quene

#pragma once

#include <condition_variable>
#include <mutex>
#include <queue>

template <typename T> class Queue {
public:
  void push(const T &item) {
    {
      std::scoped_lock lock(mtx_);
      queue_.push(item);
    }
    cond_.notify_one();
  }

  void push(T &&item) {
    {
      std::scoped_lock lock(mtx_);
      queue_.push(std::move(item));
    }
    cond_.notify_one();
  }

  bool pop(T &item) {
    std::unique_lock lock(mtx_);
    cond_.wait(lock, [&]() { return !queue_.empty() || stop_; });
    if (queue_.empty())
      return false;
    item = std::move(queue_.front());
    queue_.pop();
    return true;
  }

  std::size_t size() const {
    std::scoped_lock lock(mtx_);
    return queue_.size();
  }

  bool empty() const {
    std::scoped_lock lock(mtx_);
    return queue_.empty();
  }

  void stop() {
    {
      std::scoped_lock lock(mtx_);
      stop_ = true;
    }
    cond_.notify_all();
  }

private:
  std::condition_variable cond_;
  mutable std::mutex mtx_;
  std::queue<T> queue_;
  bool stop_ = false;
};