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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: Response) -> bool:
return getattr(response, "from_cache", False)
@contextmanager
def suppressed_cache_errors() -> 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: str) -> None:
assert directory is not None, "Cache directory must not be None."
super().__init__()
self.directory = directory
def _get_cache_path(self, name: 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: 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: str, value: 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: str) -> None:
path = self._get_cache_path(key)
with suppressed_cache_errors():
os.remove(path)
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