libevent 编程 二：bufferevent

一个简单的 echo 程序

参考链接：

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/****************************************************
    支持大量并发的echo 服务器
    参考链接javascript:void(0)
*****************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <assert.h>

#include <event2/event.h>
#include <event2/bufferevent.h>


#define LISTEN_PORT 8888
#define LISTEN_BACKLOG  32

void do_accept(evutil_socket_t listener, short event, void *arg);
void read_cb(struct bufferevent *bev, void *arg);
void error_cb(struct bufferevent *bev, short event, void *arg);
void write_cb(struct bufferevent *bev, void *arg);


int main(int argc, char *argv[])
{
    int ret;
    evutil_socket_t listener;

    listener = socket(AF_INET, SOCK_STREAM, 0);
    assert(listener > 0);
    evutil_make_listen_socket_reuseable(listener);

    struct sockaddr_in sin;
    sin.sin_family = AF_INET;
    sin.sin_addr.s_addr = 0;
    sin.sin_port = htons(LISTEN_PORT);

    if(bind(listener, (struct sockaddr *)&sin, sizeof(sin)) < 0)
    {
        perror("bind");
        return -1;
    }

    if(listen(listener, LISTEN_BACKLOG) < 0)
    {
        perror("listen");
        return -1;
    }

    printf("Listening...\r\n");

    evutil_make_socket_nonblocking(listener);

    struct event_base *base = event_base_new();
    assert(base != NULL);

    struct event* listen_event;
    listen_event = event_new(base, listener, EV_READ | EV_PERSIST, do_accept, (void *)base);
    event_add(listen_event, NULL);
    event_base_dispatch(base);

    printf("End \r\n");
    return 0;
}

/* 连接事件 */
void do_accept(evutil_socket_t listener, short event, void *arg)
{
    struct event_base *base = (struct event_base *)arg;
    evutil_socket_t fd;
    struct sockaddr_in sin;
    socklen_t slen = sizeof(struct sockaddr);

    fd = accept(listener, (struct sockaddr *)&sin, &slen);
    if(fd < 0){
        perror("accept");
        return ;
    }
    if(fd > FD_SETSIZE){
        perror("fd > FD_SETSIZE \r\n");
        return ;
    }

    printf("ACCEPT : fd = %u \r\n", fd);

    struct bufferevent *bev = bufferevent_socket_new(base, fd, BEV_OPT_CLOSE_ON_FREE);
    if(bev == NULL){
        close(fd);
        printf("bufferevent_socket_new err \r\n");
        return ;
    }

    bufferevent_setcb(bev, read_cb, NULL, error_cb, arg);
    bufferevent_enable(bev, EV_READ|EV_WRITE|EV_PERSIST);
}

void read_cb(struct bufferevent *bev, void *arg)
{
    char line[1204];
    int n;
    evutil_socket_t fd = bufferevent_getfd(bev);

    while((n = bufferevent_read(bev, line, 1024 - 1)) > 0)
    {
        line[n] = '\0';
        printf("fd = %u, read line: %s\n", fd, line);
        bufferevent_write(bev, line, n);
    }
}

void write(struct bufferevent *bev, void *arg){}

void error_cb(struct bufferevent *bev, short event, void *arg)
{
    evutil_socket_t fd = bufferevent_getfd(bev);
    printf("fd = %u, ", fd);
    if (event & BEV_EVENT_TIMEOUT) {
        printf("Timed out\n"); //if bufferevent_set_timeouts() called
    }
    else if (event & BEV_EVENT_EOF) {
        printf("connection closed\n");
    }
    else if (event & BEV_EVENT_ERROR) {
        printf("some other error\n");
    }
    bufferevent_free(bev);
}