Libevent使用例子，從簡單到複雜

轉載請註明出處： http://blog.csdn.net/luotuo44/article/details/39670221

本文從簡單到複雜，展示怎麼使用Libevent。另外網上的很多例子都是隻有服務器端的，本文裏面客戶端和服務器端都有。不說這麼多了，直接上代碼。

初等：

客戶端代碼：

#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;
  }


  //兩個參數依次是服務器端的IP地址、端口號
  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);

  //監聽終端輸入事件
  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);

  //把終端的消息發送給服務器端
  //爲了簡單起見，不考慮寫一半數據的情況
  write(sockfd, msg, ret);
}


void socket_read_cb(int fd, short events, void *arg)
{
  char msg[1024];

  //爲了簡單起見，不考慮讀一半數據的情況
  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;
}

服務器端代碼：

#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();

  //添加監聽客戶端請求連接事件
  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;

  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;

  //僅僅是爲了動態創建一個event結構體
  struct event *ev = event_new(NULL, -1, 0, NULL, NULL);
  //將動態創建的結構體作爲event的回調參數
  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");
    close(event_get_fd(ev));
    event_free(ev);
    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;

  //允許多次綁定同一個地址。要用在socket和bind之間
  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;


  //跨平臺統一接口，將套接字設置爲非阻塞狀態
  evutil_make_socket_nonblocking(listener);

  return listener;

  error:
    errno_save = errno;
    evutil_closesocket(listener);
    errno = errno_save;

    return -1;
}

中等：

客戶端代碼：

#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;
  }


  //兩個參數依次是服務器端的IP地址、端口號
  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);

  //監聽終端輸入事件
  struct event* ev_cmd = event_new(base, STDIN_FILENO,
                    EV_READ | EV_PERSIST, cmd_msg_cb,
                    (void*)bev);
  event_add(ev_cmd, NULL);

  //當socket關閉時會用到回調參數
  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;

  //把終端的消息發送給服務器端
  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");

  //這將自動close套接字和free讀寫緩衝區
  bufferevent_free(bev);

  struct event *ev = (struct event*)arg;
  //因爲socket已經沒有，所以這個event也沒有存在的必要了
  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;
}

服務器端代碼：

#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();

  //添加監聽客戶端請求連接事件
  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;

  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");

  //這將自動close套接字和free讀寫緩衝區
  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;

  //允許多次綁定同一個地址。要用在socket和bind之間
  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;


  //跨平臺統一接口，將套接字設置爲非阻塞狀態
  evutil_make_socket_nonblocking(listener);

  return listener;

  error:
    errno_save = errno;
    evutil_closesocket(listener);
    errno = errno_save;

    return -1;
}

高等：

客戶端代碼：

#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 )
  {
    //兩個參數依次是服務器端的IP地址、端口號
    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);

  //監聽終端輸入事件
  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;

  //把終端的消息發送給服務器端
  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 ;
  }

  //這將自動close套接字和free讀寫緩衝區
  bufferevent_free(bev);

  struct event *ev = (struct event*)arg;
  event_free(ev);
}

服務器端代碼：

#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;
}


//一個新客戶端連接上服務器了
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;

  //爲這個客戶端分配一個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");

  //這將自動close套接字和free讀寫緩衝區
  bufferevent_free(bev);
}

Libevent使用例子，從簡單到複雜

初等：

客戶端代碼：

服務器端代碼：

中等：

客戶端代碼：

服務器端代碼：

高等：

客戶端代碼：

服務器端代碼：

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