struct epoll_event 
{ 
__uint32_t events; 
epoll_data_t data; 
}

typedef union epoll_data 
{ 
void *ptr; 
int fd; 
__uinit32_t u32; 
__uint64_t u64; 
} epoll_data_t;

/**  
 * @brief    該函數(shù)生成一個(gè)epoll專用的文件描述符。它其實(shí)是在內(nèi)核申請一空間，用來存放你想關(guān)注的socket fd上是否發(fā)生以及發(fā)生了什么事件。 
 *  
 * @param    size    size就是你在這個(gè)epoll fd上能關(guān)注的最大socket fd數(shù) 
 *  
 * @return   生成的文件描述符 
 */  
int epoll_create(int size);

/**  
 * @brief    該函數(shù)用于控制某個(gè)epoll文件描述符上的事件，可以注冊事件，修改事件，刪除事件。 
 *  
 * @param    epfd    由 epoll_create 生成的epoll專用的文件描述符 
 * @param    op      要進(jìn)行的操作例如注冊事件，可能的取值EPOLL_CTL_ADD 注冊、EPOLL_CTL_MOD 修 改、EPOLL_CTL_DEL 刪除 
 * @param    fd      關(guān)聯(lián)的文件描述符 
 * @param    event   指向epoll_event的指針 
 *  
 * @return   0       succ 
 *           -1      fail 
 */  

int epoll_ctl(int epfd, int op, int fd, struct epoll_event *event);  

typedef union epoll_data { 
void *ptr;
int fd;
__uint32_t u32;
__uint64_t u64;
} epoll_data_t; 
struct epoll_event {
__uint32_t events; /* Epoll events */
epoll_data_t data; /* User data variable */
};

struct epoll_event ev;    
    //設(shè)置與要處理的事件相關(guān)的文件描述符    
    ev.data.fd=listenfd;    
    //設(shè)置要處理的事件類型    
    ev.events=EPOLLIN|EPOLLET;    
    //注冊epoll事件    
    epoll_ctl(epfd,EPOLL_CTL_ADD,listenfd,&ev); 

/**  
 * @brief    該函數(shù)用于輪詢I/O事件的發(fā)生 
 *  
 * @param    epfd        由epoll_create 生成的epoll專用的文件描述符 
 * @param    events      用于回傳代處理事件的數(shù)組 
 * @param    maxevents   每次能處理的事件數(shù) 
 * @param    timeout     等待I/O事件發(fā)生的超時(shí)值；-1相當(dāng)于阻塞，0相當(dāng)于非阻塞。一般用-1即可 
 *  
 * @return   >=0         返回發(fā)生事件數(shù) 
 *           -1          錯(cuò)誤 
 */  


int epoll_wait(int epfd,struct epoll_event * events,int maxevents,int timeout);  

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

#define BUF_SIZE 100
#define EPOLL_SIZE 50
void error_handling(char *buf);

int main(int argc, const char * argv[]) {
    int serv_sock, clnt_sock;
    struct sockaddr_in serv_adr, clnt_adr;
    socklen_t adr_sz;
    int str_len, i;
    char buf[BUF_SIZE];

    //類似select的fd_set變量查看監(jiān)視對象的狀態(tài)變化，epoll_event結(jié)構(gòu)體將發(fā)生變化的文件描述符單獨(dú)集中到一起
    struct epoll_event *ep_events;
    struct epoll_event event;
    int epfd, event_cnt;

    if(argc != 2)
    {
        printf("Usage: %s <port> \n", argv[0]);
        exit(1);
    }

    serv_sock = socket(PF_INET, SOCK_STREAM, 0);
    if(serv_sock == -1)
        error_handling("socket() error");

    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");

    //創(chuàng)建文件描述符的保存空間稱為“epoll例程”
    epfd = epoll_create(EPOLL_SIZE);
    ep_events = malloc(sizeof(struct epoll_event) *EPOLL_SIZE);

    //添加讀取事件的監(jiān)視(注冊事件)
    event.events = EPOLLIN;  //讀取數(shù)據(jù)事件
    event.data.fd = serv_sock;
    epoll_ctl(epdf, EPOLL_CTL_ADD, serv_sock, &event);

    while (1)
    {
        //響應(yīng)事件，返回發(fā)生事件的文件描述符數(shù)
        event_cnt = epoll_wait(epfd, ep_events, EPOLL_SIZE, -1);  //傳-1時(shí)，一直等待直到事件發(fā)生
        if(event_cnt == -1)
        {
            puts("epoll_wait() error");
            break;
        }

        //服務(wù)端套接字和客服端套接字
        for (i = 0; i < event_cnt; i++) {
            if(ep_events[i].data.fd == serv_sock)//服務(wù)端與客服端建立連接
            {
                adr_sz = sizeof(clnt_adr);
                clnt_sock = accept(serv_sock, (struct sockaddr *)&clnt_adr, &adr_sz);
                event.events = EPOLLIN;
                event.data.fd = clnt_sock;
                epoll_ctl(epfd, EPOLL_CTL_ADD, clnt_sock, &event);
                printf("connected client: %d \n", clnt_sock);
            }
            else  //連接之后傳遞數(shù)據(jù)
            {
                str_len = read(ep_events[i].data.fd, buf, BUF_SIZE);
                if(str_len == 0)
                {
                    //刪除事件
                    epoll_ctl(epfd, EPOLL_CTL_DEL, ep_events[i].data.fd, NULL);
                    close(ep_events[i].data.fd);
                    printf("closed client: %d \n", ep_events[i].data.fd);
                }
                else
                {
                    write(ep_events[i].data.fd, buf, str_len);
                }
            }
        }
    }

    close(serv_sock);
    close(epfd);
    return 0;
}

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

#define _GNU_SOURCE
#include "sysutil.h"
#include "buffer.h"
#include <sys/epoll.h>

int main(int argc, char const *argv[])
{
    //創(chuàng)建client套接字
    int sockfd = tcp_client(0);
    //調(diào)用非阻塞connect函數(shù)
    int ret = nonblocking_connect(sockfd, "localhost", 9981, 5000);
    if(ret == -1)
    {
        perror("Connect Timeout .");
        exit(EXIT_FAILURE);
    }

    //將三個(gè)fd設(shè)置為Non-Blocking
    activate_nonblock(sockfd);
    activate_nonblock(STDIN_FILENO);
    activate_nonblock(STDOUT_FILENO);

    buffer_t recvbuf; //sockfd -> Buffer -> stdout
    buffer_t sendbuf; //stdin -> Buffer -> sockfd

    //初始化緩沖區(qū)
    buffer_init(&recvbuf);
    buffer_init(&sendbuf);

    //創(chuàng)建epoll
    int epollfd = epoll_create1(0);
    if(epollfd == -1)
        ERR_EXIT("create epoll");
    struct epoll_event events[1024];

    uint32_t sockfd_event = 0;
    uint32_t stdin_event = 0;
    uint32_t stdout_event = 0;

    epoll_add_fd(epollfd, sockfd, sockfd_event);
    epoll_add_fd(epollfd, STDIN_FILENO, stdin_event);
    epoll_add_fd(epollfd, STDOUT_FILENO, stdout_event);

    while(1)
    {
        //重新裝填epoll事件
        sockfd_event = 0;
        stdin_event = 0;
        stdout_event = 0;
        //epoll無法每次都重新裝填，所以給每個(gè)fd添加一個(gè)空事件
        
        if(buffer_is_readable(&sendbuf))
        {
            sockfd_event |= kWriteEvent;
        }
        if(buffer_is_writeable(&sendbuf))
        {
            stdin_event |= kReadEvent;
        }
        if(buffer_is_readable(&recvbuf))
        {
            stdout_event |= kWriteEvent;
        }
        if(buffer_is_writeable(&recvbuf))
        {
            sockfd_event |= kReadEvent;
        }
        epoll_mod_fd(epollfd, sockfd, sockfd_event);
        epoll_mod_fd(epollfd, STDIN_FILENO, stdin_event);
        epoll_mod_fd(epollfd, STDOUT_FILENO, stdout_event);
       
       //監(jiān)聽fd數(shù)組
        int nready = epoll_wait(epollfd, events, 1024, 5000);
        if(nready == -1)
            ERR_EXIT("epoll wait");
        else if(nready == 0)
        {
            printf("epoll timeout.\n");
            continue;
        }
        else
        {
            int i;
            for(i = 0; i < nready; ++i)
            {
                int peerfd = events[i].data.fd;
                int revents = events[i].events;
                if(peerfd == sockfd && revents & kReadREvent)
                {
                    //從sockfd接收數(shù)據(jù)到recvbuf
                    if(buffer_read(&recvbuf, peerfd) == 0)
                    {
                        fprintf(stderr, "server close.\n");
                        exit(EXIT_SUCCESS);
                    } 
                }                 
                if(peerfd == sockfd && revents & kWriteREvent)
                {
                    buffer_write(&sendbuf, peerfd); //將sendbuf中的數(shù)據(jù)寫入sockfd
                }

                if(peerfd == STDIN_FILENO && revents & kReadREvent)
                {
                    //從stdin接收數(shù)據(jù)寫入sendbuf
                    if(buffer_read(&sendbuf, peerfd) == 0)
                    {
                        fprintf(stderr, "exit.\n");
                        exit(EXIT_SUCCESS);
                    } 
                }
                if(peerfd == STDOUT_FILENO && revents & kWriteREvent)
                {
                    buffer_write(&recvbuf, peerfd); //將recvbuf中的數(shù)據(jù)輸出至stdout
                }
            }
        }
    }
}

str_len = read(...);
if(str_len < 0)
{
    if(errno == EAGAIN) //讀取輸入緩沖中的全部數(shù)據(jù)的標(biāo)志
        break;
}

//fd套接字文件描述符，將此套接字?jǐn)?shù)據(jù)傳輸模式修改為非阻塞
void setnonblockingmode(int fd)
{
    int flag = fcntl(fd, F_GETFL,0); //得到套接字原來屬性
    fcntl(fd, F_SETFL, flag | O_NONBLOCK);//在原有屬性基礎(chǔ)上設(shè)置添加非阻塞模式
}