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 3 /* 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);
29 //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);
106 @Commit_point_clear: true
107 @Label: Enqueue_Clear
110 /**** detected UL ****/
111 tail = atomic_load_explicit(&q->tail, acquire);
114 @Commit_point_define_check: true
115 @Label: Enqueue_Read_Tail
118 /****FIXME: miss ****/
119 next = atomic_load_explicit(&q->nodes[get_ptr(tail)].next, acquire);
120 //printf("miss1_enqueue\n");
121 if (tail == atomic_load_explicit(&q->tail, relaxed)) {
123 /* Check for uninitialized 'next' */
124 //MODEL_ASSERT(get_ptr(next) != POISON_IDX);
126 if (get_ptr(next) == 0) { // == NULL
127 pointer value = MAKE_POINTER(node, get_count(next) + 1);
128 /**** detected UL ****/
129 // Second release can be just relaxed
130 success = atomic_compare_exchange_strong_explicit(&q->nodes[get_ptr(tail)].next,
131 &next, value, release, relaxed);
134 @Commit_point_define_check: success
135 @Label: Enqueue_UpdateNext
140 // This routine helps the other enqueue to update the tail
141 /**** detected UL ****/
142 unsigned int ptr = get_ptr(atomic_load_explicit(&q->nodes[get_ptr(tail)].next, acquire));
143 pointer value = MAKE_POINTER(ptr,
144 get_count(tail) + 1);
145 /****FIXME: miss ****/
146 // Second release can be just relaxed
148 succ = atomic_compare_exchange_strong_explicit(&q->tail,
149 &tail, value, release, relaxed);
151 //printf("miss2_enqueue CAS succ\n");
153 //printf("miss2_enqueue\n");
158 /**** dectected UL ****/
159 // Second release can be just relaxed
160 bool succ = atomic_compare_exchange_strong_explicit(&q->tail,
162 MAKE_POINTER(node, get_count(tail) + 1),
166 @Commit_point_define_check: succ
167 @Label: Enqueue_UpdateOrLoad_Tail
174 @Interface_define: Dequeue
177 bool dequeue(queue_t *q, int *retVal)
188 @Commit_point_clear: true
189 @Label: Dequeue_Clear
192 /**** detected correctness error ****/
193 head = atomic_load_explicit(&q->head, acquire);
196 @Commit_point_define_check: true
197 @Label: Dequeue_Read_Head
200 tail = atomic_load_explicit(&q->tail, acquire);
203 @Potential_commit_point_define: true
204 @Label: Dequeue_Potential_Read_Tail
208 /****FIXME: miss ****/
209 next = atomic_load_explicit(&q->nodes[get_ptr(head)].next, acquire);
212 @Potential_commit_point_define: true
213 @Label: Dequeue_Potential_LoadNext
217 if (atomic_load_explicit(&q->head, relaxed) == head) {
218 if (get_ptr(head) == get_ptr(tail)) {
220 /* Check for uninitialized 'next' */
221 //MODEL_ASSERT(get_ptr(next) != POISON_IDX);
223 if (get_ptr(next) == 0) { // NULL
226 @Commit_point_define: true
227 @Potential_commit_point_label: Dequeue_Potential_Read_Tail
228 @Label: Dequeue_Read_Tail
231 return false; // NULL
233 /****FIXME: miss (not reached) ****/
234 // Second release can be just relaxed
236 succ = atomic_compare_exchange_strong_explicit(&q->tail,
238 MAKE_POINTER(get_ptr(next), get_count(tail) + 1),
241 //printf("miss4_dequeue CAS succ\n");
243 //printf("miss4_dequeue\n");
248 @Commit_point_define: true
249 @Potential_commit_point_label: Dequeue_Potential_LoadNext
250 @Label: Dequeue_LoadNext
253 value = load_32(&q->nodes[get_ptr(next)].value);
255 //value = q->nodes[get_ptr(next)].value;
256 /****FIXME: correctness error ****/
257 success = atomic_compare_exchange_strong_explicit(&q->head,
259 MAKE_POINTER(get_ptr(next), get_count(head) + 1),
266 reclaim(get_ptr(head));