QueueSpinLock

//
// Created by ludaludaed on 08.05.2023.
//

#ifndef ALLIGATOR_SPIN_LOCK_H
#define ALLIGATOR_SPIN_LOCK_H

#include <thread>

namespace lu {
    class QueueSpinLock {
        struct Node {
            Node *next;
            bool value;

            Node() : next(nullptr), value(false) {}
        };

        friend class QueueSpinLockGuard;

    private:
        void lock(Node *node) {
            Node *prev_tail = tail_.exchange(node);
            if (prev_tail != nullptr) {
                prev_tail->next = node;
                while (!node->value) {
                    std::this_thread::yield();
                }
            }
        }

    public:
        QueueSpinLock() : tail_(nullptr) {}

    private:
        std::atomic<Node *> tail_;
    };

    class QueueSpinLockGuard {
    public:
        explicit QueueSpinLockGuard(QueueSpinLock &lock) : lock_(lock) {
            lock_.lock(&node_);
        }

        ~QueueSpinLockGuard() {
            if (node_.next != nullptr) {
                node_.next->value = true;
            }
        }

    private:
        QueueSpinLock &lock_;
        QueueSpinLock::Node node_;
    };
}

#endif //ALLIGATOR_SPIN_LOCK_H