gpr_mpscq_node *gpr_mpscq_pop(gpr_mpscq *q) {
gpr_mpscq_node *tail = q->tail;
gpr_mpscq_node *next = (gpr_mpscq_node *)gpr_atm_acq_load(&tail->next);
if (tail == &q->stub) {
// indicates the list is actually (ephemerally) empty
if (next == NULL) return NULL;
q->tail = next;
tail = next;
next = (gpr_mpscq_node *)gpr_atm_acq_load(&tail->next);
}
if (next != NULL) {
q->tail = next;
return tail;
}
gpr_mpscq_node *head = (gpr_mpscq_node *)gpr_atm_acq_load(&q->head);
if (tail != head) {
// indicates a retry is in order: we're still adding
return NULL;
}
gpr_mpscq_push(q, &q->stub);
next = (gpr_mpscq_node *)gpr_atm_acq_load(&tail->next);
if (next != NULL) {
q->tail = next;
return tail;
}
// indicates a retry is in order: we're still adding
return NULL;
}
static void test_thread(void *args) {
thd_args *a = args;
gpr_event_wait(a->start, gpr_inf_future(GPR_CLOCK_REALTIME));
for (size_t i = 1; i <= THREAD_ITERATIONS; i++) {
gpr_mpscq_push(a->q, &new_node(i, &a->ctr)->node);
}
}
void grpc_workqueue_enqueue(grpc_exec_ctx *exec_ctx, grpc_workqueue *workqueue,
grpc_closure *closure, grpc_error *error) {
GPR_TIMER_BEGIN("workqueue.enqueue", 0);
gpr_atm last = gpr_atm_full_fetch_add(&workqueue->state, 2);
GPR_ASSERT(last & 1);
closure->error = error;
gpr_mpscq_push(&workqueue->queue, &closure->next_data.atm_next);
if (last == 1) {
wakeup(exec_ctx, workqueue);
}
GPR_TIMER_END("workqueue.enqueue", 0);
}
static void test_serial(void) {
gpr_log(GPR_DEBUG, "test_serial");
gpr_mpscq q;
gpr_mpscq_init(&q);
for (size_t i = 0; i < 10000000; i++) {
gpr_mpscq_push(&q, &new_node(i, NULL)->node);
}
for (size_t i = 0; i < 10000000; i++) {
test_node *n = (test_node *)gpr_mpscq_pop(&q);
GPR_ASSERT(n);
GPR_ASSERT(n->i == i);
gpr_free(n);
}
}
static bool cq_event_queue_push(grpc_cq_event_queue *q, grpc_cq_completion *c) {
gpr_mpscq_push(&q->queue, (gpr_mpscq_node *)c);
return gpr_atm_no_barrier_fetch_add(&q->num_queue_items, 1) == 0;
}
