Bachelorarbeit/ConditionMonitoring/ts_queue.h

/*
MMO Client/Server Framework using ASIO
"Happy Birthday Mrs Javidx9!" - javidx9

Videos:
Part #1: https://youtu.be/2hNdkYInj4g
Part #2: https://youtu.be/UbjxGvrDrbw

License (OLC-3)
~~~~~~~~~~~~~~~

Copyright 2018 - 2020 OneLoneCoder.com

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:

1. Redistributions or derivations of source code must retain the above
copyright notice, this list of conditions and the following disclaimer.

2. Redistributions or derivative works in binary form must reproduce
the above copyright notice. This list of conditions and the following
disclaimer must be reproduced in the documentation and/or other
materials provided with the distribution.

3. Neither the name of the copyright holder nor the names of its
contributors may be used to endorse or promote products derived
from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Links
~~~~~
YouTube:	https://www.youtube.com/javidx9
Discord:	https://discord.gg/WhwHUMV
Twitter:	https://www.twitter.com/javidx9
Twitch:		https://www.twitch.tv/javidx9
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Author
~~~~~~
David Barr, aka javidx9, <EFBFBD>OneLoneCoder 2019, 2020

*/


#pragma once
#include <queue>
#include <mutex>
#include <condition_variable>
/*
Threadsafe Queue to be accessed from different threads
*/
template <typename T>
class ts_queue
{
	public:
		ts_queue() = default;
		ts_queue(const ts_queue<T>&) = delete;
		virtual ~ts_queue() { clear(); }

	public:
		// Returns and maintains item at front of Queue
		const T& front()
		{
			std::scoped_lock lock(muxQueue);
			return queue.front();
		}

		// Returns and maintains item at back of Queue
		const T& back()
		{
			std::scoped_lock lock(muxQueue);
			return queue.back();
		}

        // Removes and returns the first item from Queue
		T pop_front()
		{
			std::scoped_lock lock(muxQueue);
			auto t = std::move(queue.front());
            queue.pop();
			return t;
		}

		// Adds an item to front of Queue
		void push(const T& item)
		{
            std::scoped_lock lock(muxQueue);
			queue.push(std::move(item));
			std::unique_lock<std::mutex> ul(muxBlocking);
			cvBlocking.notify_one();
		}

		// Returns true if Queue has no items
		bool empty()
		{
			std::scoped_lock lock(muxQueue);
			return queue.empty();
		}

		// Returns number of items in Queue
        size_t size()
		{
			std::scoped_lock lock(muxQueue);
			return queue.size();
		}

		// Clears Queue
		void clear()
		{
			std::scoped_lock lock(muxQueue);
			std::queue<T> empty;
			std::swap(queue, empty);
		}

		void wait()
		{
			while (empty())
			{
				std::unique_lock<std::mutex> ul(muxBlocking);
				cvBlocking.wait(ul);
			}
		}

	protected:
		std::mutex muxQueue;
		std::queue<T> queue;
		std::condition_variable cvBlocking;
		std::mutex muxBlocking;

};