C++用条件变量实现线程安全的queue容器

#include <queue>
#include <memory>
#include <mutex>
#include <condition_variable>
template<typename T>
class threadsafe_queue
{
private:mutable std::mutex mut;  // 1 互斥量必须是可变的 std::queue<T> data_queue;std::condition_variable data_cond;
public:threadsafe_queue(){}threadsafe_queue(threadsafe_queue const& other){std::lock_guard<std::mutex> lk(other.mut);data_queue=other.data_queue;}void push(T new_value){std::lock_guard<std::mutex> lk(mut);data_queue.push(new_value);data_cond.notify_one();}void wait_and_pop(T& value){std::unique_lock<std::mutex> lk(mut);data_cond.wait(lk,[this]{return !data_queue.empty();});value=data_queue.front();data_queue.pop();}std::shared_ptr<T> wait_and_pop(){std::unique_lock<std::mutex> lk(mut);data_cond.wait(lk,[this]{return !data_queue.empty();});std::shared_ptr<T> res(std::make_shared<T>(data_queue.front()));data_queue.pop();return res;}bool try_pop(T& value){std::lock_guard<std::mutex> lk(mut);if(data_queue.empty())return false;value=data_queue.front();data_queue.pop();return true;}std::shared_ptr<T> try_pop(){std::lock_guard<std::mutex> lk(mut);if(data_queue.empty())return std::shared_ptr<T>();std::shared_ptr<T> res(std::make_shared<T>(data_queue.front()));data_queue.pop();return res;}bool empty() const{std::lock_guard<std::mutex> lk(mut);return data_queue.empty();}
};