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 3 /* 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         for (i = 0; i < MAX_NODES; i++) {
  67                 atomic_init(&q->nodes[i].next, MAKE_POINTER(POISON_IDX, 0));
  68         }
  69
  70         /* Initialize each thread's free list with INITIAL_FREE pointers */
  71         /* The actual nodes are initialized with poison indexes */
  72         free_lists = malloc(num_threads * sizeof(*free_lists));
  73         for (i = 0; i < num_threads; i++) {
  74                 for (j = 0; j < INITIAL_FREE; j++) {
  75                         free_lists[i][j] = 2 + i * MAX_FREELIST + j;
  76                         atomic_init(&q->nodes[free_lists[i][j]].next, MAKE_POINTER(POISON_IDX, 0));
  77                 }
  78         }
  79
  80         /* initialize queue */
  81         atomic_init(&q->head, MAKE_POINTER(1, 0));
  82         atomic_init(&q->tail, MAKE_POINTER(1, 0));
  83         atomic_init(&q->nodes[1].next, MAKE_POINTER(0, 0));
  84 }
  85
  86 /**
  87         @Begin
  88         @Interface_define: Enqueue
  89         @End
  90 */
  91 void enqueue(queue_t *q, unsigned int val)
  92 {
  93         int success = 0;
  94         unsigned int node;
  95         pointer tail;
  96         pointer next;
  97         pointer tmp;
  98
  99         node = new_node();
 100         //store_32(&q->nodes[node].value, val);
 101         q->nodes[node].value = val;
 102         tmp = atomic_load_explicit(&q->nodes[node].next, relaxed);
 103         set_ptr(&tmp, 0); // NULL
 104         atomic_store_explicit(&q->nodes[node].next, tmp, relaxed);
 105
 106         while (!success) {
 107                 /**
 108                         @Begin
 109                         @Commit_point_clear: true
 110                         @Label: Enqueue_Clear
 111                         @End
 112                 */
 113                 /**** detected UL ****/
 114                 tail = atomic_load_explicit(&q->tail, acquire);
 115                 /**
 116                         @Begin
 117                         @Commit_point_define_check: true
 118                         @Label: Enqueue_Read_Tail
 119                         @End
 120                 */
 121                 /****FIXME: miss ****/
 122                 next = atomic_load_explicit(&q->nodes[get_ptr(tail)].next, acquire);
 123                 //printf("miss1_enqueue\n");
 124                 if (tail == atomic_load_explicit(&q->tail, relaxed)) {
 125
 126                         /* Check for uninitialized 'next' */
 127                         //MODEL_ASSERT(get_ptr(next) != POISON_IDX);
 128
 129                         if (get_ptr(next) == 0) { // == NULL
 130                                 pointer value = MAKE_POINTER(node, get_count(next) + 1);
 131                                 /**** detected UL ****/
 132                                 // Second release can be just relaxed
 133                                 success = atomic_compare_exchange_strong_explicit(&q->nodes[get_ptr(tail)].next,
 134                                                 &next, value, release, relaxed);
 135                                 /**
 136                                         @Begin
 137                                         @Commit_point_define_check: success
 138                                         @Label: Enqueue_UpdateNext
 139                                         @End
 140                                 */
 141                         }
 142                         if (!success) {
 143                                 // This routine helps the other enqueue to update the tail
 144                                 /**** detected UL ****/
 145                                 unsigned int ptr = get_ptr(atomic_load_explicit(&q->nodes[get_ptr(tail)].next, acquire));
 146                                 pointer value = MAKE_POINTER(ptr,
 147                                                 get_count(tail) + 1);
 148                                 /****FIXME: miss ****/
 149                                 // Second release can be just relaxed
 150                                 bool succ = false;
 151                                 succ = atomic_compare_exchange_strong_explicit(&q->tail,
 152                                                 &tail, value, release, relaxed);
 153                                 if (succ) {
 154                                         //printf("miss2_enqueue CAS succ\n");
 155                                 }
 156                                 //printf("miss2_enqueue\n");
 157                                 thrd_yield();
 158                         }
 159                 }
 160         }
 161         /**** dectected UL ****/
 162         // Second release can be just relaxed
 163         bool succ = atomic_compare_exchange_strong_explicit(&q->tail,
 164                         &tail,
 165                         MAKE_POINTER(node, get_count(tail) + 1),
 166                         release, relaxed);
 167         /**
 168                 @Begin
 169                 @Additional_ordering_point_define_check: true
 170                 @Label: Enqueue_Additional_Tail_LoadOrCAS
 171                 @End
 172         */
 173
 174 }
 175
 176 /**
 177         @Begin
 178         @Interface_define: Dequeue
 179         @End
 180 */
 181 bool dequeue(queue_t *q, int *retVal)
 182 {
 183         unsigned int value = 0;
 184         int success = 0;
 185         pointer head;
 186         pointer tail;
 187         pointer next;
 188
 189         while (!success) {
 190                 /**
 191                         @Begin
 192                         @Commit_point_clear: true
 193                         @Label: Dequeue_Clear
 194                         @End
 195                 */
 196                 /**** detected correctness error ****/
 197                 head = atomic_load_explicit(&q->head, acquire);
 198                 /**
 199                         @Begin
 200                         @Commit_point_define_check: true
 201                         @Label: Dequeue_Read_Head
 202                         @End
 203                 */
 204                 /** FIXME: A new bug has been found here!!! It should be acquire instead of
 205                  * relaxed (it introduces a bug when there's two dequeuers and one
 206                  * enqueuer)
 207                  */
 208                 tail = atomic_load_explicit(&q->tail, acquire);
 209                 /**
 210                         @Begin
 211                         @Potential_commit_point_define: true
 212                         @Label: Dequeue_Potential_Read_Tail
 213                         @End
 214                 */
 215
 216                 /**** Detected UL/DR (testcase1.c) ****/
 217                 next = atomic_load_explicit(&q->nodes[get_ptr(head)].next, acquire);
 218                 /**
 219                         @Begin
 220                         @Potential_commit_point_define: true
 221                         @Label: Dequeue_Potential_LoadNext
 222                         @End
 223                 */
 224
 225                 if (atomic_load_explicit(&q->head, relaxed) == head) {
 226                         if (get_ptr(head) == get_ptr(tail)) {
 227
 228                                 /* Check for uninitialized 'next' */
 229                                 //MODEL_ASSERT(get_ptr(next) != POISON_IDX);
 230
 231                                 if (get_ptr(next) == 0) { // NULL
 232                                         /**
 233                                                 @Begin
 234                                                 @Commit_point_define: true
 235                                                 @Potential_commit_point_label: Dequeue_Potential_Read_Tail
 236                                                 @Label: Dequeue_Read_Tail
 237                                                 @End
 238                                         */
 239                                         return false; // NULL
 240                                 }
 241                                 /**** Detected UL (testcase1.c) ****/
 242                                 // Second release can be just relaxed
 243                                 bool succ = false;
 244                                 succ = atomic_compare_exchange_strong_explicit(&q->tail,
 245                                                 &tail,
 246                                                 MAKE_POINTER(get_ptr(next), get_count(tail) + 1),
 247                                                 release, relaxed);
 248                                 if (succ) {
 249                                         //printf("miss4_dequeue CAS succ\n");
 250                                 }
 251                                 //printf("miss4_dequeue\n");
 252                                 thrd_yield();
 253                         } else {
 254                                 //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,
 258                                                 &head,
 259                                                 MAKE_POINTER(get_ptr(next), get_count(head) + 1),
 260                                                 release, relaxed);
 261                                 /**
 262                                         @Begin
 263                                         @Commit_point_define: success
 264                                         @Potential_commit_point_label: Dequeue_Potential_LoadNext
 265                                         @Label: Dequeue_LoadNext
 266                                         @End
 267                                 */
 268                                 if (!success)
 269                                         thrd_yield();
 270                         }
 271                 }
 272         }
 273         reclaim(get_ptr(head));
 274         *retVal = value;
 275         return true;
 276 }