-#include <threads.h>
-#include <stdlib.h>
-#include "librace.h"
-#include "model-assert.h"
-
-#include "my_queue.h"
-
-#define relaxed memory_order_relaxed
-#define release memory_order_release
-#define acquire memory_order_acquire
-
-#define MAX_FREELIST 4 /* Each thread can own up to MAX_FREELIST free nodes */
-#define INITIAL_FREE 2 /* Each thread starts with INITIAL_FREE free nodes */
-
-#define POISON_IDX 0x666
-
-static unsigned int (*free_lists)[MAX_FREELIST];
-
-/* Search this thread's free list for a "new" node */
-static unsigned int new_node()
-{
- int i;
- int t = get_thread_num();
- for (i = 0; i < MAX_FREELIST; i++) {
- unsigned int node = load_32(&free_lists[t][i]);
- if (node) {
- store_32(&free_lists[t][i], 0);
- return node;
- }
- }
- /* free_list is empty? */
- MODEL_ASSERT(0);
- return 0;
-}
-
-/* Place this node index back on this thread's free list */
-static void reclaim(unsigned int node)
-{
- int i;
- int t = get_thread_num();
-
- /* Don't reclaim NULL node */
- MODEL_ASSERT(node);
-
- for (i = 0; i < MAX_FREELIST; i++) {
- /* Should never race with our own thread here */
- unsigned int idx = load_32(&free_lists[t][i]);
-
- /* Found empty spot in free list */
- if (idx == 0) {
- store_32(&free_lists[t][i], node);
- return;
- }
- }
- /* free list is full? */
- MODEL_ASSERT(0);
-}
-
-void init_queue(queue_t *q, int num_threads)
-{
- /**
- @Begin
- @Entry_point
- @End
- */
-
- int i, j;
-
- /* Initialize each thread's free list with INITIAL_FREE pointers */
- /* The actual nodes are initialized with poison indexes */
- free_lists = malloc(num_threads * sizeof(*free_lists));
- for (i = 0; i < num_threads; i++) {
- for (j = 0; j < INITIAL_FREE; j++) {
- free_lists[i][j] = 2 + i * MAX_FREELIST + j;
- atomic_init(&q->nodes[free_lists[i][j]].next, MAKE_POINTER(POISON_IDX, 0));
- }
- }
-
- /* initialize queue */
- atomic_init(&q->head, MAKE_POINTER(1, 0));
- atomic_init(&q->tail, MAKE_POINTER(1, 0));
- atomic_init(&q->nodes[1].next, MAKE_POINTER(0, 0));
-}
-
-/**
- @Begin
- @Interface_define: Enqueue
- @End
-*/
void enqueue(queue_t *q, unsigned int val)
-{
- int success = 0;
- unsigned int node;
- pointer tail;
- pointer next;
- pointer tmp;
-
- node = new_node();
- store_32(&q->nodes[node].value, val);
- tmp = atomic_load_explicit(&q->nodes[node].next, relaxed);
- set_ptr(&tmp, 0); // NULL
- atomic_store_explicit(&q->nodes[node].next, tmp, relaxed);
-
- while (!success) {
- tail = atomic_load_explicit(&q->tail, acquire);
- next = atomic_load_explicit(&q->nodes[get_ptr(tail)].next, acquire);
- if (tail == atomic_load_explicit(&q->tail, relaxed)) {
-
- /* Check for uninitialized 'next' */
- MODEL_ASSERT(get_ptr(next) != POISON_IDX);
-
- if (get_ptr(next) == 0) { // == NULL
- pointer value = MAKE_POINTER(node, get_count(next) + 1);
- success = atomic_compare_exchange_strong_explicit(&q->nodes[get_ptr(tail)].next,
- &next, value, release, release);
- }
- if (!success) {
- unsigned int ptr = get_ptr(atomic_load_explicit(&q->nodes[get_ptr(tail)].next, acquire));
- pointer value = MAKE_POINTER(ptr,
- get_count(tail) + 1);
- int commit_success = 0;
- commit_success = atomic_compare_exchange_strong_explicit(&q->tail,
- &tail, value, release, release);
- /**
- @Begin
- @Commit_point_define_check: __ATOMIC_RET__ == true
- @Label: Enqueue_Success_Point
- @End
- */
- thrd_yield();
- }
- }
- }
- atomic_compare_exchange_strong_explicit(&q->tail,
- &tail,
- MAKE_POINTER(node, get_count(tail) + 1),
- release, release);
-}
-
-
-/**
- @Begin
- @Interface_define: Dequeue
- @End
-*/
-unsigned int dequeue(queue_t *q)
-{
- unsigned int value;
- int success = 0;
- pointer head;
- pointer tail;
- pointer next;
-
- while (!success) {
- head = atomic_load_explicit(&q->head, acquire);
- tail = atomic_load_explicit(&q->tail, relaxed);
- next = atomic_load_explicit(&q->nodes[get_ptr(head)].next, acquire);
- if (atomic_load_explicit(&q->head, relaxed) == head) {
- if (get_ptr(head) == get_ptr(tail)) {
-
- /* Check for uninitialized 'next' */
- MODEL_ASSERT(get_ptr(next) != POISON_IDX);
-
- if (get_ptr(next) == 0) { // NULL
- return 0; // NULL
- }
- atomic_compare_exchange_strong_explicit(&q->tail,
- &tail,
- MAKE_POINTER(get_ptr(next), get_count(tail) + 1),
- release, release);
- thrd_yield();
- } else {
- value = load_32(&q->nodes[get_ptr(next)].value);
- success = atomic_compare_exchange_strong_explicit(&q->head,
- &head,
- MAKE_POINTER(get_ptr(next), get_count(head) + 1),
- release, release);
- /**
- @Begin
- @Commit_point_define_check: __ATOMIC_RET__ == true
- @Label: Dequeue_Success_Point
- @End
- */
- if (!success)
- thrd_yield();
- }
- }
- }
- reclaim(get_ptr(head));
- return value;
-}
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