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Use only the highest, premium quality pickler available at runtime. #156

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Jun 2, 2017
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Use only the highest, premium quality pickler available at runtime. #156

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10 changes: 9 additions & 1 deletion pymemcache/serde.py
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,14 @@
FLAG_COMPRESSED = 1 << 3 # unused, to main compatability with python-memcached
FLAG_TEXT = 1 << 4

# Pickle protocol version (-1 for highest available to runtime)
# Warning with `0`: If somewhere in your value lies a slotted object,
# ie defines `__slots__`, even if you do not include it in your pickleable
# state via `__getstate__`, python will complain with something like:
# TypeError: a class that defines __slots__ without defining __getstate__
# cannot be pickled
PICKLE_VERSION = -1
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Why not use https://docs.python.org/2/library/pickle.html#pickle.HIGHEST_PROTOCOL?

Also note that in python3 the default is not 0. https://docs.python.org/3.1/library/pickle.html

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Because -1 is always the highest protocol.

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@akatrevorjay akatrevorjay Jun 2, 2017 •
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I can use the const if you want, but using -1 is pretty standard imo and doesn't have an attr lookup tax (which is of course not worth mentioning though)

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Correct, in python 3 the default is the new py3+ pickle. But in pymemcache, we always use zero and it unfortunately is a pretty broken version :)

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@cgordon looks like you added this originally any specific reason for the old behavior? Looks like this is based on https://github.com/linsomniac/python-memcached/blob/5b75728565393d53768f4622fdd43e3e742c4741/memcache.py

Also this is a a backwards incompatible change.

Perhaps it would be better to make this field an argument that can be set?



def python_memcache_serializer(key, value):
flags = 0
Expand All @@ -55,7 +63,7 @@ def python_memcache_serializer(key, value):
else:
flags |= FLAG_PICKLE
output = BytesIO()
pickler = pickle.Pickler(output, 0)
pickler = pickle.Pickler(output, PICKLE_VERSION)
pickler.dump(value)
value = output.getvalue()

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