MaxRetryError is not pickleable (has failing test, needs fix)

[shazow]

Progress branch for #100.

Related bug report: celery/billiard#18

[shazow]

Current failure:

ERROR: test_exceptions_with_objects (test.test_exceptions.TestPickle)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/shazow/projects/urllib3/test/test_exceptions.py", line 18, in test_exceptions_with_objects
    assert pickle.dumps(MaxRetryError(HTTPConnectionPool('localhost'), '/'))
  File "/usr/lib/python2.7/pickle.py", line 1374, in dumps
    Pickler(file, protocol).dump(obj)
  File "/usr/lib/python2.7/pickle.py", line 224, in dump
    self.save(obj)
  File "/usr/lib/python2.7/pickle.py", line 331, in save
    self.save_reduce(obj=obj, *rv)
  File "/usr/lib/python2.7/pickle.py", line 419, in save_reduce
    save(state)
  File "/usr/lib/python2.7/pickle.py", line 286, in save
    f(self, obj) # Call unbound method with explicit self
  File "/usr/lib/python2.7/pickle.py", line 649, in save_dict
    self._batch_setitems(obj.iteritems())
  File "/usr/lib/python2.7/pickle.py", line 663, in _batch_setitems
    save(v)
  File "/usr/lib/python2.7/pickle.py", line 331, in save
    self.save_reduce(obj=obj, *rv)
  File "/usr/lib/python2.7/pickle.py", line 419, in save_reduce
    save(state)
  File "/usr/lib/python2.7/pickle.py", line 286, in save
    f(self, obj) # Call unbound method with explicit self
  File "/usr/lib/python2.7/pickle.py", line 649, in save_dict
    self._batch_setitems(obj.iteritems())
  File "/usr/lib/python2.7/pickle.py", line 663, in _batch_setitems
    save(v)
  File "/usr/lib/python2.7/pickle.py", line 286, in save
    f(self, obj) # Call unbound method with explicit self
  File "/usr/lib/python2.7/pickle.py", line 725, in save_inst
    save(stuff)
  File "/usr/lib/python2.7/pickle.py", line 286, in save
    f(self, obj) # Call unbound method with explicit self
  File "/usr/lib/python2.7/pickle.py", line 649, in save_dict
    self._batch_setitems(obj.iteritems())
  File "/usr/lib/python2.7/pickle.py", line 663, in _batch_setitems
    save(v)
  File "/usr/lib/python2.7/pickle.py", line 331, in save
    self.save_reduce(obj=obj, *rv)
  File "/usr/lib/python2.7/pickle.py", line 419, in save_reduce
    save(state)
  File "/usr/lib/python2.7/pickle.py", line 286, in save
    f(self, obj) # Call unbound method with explicit self
  File "/usr/lib/python2.7/pickle.py", line 649, in save_dict
    self._batch_setitems(obj.iteritems())
  File "/usr/lib/python2.7/pickle.py", line 663, in _batch_setitems
    save(v)
  File "/usr/lib/python2.7/pickle.py", line 306, in save
    rv = reduce(self.proto)
  File "/home/shazow/env/urllib3/lib64/python2.7/copy_reg.py", line 70, in _reduce_ex
    raise TypeError, "can't pickle %s objects" % base.__name__
TypeError: can't pickle lock objects

[shazow]

@kennethreitz @ask Fixed the __init__ thing (looks like pickle doesn't like super() either, goes into infinite recursion) but MaxRetryError still won't pickle as long as it holds a reference to the pool which contains a lock object.

Suggestions?

[ask]

@shazow: Does it really need the pool when it restores the object on the other side?

If not you could add:

def __reduce__(self):
    return self.__class__, (None, self.url)

[shazow]

That sounds good. If this use case becomes more popular then maybe it'll be worthwhile having a neutered version of a PickledConnectionPool or something.

[shazow]

@kennethreitz Ready to go, feel free to pull master upstream.

@ask Thank you for your help!