本文主要是介绍libevent框架使用实例，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
首先，先贴一个简单的使用libevent实现的定时器：
#include <stdio.h>
#include <event.h>void onTime(int sock, short event, void *arg)
{printf("Time Bomb!\n");struct timeval tv;tv.tv_sec = 2;tv.tv_usec = 0;event_add((struct event*)arg, &tv);
}int main()
{event_init();struct event evTimer;evtimer_set(&evTimer, onTime, &evTimer);struct timeval tv;tv.tv_sec = 2;tv.tv_usec = 0;event_add(&evTimer, &tv);event_dispatch();return 0;
}
再来一个简单的客户端和服务器通信的例子：
//客户端
#define _GNU_SOURCE
#include <sys/types.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <string.h>
#include <signal.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <errno.h>
#include <stdio.h>
#include <event.h>
#include <event2/util.h>#define BUFFSIZE 1024int tcp_connect(char *ipaddress, char *port);
void socket_info(int, short, void*);
void cmd_read(int ,short, void *);static int pipefd[2]; //用于终端输入int main(int ac, char *av[])
{if(ac != 3){fprintf(stderr, "Usage: %s addr port\n",av[0]);exit(1);}int listenfd = tcp_connect(av[1], av[2]);if(listenfd < 0){perror("Connecting Error");exit(1);}struct event_base *base = event_init();struct event evlisten;event_set(&evlisten, listenfd, EV_READ | EV_PERSIST, socket_info, (void*)&evlisten);event_base_set(base, &evlisten);event_add(&evlisten, NULL);if(pipe(pipefd) < 0){perror("pipe error");exit(1);}struct event cmd;event_set(&cmd, STDIN_FILENO, EV_READ | EV_PERSIST, cmd_read, (void*)&listenfd);event_base_set(base, &cmd);event_add(&cmd, NULL);event_base_dispatch(base);return 0;
}//客户端连接服务器
int tcp_connect(char *ipaddress, char *po)
{char *ip = ipaddress;int port = atoi(po);int ret;int save_errno;struct sockaddr_in addr;bzero(&addr, sizeof(addr));addr.sin_family = AF_INET;addr.sin_port = htons(port);inet_pton(AF_INET, ip, &addr.sin_addr);int sock = socket(AF_INET, SOCK_STREAM, 0);if(sock < 0)return -1;ret = connect(sock, (struct sockaddr *)&addr, sizeof(addr));if(ret < 0){save_errno = errno;close(sock);errno = save_errno;return -1;}evutil_make_socket_nonblocking(sock);return sock;
}//客户端接收到服务器的响应
void socket_info(int fd, short events, void *arg)
{char buf[BUFFSIZE];int ret;struct event *ev = (struct event*)arg;while(1){bzero(buf, sizeof(buf));ret = recv(fd, buf, BUFFSIZE, 0);if(ret < 0){if(errno == EAGAIN || errno == EWOULDBLOCK)break;else{perror("recv error");return;}}else if(ret == 0){printf("server closed the connection\n");close(fd);event_del(ev);exit(0);}elseprintf("get %d bytes from the server :\n %s",ret,buf);}
}//客户端从终端读取数据发送到服务器
void cmd_read(int fd, short events, void *arg)
{int lisfd = *(int *)arg;splice(fd, NULL, pipefd[1], NULL, 32768, SPLICE_F_MOVE | SPLICE_F_MORE);splice(pipefd[0], NULL, lisfd, NULL, 32768, SPLICE_F_MOVE | SPLICE_F_MORE);
}//服务器端
#include <sys/types.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <string.h>
#include <signal.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <errno.h>
#include <stdio.h>
#include <event.h>
#include <event2/util.h>#define BUFFSIZE 1024int tcp_listen(char *, char *);
void tcp_accept(int fd, short events, void *arg);
void sock_info(int fd, short events, void *arg);int main(int ac, char *av[])
{if(ac != 3){fprintf(stderr, "Usage: %s addr port\n",av[0]);exit(1);}int listenfd = tcp_listen(av[1], av[2]);if(listenfd < 0){perror("listen error");exit(1);}struct event_base *base = event_init();struct event ev_lis;event_set(&ev_lis, listenfd, EV_READ | EV_PERSIST, tcp_accept, (void*)base);event_base_set(base, &ev_lis);event_add(&ev_lis, NULL);event_base_dispatch(base); return 0;
}int tcp_listen(char *i, char *po)
{char *ip = i;int port = atoi(po);int ret;int save_errno;struct sockaddr_in addr;bzero(&addr, sizeof(addr));addr.sin_family = AF_INET;addr.sin_port = htons(port);inet_pton(AF_INET, ip, &addr.sin_addr);int sock = socket(AF_INET, SOCK_STREAM, 0);if(sock < 0)return -1;ret = bind(sock, (struct sockaddr *)&addr, sizeof(addr));if(ret < 0){save_errno = errno;close(sock);errno = save_errno;return -1;}ret = listen(sock, 10);if(ret < 0){save_errno = errno;close(sock);errno = save_errno;return -1;}return sock;
}//有新的连接
void tcp_accept(int fd, short events, void *arg)
{struct event_base *base = (struct event_base *)arg;int connfd;struct sockaddr_in cli_addr;socklen_t cli_len = sizeof(cli_addr);connfd = accept(fd, &cli_addr, &cli_len);if(connfd < 0){perror("accept error");return;}evutil_make_socket_nonblocking(connfd); struct event *ev_conn = (struct event*)malloc(sizeof(struct event));event_set(ev_conn, connfd, EV_READ | EV_PERSIST, sock_info, (void*)ev_conn);event_base_set(base, ev_conn);event_add(ev_conn, NULL);}//客户有信息发来
void sock_info(int fd, short events, void *arg)
{struct event *evconn = (struct event*)arg;char buf[BUFFSIZE];int bytes = 0;int ret;printf("client send somthing to me!\n");while(1){memset(buf, '\0', BUFFSIZE);ret = recv(fd, buf, BUFFSIZE, 0);if(ret < 0){if(errno == EAGAIN)break;else{perror("recv error");return;}}else if(ret == 0){printf("client has closed the connecction\n");close(fd);event_del(evconn);return;}else{bytes += ret;printf("get %d bytes from the client : %s",ret,buf);}}memset(buf, '\0', BUFFSIZE);snprintf(buf, BUFFSIZE, "I have recevied your %d bytes.\n", bytes);ret = strlen(buf);if(send(fd, buf, strlen(buf), 0) != ret){perror("send error");return;}
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