#include <queue>
#include <mutex>
#include <memory>
#include <condition_variable>
template<typename T>
class SafeQueue
{
public:
    SafeQueue() {}
    ~SafeQueue() {}
    void push(T new_data) {
        std::lock_guard<std::m_mutex> lk(m_mut); // 1.全局加锁
        m_dataQueue.push(std::move(new_data)); // 2.push时独占锁
        m_cond.notify_one();
    }
    void wait_and_pop(T& val) {
        std::unique_lock<std::m_mutex> ulk(m_mut); // 3.全局加锁
        m_cond.wait(ulk,[this]() { return !m_dataQueue.empty(); }); // 4.front 和 pop_front时独占锁
        val=std::move(m_dataQueue.front());
        m_dataQueue.pop();
    }
    std::shared_ptr<T> wait_and_pop() {
        std::unique_lock<std::m_mutex> ulk(m_mut);
        m_cond.wait(ulk,[this]() { return !m_dataQueue.empty(); });
        std::shared_ptr<T> val(std::make_shared<T>(std::move(m_dataQueue.front())));
        m_dataQueue.pop();
        return val;
    }
    bool try_pop(T& val) {
        std::lock_guard<std::m_mutex> lk(m_mut);
        if(m_dataQueue.empty())
            return false;
        val=std::move(m_dataQueue.front());
        m_dataQueue.pop();
        return true;
    }
    std::shared_ptr<T> try_pop() {
        std::shared_ptr<T> val;
        std::lock_guard<std::m_mutex> lk(m_mut);
        if(m_dataQueue.empty())
            return val;
        val=std::make_shared<T>(std::move(m_dataQueue.front()));
        m_dataQueue.pop();
        return val;
    }
    bool empty() {
        std::lock_guard<std::m_mutex> lk(m_mut);
        return m_dataQueue.empty();
    }
    int count() {
        std::lock_guard<std::m_mutex> lk(m_mut);
        return m_dataQueue.size();
    }
private:
    std::queue<T> m_dataQueue;
    std::mutex m_mut;
    std::condition_variable m_cond;
}