Fixed: Rare timing issue on first-use causing duplicate naming config (#2790)

Fixes #2773

src/NzbDrone.Core/Datastore/Migration/148_remove_extra_naming_config.cs

@@ -0,0 +1,15 @@
+using FluentMigrator;
+using NzbDrone.Core.Datastore.Migration.Framework;
+
+namespace NzbDrone.Core.Datastore.Migration
+{
+    [Migration(148)]
+    public class remove_extra_naming_config : NzbDroneMigrationBase
+    {
+        protected override void MainDbUpgrade()
+        {
+            // Remove all but 1 NamingConfig
+            Execute.Sql("DELETE FROM NamingConfig WHERE ID NOT IN(SELECT ID FROM NamingConfig LIMIT 1)");
+        }
+    }
+}

src/NzbDrone.Core/NzbDrone.Core.csproj

@@ -125,6 +125,7 @@
     <Compile Include="Authentication\UserRepository.cs" />
     <Compile Include="Authentication\UserService.cs" />
     <Compile Include="Datastore\Migration\123_create_netimport_table.cs" />
+    <Compile Include="Datastore\Migration\148_remove_extra_naming_config.cs" />
     <Compile Include="Datastore\Migration\146_naming_config_colon_replacement_format.cs" />
     <Compile Include="Datastore\Migration\143_clean_core_tv.cs" />
     <Compile Include="Datastore\Migration\142_movie_extras.cs" />

src/NzbDrone.Core/Organizer/NamingConfigService.cs

@@ -21,8 +21,16 @@ namespace NzbDrone.Core.Organizer
 
             if (config == null)
             {
-                _repository.Insert(NamingConfig.Default);
-                config = _repository.Single();
+                lock (_repository)
+                {
+                    config = _repository.SingleOrDefault();
+
+                    if (config == null)
+                    {
+                        _repository.Insert(NamingConfig.Default);
+                        config = _repository.Single();
+                    }
+                }
             }
 
             return config;
@@ -33,4 +41,4 @@ namespace NzbDrone.Core.Organizer
             _repository.Upsert(namingConfig);
         }
     }
-}
+}