diff options
| -rw-r--r-- | Lib/functools.py | 6 | ||||
| -rw-r--r-- | Lib/test/test_functools.py | 13 | ||||
| -rw-r--r-- | Misc/NEWS | 3 |
3 files changed, 20 insertions, 2 deletions
diff --git a/Lib/functools.py b/Lib/functools.py index 214523c..60cf3c4 100644 --- a/Lib/functools.py +++ b/Lib/functools.py @@ -516,14 +516,16 @@ def _lru_cache_wrapper(user_function, maxsize, typed, _CacheInfo): last = root[PREV] link = [last, root, key, result] last[NEXT] = root[PREV] = cache[key] = link - full = (len(cache) >= maxsize) + # Use the __len__() method instead of the len() function + # which could potentially be wrapped in an lru_cache itself. + full = (cache.__len__() >= maxsize) misses += 1 return result def cache_info(): """Report cache statistics""" with lock: - return _CacheInfo(hits, misses, maxsize, len(cache)) + return _CacheInfo(hits, misses, maxsize, cache.__len__()) def cache_clear(): """Clear the cache and cache statistics""" diff --git a/Lib/test/test_functools.py b/Lib/test/test_functools.py index 6a3bf64..b431e05 100644 --- a/Lib/test/test_functools.py +++ b/Lib/test/test_functools.py @@ -1,4 +1,5 @@ import abc +import builtins import collections import copy from itertools import permutations @@ -1162,6 +1163,18 @@ class TestLRU: self.assertEqual(misses, 4) self.assertEqual(currsize, 2) + def test_lru_reentrancy_with_len(self): + # Test to make sure the LRU cache code isn't thrown-off by + # caching the built-in len() function. Since len() can be + # cached, we shouldn't use it inside the lru code itself. + old_len = builtins.len + try: + builtins.len = self.module.lru_cache(4)(len) + for i in [0, 0, 1, 2, 3, 3, 4, 5, 6, 1, 7, 2, 1]: + self.assertEqual(len('abcdefghijklmn'[:i]), i) + finally: + builtins.len = old_len + def test_lru_type_error(self): # Regression test for issue #28653. # lru_cache was leaking when one of the arguments @@ -13,6 +13,9 @@ Core and Builtins - Issue #28512: Fixed setting the offset attribute of SyntaxError by PyErr_SyntaxLocationEx() and PyErr_SyntaxLocationObject(). +- Issue #28991: functools.lru_cache() was susceptible to an obscure reentrancy + bug caused by a monkey-patched len() function. + - Issue #28648: Fixed crash in Py_DecodeLocale() in debug build on Mac OS X when decode astral characters. Patch by Xiang Zhang. |