见到的一篇IOCP流程 自己用demo实现了一下， 简单照抄，改动了一点点

要分析的实例分为两个线程：


分别是主线程(MAIN),还有一个是创建的线程(ServerThread)


1.主函数完成初始化工作:
  1.1: (主线程)HANDLE hCompletion = ::CreateIoCompletionPort(INVALID_HANDLE_VALUE, 0, 0, 0);    创建完成端口对象
  1.2: (主线程)::CreateThread(NULL, 0, ServerThread, (LPVOID)hCompletion, 0, 0);   创建线程用于接收等
  1.3：(主线程)调用socket(),SOCKADDR_IN,bind(),listen()，初始化套接字
  1.4: (线程函数)HANDLE hCompletion = (HANDLE)lpParam;   通过线程参数得到完成端口对象
  1.5: (线程函数) while(TRUE)     定义循环  循环等待套接字上发生事件
  1.6：(线程函数) ::GetQueuedCompletionStatus() 在关联到此完成端口的所有套节字上等待I/O完成
  1.7: (主线程) SOCKADDR_IN saRemote; SOCKET sNew = ::accept(sListen, (sockaddr*)&saRemote, &nRemoteLen); 为新连接建立结构并等待连接请求


2.有连接发生:
  2.1: (主线程while循环中) PPER_HANDLE_DATA pPerHandle = (PPER_HANDLE_DATA)::GlobalAlloc(GPTR, sizeof(PER_HANDLE_DATA));
                           创建PPER_HANDLE_DATA结构 
  2.2: (主线程while循环中) ::CreateIoCompletionPort((HANDLE)pPerHandle->s, hCompletion, (DWORD)pPerHandle, 0);
    完成 完成端口 与 套接字关联
  2.3: (主线程while循环中)    给pPerIO结构   添加类型
PPER_IO_DATA pPerIO = (PPER_IO_DATA)::GlobalAlloc(GPTR, sizeof(PER_IO_DATA));
pPerIO->nOperationType = OP_READ;
WSABUF buf;
buf.buf = pPerIO->buf;
buf.len = BUFFER_SIZE;
DWORD dwRecv;
DWORD dwFlags = 0;
  2.4: (主线程while循环中) ::WSARecv(pPerHandle->s, &buf, 1, &dwRecv, &dwFlags, &pPerIO->ol, NULL);     发送异步接收请求
  2.5: (主线程while循环中)  回到WHILE循环accept()函数处  等待新连接
  2.6: (线程函数while循环中)GetQueuedCompletionStatus() 此时I/O完成 开始处理消息
  2.7: (线程函数while循环中)pPerIO->nOperationType  通过类型判断  消息类型
  2.7：(线程函数while循环中)打印接收的消息  并在此投递  一个完成端口
pPerIO->buf[dwTrans] = '\0';
printf(pPerIO -> buf);

WSABUF buf;
buf.buf = pPerIO->buf ;
buf.len = BUFFER_SIZE;
pPerIO->nOperationType = OP_READ;
DWORD nFlags = 0;
printf("12\n");
::WSARecv(pPerHandle->s, &buf, 1, &dwTrans, &nFlags, &pPerIO->ol, NULL);
  2.8：(线程函数while循环中)  由于又有端口I/O完成 ::GetQueuedCompletionStatus()函数  继续判断并处理
  2.9：(线程函数while循环中)  由于没有数据 GetQueuedCompletionStatus()返回值为错误  调用一下函数关闭
::closesocket(pPerHandle->s);
::GlobalFree(pPerHandle);
::GlobalFree(pPerIO);

  2.10:(线程函数while循环中)  在此回到while循环 调用::GetQueuedCompletionStatus()函数  继续等待

// iocpTP.cpp : Defines the entry point for the console application.
//


#include "stdafx.h"


#include <stdio.h>
#include <windows.h>


// 初始化Winsock库
#include <winsock2.h>
#pragma comment(lib,"WS2_32.lib") // 






#define BUFFER_SIZE 1024


typedef struct _PER_HANDLE_DATA // per-handle数据
{
SOCKET s; // 对应的套节字句柄
sockaddr_in addr;// 客户方地址
} PER_HANDLE_DATA, *PPER_HANDLE_DATA;




typedef struct _PER_IO_DATA // per-I/O数据
{
OVERLAPPED ol;// 重叠结构
char buf[BUFFER_SIZE];// 数据缓冲区
int nOperationType;// 操作类型
#define OP_READ   1
#define OP_WRITE  2
#define OP_ACCEPT 3
} PER_IO_DATA, *PPER_IO_DATA;




DWORD WINAPI ServerThread(LPVOID lpParam)
{
// 得到完成端口对象句柄
HANDLE hCompletion = (HANDLE)lpParam;
printf("ServerThread Processor\n");
DWORD dwTrans;
PPER_HANDLE_DATA pPerHandle;
PPER_IO_DATA pPerIO;
while(TRUE)
{
// 在关联到此完成端口的所有套节字上等待I/O完成
printf("wait GetQueuedCompletionStatus  Done \n");
BOOL bOK = ::GetQueuedCompletionStatus(hCompletion, 
&dwTrans, (LPDWORD)&pPerHandle, (LPOVERLAPPED*)&pPerIO, WSA_INFINITE);
if(!bOK) // 在此套节字上有错误发生
{
printf("9\n");
::closesocket(pPerHandle->s);
::GlobalFree(pPerHandle);
::GlobalFree(pPerIO);
continue;
}

if(dwTrans == 0 &&// 套节字被对方关闭
(pPerIO->nOperationType == OP_READ || pPerIO->nOperationType == OP_WRITE))

{
printf("10\n");
::closesocket(pPerHandle->s);
::GlobalFree(pPerHandle);
::GlobalFree(pPerIO);
continue;
}
printf("11\n");
switch(pPerIO->nOperationType)// 通过per-I/O数据中的nOperationType域查看什么I/O请求完成了
{
case OP_READ: // 完成一个接收请求
{
pPerIO->buf[dwTrans] = '\0';
printf(pPerIO -> buf);

// 继续投递接收I/O请求
WSABUF buf;
buf.buf = pPerIO->buf ;
buf.len = BUFFER_SIZE;
pPerIO->nOperationType = OP_READ;


DWORD nFlags = 0;
printf("12\n");
::WSARecv(pPerHandle->s, &buf, 1, &dwTrans, &nFlags, &pPerIO->ol, NULL);

}
break;
case OP_WRITE: // 本例中没有投递这些类型的I/O请求
{
WSABUF buf;
buf.buf = pPerIO->buf ;
buf.len = BUFFER_SIZE;
pPerIO->nOperationType = OP_READ;
DWORD nFlags = 0;
::WSASend(pPerHandle->s, &buf, 1, &dwTrans, nFlags, &pPerIO->ol, NULL);
}
break;
case OP_ACCEPT:
{
}
break;
}
}
return 0;
}




void main()
{
// 初始化WS2_32.dll
BYTE minorVer = 0x02;
BYTE majorVer = 0x02;
WSADATA wsaData;
WORD sockVersion = MAKEWORD(minorVer, majorVer);
if(::WSAStartup(sockVersion, &wsaData) != 0)
{
}
int nPort = 5000;
// 创建完成端口对象，创建工作线程处理完成端口对象中事件
printf("Init NetWork\n");
HANDLE hCompletion = ::CreateIoCompletionPort(INVALID_HANDLE_VALUE, 0, 0, 0);
printf("CreateIoCompletionPort Done\n");
::CreateThread(NULL, 0, ServerThread, (LPVOID)hCompletion, 0, 0);
printf("Create Server Thread \n");
// 创建监听套节字，绑定到本地地址，开始监听
SOCKET sListen = ::socket(AF_INET, SOCK_STREAM, 0);
SOCKADDR_IN si;
si.sin_family = AF_INET;
si.sin_port = ::ntohs(nPort);
si.sin_addr.S_un.S_addr = INADDR_ANY;
::bind(sListen, (sockaddr*)&si, sizeof(si));
::listen(sListen, 5);


printf("Start Listen \n");
// 循环处理到来的连接
while(TRUE)
{
// 等待接受未决的连接请求
printf("Wait for Connect...\n");
SOCKADDR_IN saRemote;
int nRemoteLen = sizeof(saRemote);
SOCKET sNew = ::accept(sListen, (sockaddr*)&saRemote, &nRemoteLen);


// 接受到新连接之后，为它创建一个per-handle数据，并将它们关联到完成端口对象。
PPER_HANDLE_DATA pPerHandle = 
(PPER_HANDLE_DATA)::GlobalAlloc(GPTR, sizeof(PER_HANDLE_DATA));
pPerHandle->s = sNew;
memcpy(&pPerHandle->addr, &saRemote, nRemoteLen);
::CreateIoCompletionPort((HANDLE)pPerHandle->s, hCompletion, (DWORD)pPerHandle, 0);
printf("Accept connect , assigned a CreateIoCompletionPort \n");
// 投递一个接收请求
PPER_IO_DATA pPerIO = (PPER_IO_DATA)::GlobalAlloc(GPTR, sizeof(PER_IO_DATA));
pPerIO->nOperationType = OP_READ;
WSABUF buf;
buf.buf = pPerIO->buf;
buf.len = BUFFER_SIZE;
DWORD dwRecv;
DWORD dwFlags = 0;
printf(" Mail a request!!! \n");
::WSARecv(pPerHandle->s, &buf, 1, &dwRecv, &dwFlags, &pPerIO->ol, NULL);
}


::WSACleanup();
}

测试程序:

//
// TCPClient.cppÎļþ
#include <stdio.h>
#include <winsock2.h>
#pragma comment(lib, "ws2_32.lib")


int main()
{
BYTE minorVer = 0x02;
BYTE majorVer = 0x02;
//WS2_32.dll
WSADATA wsaData;
WORD sockVersion = MAKEWORD(minorVer, majorVer);
if(::WSAStartup(sockVersion, &wsaData) != 0)
{
exit(0);
}


// ´´½¨Ì×½Ú×Ö
SOCKET s = ::socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if(s == INVALID_SOCKET)
{
printf(" Failed socket() \n");
return 0;
}

// Ò²¿ÉÒÔÔÚÕâÀïµ÷ÓÃbindº¯Êý°ó¶¨Ò»¸ö±¾µØµØÖ·
// ·ñÔòϵͳ½«»á×Ô¶¯°²ÅÅ

// ÌîдԶ³ÌµØÖ·ÐÅÏ¢
sockaddr_in servAddr; 
servAddr.sin_family = AF_INET;
servAddr.sin_port = htons(5000);
// ×¢Ò⣬ÕâÀïÒªÌîд·þÎñÆ÷³ÌÐò£¨TCPServer³ÌÐò£©ËùÔÚ»úÆ÷µÄIPµØÖ·
// Èç¹ûÄãµÄ¼ÆËã»úûÓÐÁªÍø£¬Ö±½ÓʹÓÃ127.0.0.1¼´¿É
servAddr.sin_addr.S_un.S_addr = inet_addr("127.0.0.1");

if(::connect(s, (sockaddr*)&servAddr, sizeof(servAddr)) == -1)
{
printf(" Failed connect() \n");
return 0;
}

// ·¢ËÍÊý¾Ý
send(s,"dddd",sizeof("dddd"),0);
// ½ÓÊÕÊý¾Ý
char buff[256];
int nRecv = ::recv(s, buff, 256, 0);
if(nRecv > 0)
{
buff[nRecv] = '\0';
printf(" ½ÓÊÕµ½Êý¾Ý£º%s", buff);
}

// ¹Ø±ÕÌ×½Ú×Ö
::closesocket(s);


::WSACleanup();
return 0;
}