some optimization on token id creation

wcs/qommon/storage.py

@@ -137,7 +137,8 @@ class StorableObject(object):
     select = classmethod(select)
 
     def has_key(cls, id):
-        return fix_key(id) in cls.keys()
+        filename = os.path.join(cls.get_objects_dir(), fix_key(id))
+        return os.path.exists(filename)
     has_key = classmethod(has_key)
 
     def get_new_id(cls, create=False):

wcs/qommon/tokens.py

@@ -35,11 +35,10 @@ class Token(StorableObject):
             self.expiration = time.time() + expiration_delay
 
     def get_new_id(cls, size, chars):
-        keys = cls.keys()
         r = random.SystemRandom()
         while True:
             id = ''.join([r.choice(chars) for x in range(size)])
-            if not id in keys:
+            if not cls.has_key(id):
                 return id
 
     def migrate(self):