Initial Commit - Lesson 31 (Commit #1)

Plugins/GameLiftServerSDK/ThirdParty/concurrentqueue/benchmarks/lockbasedqueue.h

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+// ©2013-2014 Cameron Desrochers.
+// Distributed under the simplified BSD license (see the LICENSE file that
+// should have come with this file).
+
+#pragma once
+
+#include "wrappers.h"
+#include <mutex>
+
+// Naïve implementation of a simple lock-based queue. A std::mutex is obtained for every
+// method. Note that while the queue size is not fixed, each enqueue operation allocates
+// memory, and each dequeue frees memory.
+template<typename T>
+class LockBasedQueue
+{
+public:
+	typedef DummyToken producer_token_t;
+	typedef DummyToken consumer_token_t;
+	
+public:
+	LockBasedQueue()
+	{
+		tail = nullptr;
+		head = nullptr;
+	}
+	
+	~LockBasedQueue()
+	{
+		while (head != nullptr) {
+			Node* next = head->next;
+			delete head;
+			head = next;
+		}
+	}
+	
+	template<typename U>
+	inline bool enqueue(U&& item)
+	{
+		Node* node = new Node(item);
+		
+		std::lock_guard<std::mutex> guard(mutex);
+		if (tail == nullptr) {
+			head = tail = node;
+		}
+		else {
+			tail->next = node;
+			tail = node;
+		}
+		
+		return true;
+	}
+	
+	inline bool try_dequeue(T& item)
+	{
+		std::lock_guard<std::mutex> guard(mutex);
+		if (head == nullptr) {
+			return false;
+		}
+		else {
+			item = std::move(head->item);
+			Node* next = head->next;
+			delete head;
+			head = next;
+			if (head == nullptr) {
+				tail = nullptr;
+			}
+			return true;
+		}
+	}
+	
+	// Dummy token methods (not used)
+	bool enqueue(producer_token_t const&, T const&) { return false; }
+	bool try_enqueue(producer_token_t, T const&) { return false; }
+	bool try_dequeue(consumer_token_t, T& item) { return false; }
+	template<typename It> bool enqueue_bulk(It, size_t) { return false; }
+	template<typename It> bool enqueue_bulk(producer_token_t const&, It, size_t) { return false; }
+	template<typename It> size_t try_dequeue_bulk(It, size_t) { return 0; }
+	template<typename It> size_t try_dequeue_bulk(consumer_token_t, It, size_t) { return 0; }
+	
+private:
+	struct Node
+	{
+		T item;
+		Node* next;
+		
+		template<typename U>
+		Node(U&& item)
+			: item(std::forward<U>(item)), next(nullptr)
+		{
+		}
+	};
+	
+	std::mutex mutex;
+	Node* head;
+	Node* tail;
+};