IOCP底层，支持超过15000个连接

#pragma comment(lib,"ws2_32.lib")
#include <winsock2.h>
#include <stdio.h>
//////////////////////////////////////////////////////////////////////////
// 仅供测试软件用


#define DATA_BUFSIZE 1024        // 接收缓冲区大小
typedef enum{ IOSEND,IORECV,IOQUIT } IO_TYPE;
typedef struct _SOCKET_INFORMATION {
OVERLAPPED Overlapped;
SOCKET        Socket;
IO_TYPE  IoType;
char                buffer[DATA_BUFSIZE];
WSABUF        DataBuf;
DWORD        BytesSEND;
DWORD        BytesRECV;
} SOCKET_INFORMATION, * LPSOCKET_INFORMATION;
DWORD   Flags = 0,
Bytes = 0;
DWORD WINAPI WorkThread(LPVOID CompletionPortID);
DWORD WINAPI AcceptThread(LPVOID lpParameter)
{
WSADATA wsaData;
HANDLE hCompPort;
DWORD ThreadID;
DWORD Ret;
if ((Ret = WSAStartup(0x0202, &wsaData)) != 0)
  {
printf("WSAStartup failed with error %d\n", Ret);
return FALSE;
  }
if ((hCompPort = CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, 0)) == NULL)
  {
printf( "CreateIoCompletionPort failed with error: %d\n", GetLastError());
return FALSE;
  }
// 根据CPU个数来创建线程，以达到最佳性能
SYSTEM_INFO SystemInfo;
GetSystemInfo(&SystemInfo);
for(unsigned int i=0; i<SystemInfo.dwNumberOfProcessors*2; i++)
  {
HANDLE ThreadHandle;
if ((ThreadHandle = CreateThread(NULL, 0, WorkThread, hCompPort, 0, &ThreadID)) == NULL)
    {
printf("CreateThread() failed with error %d\n", GetLastError());
return FALSE;
    }
CloseHandle(ThreadHandle);
  }
SOCKET ListenSocket = WSASocket(AF_INET, SOCK_STREAM, IPPROTO_TCP, NULL, NULL, WSA_FLAG_OVERLAPPED);
SOCKADDR_IN ServerAddr;
ServerAddr.sin_family = AF_INET;
ServerAddr.sin_addr.S_un.S_addr = htonl(INADDR_ANY);
ServerAddr.sin_port = htons(7999);
bind(ListenSocket,(LPSOCKADDR)&ServerAddr,sizeof(ServerAddr));
listen(ListenSocket,100);
printf("listenning...\n");
SOCKADDR_IN ClientAddr;
int addr_length=sizeof(ClientAddr);
while (TRUE)
  {
LPSOCKET_INFORMATION  SI = new SOCKET_INFORMATION;
if ((SI->Socket = accept(ListenSocket,(SOCKADDR*)&ClientAddr, &addr_length)) != INVALID_SOCKET)
    {
printf("accept ip:%s port:%d\n",inet_ntoa(ClientAddr.sin_addr),ClientAddr.sin_port);
// 相关参数初始化
memset(&SI->Overlapped,0,sizeof(WSAOVERLAPPED));
memset(SI->buffer, 0, DATA_BUFSIZE);
SI->DataBuf.buf = SI->buffer;
SI->DataBuf.len = DATA_BUFSIZE;
SI->BytesRECV        = 0;
SI->BytesSEND        = 0;
SI->IoType           = IORECV;


if (CreateIoCompletionPort((HANDLE)SI->Socket, hCompPort, (DWORD)SI, 0) == NULL)
      {
printf("CreateIoCompletionPort failed with error %d\n", GetLastError());
return FALSE;
      }
// 发出一个重叠I\O请求
if(WSARecv(SI->Socket, &SI->DataBuf, 1, &Bytes, &Flags, &SI->Overlapped, NULL) == SOCKET_ERROR)
      {
if(WSAGetLastError() != WSA_IO_PENDING)
        {
printf("disconnect\n");
closesocket(SI->Socket); 
delete SI;
continue;
        }
      }
    }


  }
return FALSE;
}
DWORD WINAPI WorkThread(LPVOID CompletionPortID)
{
HANDLE hCompPort = (HANDLE)CompletionPortID;
while (TRUE)
  {
DWORD BytesTransferred = 0;
LPSOCKET_INFORMATION SI = NULL;
LPWSAOVERLAPPED Overlapped = NULL;
// 线程进入线程池，等待被唤醒
if (GetQueuedCompletionStatus(hCompPort, &BytesTransferred, (LPDWORD)&SI, &Overlapped, INFINITE))
    {
if (0 == BytesTransferred && IOQUIT != SI->IoType)
      {
printf("disconnect\n");
closesocket(SI->Socket); 
delete SI;
continue;
      }
switch(SI->IoType)
      {
case IORECV:
        {
printf("%s \n", SI->buffer);
// 目前的功能是将接收到的数据原封不动的返回
SI->DataBuf.len = BytesTransferred;
SI->BytesRECV = BytesTransferred;
SI->IoType = IOSEND;
if (WSASend(SI->Socket, &SI->DataBuf, 1, &Bytes, Flags, &SI->Overlapped, NULL) == SOCKET_ERROR)
          {
if(WSAGetLastError() != WSA_IO_PENDING)
            {
printf("disconnect\n");
closesocket(SI->Socket); 
delete SI;
continue;
            }
          }
break;
        }
case IOSEND:
        {
SI->BytesSEND += BytesTransferred;


//返回是否彻底，若未发完，接着发
if (SI->BytesSEND < SI->BytesRECV)
          {
SI->DataBuf.buf += BytesTransferred; 
SI->DataBuf.len -= BytesTransferred; 
SI->IoType = IOSEND;
if (WSASend(SI->Socket, &SI->DataBuf, 1, &Bytes, Flags, &SI->Overlapped, NULL) == SOCKET_ERROR)
            {
if(WSAGetLastError() != WSA_IO_PENDING)
              {
printf("disconnect\n");
closesocket(SI->Socket); 
delete SI;
continue;
              }
            }
          }
else if (SI->BytesSEND > SI->BytesRECV)
          {
printf("BytesSEND:%d > BytesRECV:%d\n",SI->BytesSEND,SI->BytesRECV);
memset(SI->buffer, 0, DATA_BUFSIZE);
SI->BytesRECV = 0;
SI->BytesSEND = 0;


SI->IoType = IORECV;
SI->DataBuf.len = DATA_BUFSIZE;
SI->DataBuf.buf = SI->buffer;
          }
else
          {
memset(SI->buffer, 0, DATA_BUFSIZE);
SI->BytesRECV = 0;
SI->BytesSEND = 0;
SI->IoType = IORECV;
SI->DataBuf.len = DATA_BUFSIZE;
SI->DataBuf.buf = SI->buffer;
if (WSARecv(SI->Socket, &SI->DataBuf, 1, &Bytes, &Flags, &SI->Overlapped, NULL) == SOCKET_ERROR)
            {
if(WSAGetLastError() != WSA_IO_PENDING)
              {
printf("disconnect\n");
closesocket(SI->Socket); 
delete SI;
continue;
              }
            }
          }
break;
        }


case IOQUIT:
        {
// 让线程安全退出
return FALSE;
break;
        }


default:
break;
      }
    }        
  }        
return FALSE;
}
void main()   
{
HANDLE hThreads = CreateThread(NULL, 0, AcceptThread, NULL, NULL, NULL); 


WaitForSingleObject(hThreads,INFINITE);
printf("exit\n");
CloseHandle(hThreads);
}