Add update_tables method to Idl

The method adds given tables to the current connection schema. If the
table is not already there, it's added. If the table in current
connection doesn't exist in the provided schema, it's not added, which
seems like it's been removed.

This behavior is handy for cases where ovsdb-server is changed to new
schema.

Related-bug: #1901527

Change-Id: Ib071dd0f4d9c6e08fafc282c7551086de4b59500
Co-Authored-By: Terry Wilson <twilson@redhat.com>
Signed-off-by: Jakub Libosvar <libosvar@redhat.com>

ovsdbapp/backend/ovs_idl/connection.py

@@ -19,6 +19,7 @@ import threading
 import time
 import traceback
 
+from ovs.db import custom_index
 from ovs.db import idl
 from ovs import poller
 
@@ -168,3 +169,33 @@ class OvsdbIdl(idl.Idl):
         An example would be to set up Idl notification handling for watching
         and unwatching certain OVSDB change events
         """
+
+    def update_tables(self, tables, schema):
+        """Add the tables to the current Idl if they are present in the schema
+
+        :param tables: List of tables to be registered
+        :type tables: List
+        :param schema: Schema description
+        :type schema: dict or string
+        """
+
+        schema_helper = idlutils.create_schema_helper(schema)
+
+        # Register only available registered tables - DB downgrade, and the
+        # newly added tables - DB upgrade
+        for table in self.tables.keys() | tables:
+            if table in schema_helper.schema_json['tables']:
+                schema_helper.register_table(table)
+
+        schema = schema_helper.get_idl_schema()
+        self._db = schema
+        self.tables = schema.tables
+        for table in schema.tables.values():
+            for column in table.columns.values():
+                if not hasattr(column, 'alert'):
+                    column.alert = True
+            table.need_table = False
+            table.rows = custom_index.IndexedRows(table)
+            table.idl = self
+            table.condition = [True]
+            table.cond_changed = False

ovsdbapp/backend/ovs_idl/idlutils.py

@@ -14,6 +14,9 @@
 
 import collections
 from collections import abc
+# json is not deprecated
+# pylint: disable=deprecated-module
+import json
 import logging
 import os
 import sys
@@ -154,6 +157,17 @@ class ExceptionResult(object):
         self.tb = tb
 
 
+def create_schema_helper(schema):
+    """Create a schema helper object based on the provided schema.
+
+    :param schema: The description of the schema
+    :type schema: dict or string
+    """
+    if isinstance(schema, str):
+        schema = json.loads(schema)
+    return idl.SchemaHelper(None, schema)
+
+
 def get_schema_helper(connection, schema_name):
     """Create a schema helper object by querying an ovsdb-server
 
@@ -186,7 +200,7 @@ def get_schema_helper(connection, schema_name):
                       "%(err)s", {'conn': c,
                                   'err': resp.error})
             continue
-        return idl.SchemaHelper(None, resp.result)
+        return create_schema_helper(resp.result)
     raise Exception("Could not retrieve schema from %s" % connection)
 
 

ovsdbapp/tests/functional/backend/ovs_idl/test_connection.py

@@ -0,0 +1,85 @@
+#    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 unittest import mock
+
+from ovsdbapp.backend.ovs_idl import connection
+from ovsdbapp.backend.ovs_idl import idlutils
+from ovsdbapp import constants
+from ovsdbapp.tests.functional import base
+
+
+def create_schema_helper(sh):
+    return sh
+
+
+class TestingOvsIdl(connection.OvsdbIdl):
+    schema = 'Open_vSwitch'
+
+    @classmethod
+    def from_server(cls, schema_map, tables):
+        """Create the Idl instance by pulling the schema from OVSDB server"""
+        connection_string = schema_map[cls.schema]
+        helper = idlutils.get_schema_helper(connection_string, cls.schema)
+        for table in tables:
+            helper.register_table(table)
+        return cls(connection_string, helper)
+
+
+class TestOvsdbIdl(base.FunctionalTestCase):
+    default_tables = ["Open_vSwitch", "Bridge"]
+
+    def setUp(self):
+        super().setUp()
+        self.schema = self.get_schema()
+
+    @property
+    def idl(self):
+        return self._connection.idl
+
+    @classmethod
+    def set_connection(cls):
+        idl = TestingOvsIdl.from_server(cls.schema_map, cls.default_tables)
+        cls._connection = connection.Connection(idl, constants.DEFAULT_TIMEOUT)
+
+    def get_schema(self):
+        with mock.patch.object(
+                idlutils, 'create_schema_helper',
+                side_effect=create_schema_helper):
+            return idlutils.get_schema_helper(
+                self.schema_map[TestingOvsIdl.schema], TestingOvsIdl.schema)
+
+    def validate_tables(self, tables, present):
+        valid_func = self.assertIn if present else self.assertNotIn
+
+        for table in tables:
+            valid_func(table, self.idl.tables)
+
+    def test_add_new_table(self):
+        tables = ["Port", "Interface"]
+
+        self.validate_tables(tables, present=False)
+        self.idl.update_tables(tables, self.schema)
+        self.validate_tables(tables, present=True)
+
+    def test_remove_table(self):
+        removed_table = "Open_vSwitch"
+        new_tables = self.default_tables[:]
+        new_tables.remove(removed_table)
+
+        self.validate_tables([removed_table], present=True)
+
+        del self.schema["tables"][removed_table]
+        self.idl.update_tables(self.default_tables, self.schema)
+
+        self.validate_tables(new_tables, present=True)
+        self.validate_tables([removed_table], present=False)