Ticket #16858: locmem_incr_expiration_16858.diff

django/core/cache/backends/locmem.py

@@ -15 +15 @@
 _expire_info = {}
 _locks = {}
 
+# Special timeout value used by incr and decr to instruct the cache to 
+# not change the existing timeout value
+IGNORE_TIMEOUT = 'ignore'
+
 class LocMemCache(BaseCache):
     def __init__(self, name, params):
         BaseCache.__init__(self, params)
@@ -71 +75 @@
         if timeout is None:
             timeout = self.default_timeout
         self._cache[key] = value
-        self._expire_info[key] = time.time() + timeout
+        if timeout != IGNORE_TIMEOUT:
+            self._expire_info[key] = time.time() + timeout
 
     def set(self, key, value, timeout=None, version=None):
         key = self.make_key(key, version=version)
@@ -84 +89 @@
         finally:
             self._lock.writer_leaves()
 
+    def incr(self, key, delta=1, version=None):
+        """
+        Add delta to value in the cache. If the key does not exist, raise a
+        ValueError exception.
+        """
+        value = self.get(key, version=version)
+        if value is None:
+            raise ValueError("Key '%s' not found" % key)
+        new_value = value + delta
+        self.set(key, new_value, version=version, timeout=IGNORE_TIMEOUT)
+        return new_value
+
     def has_key(self, key, version=None):
         key = self.make_key(key, version=version)
         self.validate_key(key)

tests/regressiontests/cache/tests.py

@@ -822 +822 @@
         self.assertEqual(mirror_cache.get('value1'), 42)
         self.assertEqual(other_cache.get('value1'), None)
 
+    def test_incr_expiration(self):
+        self.cache.set('val', 42, timeout=2)
+        full_key = self.cache.make_key('val')
+        exp = self.cache._expire_info[full_key]
+        self.cache.incr('val')
+        exp2 = self.cache._expire_info[full_key]
+        self.assertEqual(exp, exp2)
+                
 
 # memcached backend isn't guaranteed to be available.
 # To check the memcached backend, the test settings file will