Iterative Optimization on Hot Paths: Optimization 3: Re-use of allocations

sqlgen.go.diff

func parseQueryRow(table *Table, rows *sql.Rows) (interface{}, error) {
	// ...
-	values := make([]interface{}, len(table.Columns))
+	values := table.Scanners.Get().([]interface{})
+	defer table.Scanners.Put(values)

	for i, column := range table.Columns {
-		scanner := column.Descriptor.Scanner()
-		scanner.Target(field)
-		values[i] = scanner
+		values[i].(*fields.Scanner).Target(field)
	}

	if err := scanner.Scan(values...); err != nil {
	// ...
}