蟒蛇 - 重新蹬連接時死

Question

按照該documentation，因爲我已經實例化的連接：

>>> import stomp 
>>> c = stomp.Connection([('127.0.0.1', 62615)]) 
>>> c.start() 
>>> c.connect('admin', 'password', wait=True) 

，如何監控，以便它重新連接上c.is_connected == False？

>>> reconnect_on_dead_connection(c) 
... 
>>> [1479749503] reconnected dead connection 

Answer 1

您可以包裝連接並檢查它是否連接了每個呼叫。

import stomp 


def reconnect(connection): 
    """reconnect here""" 


class ReconnectWrapper(object): 
    def __init__(self, connection): 
     self.__connection = connection 

    def __getattr__(self, item): 
     if not self.__connection.is_connected: 
      reconnect(self.__connection) 
     return getattr(self.__connection, item) 


if __name__ == '__main__': 
    c = stomp.Connection([('127.0.0.1', 62615)]) 
    c.start() 
    c.connect('admin', 'password', wait=True) 
    magic_connection = ReconnectWrapper(c) 

測試：

from scratch_35 import ReconnectWrapper 
import unittest 
import mock 


class TestReconnection(unittest.TestCase): 

    def setUp(self): 
     self.connection = mock.MagicMock() 
     self.reconnect_patcher = mock.patch("scratch_35.reconnect") 
     self.reconnect = self.reconnect_patcher.start() 

    def tearDown(self): 
     self.reconnect_patcher.stop() 

    def test_pass_call_to_warapped_connection(self): 
     connection = ReconnectWrapper(self.connection) 
     connection.send("abc") 
     self.reconnect.assert_not_called() 
     self.connection.send.assert_called_once_with("abc") 

    def test_reconnect_when_disconnected(self): 
     self.connection.is_connected = False 
     connection = ReconnectWrapper(self.connection) 
     connection.send("abc") 
     self.reconnect.assert_called_once_with(self.connection) 
     self.connection.send.assert_called_once_with("abc") 


if __name__ == '__main__': 
    unittest.main() 

結果：

.. 
---------------------------------------------------------------------- 
Ran 2 tests in 0.004s 

OK 

的關鍵是魔術方法__getatter__這就是所謂的每次您嘗試訪問不是由一個對象所提供的屬性。關於方法__getattr__的更多信息，請訪問doucmentation https://docs.python.org/2/reference/datamodel.html#object.getattr。