epoll服务器代码实现

<span style="font-family: Arial, Helvetica, sans-serif; background-color: rgb(255, 255, 255);">这个程序可以完整的在linux上进行测试运行，主要功能有，将用户输入的数据存储到用户缓冲区中，然后每次从用户缓冲区中读取数据并打印，使用非阻塞IO实现多用户同时访问服务器对于epoll的介绍这里就不做介绍了，推荐阅读https://segmentfault.com/a/1190000003063859 这篇文章比较详细介绍了select，epoll，poll的作用</span>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <stdarg.h>
#include <errno.h>
#include <sys/epoll.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <time.h>

#define MAX_USER_CONNECTED     (4)
#define MAX_BUFFER_SIZE        (1024)

#define EVENT_COUNT            (8)

#define PERROR   printf

typedef struct tagUSERINFO{
    int sockfd;
    unsigned short recvLen,verified;
    unsigned char recvBuf[MAX_BUFFER_SIZE];
    time_t        lastheart;   // 用来标记最后一次收到心跳反馈的时间
}UserInfo, *UserIPtr;

typedef struct tagPROGINFO{
    int            fdListen;
    UserInfo       users[MAX_USER_CONNECTED];
    int            epollfd;
    struct epoll_event  events[EVENT_COUNT];
}ProgInfo, *ProgIPtr;

extern ProgInfo gProgInfo;
int netio_main_tcpserver(ProgIPtr prog);


ProgInfo gProgInfo;

int main(int argc, char *argv[])
{
    ProgIPtr prog = &gProgInfo;
    int sockfd;
    struct sockaddr_in saddr;
    struct epoll_event ev; 
    int ret;
    char buf[1024];

    memset(prog, 0 ,sizeof(ProgInfo));

    if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) 
    {   
        PERROR("create socket error:");
        return -1; 
    }   

    int opt = 1; //解决地址复用关系
    if(setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(int)) == -1) 
    {   
        PERROR("setsockopt failed!");
        return -1; 
    }   

    bzero(&saddr, sizeof(saddr));
    saddr.sin_family = AF_INET;
    saddr.sin_addr.s_addr = htonl(INADDR_ANY);
    saddr.sin_port = htons(1234);

    if(bind(sockfd, (struct sockaddr *)&saddr, sizeof(saddr)) == -1)
    {
        PERROR("bind error:");
        return -1;
    }

    if(listen(sockfd , 5) == -1)
    {
        PERROR("bind error:");
        return -1;
    }

    prog->fdListen = sockfd; //listen socket fd;

    prog->epollfd = epoll_create(MAX_USER_CONNECTED);  //4表示创建epollfd连接的最大数量
    if(prog->epollfd == -1)
    {
        PERROR("Create epoll error:");
        return -1;
    }
	//添加监听描述符事件
    ev.events = EPOLLIN;
    ev.data.fd = sockfd;
    if( epoll_ctl(prog->epollfd, EPOLL_CTL_ADD, sockfd, &ev) == -1)
    {
        PERROR("create_tcpserver:epoll_ctl error: ");
        return -1;
    }

    while(1)
    {
        netio_main_tcpserver(prog);
    }

    return 0;
}
static int err_connect(ProgIPtr prog, int n)
{
    PERROR("epoll error: client closed\n");
    UserIPtr user = (UserIPtr) prog->events[n].data.ptr;
    close(user->sockfd);
    bzero(user, sizeof(UserInfo));

    return 0;
}

static int new_connect(ProgIPtr prog)
{
    int i, flags, connfd;
    struct epoll_event ev;
    struct sockaddr_in caddr;
    socklen_t client_size = sizeof(caddr);

    if((connfd = accept(prog->fdListen,(struct sockaddr *)&caddr, &client_size)) == -1)
    {
        PERROR("accept error:");
        return -1;
    }

    // 先检查已连接数量，
    for(i=0;i<MAX_USER_CONNECTED; ++i){
        if(prog->users[i].sockfd == 0)
        {
            break;// 还有可用的连接
        }
    }
     连接已满
    if(i == MAX_USER_CONNECTED)
    {
        close(connfd);
        PERROR("Connection is full \n");
        return -1;
    }
    PERROR("ACCEPT......%d\n",i+1);

    flags = fcntl(connfd, F_GETFL, 0); // 设置为no block
    fcntl(connfd, F_SETFL, flags | O_NONBLOCK);

    prog->users[i].sockfd = connfd;// 先加入后认证
    prog->users[i].lastheart = time(NULL);// 从现在开始计时

    // 加入到epollfd中去
    ev.events = EPOLLIN | EPOLLET;
    ev.data.ptr = &prog->users[i];
    if(epoll_ctl(prog->epollfd, EPOLL_CTL_ADD, connfd, &ev) == -1)
    {
        PERROR("epoll_ctl error:");
        return -1;
    }
    return 0;
}

//接收数据，保存到用户缓存中
static int recv_data(ProgIPtr prog, int n)
{
    UserIPtr user = (UserIPtr)prog->events[n].data.ptr;
    int buflen = user->recvLen, recvlen=0;
    int freelen = MAX_BUFFER_SIZE - buflen;

    if(freelen > 0)
    {
        if((recvlen = recv(user->sockfd, user->recvBuf+buflen, freelen, 0)) == -1)
            PERROR("Recv Failed: %s",strerror(errno));
        else if(recvlen == 0){//表示客户端关闭
            close(user->sockfd);
            bzero(user,sizeof(UserInfo));
            PERROR("Connection is closed!\n");
        }
        else
        {
            user->recvLen += recvlen;
            PERROR(">>>>>>>>>>>>>>>>>%s>>>>>>>>>>>>>>>>%d\n",user->recvBuf, user->recvLen);
            return 0;
        }
    }

    return -1;
}

// 从当前缓冲区中查找一条完整的命令
// // @src,ilen   查找缓冲区地址及大小
// // @cmdPkt     完整命令存取地址
// // @olen       缓冲区使用大小，注意它可能会大于当前命令的长度
// // @result     执行结果
//int npto_Parse(void *src, int ilen, NetPtoPtr cmdPkt, int *olen, int *result)
int npto_Parse(void *src, int ilen, int *olen, int *result)
{
    int i;
    unsigned char *ptr = (unsigned char*)src, checksum;

    for(i =0 ; i< ilen;i++){
        printf("%c ",ptr[i]);
    }
    printf("LEN=%d\n",ilen);

    *olen = ilen;
    *result = -1;
    return 0;
}

static int get_recv_buf(ProgIPtr prog, int n)
{
    int buflen = 0, result = 0;
    int recvlen = prog->users[n].recvLen;

    //从缓存中获取一条数据打印
    npto_Parse(prog->users[n].recvBuf, prog->users[n].recvLen, &buflen,&result);
    // 将获取过的或者错误的数据覆盖掉
    if (buflen > 0 && recvlen - buflen >= 0) {
        memmove(prog->users[n].recvBuf, prog->users[n].recvBuf + buflen, recvlen - buflen);
        prog->users[n].recvLen -= buflen;
    }
    return result == 0 ? 0 : -1;
}
int netio_main_tcpserver(ProgIPtr prog)
{
    int i;
    int nfds; // 准备好的文件描述符数量
    int fd;

    // epoll wait 8ms
    nfds = epoll_wait(prog->epollfd, prog->events, EVENT_COUNT, 8);
    if(nfds == -1){
        PERROR("epoll_wait error!");
        return -1;
    }

    for(i = 0; i< nfds; ++i)
    {
        fd = prog->events[i].data.fd;
        if(prog->events[i].events & (EPOLLERR | EPOLLRDHUP)) 有客户端关闭或者遇到错误
        {
            err_connect(prog,i);// 连接错误, 关闭连接
        }
        else if(fd == prog->fdListen)// 有新的连接请求
        {
            new_connect(prog);
        }
        else if(prog->events[i].events & EPOLLIN)// 已经准备好，可用进行读写
        {
            recv_data(prog, i);
        }
    }
#if 1
    for(i = 0; i< MAX_USER_CONNECTED; ++i)// do command
    {
        if(!prog->users[i].sockfd || !prog->users[i].recvLen)
            continue;// 没有连接，或者没有数据的

        while(get_recv_buf(prog, i) != -1)
        {
            if(!prog->users[i].verified){
                //get_recv_buf获取到的数据在这里进行处理
            }
        }

    }
#endif
}