Function usage

ds4_server.c:11482–11484

        free(disk_cache_path);
        if (job_cancelled(j)) {
            request_live_state_clear(s, slot);
            trace_event(s, trace_id, "cancelled during prefill");
            return;
        }
        trace_event(s, trace_id, "prefill failed: %s", err);
        send_prefill_failure_response(s, j, &progress, ctx_span, req_flags, err);