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authorblackhao <13851610112@163.com>2025-08-22 02:51:50 -0500
committerblackhao <13851610112@163.com>2025-08-22 02:51:50 -0500
commit4aab4087dc97906d0b9890035401175cdaab32d4 (patch)
tree4e2e9d88a711ec5b1cfa02e8ac72a55183b99123 /.venv/lib/python3.12/site-packages/pip/_internal/network/cache.py
parentafa8f50d1d21c721dabcb31ad244610946ab65a3 (diff)
2.0
Diffstat (limited to '.venv/lib/python3.12/site-packages/pip/_internal/network/cache.py')
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+"""HTTP cache implementation."""
+
+from __future__ import annotations
+
+import os
+import shutil
+from collections.abc import Generator
+from contextlib import contextmanager
+from datetime import datetime
+from typing import Any, BinaryIO, Callable
+
+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) -> bytes | None:
+ # 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_to_file(self, path: str, writer_func: Callable[[BinaryIO], Any]) -> None:
+ """Common file writing logic with proper permissions and atomic replacement."""
+ with suppressed_cache_errors():
+ ensure_dir(os.path.dirname(path))
+
+ with adjacent_tmp_file(path) as f:
+ writer_func(f)
+ # Inherit the read/write permissions of the cache directory
+ # to enable multi-user cache use-cases.
+ mode = (
+ os.stat(self.directory).st_mode
+ & 0o666 # select read/write permissions of cache directory
+ | 0o600 # set owner read/write permissions
+ )
+ # Change permissions only if there is no risk of following a symlink.
+ if os.chmod in os.supports_fd:
+ os.chmod(f.fileno(), mode)
+ elif os.chmod in os.supports_follow_symlinks:
+ os.chmod(f.name, mode, follow_symlinks=False)
+
+ replace(f.name, path)
+
+ def _write(self, path: str, data: bytes) -> None:
+ self._write_to_file(path, lambda f: f.write(data))
+
+ def _write_from_io(self, path: str, source_file: BinaryIO) -> None:
+ self._write_to_file(path, lambda f: shutil.copyfileobj(source_file, f))
+
+ def set(
+ self, key: str, value: bytes, expires: 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) -> BinaryIO | None:
+ # 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)
+
+ def set_body_from_io(self, key: str, body_file: BinaryIO) -> None:
+ """Set the body of the cache entry from a file object."""
+ path = self._get_cache_path(key) + ".body"
+ self._write_from_io(path, body_file)