，无信号 SetEvent(hEvent); CloseHandle(hThread1); CloseHandle(hThread2); Sleep(4000); return 0; } DWORD WINAPI ThreadProc1( LPVOID lpParameter // thread data ) { while(TRUE) { WaitForSingleObject(hEvent,INFINITE); if(tickes>0) { cout$amp;<> //关键代码段，临界区域 //如果只是Enter了但是没有Leave则下一个线程获取不了信号，下一个线程得不到执行 /* #include<windows.h> #include<iostream.h> DWORD WINAPI ThreadProc1( LPVOID lpParameter ); DWORD WINAPI ThreadProc2( LPVOID lpParameter ); int tickes=100; CRITICAL_SECTION section; int main() { HANDLE hThread1=CreateThread(NULL,0,ThreadProc1,NULL,0,NULL); HANDLE hThread2=CreateThread(NULL,0,ThreadProc2,NULL,0,NULL); CloseHandle(hThread1); CloseHandle(hThread2); InitializeCriticalSection(§ion); Sleep(4000); DeleteCriticalSection(§ion); return 0; } DWORD WINAPI ThreadProc1( LPVOID lpParameter // thread data ) { while(TRUE) { EnterCriticalSection(§ion); if(tickes>0) { cout$amp;<> //死锁的体现 /*#include<windows.h> #include<iostream.h> DWORD WINAPI ThreadProc1 LPVOID lpParameter ); DWORD WINAPI ThreadProc2( LPVOID lpParameter ); int tickes=100; CRITICAL_SECTION sectionA; CRITICAL_SECTION sectionB; int main() { HANDLE hThread1=CreateThread(NULL,0,ThreadProc1,NULL,0,NULL); HANDLE hThread2=CreateThread(NULL,0,ThreadProc2,NULL,0,NULL); CloseHandle(hThread1); CloseHandle(hThread2); InitializeCriticalSection(§ionA); InitializeCriticalSection(§ionB); Sleep(4000); DeleteCriticalSection(§ionB); DeleteCriticalSection(§ionA); return 0; } DWORD WINAPI ThreadProc1( LPVOID lpParameter // thread data ) { while(TRUE) { EnterCriticalSection(§ionA); Sleep(1); EnterCriticalSection(§ionB); if(tickes>0) { cout$amp;<> |
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