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Diffstat (limited to '.venv/lib/python3.12/site-packages/pip/_vendor/cachecontrol/filewrapper.py')
-rw-r--r-- | .venv/lib/python3.12/site-packages/pip/_vendor/cachecontrol/filewrapper.py | 119 |
1 files changed, 119 insertions, 0 deletions
diff --git a/.venv/lib/python3.12/site-packages/pip/_vendor/cachecontrol/filewrapper.py b/.venv/lib/python3.12/site-packages/pip/_vendor/cachecontrol/filewrapper.py new file mode 100644 index 00000000..37d2fa59 --- /dev/null +++ b/.venv/lib/python3.12/site-packages/pip/_vendor/cachecontrol/filewrapper.py @@ -0,0 +1,119 @@ +# SPDX-FileCopyrightText: 2015 Eric Larson +# +# SPDX-License-Identifier: Apache-2.0 +from __future__ import annotations + +import mmap +from tempfile import NamedTemporaryFile +from typing import TYPE_CHECKING, Any, Callable + +if TYPE_CHECKING: + from http.client import HTTPResponse + + +class CallbackFileWrapper: + """ + Small wrapper around a fp object which will tee everything read into a + buffer, and when that file is closed it will execute a callback with the + contents of that buffer. + + All attributes are proxied to the underlying file object. + + This class uses members with a double underscore (__) leading prefix so as + not to accidentally shadow an attribute. + + The data is stored in a temporary file until it is all available. As long + as the temporary files directory is disk-based (sometimes it's a + memory-backed-``tmpfs`` on Linux), data will be unloaded to disk if memory + pressure is high. For small files the disk usually won't be used at all, + it'll all be in the filesystem memory cache, so there should be no + performance impact. + """ + + def __init__( + self, fp: HTTPResponse, callback: Callable[[bytes], None] | None + ) -> None: + self.__buf = NamedTemporaryFile("rb+", delete=True) + self.__fp = fp + self.__callback = callback + + def __getattr__(self, name: str) -> Any: + # The vagaries of garbage collection means that self.__fp is + # not always set. By using __getattribute__ and the private + # name[0] allows looking up the attribute value and raising an + # AttributeError when it doesn't exist. This stop things from + # infinitely recursing calls to getattr in the case where + # self.__fp hasn't been set. + # + # [0] https://docs.python.org/2/reference/expressions.html#atom-identifiers + fp = self.__getattribute__("_CallbackFileWrapper__fp") + return getattr(fp, name) + + def __is_fp_closed(self) -> bool: + try: + return self.__fp.fp is None + + except AttributeError: + pass + + try: + closed: bool = self.__fp.closed + return closed + + except AttributeError: + pass + + # We just don't cache it then. + # TODO: Add some logging here... + return False + + def _close(self) -> None: + if self.__callback: + if self.__buf.tell() == 0: + # Empty file: + result = b"" + else: + # Return the data without actually loading it into memory, + # relying on Python's buffer API and mmap(). mmap() just gives + # a view directly into the filesystem's memory cache, so it + # doesn't result in duplicate memory use. + self.__buf.seek(0, 0) + result = memoryview( + mmap.mmap(self.__buf.fileno(), 0, access=mmap.ACCESS_READ) + ) + self.__callback(result) + + # We assign this to None here, because otherwise we can get into + # really tricky problems where the CPython interpreter dead locks + # because the callback is holding a reference to something which + # has a __del__ method. Setting this to None breaks the cycle + # and allows the garbage collector to do it's thing normally. + self.__callback = None + + # Closing the temporary file releases memory and frees disk space. + # Important when caching big files. + self.__buf.close() + + def read(self, amt: int | None = None) -> bytes: + data: bytes = self.__fp.read(amt) + if data: + # We may be dealing with b'', a sign that things are over: + # it's passed e.g. after we've already closed self.__buf. + self.__buf.write(data) + if self.__is_fp_closed(): + self._close() + + return data + + def _safe_read(self, amt: int) -> bytes: + data: bytes = self.__fp._safe_read(amt) # type: ignore[attr-defined] + if amt == 2 and data == b"\r\n": + # urllib executes this read to toss the CRLF at the end + # of the chunk. + return data + + self.__buf.write(data) + if self.__is_fp_closed(): + self._close() + + return data |