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-rw-r--r--Lib/functools.py2
-rw-r--r--Lib/test/test_functools.py48
2 files changed, 49 insertions, 1 deletions
diff --git a/Lib/functools.py b/Lib/functools.py
index f6ae4f4..9f28004 100644
--- a/Lib/functools.py
+++ b/Lib/functools.py
@@ -144,7 +144,7 @@ def lfu_cache(maxsize=100):
wrapper.misses += 1
if len(cache) > maxsize:
# purge the 10% least frequently used entries
- for key, _ in nsmallest(maxsize // 10,
+ for key, _ in nsmallest(maxsize // 10 or 1,
use_count.items(),
key=itemgetter(1)):
del cache[key], use_count[key]
diff --git a/Lib/test/test_functools.py b/Lib/test/test_functools.py
index 70a8ad6..4dd6fab 100644
--- a/Lib/test/test_functools.py
+++ b/Lib/test/test_functools.py
@@ -482,6 +482,30 @@ class TestLRU(unittest.TestCase):
self.assertEqual(f.hits, 0)
self.assertEqual(f.misses, 1)
+ # test size zero (which means "never-cache")
+ f_cnt = 0
+ @functools.lru_cache(0)
+ def f():
+ nonlocal f_cnt
+ f_cnt += 1
+ return 20
+ self.assertEqual(f(), 20)
+ self.assertEqual(f(), 20)
+ self.assertEqual(f(), 20)
+ self.assertEqual(f_cnt, 3)
+
+ # test size one
+ f_cnt = 0
+ @functools.lru_cache(1)
+ def f():
+ nonlocal f_cnt
+ f_cnt += 1
+ return 20
+ self.assertEqual(f(), 20)
+ self.assertEqual(f(), 20)
+ self.assertEqual(f(), 20)
+ self.assertEqual(f_cnt, 1)
+
def test_lfu(self):
def orig(x, y):
return 3*x+y
@@ -503,6 +527,30 @@ class TestLRU(unittest.TestCase):
self.assertEqual(f.hits, 0)
self.assertEqual(f.misses, 1)
+ # test size zero (which means "never-cache")
+ f_cnt = 0
+ @functools.lfu_cache(0)
+ def f():
+ nonlocal f_cnt
+ f_cnt += 1
+ return 20
+ self.assertEqual(f(), 20)
+ self.assertEqual(f(), 20)
+ self.assertEqual(f(), 20)
+ self.assertEqual(f_cnt, 3)
+
+ # test size one
+ f_cnt = 0
+ @functools.lfu_cache(1)
+ def f():
+ nonlocal f_cnt
+ f_cnt += 1
+ return 20
+ self.assertEqual(f(), 20)
+ self.assertEqual(f(), 20)
+ self.assertEqual(f(), 20)
+ self.assertEqual(f_cnt, 1)
+
def test_main(verbose=None):
test_classes = (
TestPartial,