【libevent】hello world

• 演示了创建reactor的event base new
• evconnlistener_new_bind 似乎是服务器？
• evsignal_new 创建信号事件
• event_add 把信号事件加入到event reactor里。

最简单的hello world

/*
  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