epoll

最新推荐文章于 2025-09-11 23:12:53 发布

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最新推荐文章于 2025-09-11 23:12:53 发布

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文章标签： epoll 网络

epoll

epoll - I/O event notification facility

epoll is a variant of poll(2) that can be used either as an edge-triggered or a level-triggered interface and scales well to large numbers of watched file descriptors.

epoll_create

#include <sys/epoll.h>

int epoll_create(int size);

size不用，0即可。

int epoll_create1(int flags);

epoll_ctl

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

op: EPOLL_CTL_ADD, EPOLL_CTL_DEL, EPOLL_CTL_MOD;

typedef union epoll_data{

void *ptr;

int fd;

uint32_t u32;

uint64_t u64;

}epoll_data_t;

typedef epoll_event {

uint32_t events; /*Epoll events*/

epoll_data_t data;

};

events:EPOLLIN:可读；EPOLLOUT：可写；EPOLLET：边沿触发；EPOLLLT：水平触发（默认）。

The suggested way to use epoll as an edge-triggered (EPOLLET) interface is as follows:

          i   with nonblocking file descriptors; and

          ii  by waiting for an event only after  read(2) or write(2) return EAGAIN.

epoll_wait

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

int epoll_pwait(int epfd, struct epoll_event *events, int maxevents, int timeout, const sigset_t *sigmask);

timeout: -1死等；0，不等；>0,有限等待时间。

成功：事件个数，失败-1。

示例代码：

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

#define MAX_EVENTS 10

int
main(void)
{
    struct epoll_event ev, events[MAX_EVENTS];
    int listen_sock, connect_sock, nfds, epollfd;

    epollfd = epoll_create(MAX_EVENTS);
    if(epollfd == -1){
        perror("epoll_create");
        exit(EXIT_FAILURE);
    }

    ev.events = EPOLLIN；
    ev.data.fd = listen_sock;
    if(epoll_ctl(epollfd, EPOLL_CTL_ADD, listen_sock, &ev) == -1)
    {
        perror("epoll_ctl:listen_sock");
        exit(EXIT_FAILURE);
    }

    while(1)
    {
        nfds = epoll_wait(epollfd, events, MAX_EVENTS, -1);
        if(nfds == -1)
        {
            perror("epoll_wait");
            exit(EXIT_FAILURE);
        }

        for(n = 0; n <nfds; n++)
        {
            if(events[n].data.fd == listen_sock){
                connect_sock = accept(listen_sock, (struct sockaddr *)&local, &addrlen);
                if(connect_sock == -1)
                {
                    perror("accept");
                    exit(EXIT_FAILURE);
                }
                //setnonblocking(connect_sock);
                ev.events = EPOLLIN | EPOLLET;
                ev.data.fd = connect_sock;
                if(epoll_ctl(epollfd, EPOLL_CTL_ADD, connect_sock, \
                    &ev) == -1)
                {
                    perror("epoll_ctl:connect_sock");
                    exit(EXIT_FAILURE);
                }
            } else {
                //do_use_fd(events[n].data.fd);
            }
        }
    }

    return 0;
}