98 lines
2.9 KiB
Python
98 lines
2.9 KiB
Python
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"""Caching of formatted files with feature-based invalidation."""
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import os
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import pickle
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import tempfile
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from pathlib import Path
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from typing import Dict, Iterable, Set, Tuple
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from platformdirs import user_cache_dir
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from _black_version import version as __version__
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from black.mode import Mode
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# types
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Timestamp = float
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FileSize = int
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CacheInfo = Tuple[Timestamp, FileSize]
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Cache = Dict[str, CacheInfo]
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def get_cache_dir() -> Path:
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"""Get the cache directory used by black.
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Users can customize this directory on all systems using `BLACK_CACHE_DIR`
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environment variable. By default, the cache directory is the user cache directory
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under the black application.
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This result is immediately set to a constant `black.cache.CACHE_DIR` as to avoid
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repeated calls.
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"""
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# NOTE: Function mostly exists as a clean way to test getting the cache directory.
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default_cache_dir = user_cache_dir("black", version=__version__)
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cache_dir = Path(os.environ.get("BLACK_CACHE_DIR", default_cache_dir))
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return cache_dir
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CACHE_DIR = get_cache_dir()
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def read_cache(mode: Mode) -> Cache:
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"""Read the cache if it exists and is well formed.
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If it is not well formed, the call to write_cache later should resolve the issue.
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"""
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cache_file = get_cache_file(mode)
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if not cache_file.exists():
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return {}
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with cache_file.open("rb") as fobj:
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try:
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cache: Cache = pickle.load(fobj)
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except (pickle.UnpicklingError, ValueError, IndexError):
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return {}
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return cache
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def get_cache_file(mode: Mode) -> Path:
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return CACHE_DIR / f"cache.{mode.get_cache_key()}.pickle"
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def get_cache_info(path: Path) -> CacheInfo:
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"""Return the information used to check if a file is already formatted or not."""
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stat = path.stat()
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return stat.st_mtime, stat.st_size
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def filter_cached(cache: Cache, sources: Iterable[Path]) -> Tuple[Set[Path], Set[Path]]:
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"""Split an iterable of paths in `sources` into two sets.
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The first contains paths of files that modified on disk or are not in the
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cache. The other contains paths to non-modified files.
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"""
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todo, done = set(), set()
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for src in sources:
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res_src = src.resolve()
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if cache.get(str(res_src)) != get_cache_info(res_src):
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todo.add(src)
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else:
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done.add(src)
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return todo, done
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def write_cache(cache: Cache, sources: Iterable[Path], mode: Mode) -> None:
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"""Update the cache file."""
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cache_file = get_cache_file(mode)
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try:
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CACHE_DIR.mkdir(parents=True, exist_ok=True)
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new_cache = {
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**cache,
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**{str(src.resolve()): get_cache_info(src) for src in sources},
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}
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with tempfile.NamedTemporaryFile(dir=str(cache_file.parent), delete=False) as f:
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pickle.dump(new_cache, f, protocol=4)
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os.replace(f.name, cache_file)
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except OSError:
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pass
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