4 #include "model-assert.h"
8 #define relaxed memory_order_relaxed
9 #define release memory_order_release
10 #define acquire memory_order_acquire
12 #define MAX_FREELIST 4 /* Each thread can own up to MAX_FREELIST free nodes */
13 #define INITIAL_FREE 2 /* Each thread starts with INITIAL_FREE free nodes */
15 #define POISON_IDX 0x666
17 static unsigned int (*free_lists)[MAX_FREELIST];
19 /* Search this thread's free list for a "new" node */
20 static unsigned int new_node()
23 int t = get_thread_num();
24 for (i = 0; i < MAX_FREELIST; i++) {
25 //unsigned int node = load_32(&free_lists[t][i]);
26 unsigned int node = free_lists[t][i];
28 //store_32(&free_lists[t][i], 0);
33 /* free_list is empty? */
38 /* Place this node index back on this thread's free list */
39 static void reclaim(unsigned int node)
42 int t = get_thread_num();
44 /* Don't reclaim NULL node */
47 for (i = 0; i < MAX_FREELIST; i++) {
48 /* Should never race with our own thread here */
49 //unsigned int idx = load_32(&free_lists[t][i]);
50 unsigned int idx = free_lists[t][i];
52 /* Found empty spot in free list */
54 //store_32(&free_lists[t][i], node);
55 free_lists[t][i] = node;
59 /* free list is full? */
63 void init_queue(queue_t *q, int num_threads)
67 /* Initialize each thread's free list with INITIAL_FREE pointers */
68 /* The actual nodes are initialized with poison indexes */
69 free_lists = malloc(num_threads * sizeof(*free_lists));
70 for (i = 0; i < num_threads; i++) {
71 for (j = 0; j < INITIAL_FREE; j++) {
72 free_lists[i][j] = 2 + i * MAX_FREELIST + j;
73 atomic_init(&q->nodes[free_lists[i][j]].next, MAKE_POINTER(POISON_IDX, 0));
77 /* initialize queue */
78 atomic_init(&q->head, MAKE_POINTER(1, 0));
79 atomic_init(&q->tail, MAKE_POINTER(1, 0));
80 atomic_init(&q->nodes[1].next, MAKE_POINTER(0, 0));
85 @Interface_define: Enqueue
88 void enqueue(queue_t *q, unsigned int val)
97 //store_32(&q->nodes[node].value, val);
98 q->nodes[node].value = val;
99 tmp = atomic_load_explicit(&q->nodes[node].next, relaxed);
100 set_ptr(&tmp, 0); // NULL
101 atomic_store_explicit(&q->nodes[node].next, tmp, relaxed);
104 /****FIXME: detected UL ****/
105 tail = atomic_load_explicit(&q->tail, acquire);
106 /****FIXME: miss ****/
107 next = atomic_load_explicit(&q->nodes[get_ptr(tail)].next, acquire);
108 if (tail == atomic_load_explicit(&q->tail, relaxed)) {
110 /* Check for uninitialized 'next' */
111 //MODEL_ASSERT(get_ptr(next) != POISON_IDX);
113 if (get_ptr(next) == 0) { // == NULL
114 pointer value = MAKE_POINTER(node, get_count(next) + 1);
115 /****FIXME: first release UL, second release miss ****/
116 success = atomic_compare_exchange_strong_explicit(&q->nodes[get_ptr(tail)].next,
117 &next, value, release, release);
120 @Commit_point_define_check: success == true
121 @Label: Enqueue_Success_Point
126 /****FIXME: detected UL ****/
127 unsigned int ptr = get_ptr(atomic_load_explicit(&q->nodes[get_ptr(tail)].next, acquire));
128 pointer value = MAKE_POINTER(ptr,
129 get_count(tail) + 1);
130 /****FIXME: both miss ****/
131 atomic_compare_exchange_strong_explicit(&q->tail,
132 &tail, value, release, release);
137 /****FIXME: first UL, second miss ****/
138 atomic_compare_exchange_strong_explicit(&q->tail,
140 MAKE_POINTER(node, get_count(tail) + 1),
146 @Interface_define: Dequeue
149 unsigned int dequeue(queue_t *q)
158 /****FIXME: detected correctness error ****/
159 head = atomic_load_explicit(&q->head, acquire);
160 tail = atomic_load_explicit(&q->tail, relaxed);
161 /****FIXME: miss ****/
162 next = atomic_load_explicit(&q->nodes[get_ptr(head)].next, acquire);
163 if (atomic_load_explicit(&q->head, relaxed) == head) {
164 if (get_ptr(head) == get_ptr(tail)) {
166 /* Check for uninitialized 'next' */
167 //MODEL_ASSERT(get_ptr(next) != POISON_IDX);
169 if (get_ptr(next) == 0) { // NULL
172 @Commit_point_define_check: true
173 @Label: Dequeue_Empty_Point
178 /****FIXME: both miss ****/
179 atomic_compare_exchange_strong_explicit(&q->tail,
181 MAKE_POINTER(get_ptr(next), get_count(tail) + 1),
185 //value = load_32(&q->nodes[get_ptr(next)].value);
186 value = q->nodes[get_ptr(next)].value;
187 /****FIXME: first correctness error, second miss ****/
188 success = atomic_compare_exchange_strong_explicit(&q->head,
190 MAKE_POINTER(get_ptr(next), get_count(head) + 1),
194 @Commit_point_define_check: success == true
195 @Label: Dequeue_Success_Point
203 reclaim(get_ptr(head));