Fix SQLite concurrency problems by using BEGIN IMMEDIATE (#10368)

* Test locking immediate for SQLite3

* fix url field separator

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: zeripath <art27@cantab.net>

integrations/migration-test/migration_test.go

 		err := os.MkdirAll(path.Dir(setting.Database.Path), os.ModePerm)
 		assert.NoError(t, err)
 
-		db, err := sql.Open("sqlite3", fmt.Sprintf("file:%s?cache=shared&mode=rwc&_busy_timeout=%d", setting.Database.Path, setting.Database.Timeout))
+		db, err := sql.Open("sqlite3", fmt.Sprintf("file:%s?cache=shared&mode=rwc&_busy_timeout=%d&_txlock=immediate", setting.Database.Path, setting.Database.Timeout))
 		assert.NoError(t, err)
 		defer db.Close()
 

models/unit_tests.go

 // CreateTestEngine creates a memory database and loads the fixture data from fixturesDir
 func CreateTestEngine(fixturesDir string) error {
 	var err error
-	x, err = xorm.NewEngine("sqlite3", "file::memory:?cache=shared")
+	x, err = xorm.NewEngine("sqlite3", "file::memory:?cache=shared&_txlock=immediate")
 	if err != nil {
 		return err
 	}

modules/setting/database.go

 		if err := os.MkdirAll(path.Dir(Database.Path), os.ModePerm); err != nil {
 			return "", fmt.Errorf("Failed to create directories: %v", err)
 		}
-		connStr = fmt.Sprintf("file:%s?cache=shared&mode=rwc&_busy_timeout=%d", Database.Path, Database.Timeout)
+		connStr = fmt.Sprintf("file:%s?cache=shared&mode=rwc&_busy_timeout=%d&_txlock=immediate", Database.Path, Database.Timeout)
 	default:
 		return "", fmt.Errorf("Unknown database type: %s", Database.Type)
 	}