python 限制函数执行时间,自己实现timeout的实例

# coding=utf-8
import signal
import time
 
 
def set_timeout(num, callback):
  def wrap(func):
    def handle(signum, frame): # 收到信号 SIGALRM 后的回调函数，第一个参数是信号的数字，第二个参数是the interrupted stack frame.
      raise RuntimeError
 
    def to_do(*args, **kwargs):
      try:
        signal.signal(signal.SIGALRM, handle) # 设置信号和回调函数
        signal.alarm(num) # 设置 num 秒的闹钟
        print 'start alarm signal.'
        r = func(*args, **kwargs)
        print 'close alarm signal.'
        signal.alarm(0) # 关闭闹钟
        return r
      except RuntimeError as e:
        callback()
 
    return to_do
 
  return wrap
 
 
if __name__ == '__main__':
  def after_timeout(): # 超时后的处理函数
    print "do something after timeout."
 
 
  @set_timeout(2, after_timeout) # 限时 2 秒
  def connect(): # 要执行的函数
    time.sleep(1) # 函数执行时间，写大于2的值，可测试超时
    return 'connect success.'
 
 
  print connect()