mirror of https://github.com/pypa/pip
107 lines
3.8 KiB
Python
107 lines
3.8 KiB
Python
"""HTTP cache implementation.
|
|
"""
|
|
|
|
import os
|
|
from contextlib import contextmanager
|
|
from datetime import datetime
|
|
from typing import BinaryIO, Generator, Optional, Union
|
|
|
|
from pip._vendor.cachecontrol.cache import SeparateBodyBaseCache
|
|
from pip._vendor.cachecontrol.caches import SeparateBodyFileCache
|
|
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() -> Generator[None, None, 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(SeparateBodyBaseCache):
|
|
"""
|
|
A file based cache which is safe to use even when the target directory may
|
|
not be accessible or writable.
|
|
|
|
There is a race condition when two processes try to write and/or read the
|
|
same entry at the same time, since each entry consists of two separate
|
|
files (https://github.com/psf/cachecontrol/issues/324). We therefore have
|
|
additional logic that makes sure that both files to be present before
|
|
returning an entry; this fixes the read side of the race condition.
|
|
|
|
For the write side, we assume that the server will only ever return the
|
|
same data for the same URL, which ought to be the case for files pip is
|
|
downloading. PyPI does not have a mechanism to swap out a wheel for
|
|
another wheel, for example. If this assumption is not true, the
|
|
CacheControl issue will need to be fixed.
|
|
"""
|
|
|
|
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 = SeparateBodyFileCache.encode(name)
|
|
parts = list(hashed[:5]) + [hashed]
|
|
return os.path.join(self.directory, *parts)
|
|
|
|
def get(self, key: str) -> Optional[bytes]:
|
|
# The cache entry is only valid if both metadata and body exist.
|
|
metadata_path = self._get_cache_path(key)
|
|
body_path = metadata_path + ".body"
|
|
if not (os.path.exists(metadata_path) and os.path.exists(body_path)):
|
|
return None
|
|
with suppressed_cache_errors():
|
|
with open(metadata_path, "rb") as f:
|
|
return f.read()
|
|
|
|
def _write(self, path: str, data: bytes) -> None:
|
|
with suppressed_cache_errors():
|
|
ensure_dir(os.path.dirname(path))
|
|
|
|
with adjacent_tmp_file(path) as f:
|
|
f.write(data)
|
|
|
|
replace(f.name, path)
|
|
|
|
def set(
|
|
self, key: str, value: bytes, expires: Union[int, datetime, None] = None
|
|
) -> None:
|
|
path = self._get_cache_path(key)
|
|
self._write(path, value)
|
|
|
|
def delete(self, key: str) -> None:
|
|
path = self._get_cache_path(key)
|
|
with suppressed_cache_errors():
|
|
os.remove(path)
|
|
with suppressed_cache_errors():
|
|
os.remove(path + ".body")
|
|
|
|
def get_body(self, key: str) -> Optional[BinaryIO]:
|
|
# The cache entry is only valid if both metadata and body exist.
|
|
metadata_path = self._get_cache_path(key)
|
|
body_path = metadata_path + ".body"
|
|
if not (os.path.exists(metadata_path) and os.path.exists(body_path)):
|
|
return None
|
|
with suppressed_cache_errors():
|
|
return open(body_path, "rb")
|
|
|
|
def set_body(self, key: str, body: bytes) -> None:
|
|
path = self._get_cache_path(key) + ".body"
|
|
self._write(path, body)
|