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