c++ 网络编程（九）TCP/IP LINUX/windows--使用IOCP模型 多线程超详细教程 以及 多线程实现服务端

#include <iostream>
// 必须的头文件
#include <pthread.h>
 
using namespace std;
 
#define NUM_THREADS 5
 
// 线程的运行函数
void* say_hello(void* args)
{
    cout << "Hello Runoob！" << endl;
    return 0;
}
 
int main()
{
    // 定义线程的 id 变量，多个变量使用数组
    pthread_t tids[NUM_THREADS];
    for(int i = 0; i < NUM_THREADS; ++i)
    {
        //参数依次是：创建的线程id，线程参数，调用的函数，传入的函数参数
        int ret = pthread_create(&tids[i], NULL, say_hello, NULL);
        if (ret != 0)
        {
           cout << "pthread_create error: error_code=" << ret << endl;
        }
    }
    //等各个线程退出后，进程才结束，否则进程强制结束了，线程可能还没反应过来；
    pthread_exit(NULL);
}

//文件名：test.cpp
 
#include <iostream>
#include <cstdlib>
#include <pthread.h>
 
using namespace std;
 
#define NUM_THREADS     5
 
void *PrintHello(void *threadid)
{  
   // 对传入的参数进行强制类型转换，由无类型指针变为整形数指针，然后再读取
   int tid = *((int*)threadid);
   cout << "Hello Runoob! 线程 ID, " << tid << endl;
   pthread_exit(NULL);
}
 
int main ()
{
   pthread_t threads[NUM_THREADS];
   int indexes[NUM_THREADS];// 用数组来保存i的值
   int rc;
   int i;
   for( i=0; i < NUM_THREADS; i++ ){      
      cout << "main() : 创建线程, " << i << endl;
      indexes[i] = i; //先保存i的值
      // 传入的时候必须强制转换为void* 类型，即无类型指针        
      rc = pthread_create(&threads[i], NULL, 
                          PrintHello, (void *)&(indexes[i]));
      if (rc){
         cout << "Error:无法创建线程," << rc << endl;
         exit(-1);
      }
   }
   pthread_exit(NULL);
}

#include <iostream>
#include <cstdlib>
#include <pthread.h>
 
using namespace std;
 
#define NUM_THREADS     5
 
struct thread_data{
   int  thread_id;
   char *message;
};
 
void *PrintHello(void *threadarg)
{
   struct thread_data *my_data;
 
   my_data = (struct thread_data *) threadarg;
 
   cout << "Thread ID : " << my_data->thread_id ;
   cout << " Message : " << my_data->message << endl;
 
   pthread_exit(NULL);
}
 
int main ()
{
   pthread_t threads[NUM_THREADS];
   struct thread_data td[NUM_THREADS];
   int rc;
   int i;
 
   for( i=0; i < NUM_THREADS; i++ ){
      cout <<"main() : creating thread, " << i << endl;
      td[i].thread_id = i;
      td[i].message = (char*)"This is message";
      rc = pthread_create(&threads[i], NULL,
                          PrintHello, (void *)&td[i]);
      if (rc){
         cout << "Error:unable to create thread," << rc << endl;
         exit(-1);
      }
   }
   pthread_exit(NULL);
}

#include <iostream>
#include <cstdlib>
#include <pthread.h>
#include <unistd.h>
 
using namespace std;
 
#define NUM_THREADS     5
 
void *wait(void *t)
{
   int i;
   long tid;
 
   tid = (long)t;
 
   sleep(1);
   cout << "Sleeping in thread " << endl;
   cout << "Thread with id : " << tid << "  ...exiting " << endl;
   pthread_exit(NULL);
}
 
int main ()
{
   int rc;
   int i;
   pthread_t threads[NUM_THREADS];
   pthread_attr_t attr;
   void *status;
 
   // 初始化并设置线程为可连接的（joinable）
   pthread_attr_init(&attr);
   pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
 
   for( i=0; i < NUM_THREADS; i++ ){
      cout << "main() : creating thread, " << i << endl;
      rc = pthread_create(&threads[i], NULL, wait, (void *)&i );
      if (rc){
         cout << "Error:unable to create thread," << rc << endl;
         exit(-1);
      }
   }
 
   // 删除属性，并等待其他线程
   pthread_attr_destroy(&attr);
   for( i=0; i < NUM_THREADS; i++ ){
      rc = pthread_join(threads[i], &status);
      if (rc){
         cout << "Error:unable to join," << rc << endl;
         exit(-1);
      }
      cout << "Main: completed thread id :" << i ;
      cout << "  exiting with status :" << status << endl;
   }
 
   cout << "Main: program exiting." << endl;
   pthread_exit(NULL);
}

main() : creating thread, 0
main() : creating thread, 1
main() : creating thread, 2
main() : creating thread, 3
main() : creating thread, 4
Sleeping in thread 
Thread with id : 4  ...exiting 
Sleeping in thread 
Thread with id : 3  ...exiting 
Sleeping in thread 
Thread with id : 2  ...exiting 
Sleeping in thread 
Thread with id : 1  ...exiting 
Sleeping in thread 
Thread with id : 0  ...exiting 
Main: completed thread id :0  exiting with status :0
Main: completed thread id :1  exiting with status :0
Main: completed thread id :2  exiting with status :0
Main: completed thread id :3  exiting with status :0
Main: completed thread id :4  exiting with status :0
Main: program exiting.

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <pthread.h>
#define NUM_THREAD 100
void * thread_inc(void * arg);
void * thread_des(void * arg);
long long num = 0;   //long long类型是64位整数型，多线程共同访问

int main(int argc, char *argv[])
{
    pthread_t thread_id[NUM_THREAD];
    int i;

    //创建100个线程，一半执行thread_inc,一半执行thread_des
    for(i = 0; i < NUM_THREAD; i++)
    {
        if(i %2)
            pthread_create(&(thread_id[i]), NULL, thread_inc, NULL);
        else
            pthread_create(&(thread_id[i]), NULL, thread_des, NULL);
    }

    //等待线程返回
    for (i = 0; i < NUM_THREAD; i++)
        pthread_join(thread_id[i], NULL);

    printf("result: %lld \n", num);  //+1，-1按道理结果是0
    return 0;
}

//线程入口函数1
void * thread_inc(void * arg)
{
    for (int i = 0; i < 50000000; i++)
        num += 1;//临界区(引起问题的语句就是临界区位置)
    return NULL;
}

//线程入口函数2
void * thread_des(void * arg)
{
    for (int i = 0; i < 50000000; i++)
        num -= 1;//临界区
    return NULL;
}

- **互斥量**  互斥量技术从字面也可以理解，就是临界区有线程访问，其它线程就得排队等待，它们的访问是互斥的，实现方式就是给临界区加锁与释放锁。

#include <pthread.h>

int pthread_mutex_init(pthread_mutex_t *mutex, const pthread_mutexattr_t *attr);  //创建互斥量

int pthread_mutex_destroy(pthread_mutex_t *mutex);//销毁互斥量

int pthread_mutex_lock(pthread_mutex_t *mutex);//加锁

int pthread_mutex_unlock(pthread_mutex_t *mutex);//释放锁

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <pthread.h>
#define NUM_THREAD 100
void * thread_inc(void * arg);
void * thread_des(void * arg);

long long num = 0;
pthread_mutex_t mutex;

int main(int argc, char *argv[])
{
    pthread_t thread_id[NUM_THREAD];
    int i;

    //互斥量的创建
    pthread_mutex_init(&mutex, NULL);

    for(i = 0; i < NUM_THREAD; i++)
    {
        if(i %2)
            pthread_create(&(thread_id[i]), NULL, thread_inc, NULL);
        else
            pthread_create(&(thread_id[i]), NULL, thread_des, NULL);
    }

    for (i = 0; i < NUM_THREAD; i++)
        pthread_join(thread_id[i], NULL);

    printf("result: %lld \n", num);
    pthread_mutex_destroy(&mutex);   //互斥量的销毁
    return 0;
}

/*扩展临界区，减少加锁，释放锁调用次数，但这样变量必须加满到50000000次后其它线程才能访问.
 这样是延长了线程的等待时间，但缩短了加锁，释放锁函数调用的时间，这里没有定论，自己酌情考虑*/
void * thread_inc(void * arg)
{
    pthread_mutex_lock(&mutex);  //互斥量锁住
    for (int i = 0; i < 1000000; i++)
        num += 1;
    pthread_mutex_unlock(&mutex); //互斥量释放锁
    return NULL;
}

/*缩短了线程等待时间，但循环创建，释放锁函数调用时间增加*/
void * thread_des(void * arg)
{
    for (int i = 0; i < 1000000; i++)
    {
        pthread_mutex_lock(&mutex);
        num -= 1;
        pthread_mutex_unlock(&mutex);
    }
    return NULL;
}

#include <semaphore.h>

int sem_init(sem_t *sem, int pshared, unsigned int value);//创建信号量
int sem_destroy(sem_t *sem);//销毁信号量
int sem_post(sem_t *sem);//信号量加1
int sem_wait(sem_t *sem);//信号量减1，为0时阻塞

#include <stdio.h>
#include <pthread.h>
#include <semaphore.h>

void * read(void * arg);
void * accu(void * arg);
static sem_t sem_one;
static sem_t sem_two;
static int num;


int main(int argc, char *argv[])
{
    pthread_t id_t1, id_t2;
    sem_init(&sem_one, 0, 0);
    sem_init(&sem_two, 0, 1);

    pthread_create(&id_t1, NULL, read, NULL);
    pthread_create(&id_t2, NULL, accu, NULL);

    pthread_join(id_t1, NULL);
    pthread_join(id_t2, NULL);

    sem_destroy(&sem_one);
    sem_destroy(&sem_two);

    return 0;
}

void * read(void * arg)
{
    int i;
    for (i = 0; i < 5; i++) {
        fputs("Input num: ", stdout);
        sem_wait(&sem_two);
        scanf("%d", &num);
        sem_post(&sem_one);
    }
    return NULL;
}

void * accu(void * arg)
{
    int sum = 0 , i;
    for (i = 0; i < 5; i++) {
        sem_wait(&sem_one);
        sum+= num;
        sem_post(&sem_two);
    }
    printf("Result: %d \n", sum);
    return NULL;
}

//
//  main.cpp
//  hello_server
//
//  Created by app05 on 15-10-22.
//  Copyright (c) 2015年 app05. All rights reserved.
//临界区是：clnt_cnt和clnt_socks访问处

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <pthread.h>

#define BUF_SIZE 100
#define MAX_CLNT 256

void * handle_clnt(void * arg);
void send_msg(char *msg, int len);
void error_handling(char * msg);
int clnt_cnt = 0;
int clnt_socks[MAX_CLNT];
pthread_mutex_t mutx;

int main(int argc, char *argv[])
{
    int serv_sock, clnt_sock;
    struct sockaddr_in serv_adr, clnt_adr;
    socklen_t clnt_adr_sz;
    pthread_t t_id;
    if (argc != 2) {
        printf("Usage : %s <port> \n", argv[0]);
        exit(1);
    }

    //创建互斥量
    pthread_mutex_init(&mutx, NULL);
    serv_sock = socket(PF_INET, SOCK_STREAM, 0);

    memset(&serv_adr, 0, sizeof(serv_adr));
    serv_adr.sin_family = AF_INET;
    serv_adr.sin_addr.s_addr = htonl(INADDR_ANY);
    serv_adr.sin_port = htons(atoi(argv[1]));

    if(bind(serv_sock, (struct sockaddr *) &serv_adr, sizeof(serv_adr)) == -1)
        error_handling("bind() error");
    if(listen(serv_sock, 5) == -1)
        error_handling("listen() error");

    while (1)
    {
        clnt_adr_sz = sizeof(clnt_adr);
        clnt_sock = accept(serv_sock, (struct sockaddr*)&clnt_adr, &clnt_adr_sz); //阻断，监听客服端连接请求

        //临界区
        pthread_mutex_lock(&mutx); //加锁
        clnt_socks[clnt_cnt++] = clnt_sock; //新连接的客服端保存到clnt_socks数组里
        pthread_mutex_unlock(&mutx); //释放锁

        //创建线程
        pthread_create(&t_id, NULL, handle_clnt, (void*) &clnt_sock);
        pthread_detach(t_id); //销毁线程，线程return后自动调用销毁，不阻断

        printf("Connected client IP: %s \n", inet_ntoa(clnt_adr.sin_addr));
    }

    close(serv_sock);
    return 0;
}

//线程执行
void * handle_clnt(void * arg)
{
    int clnt_sock = *((int *)arg);
    int str_len = 0, i;
    char msg[BUF_SIZE];

    while ((str_len = read(clnt_sock, msg, sizeof(msg))) != 0)
        send_msg(msg, str_len);

    //从数组中移除当前客服端
    pthread_mutex_lock(&mutx);
    for (i = 0; i < clnt_cnt; i++)
    {
        if (clnt_sock == clnt_socks[i])
        {
            while (i++ < clnt_cnt - 1)
                clnt_socks[i] = clnt_socks[i + 1];
            break;
        }
    }
    clnt_cnt--;
    pthread_mutex_unlock(&mutx);
    close(clnt_sock);
    return NULL;
}

//向所有连接的客服端发送消息
void send_msg(char * msg, int len)
{
    int i;
    pthread_mutex_lock(&mutx);
    for (i = 0; i < clnt_cnt; i++)
        write(clnt_socks[i], msg, len);
    pthread_mutex_unlock(&mutx);
}

void error_handling(char *message)
{
    fputs(message, stderr);
    fputc('\n', stderr);
    exit(1);
}

//
//  main.cpp
//  hello_client
//
//  Created by app05 on 15-10-22.
//  Copyright (c) 2015年 app05. All rights reserved.
//
//

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <pthread.h>

#define BUF_SIZE 100
#define NAME_SIZE 20

void * send_msg(void * arg);
void * recv_msg(void * arg);
void error_handling(char *message);

char name[NAME_SIZE] = "[DEFAULT]";
char msg[BUF_SIZE];

int main(int argc, const char * argv[]) {
    int sock;
    struct sockaddr_in serv_addr;
    pthread_t snd_thread, rcv_thread;
    void * thread_return;

    if(argc != 4)
    {
        printf("Usage: %s <IP> <port> \n", argv[0]);
        exit(1);
    }

    sprintf(name, "[%s]", argv[3]); //聊天人名字，配置到编译器参数里
    sock = socket(PF_INET, SOCK_STREAM, 0);
    if(sock == -1)
        error_handling("socket() error");

    memset(&serv_addr, 0, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = inet_addr(argv[1]);
    serv_addr.sin_port = htons(atoi(argv[2]));

    if (connect(sock, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) == -1)
        error_handling("connect() error");

    //多线程分离输入和输出
    pthread_create(&snd_thread, NULL, send_msg, (void *)&sock);
    pthread_create(&rcv_thread, NULL, recv_msg, (void *)&sock);
    //阻塞，等待返回
    pthread_join(snd_thread, &thread_return);
    pthread_join(rcv_thread, &thread_return);

    close(sock);
    return 0;
}

//发送消息
void * send_msg(void * arg)
{
    int sock = *((int *)arg);
    char name_msg[NAME_SIZE + BUF_SIZE];
    while (1) {
        fgets(msg, BUF_SIZE, stdin);
        if (!strcmp(msg, "q\n") || !strcmp(msg, "Q \n")) {
            close(sock);
            exit(0);
        }
        sprintf(name_msg, "%s  %s", name, msg);
        write(sock, name_msg, strlen(name_msg));
    }
    return NULL;
}

//接收消息
void * recv_msg(void * arg)
{
    int sock = *((int *)arg);
    char name_msg[NAME_SIZE + BUF_SIZE];
    int str_len;
    while (1) {
        str_len = read(sock, name_msg, NAME_SIZE + BUF_SIZE - 1);
        if(str_len == -1)
            return (void *)-1;
        name_msg[str_len] = 0;
        fputs(name_msg, stdout);
    }
    return NULL;
}

void error_handling(char *message)
{
    fputs(message, stderr);
    fputc('\n', stderr);
    exit(1);
}

示例代码：

#include "stdafx.h"
#include<iostream>
#include<Windows.h>
using namespace std;

DWORD WINAPI Fun1Proc(LPVOID lpParameter)
{
    cout << "thread function Fun1Proc!\n";

    return 0;
}

int main()
{
    HANDLE hThread1 = CreateThread(NULL, 0, Fun1Proc, NULL, 0, NULL);
    CloseHandle(hThread1);

    Sleep(1000);
    cout << "main end!\n";
    system("pause");
    return 0;
}

 示例代码:

#include "stdafx.h"
#include<iostream>
#include<Windows.h>
#include<process.h>
using namespace std;

unsigned int _stdcall ThreadProc(LPVOID lpParameter)
{
    cout << "thread function ThreadProc!\n";
    return 0;
}

int main()
{
    _beginthreadex(NULL, 0, ThreadProc, 0, 0, NULL);

    Sleep(1000);
    cout << "main end!\n";
    system("pause");
    return 0;
}

#include "stdafx.h"
#include<windows.h>
#include<iostream>
using namespace std;
 
int number = 1;
 
unsigned long __stdcall ThreadProc1(void* lp)
{
    while (number < 100)
    {
        cout << "thread 1 :"<<number << endl;
        ++number;
        _sleep(100);
    }
 
    return 0;
}
 
unsigned long __stdcall ThreadProc2(void* lp)
{
    while (number < 100)
    {
        cout << "thread 2 :"<<number << endl;
        ++number;
        _sleep(100);
    }
 
    return 0;
}
 
int main()
{
    CreateThread(NULL, 0, ThreadProc1, NULL, 0, NULL);
    CreateThread(NULL, 0, ThreadProc2, NULL, 0, NULL);
 
    Sleep(10*1000);
 
    system("pause");
    return 0;
}

#include "stdafx.h"
#include<windows.h>
#include<iostream>
using namespace std;
 
int number = 1; //定义全局变量
CRITICAL_SECTION Critical;      //定义临界区句柄
 
unsigned long __stdcall ThreadProc1(void* lp)
{
    while (number < 100)
    {
        EnterCriticalSection(&Critical);
        cout << "thread 1 :"<<number << endl;
        ++number;
        _sleep(100);
        LeaveCriticalSection(&Critical);
    }
 
    return 0;
}
 
unsigned long __stdcall ThreadProc2(void* lp)
{
    while (number < 100)
    {
        EnterCriticalSection(&Critical);
        cout << "thread 2 :"<<number << endl;
        ++number;
        _sleep(100);
        LeaveCriticalSection(&Critical);
    }
 
    return 0;
}
 
int main()
{
    InitializeCriticalSection(&Critical);   //初始化临界区对象
 
    CreateThread(NULL, 0, ThreadProc1, NULL, 0, NULL);
    CreateThread(NULL, 0, ThreadProc2, NULL, 0, NULL);
 
    Sleep(10*1000);
 
    system("pause");
    return 0;
}

HANDLE hEvent=OpenEvent(EVENT_ALL_ACCESS,true,"MyEvent"); 
ResetEvent(hEvent);

#include "stdafx.h"
#include<windows.h>
#include<iostream>
using namespace std;
 
int number = 1; //定义全局变量
HANDLE hEvent;  //定义事件句柄
 
unsigned long __stdcall ThreadProc1(void* lp)
{
    while (number < 100)
    {
        WaitForSingleObject(hEvent, INFINITE);  //等待对象为有信号状态
        cout << "thread 1 :"<<number << endl;
        ++number;
        _sleep(100);
        SetEvent(hEvent);
    }
 
    return 0;
}
 
unsigned long __stdcall ThreadProc2(void* lp)
{
    while (number < 100)
    {
        WaitForSingleObject(hEvent, INFINITE);  //等待对象为有信号状态
        cout << "thread 2 :"<<number << endl;
        ++number;
        _sleep(100);
        SetEvent(hEvent);
    }
 
    return 0;
}
 
int main()
{
    CreateThread(NULL, 0, ThreadProc1, NULL, 0, NULL);
    CreateThread(NULL, 0, ThreadProc2, NULL, 0, NULL);
    hEvent = CreateEvent(NULL, FALSE, TRUE, "event");
 
    Sleep(10*1000);
 
    system("pause");
    return 0;
}

 HANDLE CreateSemaphore (
  　PSECURITY_ATTRIBUTE psa, //信号量的安全属性
　  LONG lInitialCount, //开始时可供使用的资源数
　  LONG lMaximumCount, //最大资源数
   PCTSTR pszName);     //信号量的名称

BOOL WINAPI ReleaseSemaphore(
  　HANDLE hSemaphore,   //要增加的信号量句柄
  　LONG lReleaseCount, //信号量的当前资源数增加lReleaseCount
  　LPLONG lpPreviousCount  //增加前的数值返回
   );

 HANDLE OpenSemaphore (
  　DWORD fdwAccess,      //access
  　BOOL bInherithandle,  //如果允许子进程继承句柄，则设为TRUE
  　PCTSTR pszName  //指定要打开的对象的名字
  );

#include "stdafx.h"
#include<windows.h>
#include<iostream>
using namespace std;
 
int number = 1; //定义全局变量
HANDLE hSemaphore;  //定义信号量句柄
 
unsigned long __stdcall ThreadProc1(void* lp)
{
    long count;
    while (number < 100)
    {
        WaitForSingleObject(hSemaphore, INFINITE);  //等待信号量为有信号状态
        cout << "thread 1 :"<<number << endl;
        ++number;
        _sleep(100);
        ReleaseSemaphore(hSemaphore, 1, &count);
    }
 
    return 0;
}
 
unsigned long __stdcall ThreadProc2(void* lp)
{
    long count;
    while (number < 100)
    {
        WaitForSingleObject(hSemaphore, INFINITE);  //等待信号量为有信号状态
        cout << "thread 2 :"<<number << endl;
        ++number;
        _sleep(100);
        ReleaseSemaphore(hSemaphore, 1, &count);
    }
 
    return 0;
}
 
int main()
{
    hSemaphore = CreateSemaphore(NULL, 1, 100, "sema");
 
    CreateThread(NULL, 0, ThreadProc1, NULL, 0, NULL);
    CreateThread(NULL, 0, ThreadProc2, NULL, 0, NULL);
 
    Sleep(10*1000);
 
    system("pause");
    return 0;
}

#include "stdafx.h"
#include<windows.h>
#include<iostream>
using namespace std;
 
int number = 1; //定义全局变量
HANDLE hMutex;  //定义互斥对象句柄
 
unsigned long __stdcall ThreadProc1(void* lp)
{
    while (number < 100)
    {
        WaitForSingleObject(hMutex, INFINITE);
        cout << "thread 1 :"<<number << endl;
        ++number;
        _sleep(100);
        ReleaseMutex(hMutex);
    }
 
    return 0;
}
 
unsigned long __stdcall ThreadProc2(void* lp)
{
    while (number < 100)
    {
        WaitForSingleObject(hMutex, INFINITE);
        cout << "thread 2 :"<<number << endl;
        ++number;
        _sleep(100);
        ReleaseMutex(hMutex);
    }
 
    return 0;
}
 
int main()
{
    hMutex = CreateMutex(NULL, false, "mutex");     //创建互斥对象
 
    CreateThread(NULL, 0, ThreadProc1, NULL, 0, NULL);
    CreateThread(NULL, 0, ThreadProc2, NULL, 0, NULL);
 
    Sleep(10*1000);
 
    system("pause");
    return 0;
}

- 1：创建IOCP对象，由它负责管理多个Socket和I/O请求。CreateIoCompletionPort需要将IOCP对象和IOCP句柄绑定。 
    -  2：创建一个工作线程池，以便Socket发送I/O请求给IOCP对象后，由这些工作线程进行I/O操作。注意，创建这些线程的时候，将这些线程绑定到IOCP上。 
        -  3：创建一个监听的socket。 
            -  4：轮询，当接收到了新的连接后，将socket和完成端口进行关联并且投递给IOCP一个I/O请求。注意：将Socket和IOCP进行关联的函数和创建IOCP的函数一样，都是CreateIoCompletionPort，不过注意传参必然是不同的。 
            -  5：因为是异步的，我们可以去做其他，等待IOCP将I/O操作完成会回馈我们一个消息，我们再进行处理。 
            -  其中需要知道的是：I/O请求被放在一个I/O请求队列里面，对，是队列，LIFO机制。当一个设备处理完I/O请求后，将会将这个完成后的I/O请求丢回IOCP的I/O完成队列。 
            -  我们应用程序则需要在GetQueuedCompletionStatus去询问IOCP，该I/O请求是否完成。 
            -  其中有一些特殊的事情要说明一下，我们有时有需要人工的去投递一些I/O请求，则需要使用PostQueuedCompletionStatus函数向IOCP投递一个I/O请求到它的请求队列中。

BOOL AcceptEx(
  _In_   SOCKET sListenSocket,
  _In_   SOCKET sAcceptSocket,
  _In_   PVOID lpOutputBuffer,
  _In_   DWORD dwReceiveDataLength,
  _In_   DWORD dwLocalAddressLength,
  _In_   DWORD dwRemoteAddressLength,
  _Out_  LPDWORD lpdwBytesReceived,
  _In_   LPOVERLAPPED lpOverlapped
);

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#include <process.h>
#include <winsock2.h>
#include <windows.h>
 
#pragma comment(lib,"ws2_32.lib");//加载ws2_32.dll
 
#define BUF_SIZE 100
#define READ    3
#define    WRITE    5
 
typedef struct    // socket info
{
    SOCKET hClntSock;
    SOCKADDR_IN clntAdr;
} PER_HANDLE_DATA, *LPPER_HANDLE_DATA;
 
typedef struct    // buffer info
{
    OVERLAPPED overlapped;
    WSABUF wsaBuf;
    char buffer[BUF_SIZE];
    int rwMode;    // READ or WRITE 读写模式
} PER_IO_DATA, *LPPER_IO_DATA;
 
unsigned int  WINAPI EchoThreadMain(LPVOID CompletionPortIO);
void ErrorHandling(char *message);
SOCKET ALLCLIENT[100];
int clientcount = 0;
HANDLE hMutex;//互斥量
 
int main(int argc, char* argv[])
{
 
    hMutex = CreateMutex(NULL, FALSE, NULL);//创建互斥量
 
    WSADATA    wsaData;
    HANDLE hComPort;
    SYSTEM_INFO sysInfo;
    LPPER_IO_DATA ioInfo;
    LPPER_HANDLE_DATA handleInfo;
 
    SOCKET hServSock;
    SOCKADDR_IN servAdr;
    int  i;
    DWORD recvBytes = 0,flags = 0;
 
    if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0)
        ErrorHandling("WSAStartup() error!");
 
    hComPort = CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, 0);//创建CP对象
    GetSystemInfo(&sysInfo);//获取当前系统的信息
 
    for (i = 0; i < sysInfo.dwNumberOfProcessors; i++)
        _beginthreadex(NULL, 0, EchoThreadMain, (LPVOID)hComPort, 0, NULL);//创建=CPU个数的线程数
 
    hServSock = WSASocket(AF_INET, SOCK_STREAM, 0, NULL, 0, WSA_FLAG_OVERLAPPED);//不是非阻塞套接字，但是重叠IO套接字。
    memset(&servAdr, 0, sizeof(servAdr));
    servAdr.sin_family = AF_INET;
    servAdr.sin_addr.s_addr = htonl(INADDR_ANY);
    servAdr.sin_port = htons(1234);
 
    bind(hServSock, (SOCKADDR*)&servAdr, sizeof(servAdr));
    listen(hServSock, 5);
 
    while (1)
    {
        SOCKET hClntSock;
        SOCKADDR_IN clntAdr;
        int addrLen = sizeof(clntAdr);
 
        hClntSock = accept(hServSock, (SOCKADDR*)&clntAdr, &addrLen);
 
        handleInfo = (LPPER_HANDLE_DATA)malloc(sizeof(PER_HANDLE_DATA));//和重叠IO一样
        handleInfo->hClntSock = hClntSock;//存储客户端套接字
 
        WaitForSingleObject(hMutex, INFINITE);//线程同步
 
        ALLCLIENT[clientcount++] = hClntSock;//存入套接字队列
 
        ReleaseMutex(hMutex);
 
        memcpy(&(handleInfo->clntAdr), &clntAdr, addrLen);
 
        CreateIoCompletionPort((HANDLE)hClntSock, hComPort, (DWORD)handleInfo, 0);//连接套接字和CP对象
                                                                                //已完成信息将写入CP对象
        ioInfo = (LPPER_IO_DATA)malloc(sizeof(PER_IO_DATA));//存储接收到的信息
        memset(&(ioInfo->overlapped), 0, sizeof(OVERLAPPED));
        ioInfo->wsaBuf.len = BUF_SIZE;
        ioInfo->wsaBuf.buf = ioInfo->buffer;//和重叠IO一样
        ioInfo->rwMode = READ;//读写模式
 
        WSARecv(handleInfo->hClntSock, &(ioInfo->wsaBuf),//非阻塞模式
            1, &recvBytes, &flags, &(ioInfo->overlapped), NULL);
    }
    CloseHandle(hMutex);//销毁互斥量
    return 0;
}
 
unsigned int WINAPI EchoThreadMain(LPVOID pComPort)//线程的执行
{
    HANDLE hComPort = (HANDLE)pComPort;
    SOCKET sock;
    DWORD bytesTrans;
    LPPER_HANDLE_DATA handleInfo;
    LPPER_IO_DATA ioInfo;
    DWORD flags = 0;
 
    while (1)//大循环
    {
        GetQueuedCompletionStatus(hComPort, &bytesTrans,//确认“已完成”的I/O！！
            (LPDWORD)&handleInfo, (LPOVERLAPPED*)&ioInfo, INFINITE);//INFINITE使用时，程序将阻塞，直到已完成的I/O信息写入CP对象
        sock = handleInfo->hClntSock;//客户端套接字
 
        if (ioInfo->rwMode == READ)//读写模式（此时缓冲区有数据）
        {
            puts("message received!");
            if (bytesTrans == 0)    // 连接结束
            {
                WaitForSingleObject(hMutex, INFINITE);//线程同步
 
                closesocket(sock);
                int i = 0;
                while (ALLCLIENT[i] == sock){ i++; }
                ALLCLIENT[i] = 0;//断开置0
 
                ReleaseMutex(hMutex);
 
                free(handleInfo); free(ioInfo);
                continue;
            }
            int i = 0;
 
            for (; i < clientcount;i++)
            {
                if (ALLCLIENT[i] != 0)//判断是否为已连接的套接字
                {
                    if (ALLCLIENT[i] != sock)
                    {
                        LPPER_IO_DATA newioInfo;
                        newioInfo = (LPPER_IO_DATA)malloc(sizeof(PER_IO_DATA));//动态分配内存
                        memset(&(newioInfo->overlapped), 0, sizeof(OVERLAPPED));
                        strcpy(newioInfo->buffer, ioInfo->buffer);//重新构建新的内存，防止多次释放free
                        newioInfo->wsaBuf.buf = newioInfo->buffer;
                        newioInfo->wsaBuf.len = bytesTrans;
                        newioInfo->rwMode = WRITE;
 
                        WSASend(ALLCLIENT[i], &(newioInfo->wsaBuf),//回声
                            1, NULL, 0, &(newioInfo->overlapped), NULL);
                    }
                    else
                    {
                        memset(&(ioInfo->overlapped), 0, sizeof(OVERLAPPED));
                        ioInfo->wsaBuf.len = bytesTrans;
                        ioInfo->rwMode = WRITE;
                        WSASend(ALLCLIENT[i], &(ioInfo->wsaBuf),//回声
                            1, NULL, 0, &(ioInfo->overlapped), NULL);
                    }
                }
            }
            ioInfo = (LPPER_IO_DATA)malloc(sizeof(PER_IO_DATA));//动态分配内存
            memset(&(ioInfo->overlapped), 0, sizeof(OVERLAPPED));
            ioInfo->wsaBuf.len = BUF_SIZE;
            ioInfo->wsaBuf.buf = ioInfo->buffer;
            ioInfo->rwMode = READ;
            WSARecv(sock, &(ioInfo->wsaBuf),//再非阻塞式接收
                1, NULL, &flags, &(ioInfo->overlapped), NULL);
        }
        else
        {
            puts("message sent!");
            free(ioInfo);
        }
    }
    return 0;
}
 
void ErrorHandling(char *message)
{
    fputs(message, stderr);
    fputc('\n', stderr);
    exit(1);
}

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <windows.h>
#include <process.h> 
#define BUF_SIZE 1000
#define NAME_SIZE 20
 
#pragma comment(lib, "ws2_32.lib")  //加载 ws2_32.dll  
 
unsigned WINAPI SendMsg(void * arg);//发送信息函数
unsigned WINAPI RecvMsg(void * arg);//接受信息函数
void ErrorHandling(char * msg);//错误返回函数
 
int haveread = 0;
char NAME[50];//[名字]
char ANAME[50];
char msg[BUF_SIZE];//信息
 
int main(int argc, char *argv[])
{
 
    printf("请输入网名：");
    scanf("%s", NAME);
    WSADATA wsaData;
    SOCKET hSock;
    SOCKADDR_IN servAdr;
    HANDLE hSndThread, hRcvThread;
    if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0)
        ErrorHandling("WSAStartup() error!");
 
    hSock = socket(PF_INET, SOCK_STREAM, 0);
    memset(&servAdr, 0, sizeof(servAdr));
    servAdr.sin_family = AF_INET;
    servAdr.sin_addr.s_addr = inet_addr("127.0.0.1");
    servAdr.sin_port = htons(1234);
 
    if (connect(hSock, (SOCKADDR*)&servAdr, sizeof(servAdr)) == SOCKET_ERROR)
        ErrorHandling("connect() error");
 
    int resultsend;
    puts("Welcome to joining our chatting room!\n");
    sprintf(ANAME, "[%s]", NAME);
 
    hSndThread =
        (HANDLE)_beginthreadex(NULL, 0, SendMsg, (void*)&hSock, 0, NULL);//写线程
    hRcvThread =
        (HANDLE)_beginthreadex(NULL, 0, RecvMsg, (void*)&hSock, 0, NULL);//读线程
 
    WaitForSingleObject(hSndThread, INFINITE);//等待线程结束
    WaitForSingleObject(hRcvThread, INFINITE);
    closesocket(hSock);
    WSACleanup();
    system("pause");
    return 0;
}
 
unsigned WINAPI SendMsg(void * arg)   // send thread main
{
    SOCKET sock = *((SOCKET*)arg);
    char name_msg[NAME_SIZE + BUF_SIZE];
    char padd[2];
    fgets(padd, 2, stdin);//多余的'\n'
    printf("\n send message:");
    while (1)
    {
        {
            fgets(msg, BUF_SIZE, stdin);
            if (!strcmp(msg, "q\n") || !strcmp(msg, "Q\n"))
            {
                closesocket(sock);
                exit(0);
            }
            sprintf(name_msg, "[%s] %s", NAME, msg);
            char numofmsg = strlen(name_msg) + '0';
            char newmsg[100]; newmsg[0] = numofmsg; newmsg[1] = 0;//第一个字符表示消息的长度
            strcat(newmsg, name_msg);
            int result = send(sock, newmsg, strlen(newmsg), 0);
            if (result == -1)return -1;//发送错误
        }
    }
    return NULL;
}
 
unsigned WINAPI RecvMsg(void * arg)  // read thread main
{
    SOCKET sock = *((SOCKET*)arg);
    char name_msg[NAME_SIZE + BUF_SIZE];
    int str_len = 0;
    while (1)
    {
        {
            char lyfstr[1000] = { 0 };
            int totalnum = 0;
            str_len = recv(sock, name_msg, 1, 0);//读取第一个字符！获取消息的长度
            if (str_len == -1)//读取错误
            {
                printf("return -1\n");
                return -1;
            }
            if (str_len == 0)//读取结束
            {
                printf("return 0\n");
                return 0;//读取结束
            }
            totalnum = name_msg[0] - '0';
            int count = 0;
 
            do
            {
                str_len = recv(sock, name_msg, 1, 0);
 
                name_msg[str_len] = 0;
 
                if (str_len == -1)//读取错误
                {
                    printf("return -1\n");
                    return -1;
                }
                if (str_len == 0)
                {
                    printf("return 0\n");
                    return 0;//读取结束
                }
                strcat(lyfstr, name_msg);
                count = str_len + count;
 
            } while (count < totalnum);
 
            lyfstr[count] = '\0';
            printf("\n");
            strcat(lyfstr, "\n");
            fputs(lyfstr, stdout);
            printf(" send message:");
            fflush(stdout);
            memset(name_msg, 0, sizeof(char));
        }
    }
    return NULL;
}
 
void ErrorHandling(char * msg)
{
    fputs(msg, stderr);
    fputc('\n', stderr);
    exit(1);
}