"""HTTP cache implementation.
"""
import os
from contextlib import contextmanager
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
from pip._internal.utils.typing import MYPY_CHECK_RUNNING
if MYPY_CHECK_RUNNING:
from typing import Optional, Iterator
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, IOError):
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(SafeFileCache, self).__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)
