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- """HTTP cache implementation.
- """
- import os
- from contextlib import contextmanager
- from typing import Iterator, Optional
- from pip._vendor.cachecontrol.cache import BaseCache
- from pip._vendor.cachecontrol.caches import FileCache
- from pip._vendor.requests.models import Response
- from pip._internal.utils.filesystem import adjacent_tmp_file, replace
- from pip._internal.utils.misc import ensure_dir
- def is_from_cache(response):
- # type: (Response) -> bool
- return getattr(response, "from_cache", False)
- @contextmanager
- def suppressed_cache_errors():
- # type: () -> Iterator[None]
- """If we can't access the cache then we can just skip caching and process
- requests as if caching wasn't enabled.
- """
- try:
- yield
- except OSError:
- pass
- class SafeFileCache(BaseCache):
- """
- A file based cache which is safe to use even when the target directory may
- not be accessible or writable.
- """
- def __init__(self, directory):
- # type: (str) -> None
- assert directory is not None, "Cache directory must not be None."
- super().__init__()
- self.directory = directory
- def _get_cache_path(self, name):
- # type: (str) -> str
- # From cachecontrol.caches.file_cache.FileCache._fn, brought into our
- # class for backwards-compatibility and to avoid using a non-public
- # method.
- hashed = FileCache.encode(name)
- parts = list(hashed[:5]) + [hashed]
- return os.path.join(self.directory, *parts)
- def get(self, key):
- # type: (str) -> Optional[bytes]
- path = self._get_cache_path(key)
- with suppressed_cache_errors():
- with open(path, 'rb') as f:
- return f.read()
- def set(self, key, value):
- # type: (str, bytes) -> None
- path = self._get_cache_path(key)
- with suppressed_cache_errors():
- ensure_dir(os.path.dirname(path))
- with adjacent_tmp_file(path) as f:
- f.write(value)
- replace(f.name, path)
- def delete(self, key):
- # type: (str) -> None
- path = self._get_cache_path(key)
- with suppressed_cache_errors():
- os.remove(path)
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