Fix check+set race condition in APIv1/Sink

Change-Id: I02d22212511246f0c1b8138fa3413770cd5810a1
Closes-Bug: 1454262

designate/api/v1/records.py

@@ -46,9 +46,7 @@ def _find_or_create_recordset(context, domain_id, name, type, ttl):
     central_api.find_domain(context, criterion=criterion)
 
     try:
-        recordset = _find_recordset(context, domain_id, name, type)
-    except exceptions.RecordSetNotFound:
-        # Create an empty recordset
+        # Attempt to create an empty recordset
         values = {
             'name': name,
             'type': type,
@@ -58,6 +56,10 @@ def _find_or_create_recordset(context, domain_id, name, type, ttl):
         recordset = central_api.create_recordset(
             context, domain_id, objects.RecordSet(**values))
 
+    except exceptions.DuplicateRecordSet:
+        # Fetch the existing recordset
+        recordset = _find_recordset(context, domain_id, name, type)
+
     return recordset
 
 

designate/notification_handler/base.py

@@ -69,12 +69,7 @@ class NotificationHandler(ExtensionPlugin):
         name = name.encode('idna')
 
         try:
-            recordset = self.central_api.find_recordset(context, {
-                'domain_id': domain_id,
-                'name': name,
-                'type': type,
-            })
-        except exceptions.RecordSetNotFound:
+            # Attempt to create an empty recordset
             values = {
                 'name': name,
                 'type': type,
@@ -83,6 +78,14 @@ class NotificationHandler(ExtensionPlugin):
             recordset = self.central_api.create_recordset(
                 context, domain_id, RecordSet(**values))
 
+        except exceptions.DuplicateRecordSet:
+            # Fetch the existing recordset
+            recordset = self.central_api.find_recordset(context, {
+                'domain_id': domain_id,
+                'name': name,
+                'type': type,
+            })
+
         return recordset