libevent使用教程_evutil_make_socket_nonblocking_易方达蓝筹的博客-CSDN博客
一、准备
centos7下安装libevent库
yum install libevent
yum install -y libevent-devel二、代码
server.cpp
/**
You need libevent2 to compile this piece of code
Please see: http://libevent.org/
Or you can simply run this command to install on Mac: brew install libevent
Cmd to compile this piece of code: g++ LibeventQuickStartServer.c -o LibeventQuickStartServer /usr/local/lib/libevent.a
**/
#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 const *argv[])
{/* code */int listener = tcp_server_init(9999, 10);if (listener == -1){perror("tcp_server_init error");return -1;}struct event_base* base = event_base_new();// 监听客户端请求链接事件struct event* ev_listen = event_new(base, listener, EV_READ | EV_PERSIST, accept_cb, base);printf("wait for client connect\n");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;//动态创建一个event结构体，并将其作为回调参数传递给struct event* ev = event_new(NULL, -1, 0, NULL, NULL);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\n", msg);char reply_msg[4096] = "I have received 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;
} client.cpp
/**
You need libevent2 to compile this piece of code
Please see: http://libevent.org/
Or you can simply run this command to install on Mac: brew install libevent
Cmd to compile this piece of code: g++ LibeventQuickStartClient.c -o LibeventQuickStartClient /usr/local/lib/libevent.a
**/
#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)
{ //两个参数依次是服务器端的IP地址、端口号 int sockfd = tcp_connect_server("127.0.0.1", 9999); 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("get respond from server: %s \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;
} 
g++ client.cpp -std=c++11 -o client -levent
