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