Python释放内部具有类实例的对象

Question

我正在使用python请求库并尝试保留会话。

由于主机上有多个IP，因此我创建了以下方法以使会话绑定到特定IP。

class SourceAddressAdapter(HTTPAdapter):
    def __init__(self, source_address, **kwargs):
        self.source_address = source_address
        super(SourceAddressAdapter, self).__init__(**kwargs)

    def init_poolmanager(self, connections, maxsize, block=False):
        self.poolmanager = PoolManager(num_pools=connections,
                                   maxsize=maxsize,
                                   block=block,
                                   source_address=self.source_address)

以下代码段用于调用此类：

r = requests.Session()
r.mount('http://', SourceAddressAdapter((self.ip,0)))
r.mount('https://', SourceAddressAdapter((self.ip,0)))

将http和https协议安装到此适配器后，我使用pickle将对象持久化为redis，如下所示：

session = pickle.dumps(r)
redis.hset('sessions',id,session)

当我尝试释放会话对象时发生问题：

s=redis.hget('sessions', id)
pickle.loads(s)


Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.7/pickle.py", line 1382, in loads
    return Unpickler(file).load()
  File "/usr/lib/python2.7/pickle.py", line 858, in load
    dispatch[key](self)
  File "/usr/lib/python2.7/pickle.py", line 1217, in load_build
    setstate(state)
  File "/usr/local/lib/python2.7/dist-packages/requests/adapters.py", line 114, in __setstate__
    block=self._pool_block)
  File "network_driver.py", line 158, in init_poolmanager
    source_address=self.source_address)
AttributeError: 'SourceAddressAdapter' object has no attribute 'source_address'

它抱怨SourceAddressAdapter没有source_address属性。 在将此类SourceAddressAdapter添加到会话中之前，序列化工作良好。

所以我想这是定制类的酸洗/解酸的问题。

---

更新：

在我将__getstate__和__setstate__方法添加到SourceAddressAdapter之后，它可以工作

def __getstate__(self):
    # it calls HTTPAdapter's __getstate__()
    state = super(SourceAddressAdapter, self).__getstate__() 
    state['source_address'] = self.source_address
    return state

def __setstate__(self,state):
    self.source_address = state['source_address']
    # Call HTTPAdapter's __setstate__ function to pack the attributes in parent class 
    super(SourceAddressAdapter, self).__setstate__(state)

Answer 1

我相信问题在于HTTPAdapter类定义了__setstate__方法。 取消酸洗时会调用此函数，并将实例恢复为酸洗状态。 然而， HTTPAdapter不知道你的的source_address属性，因此该属性是不可恢复的（或者甚至没有摆在首位腌）。

要解决此问题，您需要重写__setstate__函数，如下所示：

def __setstate__(self, state):
    self.source_address= state['source_address'] # do this before calling __setstate__
    HTTPAdapter.__setstate__(self, state)

而且，正如前面提到的，你可能还需要重写__getstate__功能，以便source_address被腌制。