class HTTPStream(object):
  # 省略若干代码
  def add_request(self, request, readback = None):
    if not isinstance(request, urllib2.Request):
      raise ValueError, "Not a invaid requset"

    # 此处易触发timeout异常, 省略处理异常代码
    sock, data = self.http_sock.make_http_sock_data(request)

    fd = sock.fileno()
    self.fd_map[fd] = sock
    self.fd_request_map[fd] = request
    callback = partial(self._handle_events, request, data, readback)
    self.ioloop.add_handler(fd, callback, IOLoop.WRITE)

class HTTPStream(object):
  # 省略若干代码
  def _handle_events(self, request, data, readback, fd, event):
    """ 用于处理Tornado事件
    Arguments:
      `request`  -  urllib.Request
      `data`   -  socket要写入的数据
      `readback` -  读取函数
      以上参数应当使用partial封装然后将此方法作为IOLoop.add_handler的callback
      `fd`    -  IOLoop传递 文件描述符
      `event`   -  IOLoop传递 tornado
    """
    s = self.fd_map[fd]

    if event & IOLoop.READ:
      # 省略错误处理
      resp = self.http_sock.make_response(s, request)
      args = readback(resp)
      s.setblocking(False)
      if args and len(args) == 3:
        t = threading.Thread(target = self.add_delay_request, args = args)
        t.setDaemon(True)
        t.start()

      if args and len(args) == 2:
        self.add_request(*args)
      self.ioloop.remove_handler(fd)

    if event & IOLoop.WRITE:
      s.sendall(data)
      if readback:
        self.ioloop.update_handler(fd, IOLoop.READ)
      else:
        self.ioloop.remove_handler(fd)

    if event & IOLoop.ERROR:
      pass