queue.hpp

/*
 *  This file is part of SOFUS.
 *
 *  SOFUS is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  SOFUS is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with SOFUS.  If not, see <http://www.gnu.org/licenses/>.
 */

#pragma once

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

namespace sps {
template <typename T>
class queue {
 public:

  T pop()
  {
    std::unique_lock<std::mutex> mlock(mutex_);
    // Alternatively, use predicate, cond_.wait(mlock, !queue_.empty())
    while (queue_.empty()) {
      cond_.wait(mlock);
    }
    auto item = queue_.front();
    queue_.pop();
    return item;
  }

  void pop(T& item)
  {
    std::unique_lock<std::mutex> mlock(mutex_);
    // Alternatively, use predicate, cond_.wait(mlock, !queue_.empty())
    while (queue_.empty()) {
      cond_.wait(mlock);
    }
    item = queue_.front();
    queue_.pop();
  }

  void push(const T& item)
  {
    std::unique_lock<std::mutex> mlock(mutex_);
    queue_.push(item);
    mlock.unlock();
    cond_.notify_one();
  }

  void push(T&& item)
  {
    std::unique_lock<std::mutex> mlock(mutex_);
    queue_.push(std::move(item));
    mlock.unlock();
    cond_.notify_one();
  }

 private:
  std::queue<T> queue_;
  std::mutex mutex_;
  std::condition_variable cond_;
};
}  // namespace sps