本文从简单到复杂,展示如何使用libevent。网上的许多例子都是只有服务器端的,本文里面客户端和服务器端都有,以飨读者。
关于libevent编程时的一些疑问可以阅读《libevent编程疑难解答》。假如读者还想了解libevent的具体实现,可以阅读《libevent源码分析》系统文章。
不说这么多了,直接上代码。
初等:
客户端代码:
-
#include
-
#include
-
#include
-
#include
-
#include
-
#include
-
-
#include
-
#include
-
#include
-
-
#include
-
#include
-
-
-
-
-
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;
-
}
-
-
-
-
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);
-
-
-
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);
-
-
-
-
write(sockfd, msg, ret);
-
}
-
-
-
void socket_read_cb(int fd, short events, void *arg)
-
{
-
char msg[1024];
-
-
-
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 )
-
{
-
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;
-
return -1;
-
}
-
-
evutil_make_socket_nonblocking(sockfd);
-
-
return sockfd;
-
}
服务器端代码:
-
#include
-
#include
-
#include
-
-
#include
-
#include
-
-
-
-
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();
-
-
-
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;
-
-
-
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", 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;
-
-
-
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;
-
-
-
-
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
-
#include
-
#include
-
#include
-
#include
-
#include
-
-
#include
-
#include
-
#include
-
-
#include
-
#include
-
#include
-
#include
-
-
-
-
-
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;
-
}
-
-
-
-
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);
-
-
-
struct event* ev_cmd = event_new(base, STDIN_FILENO,
-
EV_READ | EV_PERSIST, cmd_msg_cb,
-
(void*)bev);
-
event_add(ev_cmd, NULL);
-
-
-
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;
-
-
-
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");
-
-
-
bufferevent_free(bev);
-
-
struct event *ev = (struct event*)arg;
-
-
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 )
-
{
-
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;
-
return -1;
-
}
-
-
evutil_make_socket_nonblocking(sockfd);
-
-
return sockfd;
-
}
服务器端代码:
-
#include
-
#include
-
#include
-
-
#include
-
#include
-
-
-
-
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();
-
-
-
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");
-
-
-
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;
-
-
-
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;
-
-
-
-
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
-
#include
-
#include
-
#include
-
#include
-
#include
-
-
#include
-
#include
-
#include
-
-
#include
-
#include
-
#include
-
#include
-
-
-
-
-
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;
-
}
-
-
struct event_base *base = event_base_new();
-
-
struct bufferevent* bev = bufferevent_socket_new(base, -1,
-
BEV_OPT_CLOSE_ON_FREE);
-
-
-
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;
-
-
-
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 ;
-
}
-
-
-
bufferevent_free(bev);
-
-
struct event *ev = (struct event*)arg;
-
event_free(ev);
-
}
服务器端代码:
-
#include
-
#include
-
#include
-
-
#include
-
#include
-
-
#include
-
#include
-
#include
-
#include
-
-
-
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()
-
{
-
-
-
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;
-
}
-
-
-
-
-
-
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;
-
-
-
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");
-
-
-
bufferevent_free(bev);
-
}
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