benchmark/ms-queue/my_queue.c

   1 #include <threads.h>
   2 #include <stdlib.h>
   3 #include "librace.h"
   4 #include "model-assert.h"
   5
   6 #include "my_queue.h"
   7
   8 #define relaxed memory_order_relaxed
   9 #define release memory_order_release
  10 #define acquire memory_order_acquire
  11
  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 */
  14
  15 #define POISON_IDX 0x666
  16
  17 static unsigned int (*free_lists)[MAX_FREELIST];
  18
  19 /* Search this thread's free list for a "new" node */
  20 static unsigned int new_node()
  21 {
  22         int i;
  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];
  27                 if (node) {
  28                         //store_32(&free_lists[t][i], 0);
  29                         free_lists[t][i] = 0;
  30                         return node;
  31                 }
  32         }
  33         /* free_list is empty? */
  34         //MODEL_ASSERT(0);
  35         return 0;
  36 }
  37
  38 /* Place this node index back on this thread's free list */
  39 static void reclaim(unsigned int node)
  40 {
  41         int i;
  42         int t = get_thread_num();
  43
  44         /* Don't reclaim NULL node */
  45         //MODEL_ASSERT(node);
  46
  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];
  51
  52                 /* Found empty spot in free list */
  53                 if (idx == 0) {
  54                         //store_32(&free_lists[t][i], node);
  55                         free_lists[t][i] = node;
  56                         return;
  57                 }
  58         }
  59         /* free list is full? */
  60         //MODEL_ASSERT(0);
  61 }
  62
  63 void init_queue(queue_t *q, int num_threads)
  64 {
  65         int i, j;
  66
  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));
  74                 }
  75         }
  76
  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));
  81 }
  82
  83 /**
  84         @Begin
  85         @Interface_define: Enqueue
  86         @End
  87 */
  88 void enqueue(queue_t *q, unsigned int val)
  89 {
  90         int success = 0;
  91         unsigned int node;
  92         pointer tail;
  93         pointer next;
  94         pointer tmp;
  95
  96         node = new_node();
  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);
 102
 103         while (!success) {
 104                 tail = atomic_load_explicit(&q->tail, acquire);
 105                 next = atomic_load_explicit(&q->nodes[get_ptr(tail)].next, acquire);
 106                 if (tail == atomic_load_explicit(&q->tail, relaxed)) {
 107
 108                         /* Check for uninitialized 'next' */
 109                         //MODEL_ASSERT(get_ptr(next) != POISON_IDX);
 110
 111                         if (get_ptr(next) == 0) { // == NULL
 112                                 pointer value = MAKE_POINTER(node, get_count(next) + 1);
 113                                 success = atomic_compare_exchange_strong_explicit(&q->nodes[get_ptr(tail)].next,
 114                                                 &next, value, release, release);
 115                                 /**
 116                                         @Begin
 117                                         @Commit_point_define_check: success == true
 118                                         @Label: Enqueue_Success_Point
 119                                         @End
 120                                 */
 121                         }
 122                         if (!success) {
 123                                 unsigned int ptr = get_ptr(atomic_load_explicit(&q->nodes[get_ptr(tail)].next, acquire));
 124                                 pointer value = MAKE_POINTER(ptr,
 125                                                 get_count(tail) + 1);
 126                                 atomic_compare_exchange_strong_explicit(&q->tail,
 127                                                 &tail, value, release, release);
 128                                 thrd_yield();
 129                         }
 130                 }
 131         }
 132         atomic_compare_exchange_strong_explicit(&q->tail,
 133                         &tail,
 134                         MAKE_POINTER(node, get_count(tail) + 1),
 135                         release, release);
 136 }
 137
 138 /**
 139         @Begin
 140         @Interface_define: Dequeue
 141         @End
 142 */
 143 unsigned int dequeue(queue_t *q)
 144 {
 145         unsigned int value;
 146         int success = 0;
 147         pointer head;
 148         pointer tail;
 149         pointer next;
 150
 151         while (!success) {
 152                 head = atomic_load_explicit(&q->head, acquire);
 153                 tail = atomic_load_explicit(&q->tail, relaxed);
 154                 next = atomic_load_explicit(&q->nodes[get_ptr(head)].next, acquire);
 155                 if (atomic_load_explicit(&q->head, relaxed) == head) {
 156                         if (get_ptr(head) == get_ptr(tail)) {
 157
 158                                 /* Check for uninitialized 'next' */
 159                                 //MODEL_ASSERT(get_ptr(next) != POISON_IDX);
 160
 161                                 if (get_ptr(next) == 0) { // NULL
 162                                         /**
 163                                                 @Begin
 164                                                 @Commit_point_define_check: true
 165                                                 @Label: Dequeue_Empty_Point
 166                                                 @End
 167                                         */
 168                                         return 0; // NULL
 169                                 }
 170                                 atomic_compare_exchange_strong_explicit(&q->tail,
 171                                                 &tail,
 172                                                 MAKE_POINTER(get_ptr(next), get_count(tail) + 1),
 173                                                 release, release);
 174                                 thrd_yield();
 175                         } else {
 176                                 //value = load_32(&q->nodes[get_ptr(next)].value);
 177                                 value = q->nodes[get_ptr(next)].value;
 178                                 success = atomic_compare_exchange_strong_explicit(&q->head,
 179                                                 &head,
 180                                                 MAKE_POINTER(get_ptr(next), get_count(head) + 1),
 181                                                 release, release);
 182                                 /**
 183                                         @Begin
 184                                         @Commit_point_define_check: success == true
 185                                         @Label: Dequeue_Success_Point
 186                                         @End
 187                                 */
 188                                 if (!success)
 189                                         thrd_yield();
 190                         }
 191                 }
 192         }
 193         reclaim(get_ptr(head));
 194         return value;
 195 }