Fix sqlalchemy engine listener

The sqlalchemy 1.4 had introduced some incompatible changes.

Change-Id: I98c9c1d193934c37e77297a04231a24585674306

trove/guestagent/datastore/mysql_common/service.py

@@ -20,6 +20,7 @@ import urllib
 
 from oslo_log import log as logging
 from oslo_utils import encodeutils
+from sqlalchemy import event
 from sqlalchemy import exc
 from sqlalchemy.sql.expression import text
 
@@ -448,8 +449,9 @@ class BaseMySqlApp(service.BaseDbApp):
         ENGINE = sqlalchemy.create_engine(
             CONNECTION_STR_FORMAT % (user,
                                      urllib.parse.quote(password.strip())),
-            pool_recycle=120, echo=CONF.sql_query_logging,
-            listeners=[mysql_util.BaseKeepAliveConnection()])
+            pool_recycle=120, echo=CONF.sql_query_logging
+        )
+        event.listen(ENGINE, 'checkout', mysql_util.connection_checkout)
 
         return ENGINE
 

trove/guestagent/utils/mysql.py

@@ -14,7 +14,6 @@
 from oslo_log import log as logging
 from pymysql import err as pymysql_err
 from sqlalchemy import exc
-from sqlalchemy import interfaces
 from sqlalchemy.sql.expression import text
 
 from trove.guestagent.common import sql_query
@@ -55,31 +54,28 @@ class SqlClient(object):
             raise
 
 
-class BaseKeepAliveConnection(interfaces.PoolListener):
+def connection_checkout(dbapi_con, con_record, con_proxy):
     """
     A connection pool listener that ensures live connections are returned
     from the connection pool at checkout. This alleviates the problem of
     MySQL connections timing out.
     """
-
-    def checkout(self, dbapi_con, con_record, con_proxy):
-        """Event triggered when a connection is checked out from the pool."""
+    try:
         try:
-            try:
-                dbapi_con.ping(False)
-            except TypeError:
-                dbapi_con.ping()
-        except dbapi_con.OperationalError as ex:
-            if ex.args[0] in (2006, 2013, 2014, 2045, 2055):
-                raise exc.DisconnectionError()
-            else:
-                raise
-        # MariaDB seems to timeout the client in a different
-        # way than MySQL and PXC
-        except pymysql_err.InternalError as ex:
-            if "Packet sequence number wrong" in str(ex):
-                raise exc.DisconnectionError()
-            elif 'Connection was killed' in str(ex):
-                raise exc.DisconnectionError()
-            else:
-                raise
+            dbapi_con.ping(False)
+        except TypeError:
+            dbapi_con.ping()
+    except dbapi_con.OperationalError as ex:
+        if ex.args[0] in (2006, 2013, 2014, 2045, 2055):
+            raise exc.DisconnectionError()
+        else:
+            raise
+    # MariaDB seems to timeout the client in a different
+    # way than MySQL and PXC
+    except pymysql_err.InternalError as ex:
+        if "Packet sequence number wrong" in str(ex):
+            raise exc.DisconnectionError()
+        elif 'Connection was killed' in str(ex):
+            raise exc.DisconnectionError()
+        else:
+            raise