add opcode for notification of redis DB

Author: batmancn

src/swsssdk/configdb.py

@@ -76,10 +76,10 @@ def unsubscribe(self, table):
         if self.handlers.has_key(table):
             self.handlers.pop(table)
 
-    def __fire(self, table, key, data):
+    def __fire(self, table, key, data, op_str='add'):
         if self.handlers.has_key(table):
             handler = self.handlers[table]
-            handler(table, key, data)
+            handler(table, key, data, op_str)
 
     def listen(self):
         """Start listen Redis keyspace events and will trigger corresponding handlers when content of a table changes.
@@ -94,7 +94,11 @@ def listen(self):
                     if self.handlers.has_key(table):
                         client = self.redis_clients[self.CONFIG_DB]
                         data = self.__raw_to_typed(client.hgetall(key))
-                        self.__fire(table, row, data)
+                        op = client.keys(key)
+                        op_str = 'add'
+                        if len(op) == 0:
+                            op_str = 'del'
+                        self.__fire(table, row, data, op_str)
                 except ValueError:
                     pass    #Ignore non table-formated redis entries