treiber-stack/stack_wildcard.h

   1 #include <stdatomic.h>
   2 #include <atomic>
   3
   4 #include "wildcard.h"
   5
   6 #define release memory_order_release
   7 #define acquire memory_order_acquire
   8 #define acq_rel memory_order_acq_rel
   9 #define relaxed memory_order_relaxed
  10
  11 struct node {
  12         unsigned int value;
  13         node *next;
  14
  15         node(unsigned int v) {
  16                 value = v;
  17                 next = NULL;
  18         }
  19 };
  20
  21 struct stack {
  22         atomic<node*> top;
  23
  24         stack() {
  25                 atomic_init(&top, NULL);
  26         }
  27
  28         void push(unsigned int val) {
  29                 node *n = new node(val);
  30                 node *old = top.load(wildcard(1)); // acquire
  31                 do {
  32                         n->next = old;
  33                 } while (!top.compare_exchange_strong(old, n, wildcard(2), wildcard(3)));
  34                 // acq_rel & relaxed
  35         }
  36
  37         unsigned int pop() {
  38                 node *old = top.load(wildcard(4)); // acquire
  39                 node *n;
  40                 do {
  41                         if (!old)
  42                                 return 0;
  43                         n = old->next;
  44                 } while (!top.compare_exchange_strong(old, n, wildcard(5), wildcard(6)));
  45                 // acq_rel & acquire
  46                 return old->value;
  47         }
  48 };
  49