如何腌制ssl.SSLContext对象

问题描述

Windows上的Python 3.5，请尝试以下操作:

Python 3.5 on windows, try these:

import ssl, pickle, multiprocessing
context = ssl.create_default_context()
foo = pickle.dumps(context)
pickle.loads(foo)

引发异常:

TypeError: __new__() missing 1 required positional argument: 'protocol'

multiprocessing.Process的子类抛出相同的异常:

subclass of multiprocessing.Process throws the same exception:

class Foo(multiprocessing.Process):
    def __init__(self):
        super().__init__()
        self.context = ssl.create_default_context()

    def run(self):
        pass

if __name__ == '__main__':
    foo = Foo()
    foo.start()

推荐答案

类似的方法应该起作用:

Something like this should work:

>>> import pickle, copyreg, ssl
>>>
>>> def save_sslcontext(obj):
...   return obj.__class__, (obj.protocol,)
...
>>> copyreg.pickle(ssl.SSLContext, save_sslcontext)
>>>
>>> context = ssl.create_default_context()
>>> foo = pickle.dumps(context)
>>> _foo = pickle.loads(foo)
>>> _foo
<ssl.SSLContext object at 0x1011812a8>
>>> _foo.protocol
2
>>>

基本上，SSLContext需要一个protocol，并且由于任何原因，腌制该实例时都不会保存protocol(例如，它不在__reduce__方法中).如果需要更多状态(即__init__方法中的其他args和kwds)，则需要扩展上述save_sslcontext函数的返回值. (请注意，如果您使用的是python 2.x，则相应的模块为copy_reg.)

Basically, a SSLContext needs a protocol, and for whatever reason, the protocol is not saved (e.g. it's not in a __reduce__ method) when the instance is pickled. If you need more state (i.e. other args and kwds from the __init__ method), then you'll need to extend the return value from the save_sslcontext function above. (Note, if you are in python 2.x, then the appropriate module is copy_reg).

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