libevent

https://blog.csdn.net/ljd680/article/details/78568709

https://blog.csdn.net/luotuo44/article/details/39670221

1.libevent官网下载 包
2.解压包 tar -zxvf libevent-1.4.13-stable.tar.gz
3.进入包
4.编译
#./configure --prefix=/usr
#make
#make install
5.编辑代码

#include<stdio.h>
#include<string.h>
#include<errno.h>
 
#include<unistd.h>
#include<event.h>
 
 
 
void accept_cb(int fd, short events, void* arg);
void socket_read_cb(int fd, short events, void *arg);
 
int tcp_server_init(int port, int listen_num);
 
int main(int argc, char** argv)
{
 
    int listener = tcp_server_init(9999, 10);
    if( listener == -1 )
    {
        perror(" tcp_server_init error ");
        return -1;
    }
 
    struct event_base* base = event_base_new();
 
    //添加监听客户端请求连接事件
    struct event* ev_listen = event_new(base, listener, EV_READ | EV_PERSIST,
                                        accept_cb, base);
    event_add(ev_listen, NULL);
 
 
    event_base_dispatch(base);
 
    return 0;
}
 
 
 
void accept_cb(int fd, short events, void* arg)
{
    evutil_socket_t sockfd;
 
    struct sockaddr_in client;
    socklen_t len = sizeof(client);
 
    sockfd = ::accept(fd, (struct sockaddr*)&client, &len );
    evutil_make_socket_nonblocking(sockfd);
 
    printf("accept a client %d\n", sockfd);
 
    struct event_base* base = (event_base*)arg;
 
    //仅仅是为了动态创建一个event结构体
    struct event *ev = event_new(NULL, -1, 0, NULL, NULL);
    //将动态创建的结构体作为event的回调参数
    event_assign(ev, base, sockfd, EV_READ | EV_PERSIST,
                 socket_read_cb, (void*)ev);
 
    event_add(ev, NULL);
}
 
 
void socket_read_cb(int fd, short events, void *arg)
{
    char msg[4096];
    struct event *ev = (struct event*)arg;
    int len = read(fd, msg, sizeof(msg) - 1);
 
 
 
    if( len <= 0 )
    {
        printf("some error happen when read\n");
        event_free(ev);
        close(fd);
        return ;
    }
 
    msg[len] = '\0';
    printf("recv the client msg: %s", msg);
 
    char reply_msg[4096] = "I have recvieced the msg: ";
    strcat(reply_msg + strlen(reply_msg), msg);
 
    write(fd, reply_msg, strlen(reply_msg) );
}
 
 
 
typedef struct sockaddr SA;
int tcp_server_init(int port, int listen_num)
{
    int errno_save;
    evutil_socket_t listener;
 
    listener = ::socket(AF_INET, SOCK_STREAM, 0);
    if( listener == -1 )
        return -1;
 
    //允许多次绑定同一个地址。要用在socket和bind之间
    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(port);
 
    if( ::bind(listener, (SA*)&sin, sizeof(sin)) < 0 )
        goto error;
 
    if( ::listen(listener, listen_num) < 0)
        goto error;
 
 
    //跨平台统一接口，将套接字设置为非阻塞状态
    evutil_make_socket_nonblocking(listener);
 
    return listener;
 
    error:
        errno_save = errno;
        evutil_closesocket(listener);
        errno = errno_save;
 
        return -1;
}

#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<errno.h>
#include<unistd.h>
 
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
 
#include<event.h>
#include<event2/util.h>
 
 
 
 
int tcp_connect_server(const char* server_ip, int port);
 
 
void cmd_msg_cb(int fd, short events, void* arg);
void socket_read_cb(int fd, short events, void *arg);
 
int main(int argc, char** argv)
{
    if( argc < 3 )
    {
        printf("please input 2 parameter\n");
        return -1;
    }
 
 
    //两个参数依次是服务器端的IP地址、端口号
    int sockfd = tcp_connect_server(argv[1], atoi(argv[2]));
    if( sockfd == -1)
    {
        perror("tcp_connect error ");
        return -1;
    }
 
    printf("connect to server successful\n");
 
    struct event_base* base = event_base_new();
 
    struct event *ev_sockfd = event_new(base, sockfd,
                                        EV_READ | EV_PERSIST,
                                        socket_read_cb, NULL);
    event_add(ev_sockfd, NULL);
 
    //监听终端输入事件
    struct event* ev_cmd = event_new(base, STDIN_FILENO,
                                      EV_READ | EV_PERSIST, cmd_msg_cb,
                                      (void*)&sockfd);
 
 
    event_add(ev_cmd, NULL);
 
    event_base_dispatch(base);
 
    printf("finished \n");
    return 0;
}
 
 
 
 
 
 
void cmd_msg_cb(int fd, short events, void* arg)
{
    char msg[1024];
 
    int ret = read(fd, msg, sizeof(msg));
    if( ret <= 0 )
    {
        perror("read fail ");
        exit(1);
    }
 
    int sockfd = *((int*)arg);
 
    //把终端的消息发送给服务器端
    //为了简单起见，不考虑写一半数据的情况
    write(sockfd, msg, ret);
}
 
 
void socket_read_cb(int fd, short events, void *arg)
{
    char msg[1024];
 
    //为了简单起见，不考虑读一半数据的情况
    int len = read(fd, msg, sizeof(msg)-1);
    if( len <= 0 )
    {
        perror("read fail ");
        exit(1);
    }
 
    msg[len] = '\0';
 
    printf("recv %s from server\n", msg);
}
 
 
 
typedef struct sockaddr SA;
int tcp_connect_server(const char* server_ip, int port)
{
    int sockfd, status, save_errno;
    struct sockaddr_in server_addr;
 
    memset(&server_addr, 0, sizeof(server_addr) );
 
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(port);
    status = inet_aton(server_ip, &server_addr.sin_addr);
 
    if( status == 0 ) //the server_ip is not valid value
    {
        errno = EINVAL;
        return -1;
    }
 
    sockfd = ::socket(PF_INET, SOCK_STREAM, 0);
    if( sockfd == -1 )
        return sockfd;
 
 
    status = ::connect(sockfd, (SA*)&server_addr, sizeof(server_addr) );
 
    if( status == -1 )
    {
        save_errno = errno;
        ::close(sockfd);
        errno = save_errno; //the close may be error
        return -1;
    }
 
    evutil_make_socket_nonblocking(sockfd);
 
    return sockfd;
}

 

6.编译 g++ -o es eventServer.cpp -levent
编译 g++ -o ec eventClient.cpp -levent

7.export LD_LIBRARY_PATH=/usr/local/lib
8.执行
./es 127.0.0.1 9999
./ec