Add new DB API method to retrieve migration for instance

New API to force live migration to complete and to cancel ongoing live
migration will take server id and migration id as arguments.
This patch adds new method to DB API to retrieve migration with given
id for particular instance id.

Partially implements: blueprint pause-vm-during-live-migration
Change-Id: I2eebf2a16b03a327348557b88fa573cb40917e9b

nova/db/api.py

@@ -472,6 +472,13 @@ def migration_get(context, migration_id):
     return IMPL.migration_get(context, migration_id)
 
 
+def migration_get_by_id_and_instance(context, migration_id, instance_uuid):
+    """Finds a migration by the migration id and the instance uuid."""
+    return IMPL.migration_get_by_id_and_instance(context,
+                                                 migration_id,
+                                                 instance_uuid)
+
+
 def migration_get_by_instance_and_status(context, instance_uuid, status):
     """Finds a migration by the instance uuid its migrating."""
     return IMPL.migration_get_by_instance_and_status(context, instance_uuid,

nova/db/sqlalchemy/api.py

@@ -4482,6 +4482,20 @@ def migration_get(context, id):
     return result
 
 
+@main_context_manager.reader
+def migration_get_by_id_and_instance(context, id, instance_uuid):
+    result = model_query(context, models.Migration).\
+                     filter_by(id=id).\
+                     filter_by(instance_uuid=instance_uuid).\
+                     first()
+
+    if not result:
+        raise exception.MigrationNotFoundForInstance(migration_id=id,
+                                                     instance_id=instance_uuid)
+
+    return result
+
+
 @main_context_manager.reader
 def migration_get_by_instance_and_status(context, instance_uuid, status):
     result = model_query(context, models.Migration, read_deleted="yes").\

nova/exception.py

@@ -1122,6 +1122,11 @@ class MigrationNotFoundByStatus(MigrationNotFound):
                 "with status %(status)s.")
 
 
+class MigrationNotFoundForInstance(MigrationNotFound):
+    msg_fmt = _("Migration %(migration_id)s not found for instance "
+                "%(instance_id)s")
+
+
 class ConsoleLogOutputException(NovaException):
     msg_fmt = _("Console log output could not be retrieved for instance "
                 "%(instance_id)s. Reason: %(reason)s")

nova/objects/migration.py

@@ -35,7 +35,8 @@ class Migration(base.NovaPersistentObject, base.NovaObject,
     # Version 1.0: Initial version
     # Version 1.1: String attributes updated to support unicode
     # Version 1.2: Added migration_type and hidden
-    VERSION = '1.2'
+    # Version 1.3: Added get_by_id_and_instance()
+    VERSION = '1.3'
 
     fields = {
         'id': fields.IntegerField(),
@@ -89,6 +90,12 @@ class Migration(base.NovaPersistentObject, base.NovaObject,
         db_migration = db.migration_get(context, migration_id)
         return cls._from_db_object(context, cls(), db_migration)
 
+    @base.remotable_classmethod
+    def get_by_id_and_instance(cls, context, migration_id, instance_uuid):
+        db_migration = db.migration_get_by_id_and_instance(
+            context, migration_id, instance_uuid)
+        return cls._from_db_object(context, cls(), db_migration)
+
     @base.remotable_classmethod
     def get_by_instance_and_status(cls, context, instance_uuid, status):
         db_migration = db.migration_get_by_instance_and_status(

nova/tests/unit/db/test_db_api.py

@@ -1523,6 +1523,20 @@ class MigrationTestCase(test.TestCase):
         self.assertRaises(exception.MigrationNotFound,
                           db.migration_update, self.ctxt, 42, {})
 
+    def test_get_migration_for_instance(self):
+        migrations = db.migration_get_all_by_filters(self.ctxt, [])
+        migration_id = migrations[0].id
+        instance_uuid = migrations[0].instance_uuid
+        instance_migration = db.migration_get_by_id_and_instance(
+            self.ctxt, migration_id, instance_uuid)
+        self.assertEqual(migration_id, instance_migration.id)
+        self.assertEqual(instance_uuid, instance_migration.instance_uuid)
+
+    def test_get_migration_for_instance_not_found(self):
+        self.assertRaises(exception.MigrationNotFoundForInstance,
+                          db.migration_get_by_id_and_instance, self.ctxt,
+                          '500', '501')
+
 
 class ModelsObjectComparatorMixin(object):
     def _dict_from_object(self, obj, ignored_keys):

nova/tests/unit/objects/test_migration.py

@@ -229,6 +229,14 @@ class _TestMigrationObject(object):
         self.assertEqual('migration', mig.migration_type)
         self.assertTrue(mig.obj_attr_is_set('migration_type'))
 
+    @mock.patch('nova.db.migration_get_by_id_and_instance')
+    def test_get_by_id_and_instance(self, fake_get):
+        ctxt = context.get_admin_context()
+        fake_migration = fake_db_migration()
+        fake_get.return_value = fake_migration
+        migration = objects.Migration.get_by_id_and_instance(ctxt, '1', '1')
+        self.compare_obj(migration, fake_migration)
+
 
 class TestMigrationObject(test_objects._LocalTest,
                           _TestMigrationObject):

nova/tests/unit/objects/test_objects.py

@@ -1147,7 +1147,7 @@ object_data = {
     'LibvirtLiveMigrateData': '1.1-4ecf40aae7fee7bb37fc3b2123e760de',
     'KeyPair': '1.3-bfaa2a8b148cdf11e0c72435d9dd097a',
     'KeyPairList': '1.2-58b94f96e776bedaf1e192ddb2a24c4e',
-    'Migration': '1.2-8784125bedcea0a9227318511904e853',
+    'Migration': '1.3-c245057c22d505a4e6462ab95fa27166',
     'MigrationContext': '1.0-d8c2f10069e410f639c49082b5932c92',
     'MigrationList': '1.2-02c0ec0c50b75ca86a2a74c5e8c911cc',
     'MonitorMetric': '1.1-53b1db7c4ae2c531db79761e7acc52ba',