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                 /**** UL & inadmissible ****/
 108                 tail = atomic_load_explicit(&q->tail, acquire);
 109                 /****FIXME: miss ****/
 110                 next = atomic_load_explicit(&q->nodes[get_ptr(tail)].next, acquire);
 111                 //printf("miss1_enqueue\n");
 112                 if (tail == atomic_load_explicit(&q->tail, relaxed)) {
 113
 114                         /* Check for uninitialized 'next' */
 115                         //MODEL_ASSERT(get_ptr(next) != POISON_IDX);
 116
 117                         if (get_ptr(next) == 0) { // == NULL
 118                                 pointer value = MAKE_POINTER(node, get_count(next) + 1);
 119                                 /**** SPEC Error (testcase1.c) ****/
 120                                 // Second release can be just relaxed
 121                                 success = atomic_compare_exchange_strong_explicit(&q->nodes[get_ptr(tail)].next,
 122                                                 &next, value, release, relaxed);
 123                                 /**
 124                                         @Begin
 125                                         @Commit_point_define_check: success
 126                                         @Label: EnqueueUpdateNext
 127                                         @End
 128                                 */
 129                         }
 130                         if (!success) {
 131                                 // This routine helps the other enqueue to update the tail
 132                                 /**** UL & Inadmissible ****/
 133                                 unsigned int ptr = get_ptr(atomic_load_explicit(&q->nodes[get_ptr(tail)].next, acquire));
 134                                 pointer value = MAKE_POINTER(ptr,
 135                                                 get_count(tail) + 1);
 136                                 /**** SPEC (sequential, testcase2.c) ****/
 137                                 // Second release can be just relaxed
 138                                 bool succ = false;
 139                                 succ = atomic_compare_exchange_strong_explicit(&q->tail,
 140                                                 &tail, value, release, relaxed);
 141                                 if (succ) {
 142                                         //printf("miss2_enqueue CAS succ\n");
 143                                 }
 144                                 //printf("miss2_enqueue\n");
 145                                 thrd_yield();
 146                         }
 147                 }
 148         }
 149         /**** UL & Inadmissible (main.c) ****/
 150         // Second release can be just relaxed
 151         bool succ = atomic_compare_exchange_strong_explicit(&q->tail,
 152                         &tail,
 153                         MAKE_POINTER(node, get_count(tail) + 1),
 154                         release, relaxed);
 155 }
 156
 157 /**
 158         @Begin
 159         @Interface_define: Dequeue
 160         @End
 161 */
 162 bool dequeue(queue_t *q, int *retVal)
 163 {
 164         unsigned int value = 0;
 165         int success = 0;
 166         pointer head;
 167         pointer tail;
 168         pointer next;
 169
 170         while (!success) {
 171                 /**
 172                         @Begin
 173                         @Commit_point_clear: true
 174                         @Label: Dequeue_Clear
 175                         @End
 176                 */
 177
 178                 /**** Inadmissible (main.c) ****/
 179                 head = atomic_load_explicit(&q->head, acquire);
 180                 /**
 181                         @Begin
 182                         @Commit_point_define_check: true
 183                         @Label: DequeueReadHead
 184                         @End
 185                 */
 186
 187                 /** A new bug has been found here!!! It should be acquire instead of
 188                  * relaxed (it introduces a bug when there's two dequeuers and one
 189                  * enqueuer) correctness bug!!
 190                  */
 191                 /**** SPEC (sequential) (testcase1.c) ****/
 192                 /**** New bug ****/
 193                 tail = atomic_load_explicit(&q->tail, acquire);
 194
 195                 /**** SPEC Error (testcase1.c) ****/
 196                 next = atomic_load_explicit(&q->nodes[get_ptr(head)].next, acquire);
 197                 if (atomic_load_explicit(&q->head, relaxed) == head) {
 198                         if (get_ptr(head) == get_ptr(tail)) {
 199
 200                                 /* Check for uninitialized 'next' */
 201                                 //MODEL_ASSERT(get_ptr(next) != POISON_IDX);
 202
 203                                 if (get_ptr(next) == 0) { // NULL
 204                                         return false; // NULL
 205                                 }
 206                                 /**** SPEC (sequential testcase3.c) ****/
 207                                 // Second release can be just relaxed
 208                                 bool succ = false;
 209                                 succ = atomic_compare_exchange_strong_explicit(&q->tail,
 210                                                 &tail,
 211                                                 MAKE_POINTER(get_ptr(next), get_count(tail) + 1),
 212                                                         release, relaxed);
 213                                 if (succ) {
 214                                         //printf("miss4_dequeue CAS succ\n");
 215                                 }
 216                                 //printf("miss4_dequeue\n");
 217                                 thrd_yield();
 218                         } else {
 219                                 //value = load_32(&q->nodes[get_ptr(next)].value);
 220                                 value = q->nodes[get_ptr(next)].value;
 221                                 /**** inadmissibility (main.c) ****/
 222                                 success = atomic_compare_exchange_strong_explicit(&q->head,
 223                                                 &head,
 224                                                 MAKE_POINTER(get_ptr(next), get_count(head) + 1),
 225                                                 release, relaxed);
 226                                 /**
 227                                         @Begin
 228                                         @Commit_point_define_check: success
 229                                         @Label: DequeueUpdateHead
 230                                         @End
 231                                 */
 232                                 if (!success)
 233                                         thrd_yield();
 234                         }
 235                 }
 236         }
 237         reclaim(get_ptr(head));
 238         *retVal = value;
 239         return true;
 240 }