实验过程：
过程一：
1.Server等待Client到来
2.Client进入
3.Server接受连接，发送"nihaihaoma"
4.Client接收"nihaihaoma"，马上退出
5.Server进入发送完成处理，Sleep(8000)
int ret = WSARecv(s,...)投递接收
结果：
WSARecv以ret=SOCKET_ERROR, GetLastError()= 10054失败
（10054远程主机强迫关闭了一个现有的连接）
过程二：
1.Server等待Client到来
2.Client进入
3.Server接受连接，发送"nihaihaoma"
4.Client接收"nihaihaoma"，closesocket(s)后马上退出
5.Server进入发送完成处理，Sleep(8000)
int ret = WSARecv(s,...)投递接收
结果：
投递成功
投递成功的WSARecv马上从GetQueuedCompletionStatus以ret=true, dwNum=0, GetLastError()=997返回
（997重叠 I/O 操作在进行中）
深入探索：
netstat -ano | findstr "4444" 查看端口状态，显示出异常：
1.直接退出：连接在Client退出的那刻被暴力关闭，跳过4步握手，不再可用
2.打声招呼再退出：
回调期间：
Client = FIN_WAIT_2
Server = CLOSE_WAIT
回调结束：
Client = TIME_WAIT
Server = CLOSED
符合四步分手优雅关闭连接
综上所述：
1.连接在Client不辞而别的那刻被暴力关闭、跳过4步握手、不再可用——>WSARecv投递在一个不可用连接上，失败在所难免
2.Client调用closesocket(s)再退出，连接在发送回调中仍旧存在、呈Server->Client的单向传输——>WSARecv投递成功
跳出回调IOCP关闭连接，故投递成功的WSARecv从GetQueuedCompletionStatus返回
测试客户端：与IOCP九—Client退出后投递请求相同
实验代码：
#include <WinSock2.h>
#include <Windows.h>
#include <iostream>
#include <process.h>
#include <string>
#include <MSWSock.h>
#include <set>
#pragma comment(lib, "Ws2_32.lib")
#pragma comment(lib, "Kernel32.lib")
#pragma comment(lib, "Mswsock.lib")
#define BUF_LEN 1024
enum OperateType
{
OP_RECV,
OP_SEND,
OP_ACCEPT,
};
typedef struct PER_HANDLE_DATA
{
SOCKET s; //记录是哪个socket上的请求
SOCKADDR_IN addr; //记录该socket对应的客户端地址和端口
}PER_HANDLE_DATA, *LPPER_HANDLE_DATA;
typedef struct PER_IO_DATA
{
OVERLAPPED overlapped; //第一项必须为OVERLAPPED
SOCKET cs; //记录客户端socket
char buf[BUF_LEN]; //发送：此buf存储待发送数据，接收：此buf存储到来的数据
int operationType; //记录完成的请求类型：是接收？是发送? 还是连接？
int no;
}PER_IO_DATA, *LPPER_IO_DATA;
SOCKET SocketInitBindListen()
{
SOCKET s = socket(AF_INET, SOCK_STREAM, 0);
if(INVALID_SOCKET == s)
{
std::cout<<"create socket failed : "<<GetLastError()<<std::endl;
return INVALID_SOCKET;
}
SOCKADDR_IN addr;
addr.sin_family = AF_INET;
addr.sin_addr.S_un.S_addr = INADDR_ANY;
addr.sin_port = htons(4445);
int ret = bind(s, (sockaddr*)&addr, sizeof(addr));
if(SOCKET_ERROR == ret)
{
std::cout<<"bind failed : "<<GetLastError()<<std::endl;
return SOCKET_ERROR;
}
ret = listen(s, 10);
if(SOCKET_ERROR == s)
{
std::cout<<"listen fail : "<<GetLastError()<<std::endl;
return SOCKET_ERROR;
}
return s;
}
bool PostAccept(SOCKET listenSocket)
{
SOCKET cs = socket(AF_INET, SOCK_STREAM, 0);
if(INVALID_SOCKET == cs)
{
std::cout<<"Create Socket Failed : "<<GetLastError()<<std::endl;
return false;
}
LPPER_IO_DATA ppiod = new PER_IO_DATA;
ZeroMemory(&(ppiod->overlapped), sizeof(OVERLAPPED));
ppiod->operationType = OP_ACCEPT;
ppiod->cs = cs;
DWORD dwRecv;
int len = sizeof(sockaddr_in) + 16;
bool ret = AcceptEx(listenSocket, ppiod->cs, ppiod->buf, 0, len, len, &dwRecv, &ppiod->overlapped);
if(false == ret && ERROR_IO_PENDING != GetLastError())
{
std::cout<<"AcceptEx Failed : "<<GetLastError()<<std::endl;
return false;
}
return true;
}
bool PostSend(SOCKET s, const char *buf, int len)
{
LPPER_IO_DATA ppiod = new PER_IO_DATA;
ZeroMemory(&(ppiod->overlapped), sizeof(OVERLAPPED));
ppiod->operationType = OP_SEND;
memset(ppiod->buf, 0, BUF_LEN);
memcpy(ppiod->buf, buf, len);
WSABUF databuf;
databuf.buf = ppiod->buf;
databuf.len = len;
DWORD dwRecv = 0;
DWORD dwFlags = 0;
WSASend(s, &databuf, 1, &dwRecv, dwFlags, &ppiod->overlapped, NULL);
return true;
}
bool PostRecv(SOCKET s, int n)
{
LPPER_IO_DATA ppiod = new PER_IO_DATA;
ZeroMemory(&(ppiod->overlapped), sizeof(OVERLAPPED));
ppiod->operationType = OP_RECV;
ppiod->no = n;
memset(ppiod->buf, 0, BUF_LEN);
WSABUF databuf;
databuf.buf = ppiod->buf;
databuf.len = BUF_LEN;
DWORD dwRecv = 0;
DWORD dwFlags = 0;
int ret = WSARecv(s, &databuf, 1, &dwRecv, &dwFlags, &ppiod->overlapped, NULL);
if(SOCKET_ERROR == ret && WSA_IO_PENDING != GetLastError())
return false;
return true;
}
unsigned int __stdcall Func(void *arg)
{
SOCKET s = (SOCKET)arg;
Sleep(3000);
std::string str = "nihaihaoma";
PostSend(s, str.c_str(), str.length());
_endthreadex(0);
return 0;
}
unsigned int __stdcall ThreadFunc(void *arg)
{
HANDLE hcp = (HANDLE)arg;
if(NULL == hcp)
{
std::cout<<"thread arg error"<<std::endl;
return -1;
}
DWORD dwNum = 0;
LPPER_HANDLE_DATA pphd;
LPPER_IO_DATA ppiod;
while(true)
{
bool ret = GetQueuedCompletionStatus(hcp, &dwNum, (LPDWORD)&pphd, (LPOVERLAPPED*)&ppiod, WSA_INFINITE);
//线程退出控制，没有释放申请的堆空间，还不完善
if(-1 == dwNum)
{
std::cout<<"Thread Exit"<<std::endl;
_endthreadex(0);
return 0;
}
int type = ppiod->operationType;
//连接关闭
if(dwNum == 0 && type != OP_ACCEPT)
{
std::cout<<"The Connection Be Closed: "<<GetLastError()<<std::endl;
std::cout<<"ret="<<ret<<" operateType="<<ppiod->operationType<<" no="<<ppiod->no<<std::endl;
closesocket(pphd->s);
delete pphd;
delete ppiod;
continue;
}
//其他错误
if(false == ret)
{
std::cout<<"An Error Occurs : "<<GetLastError()<<std::endl;
closesocket(pphd->s);
delete pphd;
delete ppiod;
continue;
}
if(OP_RECV == type)
{
//
std::cout<<"接收完成"<<std::endl;
std::cout<<"接收端口号 ："<<pphd->s<<std::endl;
//
}
else if(OP_SEND == type)
{
//
std::cout<<"发送完成"<<std::endl;
std::cout<<"完成发送的端口号 : "<<pphd->s<<std::endl;
//
Sleep(8000);
DWORD errcode;
ZeroMemory(&(ppiod->overlapped), sizeof(OVERLAPPED));
ppiod->operationType = OP_RECV;
WSABUF databuf;
databuf.buf = ppiod->buf;
databuf.len = BUF_LEN;
DWORD dwRecv = 0;
DWORD dwFlags = 0;
std::cout<<"开始投递WSARecv"<<std::endl;
int ret = WSARecv(ppiod->cs, &databuf, 1, &dwRecv, &dwFlags, &ppiod->overlapped, NULL);
if(SOCKET_ERROR == ret && (errcode = GetLastError()) != WSA_IO_PENDING)
std::cout<<"WSARecv Error: "<<errcode<<std::endl;
else
std::cout<<"成功"<<std::endl;
}
else if(OP_ACCEPT == type)
{
//
std::cout<<"连接完成"<<std::endl;
//
SOCKET cs = ppiod->cs;
int len = sizeof(sockaddr_in) + 16;
int localLen, remoteLen;
LPSOCKADDR localAddr, remoteAddr;
GetAcceptExSockaddrs(ppiod->buf, 0, len, len, (SOCKADDR **)&localAddr, &localLen, (SOCKADDR **)&remoteAddr, &remoteLen);
LPPER_HANDLE_DATA p = new PER_HANDLE_DATA;
p->s = cs;
memcpy(&p->addr, remoteAddr, remoteLen);
char *ch = inet_ntoa(p->addr.sin_addr);
CreateIoCompletionPort((HANDLE)cs, hcp, (DWORD)p, 0);
ZeroMemory(&(ppiod->overlapped), sizeof(OVERLAPPED));
ppiod->operationType = OP_SEND;
ppiod->no = 0;
std::string str = "nihaihaoma";
strcpy(ppiod->buf, str.c_str());
WSABUF databuf;
databuf.buf = ppiod->buf;
databuf.len = str.length();
DWORD dwRecv = 0;
DWORD dwFlags = 0;
WSASend(cs, &databuf, 1, &dwRecv, dwFlags, &ppiod->overlapped, NULL);
PostAccept(pphd->s);
PostAccept(pphd->s);
}
}
return 0;
}
int main()
{
WSADATA ws;
if(WSAStartup(MAKEWORD(2, 2), &ws) != 0)
{
std::cout<<"WSAStartup error : "<<GetLastError()<<std::endl;
return -1;
}
HANDLE hcp = CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, 0);
if(NULL == hcp)
{
std::cout<<"create completion port failed : "<<GetLastError()<<std::endl;
return -1;
}
std::set<HANDLE> setWorkers;
SYSTEM_INFO si;
GetSystemInfo(&si);
for(int i = 0; i < si.dwNumberOfProcessors * 2 + 2; i++)
{
HANDLE worker = (HANDLE)_beginthreadex(NULL, 0, ThreadFunc, (LPVOID)hcp, 0, NULL);
if(NULL == worker)
{
std::cout<<"create thread failed : "<<GetLastError()<<std::endl;
return -1;
}
setWorkers.insert(worker);
}
SOCKET s = SocketInitBindListen();
if(INVALID_SOCKET == s)
{
std::cout<<"socket init failed"<<std::endl;
return -1;
}
LPPER_HANDLE_DATA pphd = (LPPER_HANDLE_DATA)GlobalAlloc(GPTR, sizeof(PER_HANDLE_DATA));
pphd->s = s;
CreateIoCompletionPort((HANDLE)s, hcp, (DWORD)pphd, 0);
bool ret = PostAccept(s);
if(false == ret)
{
std::cout<<"PostAccept Failed"<<std::endl;
return -1;
}
//退出控制
/*std::cin.get();
for(int i = 0; i < setWorkers.size(); i++)
PostQueuedCompletionStatus(hcp, -1, NULL, NULL);*/
auto iter = setWorkers.begin();
for(; iter != setWorkers.end(); iter++)
WaitForSingleObject(*iter, INFINITE);
WSACleanup();
std::cin.get();
return 0;
}