change Connector for use singleton

src/database/Connector.py

@@ -3,17 +3,25 @@ from sqlalchemy.orm import sessionmaker
 from scrapy.conf import settings
 
 
-class Connector:
-    connection = None
-    engine = create_engine(settings['CONNECTION_STRING'])
-    Session = sessionmaker(bind=engine)
+class Singleton(type):
+    _instances = {}
+    def __call__(cls, *args, **kwargs):
+        if cls not in cls._instances:
+            cls._instances[cls] = super(Singleton, cls).__call__(*args, **kwargs)
+        return cls._instances[cls]
+
+
+class Connector(metaclass=Singleton):
+    __connection = None
+    __engine = create_engine(settings['CONNECTION_STRING'])
+    __Session = sessionmaker(bind=__engine)
 
     @staticmethod
     def get_session():
-        return Connector.Session()
+        return Connector.__Session()
 
     @staticmethod
     def get_connection():
-        if not Connector.connection:
-            Connector.connection = Connector.engine.connect()
-        return Connector.connection
+        if not Connector.__connection:
+            Connector.__connection = Connector.__engine.connect()
+        return Connector.__connection