109 lines
3.2 KiB
C
109 lines
3.2 KiB
C
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#ifndef CONCURRENTQUEUE_H
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#define CONCURRENTQUEUE_H
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#include <atomic>
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#include <memory>
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/**
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* @namespace CTL
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* @brief 并发数据结构库
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*/
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namespace CTL {
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/**
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* @template class ConcurrentQueue
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* @brief 无锁并发队列实现
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*
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* 该队列设计用于多线程环境，允许多个线程在无需锁的情况下安全地入队和出队元素。通过使用原子操作实现线程安全性。
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*/
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template<typename T>
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class ConcurrentQueue {
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/**
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* @struct Node
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* @brief 队列内部节点结构
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*/
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struct Node {
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std::shared_ptr<T> data; // 节点存储的数据
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std::atomic<Node*> next; // 指向下一个节点的指针
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/**
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* Node 构造函数
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*
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* @param value 要存储在节点中的数据
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*/
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explicit Node(T const& value) : data(std::make_shared<T>(value)) {}
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};
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std::atomic<Node*> head; // 队列头指针
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std::atomic<Node*> tail; // 队列尾指针
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std::atomic<size_t> size_; // 新增一个原子计数器来记录队列大小
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public:
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/**
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* ConcurrentQueue 构造函数
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* 初始化头指针和尾指针，并将大小设置为0
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*/
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ConcurrentQueue() : head(new Node(T())), tail(head.load()), size_(0) {}
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/**
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* ConcurrentQueue 析构函数
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* 删除队列中的所有节点
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*/
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~ConcurrentQueue() {
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while (Node* const oldHead = head.load()) {
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head.store(oldHead->next);
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delete oldHead;
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}
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}
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/**
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* 将元素添加到队列末尾
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*
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* @param data 要添加到队列中的数据
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*/
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void add(T const& data) {
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std::shared_ptr<T> newData(std::make_shared<T>(data));
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Node* p = new Node(T());
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Node* oldTail = tail.load();
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oldTail->data.swap(newData);
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oldTail->next.store(p);
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tail.store(p);
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size_.fetch_add(1); // 增加计数器
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}
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/**
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* 移除并返回队列的第一个元素
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*
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* @return 指向移除元素的共享指针，如果队列为空则返回空的共享指针
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*/
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std::shared_ptr<T> front() {
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Node* oldHead = head.load();
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while (oldHead && !head.compare_exchange_weak(oldHead, oldHead->next)) {
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// 重试
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}
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if (!oldHead) {
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return std::shared_ptr<T>();
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}
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std::shared_ptr<T> res(oldHead->data);
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delete oldHead;
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size_.fetch_sub(1); // 减少计数器
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return res;
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}
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/**
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* 返回当前队列的大小
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*
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* @return 队列的大小
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*/
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[[nodiscard]] size_t size() const {
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return size_.load(); // 返回当前队列大小
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}
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/**
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* 检查队列是否为空
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*
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* @return 如果队列为空返回 true，否则返回 false
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*/
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[[nodiscard]] bool isEmpty() const {
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return size_.load() == 0; // 判断队列是否为空
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}
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};
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}
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#endif
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