Add postgres database engine

synapse/storage/engines/postgres.py

@@ -0,0 +1,44 @@
+# -*- coding: utf-8 -*-
+# Copyright 2015 OpenMarket Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from synapse.storage import prepare_database
+
+
+class PostgresEngine(object):
+    def __init__(self, database_module):
+        self.module = database_module
+        self.module.extensions.register_type(self.module.extensions.UNICODE)
+
+    def convert_param_style(self, sql):
+        return sql.replace("?", "%s")
+
+    def encode_parameter(self, param):
+        return param
+
+    def on_new_connection(self, db_conn):
+        db_conn.set_isolation_level(
+            self.module.extensions.ISOLATION_LEVEL_REPEATABLE_READ
+        )
+
+    def prepare_database(self, db_conn):
+        prepare_database(db_conn, self)
+
+    def is_deadlock(self, error):
+        if isinstance(error, self.module.DatabaseError):
+            return error.pgcode == "40P01"
+        return False
+
+    def load_unicode(self, v):
+        return bytes(v).decode("UTF8")