Fix bug: use instance variable instead of class variable in ConfigDBC…

…onnector (#99)

And add instance method `serialize_key` using instance variable.

src/swsssdk/configdb.py

@@ -26,8 +26,6 @@
 class ConfigDBConnector(SonicV2Connector):
 
  INIT_INDICATOR = 'CONFIG_DB_INITIALIZED'
- TABLE_NAME_SEPARATOR = '|'
- KEY_SEPARATOR = '|'
 
  def __init__(self, decode_responses=True, **kwargs):
  # By default, connect to Redis through TCP, which does not requires root.
@@ -49,19 +47,26 @@ def __init__(self, decode_responses=True, **kwargs):
  'namespace' is implicitly passed to the parent SonicV2Connector class.
  """
  super(ConfigDBConnector, self).__init__(**kwargs)
+ # Trick: to achieve static/instance method "overload", we must use initize the function in ctor
+ # ref: https://stackoverflow.com/a/28766809/2514803
+ self.serialize_key = self._serialize_key
+ self.deserialize_key = self._deserialize_key
+
+ self.TABLE_NAME_SEPARATOR = '|'
+ self.KEY_SEPARATOR = '|'
  self.handlers = {}
 
  def __wait_for_db_init(self):
  client = self.get_redis_client(self.db_name)
  pubsub = client.pubsub()
- initialized = client.get(self.INIT_INDICATOR)
+ initialized = client.get(ConfigDBConnector.INIT_INDICATOR)
  if not initialized:
- pattern = "__keyspace@{}__:{}".format(self.get_dbid(self.db_name), self.INIT_INDICATOR)
+ pattern = "__keyspace@{}__:{}".format(self.get_dbid(self.db_name), ConfigDBConnector.INIT_INDICATOR)
  pubsub.psubscribe(pattern)
  for item in pubsub.listen():
  if item['type'] == 'pmessage':
  key = item['channel'].split(':', 1)[1]
- if key == self.INIT_INDICATOR:
+ if key == ConfigDBConnector.INIT_INDICATOR:
  initialized = client.get(self.INIT_INDICATOR)
  if initialized:
  break
@@ -151,21 +156,30 @@ def typed_to_raw(self, typed_data):
  raw_data[key] = str(value)
  return raw_data
 
+ # Note: we could not use a class variable for KEY_SEPARATOR, but original dependent code is using
+ # these static functions. So we implement both static and instance functions with the same name.
+ # The static function will behave according to ConfigDB separators.
  @staticmethod
- def serialize_key(key):
+ def serialize_key(key, separator='|'):
  if type(key) is tuple:
- return ConfigDBConnector.KEY_SEPARATOR.join(key)
+ return separator.join(key)
  else:
  return str(key)
 
+ def _serialize_key(self, key):
+ return ConfigDBConnector.serialize_key(key, self.KEY_SEPARATOR)
+
  @staticmethod
- def deserialize_key(key):
- tokens = key.split(ConfigDBConnector.KEY_SEPARATOR)
+ def deserialize_key(key, separator='|'):
+ tokens = key.split(separator)
  if len(tokens) > 1:
  return tuple(tokens)
  else:
  return key
 
+ def _deserialize_key(self, key):
+ return ConfigDBConnector.deserialize_key(key, self.KEY_SEPARATOR)
+
  def set_entry(self, table, key, data):
  """Write a table entry to config db.
  Remove extra fields in the db which are not in the data.
@@ -276,7 +290,6 @@ def delete_table(self, table):
  client = self.get_redis_client(self.db_name)
  pattern = '{}{}*'.format(table.upper(), self.TABLE_NAME_SEPARATOR)
  keys = client.keys(pattern)
- data = {}
  for key in keys:
  client.delete(key)