7 #define relaxed memory_order_relaxed
8 #define release memory_order_release
9 #define acquire memory_order_acquire
11 static unsigned int *node_nums;
13 static unsigned int new_node()
15 return node_nums[get_thread_num()];
18 static void reclaim(unsigned int node)
20 node_nums[get_thread_num()] = node;
23 void init_queue(queue_t *q, int num_threads)
30 node_nums = malloc(num_threads * sizeof(*node_nums));
31 for (i = 0; i < num_threads; i++)
34 /* initialize queue */
35 head = MAKE_POINTER(1, 0);
36 tail = MAKE_POINTER(1, 0);
37 next = MAKE_POINTER(0, 0); // (NULL, 0)
39 atomic_init(&q->head, head);
40 atomic_init(&q->tail, tail);
41 atomic_init(&q->nodes[1].next, next);
43 /* initialize avail list */
44 for (i = 2; i < MAX_NODES; i++) {
45 next = MAKE_POINTER(i + 1, 0);
46 atomic_init(&q->nodes[i].next, next);
49 next = MAKE_POINTER(0, 0); // (NULL, 0)
50 atomic_init(&q->nodes[MAX_NODES].next, next);
53 void enqueue(queue_t *q, unsigned int val)
62 store_32(&q->nodes[node].value, val);
63 tmp = atomic_load_explicit(&q->nodes[node].next, relaxed);
64 set_ptr(&tmp, 0); // NULL
65 atomic_store_explicit(&q->nodes[node].next, tmp, relaxed);
68 tail = atomic_load_explicit(&q->tail, acquire);
69 next = atomic_load_explicit(&q->nodes[get_ptr(tail)].next, acquire);
70 if (tail == atomic_load_explicit(&q->tail, relaxed)) {
71 if (get_ptr(next) == 0) { // == NULL
72 pointer value = MAKE_POINTER(node, get_count(next) + 1);
73 success = atomic_compare_exchange_strong_explicit(&q->nodes[get_ptr(tail)].next,
74 &next, value, memory_order_acq_rel, memory_order_acq_rel);
77 unsigned int ptr = get_ptr(atomic_load_explicit(&q->nodes[get_ptr(tail)].next, memory_order_seq_cst));
78 pointer value = MAKE_POINTER(ptr,
80 atomic_compare_exchange_strong_explicit(&q->tail,
82 memory_order_acq_rel, memory_order_acq_rel);
87 atomic_compare_exchange_strong_explicit(&q->tail,
89 MAKE_POINTER(node, get_count(tail) + 1),
90 memory_order_acq_rel, memory_order_acq_rel);
93 unsigned int dequeue(queue_t *q)
102 head = atomic_load_explicit(&q->head, acquire);
103 tail = atomic_load_explicit(&q->tail, acquire);
104 next = atomic_load_explicit(&q->nodes[get_ptr(head)].next, acquire);
105 if (atomic_load_explicit(&q->head, relaxed) == head) {
106 if (get_ptr(head) == get_ptr(tail)) {
107 if (get_ptr(next) == 0) { // NULL
110 atomic_compare_exchange_strong_explicit(&q->tail,
112 MAKE_POINTER(get_ptr(next), get_count(tail) + 1),
113 memory_order_acq_rel, memory_order_acq_rel);
116 value = load_32(&q->nodes[get_ptr(next)].value);
117 success = atomic_compare_exchange_strong_explicit(&q->head,
119 MAKE_POINTER(get_ptr(next), get_count(head) + 1),
120 memory_order_acq_rel, memory_order_acq_rel);
126 reclaim(get_ptr(head));