ms-queue-loose/queue.c

   1 #include <threads.h>
   2 #include <stdlib.h>
   3 #include "librace.h"
   4 #include "model-assert.h"
   5
   6 #include "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 /* Simulate the fact that when a node got recycled, it will get assigned to the
  39  * same queue or for other usage */
  40 void simulateRecycledNodeUpdate(queue_t *q, unsigned int node) {
  41         atomic_store_explicit(&q->nodes[node].next, -1, memory_order_release);
  42 }
  43
  44
  45 /* Place this node index back on this thread's free list */
  46 static void reclaim(unsigned int node)
  47 {
  48         int i;
  49         int t = get_thread_num();
  50
  51         /* Don't reclaim NULL node */
  52         //MODEL_ASSERT(node);
  53
  54         for (i = 0; i < MAX_FREELIST; i++) {
  55                 /* Should never race with our own thread here */
  56                 //unsigned int idx = load_32(&free_lists[t][i]);
  57                 unsigned int idx = free_lists[t][i];
  58
  59                 /* Found empty spot in free list */
  60                 if (idx == 0) {
  61                         //store_32(&free_lists[t][i], node);
  62                         free_lists[t][i] = node;
  63                         return;
  64                 }
  65         }
  66         /* free list is full? */
  67         //MODEL_ASSERT(0);
  68 }
  69
  70 void init_queue(queue_t *q, int num_threads)
  71 {
  72         int i, j;
  73
  74         /* Initialize each thread's free list with INITIAL_FREE pointers */
  75         /* The actual nodes are initialized with poison indexes */
  76         free_lists = ( unsigned int (*)[MAX_FREELIST] ) malloc(num_threads * sizeof(*free_lists));
  77         for (i = 0; i < num_threads; i++) {
  78                 for (j = 0; j < INITIAL_FREE; j++) {
  79                         free_lists[i][j] = 2 + i * MAX_FREELIST + j;
  80                         atomic_init(&q->nodes[free_lists[i][j]].next, MAKE_POINTER(POISON_IDX, 0));
  81                 }
  82         }
  83
  84         /* initialize queue */
  85         atomic_init(&q->head, MAKE_POINTER(1, 0));
  86         atomic_init(&q->tail, MAKE_POINTER(1, 0));
  87         atomic_init(&q->nodes[1].next, MAKE_POINTER(0, 0));
  88 }
  89
  90 /** @DeclareState: IntList *q;
  91 @Commutativity: enqueue <-> dequeue (true)
  92 @Commutativity: dequeue <-> dequeue (!M1->RET || !M2->RET) */
  93
  94 /** @Transition: STATE(q)->push_back(val); */
  95 void enqueue(queue_t *q, unsigned int val, int n)
  96 {
  97         int success = 0;
  98         unsigned int node;
  99         pointer tail;
 100         pointer next;
 101         pointer tmp;
 102
 103         node = new_node();
 104         //store_32(&q->nodes[node].value, val);
 105         q->nodes[node].value = val;
 106         tmp = atomic_load_explicit(&q->nodes[node].next, relaxed);
 107         set_ptr(&tmp, 0); // NULL
 108         // This is a found bug in AutoMO, and testcase4 can reveal this known bug
 109         atomic_store_explicit(&q->nodes[node].next, tmp, release);
 110
 111         while (!success) {
 112                 /**********    Detected UL    **********/
 113                 tail = atomic_load_explicit(&q->tail, acquire);
 114                 /**********    Detected Admissibility (testcase4)    **********/
 115                 next = atomic_load_explicit(&q->nodes[get_ptr(tail)].next, acquire);
 116                 if (tail == atomic_load_explicit(&q->tail, relaxed)) {
 117
 118                         /* Check for uninitialized 'next' */
 119                         //MODEL_ASSERT(get_ptr(next) != POISON_IDX);
 120
 121                         if (get_ptr(next) == 0) { // == NULL
 122                                 pointer value = MAKE_POINTER(node, get_count(next) + 1);
 123                                 /**********    Detected Correctness (testcase1)    **********/
 124                                 success = atomic_compare_exchange_strong_explicit(&q->nodes[get_ptr(tail)].next,
 125                                                 &next, value, release, release);
 126                                 /** @OPClearDefine: success */
 127                         }
 128                         if (!success) {
 129                                 /**********    Detected UL    **********/
 130                                 unsigned int ptr = get_ptr(atomic_load_explicit(&q->nodes[get_ptr(tail)].next, acquire));
 131                                 pointer value = MAKE_POINTER(ptr,
 132                                                 get_count(tail) + 1);
 133                                 /**********    Detected Correctness (testcase2)    **********/
 134                                 atomic_compare_exchange_strong_explicit(&q->tail,
 135                                                 &tail, value,
 136                                                 release, release);
 137                                 thrd_yield();
 138                         }
 139                 }
 140         }
 141         /**********    Detected Corrctness (testcase1) **********/
 142         atomic_compare_exchange_strong_explicit(&q->tail,
 143                         &tail,
 144                         MAKE_POINTER(node, get_count(tail) + 1),
 145                         release, release);
 146 }
 147
 148 /** @Transition: if (RET) {
 149         if (STATE(q)->empty()) return false;
 150         STATE(q)->pop_front();
 151 }
 152 @PreCondition: return RET ? !STATE(q)->empty() && STATE(q)->front() == *retVal : true; */
 153 bool dequeue(queue_t *q, unsigned int *retVal, unsigned int *reclaimNode)
 154 {
 155         int success = 0;
 156         pointer head;
 157         pointer tail;
 158         pointer next;
 159
 160         while (!success) {
 161                 /**********    Dectected Admissibility (testcase3)    **********/
 162                 head = atomic_load_explicit(&q->head, acquire);
 163                 /**********    Detected KNOWN BUG    **********/
 164                 tail = atomic_load_explicit(&q->tail, acquire);
 165                 /**********    Detected Correctness (testcase1) **********/
 166                 next = atomic_load_explicit(&q->nodes[get_ptr(head)].next, acquire);
 167                 /** @OPClearDefine: true */
 168                 if (atomic_load_explicit(&q->head, relaxed) == head) {
 169                         if (get_ptr(head) == get_ptr(tail)) {
 170
 171                                 /* Check for uninitialized 'next' */
 172                                 MODEL_ASSERT(get_ptr(next) != POISON_IDX);
 173
 174                                 if (get_ptr(next) == 0) { // NULL
 175                                         return false; // NULL
 176                                 }
 177                                 /**********    Detected UL    **********/
 178                                 atomic_compare_exchange_strong_explicit(&q->tail,
 179                                                 &tail,
 180                                                 MAKE_POINTER(get_ptr(next), get_count(tail) + 1),
 181                                                 release, release);
 182                                 thrd_yield();
 183                         } else {
 184                                 //*retVal = load_32(&q->nodes[get_ptr(next)].value);
 185                                 *retVal = q->nodes[get_ptr(next)].value;
 186                                 /**********    Detected Admissibility (testcase3)    **********/
 187                                 success = atomic_compare_exchange_strong_explicit(&q->head,
 188                                                 &head,
 189                                                 MAKE_POINTER(get_ptr(next), get_count(head) + 1),
 190                                                 release, release);
 191                                 if (!success)
 192                                         thrd_yield();
 193                         }
 194                 }
 195         }
 196         *reclaimNode = get_ptr(head);
 197         reclaim(get_ptr(head));
 198         return true;
 199 }