蟒蛇 - 重新蹬连接时死

Question

按照该documentation，因为我已经实例化的连接：

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

，如何监控，以便它重新连接上c.is_connected == False？

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

Answer 1

您可以包装连接并检查它是否连接了每个呼叫。

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) 

测试：

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() 

结果：

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

OK 

的关键是魔术方法__getatter__这就是所谓的每次您尝试访问不是由一个对象所提供的属性。关于方法__getattr__的更多信息，请访问doucmentation https://docs.python.org/2/reference/datamodel.html#object.getattr。