Deprecate engine-wise ss cursors; repair mariadbconnector

The server_side_cursors engine-wide feature relies upon
regexp parsing of statements a well as general guessing as
to when the feature should be used.   This is not within the
2.0 way of doing things and should be removed.

Additionally, mariadbconnector defaults to unbuffered cursors;
add new cursor hooks so that mariadbconnector can specify
buffered or unbuffered cursors without too much difficulty.
This will also correctly default mariadbconnector to buffered
cursors which should repair the segfaults we've been getting.

Try to restore the assert_raises that was removed in
5b6dfc0c38bf1f01da4b8 to see if mariadbconnector segfaults
are resolved.

Change-Id: I77f1c972c742e40694972f578140bb0cac8c39eb

1 files changed, 8 insertions, 3 deletions

diff --git a/lib/sqlalchemy/dialects/mysql/mariadbconnector.py b/lib/sqlalchemy/dialects/mysql/mariadbconnector.py
index aa28ffc67..4e0b4e0a9 100644
--- a/lib/sqlalchemy/dialects/mysql/mariadbconnector.py
+++ b/lib/sqlalchemy/dialects/mysql/mariadbconnector.py
@@ -40,7 +40,11 @@ mariadb_cpy_minimum_version = (1, 0, 1)
 
 
 class MySQLExecutionContext_mariadbconnector(MySQLExecutionContext):
-    pass
+    def create_server_side_cursor(self):
+        return self._dbapi_connection.cursor(buffered=False)
+
+    def create_default_cursor(self):
+        return self._dbapi_connection.cursor(buffered=True)
 
 
 class MySQLCompiler_mariadbconnector(MySQLCompiler):
@@ -75,6 +79,8 @@ class MySQLDialect_mariadbconnector(MySQLDialect):
     statement_compiler = MySQLCompiler_mariadbconnector
     preparer = MySQLIdentifierPreparer_mariadbconnector
 
+    supports_server_side_cursors = True
+
     @util.memoized_property
     def _dbapi_version(self):
         if self.dbapi and hasattr(self.dbapi, "__version__"):
@@ -89,9 +95,8 @@ class MySQLDialect_mariadbconnector(MySQLDialect):
         else:
             return (99, 99, 99)
 
-    def __init__(self, server_side_cursors=False, **kwargs):
+    def __init__(self, **kwargs):
         super(MySQLDialect_mariadbconnector, self).__init__(**kwargs)
-        self.server_side_cursors = True
         self.paramstyle = "qmark"
         if self.dbapi is not None:
             if self._dbapi_version < mariadb_cpy_minimum_version: