MFC(線程同步與異步套接字,孫鑫C++第十六講札記整理)
提問者： yaozhi3333 發(fā)布時間：2014-06-26 瀏覽：66 回復：0 懸賞：0.0希賽幣
MFC(線程同步與異步套接字,孫鑫C++第十六講筆記整理)
1.事件對象：來實現(xiàn)線程的同步。與互斥對象一樣均屬于內(nèi)核對象。
當人工重置有信號時，所有線程均得到信號，所以不能設為人工重置。代碼就不貼了，通過創(chuàng)建匿名的事件對象，也可以讓一個程序只能運行一個實例。
2.關鍵代碼段實現(xiàn)線程的同步：類似公用電話亭，只有當電話亭里面沒人了，其它人才可以再進去打電話。用了4個函數(shù)，這種方法比較簡單！但缺點是如果使用了多少關鍵代碼碼，容易贊成線程的死鎖
3.線程死鎖，用關鍵代碼示例，用了兩個臨界區(qū)對象，實戰(zhàn)中要注意避免這種錯誤！
4.使用異步套接字編寫網(wǎng)絡聊天室
1)加載套接字庫，進行版本協(xié)商，包含頭文件，鏈接庫文件，這次請示的是2.2版本！
2）在類CChatDlg中增加一個成員變量m_socket,在析構函數(shù)中釋放這個變量
3）利用WSASocket()創(chuàng)建套接字（數(shù)據(jù)報類型的UDP型的）
4）然后調(diào)用WSAAsyncSelect(m_socket,m_hWnd,UM_SOCK,FD_READ)為網(wǎng)絡事件定義消息！此時如果發(fā)生FD_READ消息，系統(tǒng)會發(fā)送UM_SOCK消息給應用程序！程序并不會阻塞在這兒了！
以上是在BOOL CChatDlg::OnInitDialog()完成
5）然后完成消息響應！
頭文件中：#define UM_SOCKWM_USER+1
afx_msg void OnSock(WPARAM,LPARAM);
源文件中：
ON_MESSAGE(UM_SOCK,OnSock)
實現(xiàn)消息響應函數(shù)：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("接收數(shù)據(jù)失??！");
return;
}
pHost=gethostbyaddr((char*)&addrFrom.sin_addr.S_un.S_addr,4,AF_INET);
//str.Format("%s說 :%s",inet_ntoa(addrFrom.sin_addr),wsabuf.buf);
str.Format("%s說 :%s",pHost->h_name,wsabuf.buf);
str+="\r\n";
GetDlgItemText(IDC_EDIT_RECV,strTemp);
str+=strTemp;
SetDlgItemText(IDC_EDIT_RECV,str);
break;
}
}
OK！
6）完成數(shù)據(jù)發(fā)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("發(fā)送數(shù)據(jù)失??！");
return;
}
}7）完成將主機名轉換為IP地址的功能，以前將IP地址轉換為主機名的功能，單線程的聊天室創(chuàng)建完畢！性能并且非常出色！
下面是一些具體的代碼：
#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);//自動，有信號 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$amp;
//CreateEvent設置自定的，并且初始有信號 /*#include<windows.h> #include<iostream.h> DWORD WINAPI ThreadProc1( LPVOID lpParameter ); DWORD WINAPI ThreadProc2( LPVOID lpParameter ); int tickes=100; HANDLE hEvent; int main() { HANDLE hThread1=CreateThread(NULL,0,ThreadProc1,NULL,0,NULL); HANDLE hThread2=CreateThread(NULL,0,ThreadProc2,NULL,0,NULL); hEvent=CreateEvent(NULL,FALSE,TRUE,NULL);//自動，有信號 CloseHandle(hThread1); CloseHandle(hThread2); Sleep(4000); return 0; } DWORD WINAPI ThreadProc1( LPVOID lpParameter // thread data ) { while(TRUE) { WaitForSingleObject(hEvent,INFINITE); if(tickes>0) { cout$amp;
//CreateEvent手動，一開始就無信號 /*#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);//手動，無信號 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$amp;
//關鍵代碼段，臨界區(qū)域 //如果只是Enter了但是沒有Leave則下一個線程獲取不了信號，下一個線程得不到執(zhí)行 /* #include<windows.h> #include<iostream.h> DWORD WINAPI ThreadProc1( LPVOID lpParameter ); DWORD WINAPI ThreadProc2( LPVOID lpParameter ); int tickes=100; CRITICAL_SECTION section; int main() { HANDLE hThread1=CreateThread(NULL,0,ThreadProc1,NULL,0,NULL); HANDLE hThread2=CreateThread(NULL,0,ThreadProc2,NULL,0,NULL); CloseHandle(hThread1); CloseHandle(hThread2); InitializeCriticalSection(§ion); Sleep(4000); DeleteCriticalSection(§ion); return 0; } DWORD WINAPI ThreadProc1( LPVOID lpParameter // thread data ) { while(TRUE) { EnterCriticalSection(§ion); if(tickes>0) { cout$amp;
//死鎖的體現(xiàn) /*#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;
