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                 if (node) {
  27                         store_32(&free_lists[t][i], 0);
  28                         return node;
  29                 }
  30         }
  31         /* free_list is empty? */
  32         MODEL_ASSERT(0);
  33         return 0;
  34 }
  35
  36 /* Place this node index back on this thread's free list */
  37 static void reclaim(unsigned int node)
  38 {
  39         int i;
  40         int t = get_thread_num();
  41
  42         /* Don't reclaim NULL node */
  43         MODEL_ASSERT(node);
  44
  45         for (i = 0; i < MAX_FREELIST; i++) {
  46                 /* Should never race with our own thread here */
  47                 unsigned int idx = load_32(&free_lists[t][i]);
  48
  49                 /* Found empty spot in free list */
  50                 if (idx == 0) {
  51                         store_32(&free_lists[t][i], node);
  52                         return;
  53                 }
  54         }
  55         /* free list is full? */
  56         MODEL_ASSERT(0);
  57 }
  58
  59 void init_queue(queue_t *q, int num_threads)
  60 {
  61         int i, j;
  62
  63         /* Initialize each thread's free list with INITIAL_FREE pointers */
  64         /* The actual nodes are initialized with poison indexes */
  65         free_lists = malloc(num_threads * sizeof(*free_lists));
  66         for (i = 0; i < num_threads; i++) {
  67                 for (j = 0; j < INITIAL_FREE; j++) {
  68                         free_lists[i][j] = 2 + i * MAX_FREELIST + j;
  69                         atomic_init(&q->nodes[free_lists[i][j]].next, MAKE_POINTER(POISON_IDX, 0));
  70                 }
  71         }
  72
  73         /* initialize queue */
  74         atomic_init(&q->head, MAKE_POINTER(1, 0));
  75         atomic_init(&q->tail, MAKE_POINTER(1, 0));
  76         atomic_init(&q->nodes[1].next, MAKE_POINTER(0, 0));
  77 }
  78
  79 /**
  80         @Begin
  81         @Global_define:
  82                 typedef struct tag_elem {
  83                         Tag id;
  84                         unsigned int data;
  85
  86                         tag_elem(Tag _id, unsigned int _data) {
  87                                 id = _id;
  88                                 data = _data;
  89                         }
  90                 } tag_elem_t;
  91
  92                 spec_queue<tag_elem_t> __queue;
  93                 Tag __tag;
  94         @Happens_before:
  95                 # Only check the happens-before relationship according to the id of the
  96                 # commit_point_set. For commit_point_set that has same ID, A -> B means
  97                 # B happens after the previous A.
  98                 Enqueue -> Dequeue
  99         @End
 100 */
 101
 102 /**
 103         @Begin
 104         @Interface: Enqueue
 105         @Commit_point_set: Enqueue_Success_Point
 106         @ID: __tag.getCurAndInc()
 107         @Action:
 108                 # __ID__ is an internal macro that refers to the id of the current
 109                 # interface call
 110                 @Code:
 111                 __queue.enqueue(tag_elem_t(__ID__, val));
 112         @End
 113 */
 114 void enqueue(queue_t *q, unsigned int val)
 115 {
 116         int success = 0;
 117         unsigned int node;
 118         pointer tail;
 119         pointer next;
 120         pointer tmp;
 121
 122         node = new_node();
 123         store_32(&q->nodes[node].value, val);
 124         tmp = atomic_load_explicit(&q->nodes[node].next, relaxed);
 125         set_ptr(&tmp, 0); // NULL
 126         atomic_store_explicit(&q->nodes[node].next, tmp, relaxed);
 127
 128         while (!success) {
 129                 tail = atomic_load_explicit(&q->tail, acquire);
 130                 next = atomic_load_explicit(&q->nodes[get_ptr(tail)].next, acquire);
 131                 if (tail == atomic_load_explicit(&q->tail, relaxed)) {
 132
 133                         /* Check for uninitialized 'next' */
 134                         MODEL_ASSERT(get_ptr(next) != POISON_IDX);
 135
 136                         if (get_ptr(next) == 0) { // == NULL
 137                                 pointer value = MAKE_POINTER(node, get_count(next) + 1);
 138                                 success = atomic_compare_exchange_strong_explicit(&q->nodes[get_ptr(tail)].next,
 139                                                 &next, value, release, release);
 140                         }
 141                         if (!success) {
 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                                 int commit_success = 0;
 146                                 commit_success = atomic_compare_exchange_strong_explicit(&q->tail,
 147                                                 &tail, value, release, release);
 148                                 /**
 149                                         @Begin
 150                                         @Commit_point_define_check: __ATOMIC_RET__ == true
 151                                         @Label: Enqueue_Success_Point
 152                                         @End
 153                                 */
 154                                 thrd_yield();
 155                         }
 156                 }
 157         }
 158         atomic_compare_exchange_strong_explicit(&q->tail,
 159                         &tail,
 160                         MAKE_POINTER(node, get_count(tail) + 1),
 161                         release, release);
 162 }
 163
 164 /**
 165         @Begin
 166         @Interface: Dequeue
 167         @Commit_point_set: Dequeue_Success_Point
 168         @ID: __queue.peak().tag
 169         @Action:
 170                 @Code:
 171                 unsigned int _Old_Val = __queue.dequeue().data;
 172         @Post_check:
 173                 _Old_Val == __RET__
 174         @End
 175 */
 176 unsigned int dequeue(queue_t *q)
 177 {
 178         unsigned int value;
 179         int success = 0;
 180         pointer head;
 181         pointer tail;
 182         pointer next;
 183
 184         while (!success) {
 185                 head = atomic_load_explicit(&q->head, acquire);
 186                 tail = atomic_load_explicit(&q->tail, relaxed);
 187                 next = atomic_load_explicit(&q->nodes[get_ptr(head)].next, acquire);
 188                 if (atomic_load_explicit(&q->head, relaxed) == head) {
 189                         if (get_ptr(head) == get_ptr(tail)) {
 190
 191                                 /* Check for uninitialized 'next' */
 192                                 MODEL_ASSERT(get_ptr(next) != POISON_IDX);
 193
 194                                 if (get_ptr(next) == 0) { // NULL
 195                                         return 0; // NULL
 196                                 }
 197                                 atomic_compare_exchange_strong_explicit(&q->tail,
 198                                                 &tail,
 199                                                 MAKE_POINTER(get_ptr(next), get_count(tail) + 1),
 200                                                 release, release);
 201                                 thrd_yield();
 202                         } else {
 203                                 value = load_32(&q->nodes[get_ptr(next)].value);
 204                                 success = atomic_compare_exchange_strong_explicit(&q->head,
 205                                                 &head,
 206                                                 MAKE_POINTER(get_ptr(next), get_count(head) + 1),
 207                                                 release, release);
 208                                 /**
 209                                         @Begin
 210                                         @Commit_point_define_check: __ATOMIC_RET__ == true
 211                                         @Label: Dequeue_Success_Point
 212                                         @End
 213                                 */
 214                                 if (!success)
 215                                         thrd_yield();
 216                         }
 217                 }
 218         }
 219         reclaim(get_ptr(head));
 220         return value;
 221 }