Walk the shadow passes and the culled model groups on worker threads in the Vulkan renderer

rendering/vulkan14/vulkan14tasks.cpp

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+/*
+This Source Code Form is subject to the
+terms of the Mozilla Public License, v.
+2.0. If a copy of the MPL was not
+distributed with this file, You can
+obtain one at
+http://mozilla.org/MPL/2.0/.
+*/
+
+#include "stdafx.h"
+#include "rendering/vulkan14/vulkan14tasks.h"
+#include "utilities/Logs.h"
+
+#include <exception>
+
+namespace vk14
+{
+
+background_tasks::~background_tasks()
+{
+	stop();
+}
+
+void background_tasks::start(std::size_t const Threads)
+{
+	if (running())
+	{
+		return;
+	}
+	{
+		std::lock_guard<std::mutex> lock(m_mutex);
+		m_stop = false;
+	}
+	for (std::size_t i = 0; i < Threads; ++i)
+	{
+		m_threads.emplace_back([this]() { work(); });
+	}
+}
+
+void background_tasks::stop()
+{
+	{
+		std::lock_guard<std::mutex> lock(m_mutex);
+		m_stop = true;
+		m_queue.clear();
+	}
+	m_wake.notify_all();
+	for (auto &thread : m_threads)
+	{
+		thread.join();
+	}
+	m_threads.clear();
+}
+
+void background_tasks::add(std::function<void()> Task, bool const Urgent)
+{
+	{
+		std::lock_guard<std::mutex> lock(m_mutex);
+		if (Urgent)
+		{
+			m_queue.emplace_front(std::move(Task));
+		}
+		else
+		{
+			m_queue.emplace_back(std::move(Task));
+		}
+	}
+	m_wake.notify_one();
+}
+
+void background_tasks::wait_idle()
+{
+	std::unique_lock<std::mutex> lock(m_mutex);
+	m_idle.wait(lock, [this]() { return m_queue.empty() && (m_busy == 0); });
+}
+
+std::size_t background_tasks::pending() const
+{
+	std::lock_guard<std::mutex> lock(m_mutex);
+	return m_queue.size() + m_busy;
+}
+
+void background_tasks::work()
+{
+	std::unique_lock<std::mutex> lock(m_mutex);
+	while (true)
+	{
+		m_wake.wait(lock, [this]() { return m_stop || (false == m_queue.empty()); });
+		if (m_stop)
+		{
+			return;
+		}
+		auto task{std::move(m_queue.front())};
+		m_queue.pop_front();
+		++m_busy;
+		lock.unlock();
+		try
+		{
+			task();
+		}
+		catch (std::exception const &Exception)
+		{
+			ErrorLog(std::string("vulkan: a background task failed: ") + Exception.what());
+		}
+		lock.lock();
+		--m_busy;
+		if (m_queue.empty() && (m_busy == 0))
+		{
+			m_idle.notify_all();
+		}
+	}
+}
+
+} // namespace vk14