Fix DBDeadLock error resulting into 500

When user requests the record registration request continuously,
sometimes designate hits DBDeadLock resuting into 500 InternalServerError.

We get below error:

2019-02-21 21:30:39.925 49752 ERROR designate.api.middleware RemoteError:
Remote error: DBDeadlock (pymysql.err.InternalError)
(1213, u'Deadlock found when trying to get lock; try restarting transaction')
[SQL: u'UPDATE records SET version=(records.version + %(version_1)s),
updated_at=%(updated_at)s, data=%(data)s, hash=%(hash)s, status=%(status)s,
action=%(action)s, serial=%(serial)s WHERE records.id = %(id_1)s']
[parameters: {'status': 'PENDING', 'hash': '39795ee18c6e3c9ad1c0190c6a3d8d4f',
'updated_at': datetime.datetime(2019, 2, 21, 12, 30, 39, 909846), u'version_1': 1,
u'id_1': '7a655eeda4d446cdaa81caf19ab55fcc', 'action': 'UPDATE',
'serial': 1550752338,
'data': u'ns2.example.jp. domain.example.com. 1550752338 3552 600 86400 3600'}]

In the process of record registeration, designate first tried to update
the reocrd and then update the zone status.

Updating the zone_status and registering the record process[1] and after synced
update record_status and zone_status process[2] are in reverse order. So If user
request the registering record many time and same time, Designate will get the
DBDeadLock, when these processes run the same time.

We observed that changing the order of the operations solves this issue.

[1] https://github.com/openstack/designate/blob/master/designate/central/service.py#L1292-L1320
[2] https://github.com/openstack/designate/blob/master/designate/central/service.py#L2310-L2322

1. transaction [1]-1 updating zone status process <- run    ---> table_name-zone
2. transaction [2]-1 updating record status process <- run  ---> table_name-record
3. transaction [1]-2 registering record process <- run and wait  ---> table_name-record
4. transaction [2]-2 updating zone process <-deadlock!           ---> table_name-zone

Change-Id: Icd6e690ac84a2fe0db0f4a8a513de47f7916f5ea
Related-Bug: #1785459

designate/central/service.py

@@ -2317,8 +2317,8 @@ class Service(service.RPCService, service.Service):
         """
         # TODO(kiall): If the status is SUCCESS and the zone is already ACTIVE,
         #              we likely don't need to do anything.
-        self._update_record_status(context, zone_id, status, serial)
         zone = self._update_zone_status(context, zone_id, status, serial)
+        self._update_record_status(context, zone_id, status, serial)
         return zone
 
     def _update_zone_status(self, context, zone_id, status, serial):

designate/tests/unit/test_central/test_basic.py

@@ -443,6 +443,32 @@ class CentralServiceTestCase(CentralBasic):
         assert self.service._enforce_record_quota.called
         assert self.service._update_zone_in_storage.called
 
+    def test_create_recordset_checking_DBDeadLock(self):
+        self.service._enforce_recordset_quota = mock.Mock()
+        self.service._enforce_record_quota = mock.Mock()
+        self.service._is_valid_recordset_name = mock.Mock()
+        self.service._is_valid_recordset_placement = mock.Mock()
+        self.service._is_valid_recordset_placement_subzone = mock.Mock()
+        self.service._is_valid_ttl = mock.Mock()
+
+        self.service.storage.create_recordset = mock.Mock(return_value='rs')
+        self.service._update_zone_in_storage = mock.Mock()
+
+        # NOTE(thirose): Since this is a race condition we assume that
+        #  we will hit it if we try to do the operations in a loop 100 times.
+        for num in range(100):
+            recordset = Mock()
+            recordset.name = "b%s".format(num)
+            recordset.obj_attr_is_set.return_value = True
+            recordset.records = [MockRecord()]
+
+            rs, zone = self.service._create_recordset_in_storage(
+                self.context, Mockzone(), recordset
+            )
+            assert not self.service.storage._retry_on_deadlock.called
+            assert self.service._update_zone_in_storage.called
+            assert self.service.storage.create_recordset.called
+
     def test__create_soa(self):
         self.service._create_recordset_in_storage = Mock(
             return_value=(None, None)