C++一种线程安全栈的设计

#include <atomic>
#include <condition_variable>
#include <memory>
#include <mutex>
#include <stack>
#include <stdexcept>
#include <thread>


struct empty_stack : public std::exception {
    const char* what() const noexcept { return "Empty stack"; }
};

template <typename T> class threadsafe_stack {
private:
    std::stack<T> data;
    mutable std::mutex m;
    std::condition_variable data_condition;
    std::atomic<bool> in_waiting_state{true};

public:
    threadsafe_stack() {}
    ~threadsafe_stack() { stop(); }
    threadsafe_stack(const threadsafe_stack& other)
    {
        std::lock_guard<std::mutex> lock(m);
        data = other.data;
    }
    threadsafe_stack& operator=(const threadsafe_stack& other) = delete;

    void push(T new_value)
    {
        std::lock_guard<std::mutex> lock(m);
        data.push(std::move(new_value));
        data_condition.notify_one(