3 // #include "librace.h"
4 #include "model-assert.h"
5 #include "libinterface.h"
7 #include "trieber-stack.h"
9 #define MAX_FREELIST 4 /* Each thread can own up to MAX_FREELIST free nodes */
10 #define INITIAL_FREE 2 /* Each thread starts with INITIAL_FREE free nodes */
12 #define POISON_IDX 0x666
14 static unsigned int (*free_lists)[MAX_FREELIST];
16 /* Search this thread's free list for a "new" node */
17 static unsigned int new_node()
20 int t = get_thread_num();
21 for (i = 0; i < MAX_FREELIST; i++) {
22 unsigned int node = load_64(&free_lists[t][i]);
24 store_64(&free_lists[t][i], 0);
28 /* free_list is empty? */
33 /* Place this node index back on this thread's free list */
34 static void reclaim(unsigned int node)
37 int t = get_thread_num();
39 /* Don't reclaim NULL node */
42 for (i = 0; i < MAX_FREELIST; i++) {
43 /* Should never race with our own thread here */
44 unsigned int idx = load_64(&free_lists[t][i]);
46 /* Found empty spot in free list */
48 store_64(&free_lists[t][i], node);
52 /* free list is full? */
56 void init_stack(stack_t *s, int num_threads)
60 /* Initialize each thread's free list with INITIAL_FREE pointers */
61 /* The actual nodes are initialized with poison indexes */
62 free_lists = malloc(num_threads * sizeof(*free_lists));
63 for (i = 0; i < num_threads; i++) {
64 for (j = 0; j < INITIAL_FREE; j++) {
65 free_lists[i][j] = 1 + i * MAX_FREELIST + j;
66 atomic_init(&s->nodes[free_lists[i][j]].next, MAKE_POINTER(POISON_IDX, 0));
70 /* initialize stack */
71 atomic_init(&s->top, MAKE_POINTER(0, 0));
74 void push(stack_t *s, unsigned int val) {
75 unsigned int nodeIdx = new_node();
76 node_t *node = &s->nodes[nodeIdx];
78 pointer oldTop, newTop;
82 oldTop = atomic_load_explicit(&s->top, acquire);
83 newTop = MAKE_POINTER(nodeIdx, get_count(oldTop) + 1);
85 store_64(&node->next, oldTop);
88 success = rmw_64(CAS, &s->top, &oldTop, newTop);
94 unsigned int pop(stack_t *s)
96 pointer oldTop, newTop, next;
102 oldTop = atomic_load_explicit(&s->top, acquire);
103 if (get_ptr(oldTop) == 0)
105 node = &s->nodes[get_ptr(oldTop)];
107 next = atomic_load_explicit(&node->next, relaxed);
108 newTop = MAKE_POINTER(get_ptr(next), get_count(oldTop) + 1);
110 success = atomic_compare_exchange_strong_explicit(&s->top, &oldTop,
111 newTop, release, relaxed);
116 /* Reclaim the used slot */
117 reclaim(get_ptr(oldTop));