/*
---- 
This file is part of SECONDO.

Copyright (C) 2019, University in Hagen, Department of Computer Science, 
Database Systems for New Applications.

SECONDO is free software; you can redistribute it and/or modify
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----

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1 Header File: ThreadsafeQueue

September 2019, Fischer Thomas

1.1 Overview

The ~ThreadsafeQueue~ is a version of the std:queue supporting concurrent access.

1.2 Imports

*/

#ifndef SECONDO_PARTHREAD_THREADSAFE_QUEUE_H
#define SECONDO_PARTHREAD_THREADSAFE_QUEUE_H

#include <memory>
#include <queue>
#include <mutex>

namespace parthread
{

template <typename T>
class ThreadsafeQueue
{
public: //methods
  ThreadsafeQueue(size_t maxCapacity = SIZE_MAX)
  : m_maxCapacity(maxCapacity)
  {

  };

  ThreadsafeQueue(const ThreadsafeQueue &other)
  {
    std::lock_guard<std::mutex> lock(other.m_access);
    m_queue = other.m_queue;
  };

  ~ThreadsafeQueue()
  {
  };

  ThreadsafeQueue &operator=(const ThreadsafeQueue &other) = delete;

  bool TryPush(T&& value)
  {
    std::lock_guard<std::mutex> lock(m_access);
    if (m_queue.size() <= m_maxCapacity)
    {
      m_queue.push(std::move(value));
      return true;
    }
    return false;
  };

  bool TryPush(const T value)
  {
    std::lock_guard<std::mutex> lock(m_access);
    if (m_queue.size() <= m_maxCapacity)
    {
      m_queue.push(value);
      return true;
    }
    return false;
  };

  bool TryPop(T& value)
  {
    std::lock_guard<std::mutex> lock(m_access);
    if (!m_queue.empty())
    {
      value = std::move(m_queue.front());
      m_queue.pop();
      return true;
    }

    return false;
  };

  size_t Size() const
  {
    std::lock_guard<std::mutex> lock(m_access);
    return m_queue.size();
  };

  bool IsEmpty() const
  {
    std::lock_guard<std::mutex> lock(m_access);
    return m_queue.empty();
  };

private: //methods
private: //member
  const size_t m_maxCapacity;
  mutable std::mutex m_access;
  std::queue<T> m_queue;
};

} // namespace parthread
#endif