Visual Studio 2017开发linux程序之libevent使用实例

Posted 2022-06-09 shixin_0125

下载源码编译安装后，samle里面有个hello-world.c就是最简单的一个tcp server端程序了

/*
  This example program provides a trivial server program that listens for TCP
  connections on port 9995.  When they arrive, it writes a short message to
  each client connection, and closes each connection once it is flushed.

  Where possible, it exits cleanly in response to a SIGINT (ctrl-c).
*/


#include <string.h>
#include <errno.h>
#include <stdio.h>
#include <signal.h>
#ifndef _WIN32
#include <netinet/in.h>
# ifdef _XOPEN_SOURCE_EXTENDED
#  include <arpa/inet.h>
# endif
#include <sys/socket.h>
#endif

#include <event2/bufferevent.h>
#include <event2/buffer.h>
#include <event2/listener.h>
#include <event2/util.h>
#include <event2/event.h>

static const char MESSAGE[] = "Hello, World!\\n";

static const int PORT = 9995;

static void listener_cb(struct evconnlistener *, evutil_socket_t,
    struct sockaddr *, int socklen, void *);
static void conn_writecb(struct bufferevent *, void *);
static void conn_eventcb(struct bufferevent *, short, void *);
static void signal_cb(evutil_socket_t, short, void *);

int
main(int argc, char **argv)

  struct event_base *base;
  struct evconnlistener *listener;
  struct event *signal_event;

  struct sockaddr_in sin;
#ifdef _WIN32
  WSADATA wsa_data;
  WSAStartup(0x0201, &wsa_data);
#endif

  base = event_base_new();
  if (!base) 
    fprintf(stderr, "Could not initialize libevent!\\n");
    return 1;
  

  memset(&sin, 0, sizeof(sin));
  sin.sin_family = AF_INET;
  sin.sin_port = htons(PORT);

  listener = evconnlistener_new_bind(base, listener_cb, (void *)base,
      LEV_OPT_REUSEABLE|LEV_OPT_CLOSE_ON_FREE, -1,
      (struct sockaddr*)&sin,
      sizeof(sin));

  if (!listener) 
    fprintf(stderr, "Could not create a listener!\\n");
    return 1;
  

  signal_event = evsignal_new(base, SIGINT, signal_cb, (void *)base);

  if (!signal_event || event_add(signal_event, NULL)<0) 
    fprintf(stderr, "Could not create/add a signal event!\\n");
    return 1;
  

  event_base_dispatch(base);

  evconnlistener_free(listener);
  event_free(signal_event);
  event_base_free(base);

  printf("done\\n");
  return 0;


static void
listener_cb(struct evconnlistener *listener, evutil_socket_t fd,
    struct sockaddr *sa, int socklen, void *user_data)

  struct event_base *base = user_data;
  struct bufferevent *bev;

  bev = bufferevent_socket_new(base, fd, BEV_OPT_CLOSE_ON_FREE);
  if (!bev) 
    fprintf(stderr, "Error constructing bufferevent!");
    event_base_loopbreak(base);
    return;
  
  bufferevent_setcb(bev, NULL, conn_writecb, conn_eventcb, NULL);
  bufferevent_enable(bev, EV_WRITE);
  bufferevent_disable(bev, EV_READ);

  bufferevent_write(bev, MESSAGE, strlen(MESSAGE));


static void
conn_writecb(struct bufferevent *bev, void *user_data)

  struct evbuffer *output = bufferevent_get_output(bev);
  if (evbuffer_get_length(output) == 0) 
    printf("flushed answer\\n");
    bufferevent_free(bev);
  


static void
conn_eventcb(struct bufferevent *bev, short events, void *user_data)

  if (events & BEV_EVENT_EOF) 
    printf("Connection closed.\\n");
   else if (events & BEV_EVENT_ERROR) 
    printf("Got an error on the connection: %s\\n",
        strerror(errno));/*XXX win32*/
  
  /* None of the other events can happen here, since we havent enabled
   * timeouts */
  bufferevent_free(bev);


static void
signal_cb(evutil_socket_t sig, short events, void *user_data)

  struct event_base *base = user_data;
  struct timeval delay =  2, 0 ;

  printf("Caught an interrupt signal; exiting cleanly in two seconds.\\n");

  event_base_loopexit(base, &delay);

设置好链接库的路径和链接库

写一个简单的client端，代码如下：

// sample_tcpclient.cpp : 定义控制台应用程序的入口点。
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