Fixed #16378. Locmem now uses pickle.HIGHEST_PROTOCOL for better compatibility with other hash backends. Thanks aaugustin for the initial patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@17136 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/core/cache/backends/db.py

@@ -102,7 +102,8 @@ class DatabaseCache(BaseDatabaseCache):
         exp = exp.replace(microsecond=0)
         if num > self._max_entries:
             self._cull(db, cursor, now)
-        encoded = base64.encodestring(pickle.dumps(value, 2)).strip()
+        pickled = pickle.dumps(value, pickle.HIGHEST_PROTOCOL)
+        encoded = base64.encodestring(pickled).strip()
         cursor.execute("SELECT cache_key, expires FROM %s "
                        "WHERE cache_key = %%s" % table, [key])
         try:

django/core/cache/backends/locmem.py

@@ -31,7 +31,8 @@ class LocMemCache(BaseCache):
             exp = self._expire_info.get(key)
             if exp is None or exp <= time.time():
                 try:
-                    self._set(key, pickle.dumps(value), timeout)
+                    pickled = pickle.dumps(value, pickle.HIGHEST_PROTOCOL)
+                    self._set(key, pickled, timeout)
                     return True
                 except pickle.PickleError:
                     pass
@@ -49,7 +50,8 @@ class LocMemCache(BaseCache):
                 return default
             elif exp > time.time():
                 try:
-                    return pickle.loads(self._cache[key])
+                    pickled = self._cache[key]
+                    return pickle.loads(pickled)
                 except pickle.PickleError:
                     return default
         finally:
@@ -78,7 +80,8 @@ class LocMemCache(BaseCache):
         self.validate_key(key)
         self._lock.writer_enters()
         try:
-            self._set(key, pickle.dumps(value), timeout)
+            pickled = pickle.dumps(value, pickle.HIGHEST_PROTOCOL)
+            self._set(key, pickled, timeout)
         except pickle.PickleError:
             pass
         finally:

docs/releases/1.4.txt

@@ -501,6 +501,10 @@ Django 1.4 also includes several smaller improvements worth noting:
 * Changed the default value for ``httponly`` on session cookies to
   ``True`` to help reduce the impact of potential XSS attacks.
 
+* Changed the ``locmem`` cache backend to use
+  ``pickle.HIGHEST_PROTOCOL`` for better compatibility with the other
+  cache backends.
+
 .. _backwards-incompatible-changes-1.4:
 
 Backwards incompatible changes in 1.4