libevent 的bufferevent和evconnlistener用法（echo示例）

60 阅读 0 评论 40 点赞

我是靠谱客的博主清脆绿茶，最近开发中收集的这篇文章主要介绍libevent 的bufferevent和evconnlistener用法（echo示例），觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

libevent 的bufferevent和evconnlistener用法（echo示例）

#include <arpa/inet.h>
#include <errno.h>
#include <event2/buffer.h>
#include <event2/bufferevent.h>
#include <event2/event.h>
#include <event2/listener.h>
#include <event2/thread.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <string.h>

#define LISTEN_BACKLOG 10

static void acceptErr(struct evconnlistener *listener,void *);
static void accept_callbk(struct evconnlistener *listener,evutil_socket_t fd,struct sockaddr *sa,int , void *);

static void readSock(struct bufferevent* bev,void *);
static void sockEvent(struct bufferevent* bev,short events,void *);


int main(int argc,char **argv)
{
    // base
    struct event_base *base;
    base = event_base_new();
    if(!base)
    {
        fprintf(stderr,"new base error.n");
        return -1;
    }

    //准备一个地址结构体并初始化
    struct sockaddr_in addr;
    memset(&addr,0,sizeof(addr));
    addr.sin_family = AF_INET;
    addr.sin_addr.s_addr = htonl(INADDR_ANY);
    addr.sin_port = htons(9001);

    //准备一个evconnlistenner
    struct evconnlistener *listener;
    //初始化 设置accept回调函数
    listener = evconnlistener_new_bind(base,accept_callbk,NULL,
            LEV_OPT_CLOSE_ON_FREE | LEV_OPT_REUSEABLE,
            LISTEN_BACKLOG,
            (struct sockaddr *)&addr,sizeof(addr));
    if(!listener)
    {
        perror("listen:");
        return -1;
    }

    //设置accept的出错处理函数
    evconnlistener_set_error_cb(listener,acceptErr);

    //进入事件循环
    event_base_dispatch(base);
}

static void acceptErr(struct evconnlistener *listener,void *arg)
{
    //获取base
    struct event_base *base = evconnlistener_get_base(listener);
    //获取错误字符
    int err = EVUTIL_SOCKET_ERROR();

    fprintf(stderr,"Get Error %d (%s)n",err,evutil_socket_error_to_string(err));

    event_base_loopexit(base,NULL);
    //如果有多个监听，只把这个监听端口shutdown
}

//[4] accept
static void accept_callbk(struct evconnlistener *listener,evutil_socket_t fd,struct sockaddr *sa,int d, void *test)
{
    //重要，获取base
    struct event_base *base = evconnlistener_get_base(listener);

    //获取client address
    //struct sockaddr_in *clientsa = (sockaddr_in*) sa;

    //下面是 bufferevent 的技术
    struct bufferevent *bev = bufferevent_socket_new(base,fd,BEV_OPT_CLOSE_ON_FREE);

    //可以对这个bev设置：read_callbk,write_callbk,event_callbk
    bufferevent_setcb(bev,readSock,NULL,sockEvent,NULL);
    bufferevent_enable(bev,EV_READ | EV_WRITE);

}

static void readSock(struct bufferevent* bev,void *tmp)
{
    printf("read data n");
    //evutil_socket_t fd = bufferevent_getfd(bev);
    struct evbuffer *input = bufferevent_get_input(bev);
    struct evbuffer *output = bufferevent_get_output(bev);

    evbuffer_add_buffer(output,input);  //假设是个echo 服务
}

static void sockEvent(struct bufferevent* bev,short event,void *ptr)
{
    //出错处理
    printf("sock Event n");
    if(event & BEV_EVENT_ERROR)
    {
        perror("Error form bufferevent");
    }
    if(event & (BEV_EVENT_EOF | BEV_EVENT_ERROR))
    {
        //获得socket
        //int sockfd = bufferevent_getfd(bev);

        bufferevent_free(bev);
    }
}