无锁队列的实现

根据网上各种博客，然后自己写的一个无锁队列。
以后尝试性用这个代替线程池中的任务队列，应该这样会快很多。
  1 #include <iostream>
  2 #include <thread>
  3 #include <atomic>
  4 
  5 template<class T>
  6 class LinkNode {
  7 public:
  8     T data;
  9     LinkNode<T> *next;
 10 };
 11 
 12 template<class T>
 13 class LockFreeQueue {
 14 public:
 15     LockFreeQueue<T>() : head_(nullptr), tail_(nullptr), len(0) {
 16         LinkNode<T> *now = new LinkNode<T>;
 17         now->next = nullptr;
 18         head_ = tail_ = now;
 19     }
 20     void push(const T &data);
 21     T pop_front();
 22     bool empty();
 23 private:
 24     LinkNode<T> *head_;
 25     LinkNode<T> *tail_;
 26     std::atomic_int len;
 27 };
 28 
 29 template <class T>
 30 void LockFreeQueue<T>::push(const T &data) {
 31     LinkNode<T> * now = new LinkNode<T>;
 32     now->data=data;
 33     now->next= nullptr;
 34     LinkNode<T> * p1,*nxt;
 35     while(1){
 36         p1 = tail_;
 37         nxt = tail_->next;
 38         if (p1!=tail_) continue;
 39         if(nxt!= nullptr) {
 40             __sync_bool_compare_and_swap(&tail_,p1,nxt);
 41             continue;
 42         }
 43         if (__sync_bool_compare_and_swap(&tail_->next,nxt,now)==1) {
 44             break;
 45         }
 46     }
 47     __sync_bool_compare_and_swap(&tail_,p1,now);
 48     len++;
 49 }
 50 
 51 template <class T>
 52 T LockFreeQueue<T>::pop_front() {
 53     LinkNode<T> *p1;
 54     do{
 55         p1=head_->next;
 56         if (p1== nullptr) {
 57             return -999999;
 58         }
 59     }while(__sync_bool_compare_and_swap(&head_->next,p1,p1->next)!=true);
 60     len--;
 61     return p1->data;
 62 }
 63 
 64 template <class T>
 65 bool LockFreeQueue<T>::empty() {
 66     if (len==0) return true;
 67     else return false;
 68 }
 69 
 70 LockFreeQueue<int> queue;
 71 
 72 void func1(void) {
 73     for (int i = 0; i < 10; i++) {
 74         queue.push(i);
 75     }
 76 }
 77 
 78 void func2(void) {
 79     for (int i = 30; i < 40; i++) {
 80         queue.push(i);
 81     }
 82 }
 83 
 84 void func3(void) {
 85     for (int i = 0; i < 10; i++) {
 86         std::cout << queue.pop_front() << " ";
 87     }
 88     std::cout << std::endl;
 89 }
 90 
 91 int main(int argc, char **argv) {
 92     std::thread t1(func1);
 93     std::thread t2(func2);
 94     std::thread t3(func3);
 95     std::thread t4(func3);
 96     t1.join();
 97     t2.join();
 98     t3.join();
 99     t4.join();
100     return 0;
101 }
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