def clean(self, stall_time=None):
        self.delete_invalid_files()

        if stall_time is None:
            stall_time = self.conf.image_cache_stall_time

        now = time.time()
        older_than = now - stall_time
        self.delete_stalled_files(older_than)
Delete any image files in the invalid directory and any
dataset/ETHPy150Open rcbops/glance-buildpackage/glance/image_cache/drivers/sqlite.py/Driver.clean