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
  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                 /**
 105                         @Begin
 106                         @Commit_point_clear: true
 107                         @Label: Enqueue_Clear
 108                         @End
 109                 */
 110                 /**** detected UL ****/
 111                 tail = atomic_load_explicit(&q->tail, acquire);
 112                 /**
 113                         @Begin
 114                         @Commit_point_define_check: true
 115                         @Label: Enqueue_Read_Tail
 116                         @End
 117                 */
 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)) {
 122
 123                         /* Check for uninitialized 'next' */
 124                         //MODEL_ASSERT(get_ptr(next) != POISON_IDX);
 125
 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);
 132                                 /**
 133                                         @Begin
 134                                         @Commit_point_define_check: success
 135                                         @Label: Enqueue_UpdateNext
 136                                         @End
 137                                 */
 138                         }
 139                         if (!success) {
 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
 147                                 bool succ = false;
 148                                 succ = atomic_compare_exchange_strong_explicit(&q->tail,
 149                                                 &tail, value, release, relaxed);
 150                                 if (succ) {
 151                                         //printf("miss2_enqueue CAS succ\n");
 152                                 }
 153                                 //printf("miss2_enqueue\n");
 154                                 thrd_yield();
 155                         }
 156                 }
 157         }
 158         /**** dectected UL ****/
 159         // Second release can be just relaxed
 160         bool succ = atomic_compare_exchange_strong_explicit(&q->tail,
 161                         &tail,
 162                         MAKE_POINTER(node, get_count(tail) + 1),
 163                         release, relaxed);
 164 }
 165
 166 /**
 167         @Begin
 168         @Interface_define: Dequeue
 169         @End
 170 */
 171 bool dequeue(queue_t *q, int *retVal)
 172 {
 173         unsigned int value = 0;
 174         int success = 0;
 175         pointer head;
 176         pointer tail;
 177         pointer next;
 178
 179         while (!success) {
 180                 /**
 181                         @Begin
 182                         @Commit_point_clear: true
 183                         @Label: Dequeue_Clear
 184                         @End
 185                 */
 186                 /**** detected correctness error ****/
 187                 head = atomic_load_explicit(&q->head, acquire);
 188                 /**
 189                         @Begin
 190                         @Commit_point_define_check: true
 191                         @Label: Dequeue_Read_Head
 192                         @End
 193                 */
 194                 /** A new bug has been found here!!! It should be acquire instead of
 195                  * relaxed (it introduces a bug when there's two dequeuers and one
 196                  * enqueuer)
 197                  */
 198                 tail = atomic_load_explicit(&q->tail, acquire);
 199                 /**
 200                         @Begin
 201                         @Potential_commit_point_define: true
 202                         @Label: Dequeue_Potential_Read_Tail
 203                         @End
 204                 */
 205
 206                 /****FIXME: miss ****/
 207                 next = atomic_load_explicit(&q->nodes[get_ptr(head)].next, acquire);
 208                 /**
 209                         @Begin
 210                         @Potential_commit_point_define: true
 211                         @Label: Dequeue_Potential_LoadNext
 212                         @End
 213                 */
 214
 215                 if (atomic_load_explicit(&q->head, relaxed) == head) {
 216                         if (get_ptr(head) == get_ptr(tail)) {
 217
 218                                 /* Check for uninitialized 'next' */
 219                                 //MODEL_ASSERT(get_ptr(next) != POISON_IDX);
 220
 221                                 if (get_ptr(next) == 0) { // NULL
 222                                         /**
 223                                                 @Begin
 224                                                 @Commit_point_define: true
 225                                                 @Potential_commit_point_label: Dequeue_Potential_Read_Tail
 226                                                 @Label: Dequeue_Read_Tail
 227                                                 @End
 228                                         */
 229                                         return false; // NULL
 230                                 }
 231                                 /****FIXME: miss (not reached) ****/
 232                                 // Second release can be just relaxed
 233                                 bool succ = false;
 234                                 succ = atomic_compare_exchange_strong_explicit(&q->tail,
 235                                                 &tail,
 236                                                 MAKE_POINTER(get_ptr(next), get_count(tail) + 1),
 237                                                 release, relaxed);
 238                                 if (succ) {
 239                                         //printf("miss4_dequeue CAS succ\n");
 240                                 }
 241                                 //printf("miss4_dequeue\n");
 242                                 thrd_yield();
 243                         } else {
 244                                 value = load_32(&q->nodes[get_ptr(next)].value);
 245                                 //value = q->nodes[get_ptr(next)].value;
 246                                 /****FIXME: correctness error ****/
 247                                 success = atomic_compare_exchange_strong_explicit(&q->head,
 248                                                 &head,
 249                                                 MAKE_POINTER(get_ptr(next), get_count(head) + 1),
 250                                                 release, relaxed);
 251                                 /**
 252                                         @Begin
 253                                         @Commit_point_define: success
 254                                         @Potential_commit_point_label: Dequeue_Potential_LoadNext
 255                                         @Label: Dequeue_LoadNext
 256                                         @End
 257                                 */
 258                                 if (!success)
 259                                         thrd_yield();
 260                         }
 261                 }
 262         }
 263         reclaim(get_ptr(head));
 264         *retVal = value;
 265         return true;
 266 }