Atomically write cache files (#674)

[etc/vim.git] / black.py

diff --git a/black.py b/black.py
index fb8e474931a7319581603b71becde15dc018665b..32693227ed2ef3428cca5bf00efc61065a85e5b0 100644 (file)
--- a/black.py
+++ b/black.py
@@ -6,7 +6,6 @@ from enum import Enum, Flag
 from functools import lru_cache, partial, wraps
 import io
 import itertools
-import keyword
 import logging
 from multiprocessing import Manager, freeze_support
 import os
@@ -15,6 +14,7 @@ import pickle
 import re
 import signal
 import sys
+import tempfile
 import tokenize
 from typing import (
     Any,
@@ -777,9 +777,7 @@ class DebugVisitor(Visitor[T]):
         list(v.visit(code))
 
 
-KEYWORDS = set(keyword.kwlist)
 WHITESPACE = {token.DEDENT, token.INDENT, token.NEWLINE}
-FLOW_CONTROL = {"return", "raise", "break", "continue"}
 STATEMENT = {
     syms.if_stmt,
     syms.while_stmt,
@@ -3650,11 +3648,11 @@ def write_cache(
     """Update the cache file."""
     cache_file = get_cache_file(line_length, mode)
     try:
-        if not CACHE_DIR.exists():
-            CACHE_DIR.mkdir(parents=True)
+        CACHE_DIR.mkdir(parents=True, exist_ok=True)
         new_cache = {**cache, **{src.resolve(): get_cache_info(src) for src in sources}}
-        with cache_file.open("wb") as fobj:
-            pickle.dump(new_cache, fobj, protocol=pickle.HIGHEST_PROTOCOL)
+        with tempfile.NamedTemporaryFile(dir=str(cache_file.parent), delete=False) as f:
+            pickle.dump(new_cache, f, protocol=pickle.HIGHEST_PROTOCOL)
+        os.replace(f.name, cache_file)
     except OSError:
         pass