71 lines
2.4 KiB
Python
71 lines
2.4 KiB
Python
from __future__ import annotations
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import datetime
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import hashlib
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import logging
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import os
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import random
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import urllib.request
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from typing import Callable
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import platformdirs
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from . import __version__
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log = logging.getLogger(f"mkdocs.{__name__}")
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def _download_url(url: str) -> bytes:
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req = urllib.request.Request(url, headers={"User-Agent": f"mkdocs-get-deps/{__version__}"})
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with urllib.request.urlopen(req) as resp:
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return resp.read()
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def download_and_cache_url(
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url: str,
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cache_duration: datetime.timedelta,
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*,
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download: Callable[[str], bytes] = _download_url,
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comment: bytes = b"# ",
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) -> bytes:
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"""Downloads a file from the URL, stores it under ~/.cache/, and returns its content.
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For tracking the age of the content, a prefix is inserted into the stored file, rather than relying on mtime.
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Args:
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url: URL to use.
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download: Callback that will accept the URL and actually perform the download.
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cache_duration: How long to consider the URL content cached.
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comment: The appropriate comment prefix for this file format.
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"""
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directory = os.path.join(platformdirs.user_cache_dir("mkdocs"), "mkdocs_url_cache")
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name_hash = hashlib.sha256(url.encode()).hexdigest()[:32]
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path = os.path.join(directory, name_hash + os.path.splitext(url)[1])
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now = int(datetime.datetime.now(datetime.timezone.utc).timestamp())
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prefix = b"%s%s downloaded at timestamp " % (comment, url.encode())
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# Check for cached file and try to return it
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if os.path.isfile(path):
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try:
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with open(path, "rb") as f:
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line = f.readline()
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if line.startswith(prefix):
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line = line[len(prefix) :]
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timestamp = int(line)
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if datetime.timedelta(seconds=(now - timestamp)) <= cache_duration:
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log.debug(f"Using cached '{path}' for '{url}'")
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return f.read()
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except (OSError, ValueError) as e:
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log.debug(f"{type(e).__name__}: {e}")
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# Download and cache the file
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log.debug(f"Downloading '{url}' to '{path}'")
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content = download(url)
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os.makedirs(directory, exist_ok=True)
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temp_filename = f"{path}.{random.randrange(1 << 32):08x}.part"
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with open(temp_filename, "wb") as f:
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f.write(b"%s%d\n" % (prefix, now))
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f.write(content)
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os.replace(temp_filename, path)
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return content
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