Made a few small tweaks to reduce persistent storage accesses in the session

backend. Refs #8311, although doesn't fix the problem there.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@8381 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/contrib/sessions/backends/base.py

@@ -121,7 +121,11 @@ class SessionBase(object):
         return self._session.iteritems()
 
     def clear(self):
-        self._session.clear()
+        # To avoid unnecessary persistent storage accesses, we set up the
+        # internals directly (loading data wastes time, since we are going to
+        # set it to an empty dict anyway).
+        self._session_cache = {}
+        self.accessed = True
         self.modified = True
 
     def _get_new_session_key(self):

django/contrib/sessions/backends/cache.py

@@ -42,6 +42,8 @@ class SessionStore(SessionBase):
 
     def delete(self, session_key=None):
         if session_key is None:
+            if self._session_key is None:
+                return
             session_key = self._session_key
         self._cache.delete(session_key)
 

django/contrib/sessions/backends/db.py

@@ -63,6 +63,8 @@ class SessionStore(SessionBase):
 
     def delete(self, session_key=None):
         if session_key is None:
+            if self._session_key is None:
+                return
             session_key = self._session_key
         try:
             Session.objects.get(session_key=session_key).delete()

django/contrib/sessions/backends/file.py

@@ -94,6 +94,8 @@ class SessionStore(SessionBase):
 
     def delete(self, session_key=None):
         if session_key is None:
+            if self._session_key is None:
+                return
             session_key = self._session_key
         try:
             os.unlink(self._key_to_file(session_key))