#include <winsock2.h>
#include <stdio.h>
#define PORT 5150
#define MSGSIZE 1024
#pragma comment(lib, "ws2_32.lib")
typedef struct
{
 WSAOVERLAPPED overlap;//为了使用重叠I/O，每一个I/O函数都要接受一个WSAOVERLAPPED结构类型的参数

WSABUF Buffer;
 char szMessage[MSGSIZE];
 DWORD NumberOfBytesRecvd;
 DWORD Flags;
}PER_IO_OPERATION_DATA, *LPPER_IO_OPERATION_DATA;
int g_iTotalConn = 0;
SOCKET g_CliSocketArr[MAXIMUM_WAIT_OBJECTS];
WSAEVENT g_CliEventArr[MAXIMUM_WAIT_OBJECTS];
LPPER_IO_OPERATION_DATA g_pPerIODataArr[MAXIMUM_WAIT_OBJECTS];
DWORD WINAPI WorkerThread(LPVOID);
void Cleanup(int);
int main()
{
 WSADATA wsaData;
 SOCKET sListen, sClient;
 SOCKADDR_IN local, client;
 DWORD dwThreadId;
 int iaddrSize = sizeof(SOCKADDR_IN);
 // Initialize Windows Socket library

WSAStartup(0x0202, &wsaData);
 // Create listening socket

sListen = ::WSASocket(AF_INET, SOCK_STREAM, IPPROTO_TCP,NULL,0,WSA_FLAG_OVERLAPPED);
 // Bind

local.sin_addr.S_un.S_addr = htonl(INADDR_ANY);
 local.sin_family = AF_INET;
 local.sin_port = htons(PORT);
 bind(sListen, (struct sockaddr *)&local, sizeof(SOCKADDR_IN));
 // Listen

listen(sListen, 3);
 // Create worker thread

CreateThread(NULL, 0, WorkerThread, NULL, 0, &dwThreadId);
 while (TRUE)
 {
  // Accept a connection

sClient = accept(sListen, (struct sockaddr *)&client, &iaddrSize);
  printf("Accepted client:%s:%d\n", inet_ntoa(client.sin_addr), ntohs(client.sin_port));
  g_CliSocketArr[g_iTotalConn] = sClient;
  // Allocate a PER_IO_OPERATION_DATA structure

g_pPerIODataArr[g_iTotalConn] = (LPPER_IO_OPERATION_DATA)HeapAlloc(
   GetProcessHeap(),
   HEAP_ZERO_MEMORY,
   sizeof(PER_IO_OPERATION_DATA));
  g_pPerIODataArr[g_iTotalConn]->Buffer.len = MSGSIZE;
  g_pPerIODataArr[g_iTotalConn]->Buffer.buf = g_pPerIODataArr[g_iTotalConn]->szMessage;
  g_CliEventArr[g_iTotalConn] = g_pPerIODataArr[g_iTotalConn]->overlap.hEvent = WSACreateEvent();
  // Launch an asynchronous operation(发起一个异步的I/O操作)

//This function receives data from a connected socket.

WSARecv(
   g_CliSocketArr[g_iTotalConn],//Socket的标示

&g_pPerIODataArr[g_iTotalConn]->Buffer,//接收数据的Buffer

1,
   &g_pPerIODataArr[g_iTotalConn]->NumberOfBytesRecvd,//Pointer to the number of bytes received by this call if the receive operation completes immediately

&g_pPerIODataArr[g_iTotalConn]->Flags,
   &g_pPerIODataArr[g_iTotalConn]->overlap,//LPWSAOVERLAPPED结构的参数

NULL);
  g_iTotalConn++;
 }
 closesocket(sListen);
 WSACleanup();
 return 0;
}
DWORD WINAPI WorkerThread(LPVOID lpParam)
{
 int ret, index;
 DWORD cbTransferred;
 while (TRUE)
 {
  ret = WSAWaitForMultipleEvents(g_iTotalConn, g_CliEventArr, FALSE, 1000, FALSE);
  //注意这里应该有相应的修正的地方，WSAWaitForMultipleEvents函数在fWaitAll设置成FALSE

//的时候只能指定一个事件对象受信，解决方法使用for循环进行循环检测

if (ret == WSA_WAIT_FAILED || ret == WSA_WAIT_TIMEOUT)
  {
   continue;
  }
  index = ret - WSA_WAIT_EVENT_0;
  WSAResetEvent(g_CliEventArr[index]);
  //获得重叠I/O的操作的结果

WSAGetOverlappedResult(
   g_CliSocketArr[index],
   &g_pPerIODataArr[index]->overlap,
   &cbTransferred,
   TRUE,
   &g_pPerIODataArr[g_iTotalConn]->Flags);
  if (cbTransferred == 0)
  {
   // The connection was closed by client

Cleanup(index);
  }
  else
  {
   // g_pPerIODataArr[index]->szMessage contains the received data

g_pPerIODataArr[index]->szMessage[cbTransferred] = '\0';
   //这个是同步的I/O的操作哦

send(g_CliSocketArr[index], g_pPerIODataArr[index]->szMessage,\
    cbTransferred, 0);
   // Launch another asynchronous operation

WSARecv(
    g_CliSocketArr[index],
    &g_pPerIODataArr[index]->Buffer,
    1,
    &g_pPerIODataArr[index]->NumberOfBytesRecvd,
    &g_pPerIODataArr[index]->Flags,
    &g_pPerIODataArr[index]->overlap,
    NULL);
  }
 }
 return 0;
}
void Cleanup(int index)
{
 closesocket(g_CliSocketArr[index]);
 WSACloseEvent(g_CliEventArr[index]);
 HeapFree(GetProcessHeap(), 0, g_pPerIODataArr[index]);
 if (index < g_iTotalConn - 1)
 {
  g_CliSocketArr[index] = g_CliSocketArr[g_iTotalConn - 1];
  g_CliEventArr[index] = g_CliEventArr[g_iTotalConn - 1];
  g_pPerIODataArr[index] = g_pPerIODataArr[g_iTotalConn - 1];
 }
 g_pPerIODataArr[--g_iTotalConn] = NULL;
}