Libevent使用例子
初等：
客户端代码： #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;
} 服务器端代码： #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;
} 中等：
客户端代码： #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/bufferevent.h>
#include<event2/buffer.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 server_msg_cb(struct bufferevent* bev, void* arg);
void event_cb(struct bufferevent *bev, short event, 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 bufferevent* bev = bufferevent_socket_new(base, sockfd,
BEV_OPT_CLOSE_ON_FREE); //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*)bev);
event_add(ev_cmd, NULL); //当socket关闭时会用到回调参数
bufferevent_setcb(bev, server_msg_cb, NULL, event_cb, (void*)ev_cmd);
bufferevent_enable(bev, EV_READ | EV_PERSIST); 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);
} struct bufferevent* bev = (struct bufferevent*)arg; //把终端的消息发送给服务器端
bufferevent_write(bev, msg, ret);
} void server_msg_cb(struct bufferevent* bev, void* arg)
{
char msg[1024]; size_t len = bufferevent_read(bev, msg, sizeof(msg));
msg[len] = '\0'; printf("recv %s from server\n", msg);
} void event_cb(struct bufferevent *bev, short event, void *arg)
{ if (event & BEV_EVENT_EOF)
printf("connection closed\n");
else if (event & BEV_EVENT_ERROR)
printf("some other error\n"); //这将自动close套接字和free读写缓冲区
bufferevent_free(bev); struct event *ev = (struct event*)arg;
//因为socket已经没有，所以这个event也没有存在的必要了
event_free(ev);
} 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;
} 服务器端代码： #include<stdio.h>
#include<string.h>
#include<errno.h> #include<event.h>
#include<event2/bufferevent.h> void accept_cb(int fd, short events, void* arg);
void socket_read_cb(bufferevent* bev, void* arg);
void event_cb(struct bufferevent *bev, short event, 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);
event_base_free(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; bufferevent* bev = bufferevent_socket_new(base, sockfd, BEV_OPT_CLOSE_ON_FREE);
bufferevent_setcb(bev, socket_read_cb, NULL, event_cb, arg); bufferevent_enable(bev, EV_READ | EV_PERSIST);
} void socket_read_cb(bufferevent* bev, void* arg)
{
char msg[4096]; size_t len = bufferevent_read(bev, msg, sizeof(msg)); 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);
bufferevent_write(bev, reply_msg, strlen(reply_msg));
} void event_cb(struct bufferevent *bev, short event, void *arg)
{ if (event & BEV_EVENT_EOF)
printf("connection closed\n");
else if (event & BEV_EVENT_ERROR)
printf("some other error\n"); //这将自动close套接字和free读写缓冲区
bufferevent_free(bev);
} 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;
} 高等：
客户端代码： #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/bufferevent.h>
#include<event2/buffer.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 server_msg_cb(struct bufferevent* bev, void* arg);
void event_cb(struct bufferevent *bev, short event, void *arg); int main(int argc, char** argv)
{
if( argc < 3 )
{
//两个参数依次是服务器端的IP地址、端口号
printf("please input 2 parameter\n");
return -1;
} struct event_base *base = event_base_new(); struct bufferevent* bev = bufferevent_socket_new(base, -1,
BEV_OPT_CLOSE_ON_FREE); //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*)bev); event_add(ev_cmd, NULL); struct sockaddr_in server_addr; memset(&server_addr, 0, sizeof(server_addr) ); server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(atoi(argv[2]));
inet_aton(argv[1], &server_addr.sin_addr); bufferevent_socket_connect(bev, (struct sockaddr *)&server_addr,
sizeof(server_addr)); bufferevent_setcb(bev, server_msg_cb, NULL, event_cb, (void*)ev_cmd);
bufferevent_enable(bev, EV_READ | EV_PERSIST); 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);
} struct bufferevent* bev = (struct bufferevent*)arg; //把终端的消息发送给服务器端
bufferevent_write(bev, msg, ret);
} void server_msg_cb(struct bufferevent* bev, void* arg)
{
char msg[1024]; size_t len = bufferevent_read(bev, msg, sizeof(msg));
msg[len] = '\0'; printf("recv %s from server\n", msg);
} void event_cb(struct bufferevent *bev, short event, void *arg)
{ if (event & BEV_EVENT_EOF)
printf("connection closed\n");
else if (event & BEV_EVENT_ERROR)
printf("some other error\n");
else if( event & BEV_EVENT_CONNECTED)
{
printf("the client has connected to server\n");
return ;
} //这将自动close套接字和free读写缓冲区
bufferevent_free(bev); struct event *ev = (struct event*)arg;
event_free(ev);
} 服务器端代码： #include<netinet/in.h>
#include<sys/socket.h>
#include<unistd.h> #include<stdio.h>
#include<string.h> #include<event.h>
#include<listener.h>
#include<bufferevent.h>
#include<thread.h> void listener_cb(evconnlistener *listener, evutil_socket_t fd,
struct sockaddr *sock, int socklen, void *arg); void socket_read_cb(bufferevent *bev, void *arg);
void socket_event_cb(bufferevent *bev, short events, void *arg); int main()
{
//evthread_use_pthreads();//enable threads struct sockaddr_in sin;
memset(&sin, 0, sizeof(struct sockaddr_in));
sin.sin_family = AF_INET;
sin.sin_port = htons(9999); event_base *base = event_base_new();
evconnlistener *listener
= evconnlistener_new_bind(base, listener_cb, base,
LEV_OPT_REUSEABLE|LEV_OPT_CLOSE_ON_FREE,
10, (struct sockaddr*)&sin,
sizeof(struct sockaddr_in)); event_base_dispatch(base); evconnlistener_free(listener);
event_base_free(base); return 0;
} //一个新客户端连接上服务器了
//当此函数被调用时，libevent已经帮我们accept了这个客户端。该客户端的
//文件描述符为fd
void listener_cb(evconnlistener *listener, evutil_socket_t fd,
struct sockaddr *sock, int socklen, void *arg)
{
printf("accept a client %d\n", fd); event_base *base = (event_base*)arg; //为这个客户端分配一个bufferevent
bufferevent *bev = bufferevent_socket_new(base, fd,
BEV_OPT_CLOSE_ON_FREE); bufferevent_setcb(bev, socket_read_cb, NULL, socket_event_cb, NULL);
bufferevent_enable(bev, EV_READ | EV_PERSIST);
} void socket_read_cb(bufferevent *bev, void *arg)
{
char msg[4096]; size_t len = bufferevent_read(bev, msg, sizeof(msg)-1 ); msg[len] = '\0';
printf("server read the data %s\n", msg); char reply[] = "I has read your data";
bufferevent_write(bev, reply, strlen(reply) );
} void socket_event_cb(bufferevent *bev, short events, void *arg)
{
if (events & BEV_EVENT_EOF)
printf("connection closed\n");
else if (events & BEV_EVENT_ERROR)
printf("some other error\n"); //这将自动close套接字和free读写缓冲区
bufferevent_free(bev);
}
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