From dfbebc23f35d38a9a43ad7bba795f25f2653202c Mon Sep 17 00:00:00 2001
From: Thomas Kemmer <tkemmer@computer.org>
Date: Thu, 14 Oct 2021 06:34:02 +0200
Subject: [PATCH] Fix #221: Change exact time of expiration in TTLCache.

---
 src/cachetools/__init__.py | 12 ++++++------
 tests/test_ttl.py          | 19 ++++++++++---------
 2 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/src/cachetools/__init__.py b/src/cachetools/__init__.py
index 42822f0..552abf1 100644
--- a/src/cachetools/__init__.py
+++ b/src/cachetools/__init__.py
@@ -358,7 +358,7 @@ def __contains__(self, key):
         except KeyError:
             return False
         else:
-            return not (link.expire < self.__timer())
+            return self.__timer() < link.expire
 
     def __getitem__(self, key, cache_getitem=Cache.__getitem__):
         try:
@@ -366,7 +366,7 @@ def __getitem__(self, key, cache_getitem=Cache.__getitem__):
         except KeyError:
             expired = False
         else:
-            expired = link.expire < self.__timer()
+            expired = not (self.__timer() < link.expire)
         if expired:
             return self.__missing__(key)
         else:
@@ -391,7 +391,7 @@ def __delitem__(self, key, cache_delitem=Cache.__delitem__):
         cache_delitem(self, key)
         link = self.__links.pop(key)
         link.unlink()
-        if link.expire < self.__timer():
+        if not (self.__timer() < link.expire):
             raise KeyError(key)
 
     def __iter__(self):
@@ -400,7 +400,7 @@ def __iter__(self):
         while curr is not root:
             # "freeze" time for iterator access
             with self.__timer as time:
-                if not (curr.expire < time):
+                if time < curr.expire:
                     yield curr.key
             curr = curr.next
 
@@ -409,7 +409,7 @@ def __len__(self):
         curr = root.next
         time = self.__timer()
         count = len(self.__links)
-        while curr is not root and curr.expire < time:
+        while curr is not root and not (time < curr.expire):
             count -= 1
             curr = curr.next
         return count
@@ -453,7 +453,7 @@ def expire(self, time=None):
         curr = root.next
         links = self.__links
         cache_delitem = Cache.__delitem__
-        while curr is not root and curr.expire < time:
+        while curr is not root and not (time < curr.expire):
             cache_delitem(self, curr.key)
             del links[curr.key]
             next = curr.next
diff --git a/tests/test_ttl.py b/tests/test_ttl.py
index 6e51a59..db5107d 100644
--- a/tests/test_ttl.py
+++ b/tests/test_ttl.py
@@ -1,3 +1,4 @@
+import math
 import unittest
 
 from cachetools import TTLCache
@@ -20,7 +21,7 @@ def tick(self):
 
 
 class TTLTestCache(TTLCache):
-    def __init__(self, maxsize, ttl=0, **kwargs):
+    def __init__(self, maxsize, ttl=math.inf, **kwargs):
         TTLCache.__init__(self, maxsize, ttl=ttl, timer=Timer(), **kwargs)
 
 
@@ -29,9 +30,9 @@ class TTLCacheTest(unittest.TestCase, CacheTestMixin):
     Cache = TTLTestCache
 
     def test_ttl(self):
-        cache = TTLCache(maxsize=2, ttl=1, timer=Timer())
+        cache = TTLCache(maxsize=2, ttl=2, timer=Timer())
         self.assertEqual(0, cache.timer())
-        self.assertEqual(1, cache.ttl)
+        self.assertEqual(2, cache.ttl)
 
         cache[1] = 1
         self.assertEqual({1}, set(cache))
@@ -84,7 +85,7 @@ def test_ttl(self):
             del cache[3]
 
     def test_ttl_lru(self):
-        cache = TTLCache(maxsize=2, ttl=0, timer=Timer())
+        cache = TTLCache(maxsize=2, ttl=1, timer=Timer())
 
         cache[1] = 1
         cache[2] = 2
@@ -112,10 +113,10 @@ def test_ttl_lru(self):
         self.assertEqual(cache[5], 5)
 
     def test_ttl_expire(self):
-        cache = TTLCache(maxsize=3, ttl=2, timer=Timer())
+        cache = TTLCache(maxsize=3, ttl=3, timer=Timer())
         with cache.timer as time:
             self.assertEqual(time, cache.timer())
-        self.assertEqual(2, cache.ttl)
+        self.assertEqual(3, cache.ttl)
 
         cache[1] = 1
         cache.timer.tick()
@@ -159,7 +160,7 @@ def test_ttl_expire(self):
         self.assertNotIn(3, cache)
 
     def test_ttl_atomic(self):
-        cache = TTLCache(maxsize=1, ttl=1, timer=Timer(auto=True))
+        cache = TTLCache(maxsize=1, ttl=2, timer=Timer(auto=True))
         cache[1] = 1
         self.assertEqual(1, cache[1])
         cache[1] = 1
@@ -173,8 +174,8 @@ def test_ttl_atomic(self):
         self.assertEqual(0, len(cache))
 
     def test_ttl_tuple_key(self):
-        cache = TTLCache(maxsize=1, ttl=0, timer=Timer())
-        self.assertEqual(0, cache.ttl)
+        cache = TTLCache(maxsize=1, ttl=1, timer=Timer())
+        self.assertEqual(1, cache.ttl)
 
         cache[(1, 2, 3)] = 42
         self.assertEqual(42, cache[(1, 2, 3)])