多读多写 无锁 lifo 队列

多读多写下，先进后出队列，可以不加锁，下面是实现代码 lifo.h

#include "cas.h"
#include <stddef.h>

struct lifo_node
{
    volatile struct lifo_node *next;
};

struct lifo
{
void init() {
    top = NULL;
    cnt=0;
}

void push(lifo_node *node) {
   struct lifo old_val, new_val;
   do {
     old_val = *this;
     node->next = old_val.top;
     new_val.top = node;
     new_val.cnt = old_val.cnt;
   }while(!CAS2(this, old_val, new_val));
}
 
lifo_node * pop() {
   struct lifo_node *node;
   struct lifo old_val, new_val;
   do {
     old_val = *this;
     node = old_val.top;
     new_val.top = old_val.top;
     new_val.cnt = old_val.cnt+1;
   }while(!CAS2((this), old_val, new_val));
   return node;
}

struct lifo_node * volatile top;
volatile unsigned int cnt;
};