anki-3d-engine/include/anki/resource/AsyncLoader.h

// Copyright (C) 2009-2016, Panagiotis Christopoulos Charitos.
// All rights reserved.
// Code licensed under the BSD License.
// http://www.anki3d.org/LICENSE

#pragma once

#include <anki/resource/Common.h>
#include <anki/util/Thread.h>

namespace anki
{

/// @addtogroup resource
/// @{

/// Loader asynchronous task.
class AsyncLoaderTask
{
	friend class AsyncLoader;

public:
	virtual ~AsyncLoaderTask()
	{
	}

	virtual ANKI_USE_RESULT Error operator()() = 0;

private:
	AsyncLoaderTask* m_next = nullptr;
};

/// Asynchronous resource loader.
class AsyncLoader
{
public:
	AsyncLoader();

	~AsyncLoader();

	ANKI_USE_RESULT Error create(const HeapAllocator<U8>& alloc);

	/// Create a new asynchronous loading task.
	template<typename TTask, typename... TArgs>
	void newTask(TArgs&&... args);

private:
	HeapAllocator<U8> m_alloc;
	Thread m_thread;
	Mutex m_mtx;
	ConditionVariable m_condVar;
	AsyncLoaderTask* m_head = nullptr;
	AsyncLoaderTask* m_tail = nullptr;
	Bool8 m_quit = false;

	/// Thread callback
	static ANKI_USE_RESULT Error threadCallback(Thread::Info& info);

	Error threadWorker();

	void stop();
};

//==============================================================================
template<typename TTask, typename... TArgs>
void AsyncLoader::newTask(TArgs&&... args)
{
	TTask* newTask =
		m_alloc.template newInstance<TTask>(std::forward<TArgs>(args)...);

	// Append task to the list
	{
		LockGuard<Mutex> lock(m_mtx);
		if(m_tail != nullptr)
		{
			ANKI_ASSERT(m_tail->m_next == nullptr);
			ANKI_ASSERT(m_head != nullptr);

			m_tail->m_next = newTask;
			m_tail = newTask;
		}
		else
		{
			ANKI_ASSERT(m_head == nullptr);
			m_head = m_tail = newTask;
		}
	}

	// Wake up the thread
	m_condVar.notifyOne();
}

/// @}

} // end namespace anki