matekasse/venv/lib/python3.11/site-packages/cachelib/serializers.py
2023-07-28 23:30:45 +02:00

114 lines
3.3 KiB
Python

import logging
import pickle
import typing as _t
class BaseSerializer:
"""This is the base interface for all default serializers.
BaseSerializer.load and BaseSerializer.dump will
default to pickle.load and pickle.dump. This is currently
used only by FileSystemCache which dumps/loads to/from a file stream.
"""
def _warn(self, e: pickle.PickleError) -> None:
logging.warning(
f"An exception has been raised during a pickling operation: {e}"
)
def dump(
self, value: int, f: _t.IO, protocol: int = pickle.HIGHEST_PROTOCOL
) -> None:
try:
pickle.dump(value, f, protocol)
except (pickle.PickleError, pickle.PicklingError) as e:
self._warn(e)
def load(self, f: _t.BinaryIO) -> _t.Any:
try:
data = pickle.load(f)
except pickle.PickleError as e:
self._warn(e)
return None
else:
return data
"""BaseSerializer.loads and BaseSerializer.dumps
work on top of pickle.loads and pickle.dumps. Dumping/loading
strings and byte strings is the default for most cache types.
"""
def dumps(self, value: _t.Any, protocol: int = pickle.HIGHEST_PROTOCOL) -> bytes:
try:
serialized = pickle.dumps(value, protocol)
except (pickle.PickleError, pickle.PicklingError) as e:
self._warn(e)
return serialized
def loads(self, bvalue: bytes) -> _t.Any:
try:
data = pickle.loads(bvalue)
except pickle.PickleError as e:
self._warn(e)
return None
else:
return data
"""Default serializers for each cache type.
The following classes can be used to further customize
serialiation behaviour. Alternatively, any serializer can be
overriden in order to use a custom serializer with a different
strategy altogether.
"""
class UWSGISerializer(BaseSerializer):
"""Default serializer for UWSGICache."""
class SimpleSerializer(BaseSerializer):
"""Default serializer for SimpleCache."""
class FileSystemSerializer(BaseSerializer):
"""Default serializer for FileSystemCache."""
class RedisSerializer(BaseSerializer):
"""Default serializer for RedisCache."""
def dumps(self, value: _t.Any, protocol: int = pickle.HIGHEST_PROTOCOL) -> bytes:
"""Dumps an object into a string for redis. By default it serializes
integers as regular string and pickle dumps everything else.
"""
return b"!" + pickle.dumps(value, protocol)
def loads(self, value: _t.Optional[bytes]) -> _t.Any:
"""The reversal of :meth:`dump_object`. This might be called with
None.
"""
if value is None:
return None
if value.startswith(b"!"):
try:
return pickle.loads(value[1:])
except pickle.PickleError:
return None
try:
return int(value)
except ValueError:
# before 0.8 we did not have serialization. Still support that.
return value
class DynamoDbSerializer(RedisSerializer):
"""Default serializer for DynamoDbCache."""
def loads(self, value: _t.Any) -> _t.Any:
"""The reversal of :meth:`dump_object`. This might be called with
None.
"""
value = value.value
return super().loads(value)