76 lines
2.4 KiB
Python
76 lines
2.4 KiB
Python
from __future__ import annotations
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import abc
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import hashlib
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from fsspec.implementations.local import make_path_posix
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class AbstractCacheMapper(abc.ABC):
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"""Abstract super-class for mappers from remote URLs to local cached
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basenames.
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"""
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@abc.abstractmethod
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def __call__(self, path: str) -> str: ...
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def __eq__(self, other: object) -> bool:
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# Identity only depends on class. When derived classes have attributes
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# they will need to be included.
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return isinstance(other, type(self))
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def __hash__(self) -> int:
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# Identity only depends on class. When derived classes have attributes
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# they will need to be included.
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return hash(type(self))
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class BasenameCacheMapper(AbstractCacheMapper):
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"""Cache mapper that uses the basename of the remote URL and a fixed number
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of directory levels above this.
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The default is zero directory levels, meaning different paths with the same
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basename will have the same cached basename.
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"""
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def __init__(self, directory_levels: int = 0):
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if directory_levels < 0:
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raise ValueError(
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"BasenameCacheMapper requires zero or positive directory_levels"
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)
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self.directory_levels = directory_levels
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# Separator for directories when encoded as strings.
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self._separator = "_@_"
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def __call__(self, path: str) -> str:
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path = make_path_posix(path)
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prefix, *bits = path.rsplit("/", self.directory_levels + 1)
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if bits:
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return self._separator.join(bits)
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else:
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return prefix # No separator found, simple filename
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def __eq__(self, other: object) -> bool:
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return super().__eq__(other) and self.directory_levels == other.directory_levels
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def __hash__(self) -> int:
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return super().__hash__() ^ hash(self.directory_levels)
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class HashCacheMapper(AbstractCacheMapper):
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"""Cache mapper that uses a hash of the remote URL."""
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def __call__(self, path: str) -> str:
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return hashlib.sha256(path.encode()).hexdigest()
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def create_cache_mapper(same_names: bool) -> AbstractCacheMapper:
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"""Factory method to create cache mapper for backward compatibility with
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``CachingFileSystem`` constructor using ``same_names`` kwarg.
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"""
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if same_names:
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return BasenameCacheMapper()
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else:
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return HashCacheMapper()
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