presto-main/src/main/java/io/prestosql/operator/DriverContext.java/DriverContext/freeSpill
class DriverContext:    public void freeSpill(long bytes)
    {
        if (bytes == 0) {
            return;
        }
        checkArgument(bytes > 0, "bytes is negative");
        pipelineContext.freeSpill(bytes);
    }