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#include "kpl.h"
extern inline void kpl_task_queue_init(kpl_task_queue *task_queue);
extern inline void kpl_task_queue_add(kpl_task_queue *task_queue, kpl_task *task);
kpl_task *kpl_task_queue_next(kpl_task_queue *task_queue) {
kpl_task *task = NULL;
for (;;) {
kpl_task *tail = task_queue->tail, *next = __atomic_load_n(&tail->next, __ATOMIC_ACQUIRE);
if (tail == (kpl_task*) &task_queue->dummy) {
if (!next)
break;
tail = task_queue->tail = next;
next = __atomic_load_n(&tail->next, __ATOMIC_ACQUIRE);
}
if (!next) {
kpl_task *head = __atomic_load_n(&task_queue->head, __ATOMIC_ACQUIRE);
if (tail != head)
continue;
kpl_task_queue_add(task_queue, (kpl_task*) &task_queue->dummy);
next = __atomic_load_n(&tail->next, __ATOMIC_ACQUIRE);
}
if (next) {
task_queue->tail = next;
task = tail;
break;
}
}
if (task)
__atomic_store_n(&task->next, NULL, __ATOMIC_RELAXED);
return task;
}
bool kpl_ring_queue_init(kpl_ring_queue *ring_queue, int8_t size_pow2) {
if (size_pow2 < KPL_RING_QUEUE_MIN_POW2 || size_pow2 > KPL_RING_QUEUE_MAX_POW2)
return false;
size_t size = 1L << size_pow2;
ring_queue->mmap_size = KPL_PAGE_SIZE_ROUND(sizeof(kpl_ring_queue_item) * size);
ring_queue->items = mmap(NULL, ring_queue->mmap_size,
PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
ring_queue->items_mask = size - 1;
__atomic_store_n(&ring_queue->head_index, 0, __ATOMIC_RELAXED);
__atomic_store_n(&ring_queue->tail_index, 0, __ATOMIC_RELAXED);
for (size_t index = 0; index < size; index++)
__atomic_store_n(&ring_queue->items[index].index, index, __ATOMIC_RELAXED);
return true;
}
extern inline void kpl_ring_queue_free(kpl_ring_queue *ring_queue);
bool kpl_ring_queue_add(kpl_ring_queue *ring_queue, void *data) {
for (;;) {
ssize_t tail_index = __atomic_load_n(&ring_queue->tail_index, __ATOMIC_RELAXED);
kpl_ring_queue_item *item = &ring_queue->items[tail_index & ring_queue->items_mask];
ssize_t item_index = __atomic_load_n(&item->index, __ATOMIC_ACQUIRE), diff = item_index - tail_index;
if (diff > 0)
continue;
if (diff < 0)
break;
if (!__atomic_compare_exchange_n(&ring_queue->tail_index, &tail_index, tail_index + 1, true,
__ATOMIC_RELAXED, __ATOMIC_RELAXED))
continue;
item->data = data;
__atomic_store_n(&item->index, tail_index + 1, __ATOMIC_RELEASE);
return true;
}
return false;
}
void *kpl_ring_queue_next(kpl_ring_queue *ring_queue) {
for (;;) {
ssize_t head_index = __atomic_load_n(&ring_queue->head_index, __ATOMIC_RELAXED);
kpl_ring_queue_item *item = &ring_queue->items[head_index & ring_queue->items_mask];
ssize_t item_index = __atomic_load_n(&item->index, __ATOMIC_ACQUIRE),
diff = item_index - (head_index + 1);
if (diff > 0)
continue;
if (diff < 0)
break;
if (!__atomic_compare_exchange_n(&ring_queue->head_index, &head_index, head_index + 1, true,
__ATOMIC_RELAXED, __ATOMIC_RELAXED))
continue;
void *data = item->data;
item->data = NULL;
__atomic_store_n(&item->index, head_index + ring_queue->items_mask + 1, __ATOMIC_RELEASE);
return data;
}
return NULL;
}
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