tube_create
if((ctx->qq_pipe = tube_create()) == NULL) {
if((ctx->rr_pipe = tube_create()) == NULL) {
struct tube* tube_create(void);
if(!(worker->cmd = tube_create())) {
if((ctx->qq_pipe = tube_create()) == NULL) {
if((ctx->rr_pipe = tube_create()) == NULL) {
struct tube* tube_create(void);