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// This code contains NVIDIA Confidential Information and is disclosed to you
// under a form of NVIDIA software license agreement provided separately to you.
//
// Notice
// NVIDIA Corporation and its licensors retain all intellectual property and
// proprietary rights in and to this software and related documentation and
// any modifications thereto. Any use, reproduction, disclosure, or
// distribution of this software and related documentation without an express
// license agreement from NVIDIA Corporation is strictly prohibited.
//
// ALL NVIDIA DESIGN SPECIFICATIONS, CODE ARE PROVIDED "AS IS.". NVIDIA MAKES
// NO WARRANTIES, EXPRESSED, IMPLIED, STATUTORY, OR OTHERWISE WITH RESPECT TO
// THE MATERIALS, AND EXPRESSLY DISCLAIMS ALL IMPLIED WARRANTIES OF NONINFRINGEMENT,
// MERCHANTABILITY, AND FITNESS FOR A PARTICULAR PURPOSE.
//
// Information and code furnished is believed to be accurate and reliable.
// However, NVIDIA Corporation assumes no responsibility for the consequences of use of such
// information or for any infringement of patents or other rights of third parties that may
// result from its use. No license is granted by implication or otherwise under any patent
// or patent rights of NVIDIA Corporation. Details are subject to change without notice.
// This code supersedes and replaces all information previously supplied.
// NVIDIA Corporation products are not authorized for use as critical
// components in life support devices or systems without express written approval of
// NVIDIA Corporation.
//
// Copyright (c) 2016-2020 NVIDIA Corporation. All rights reserved.
#pragma once
#include <thread>
#include <mutex>
#include <queue>
#include <list>
#include <future>
#include <condition_variable>
#include <memory>
#include <atomic>
class TaskDispatcher
{
public:
class Task
{
public:
virtual void process() = 0;
virtual ~Task() {};
};
typedef std::function<void(TaskDispatcher& dispatcher, std::unique_ptr<Task>)> OnTaskFinishedFunction;
TaskDispatcher(uint32_t threadCount, OnTaskFinishedFunction onTaskFinished) :
m_workingThreadsCount(0), m_onTaskFinished(onTaskFinished)
{
m_threads.resize(threadCount);
for (uint32_t i = 0; i < threadCount; i++)
{
m_threads[i] = std::unique_ptr<Thread>(new Thread(i, m_completionSemaphore));
m_threads[i]->start();
m_freeThreads.push(m_threads[i].get());
}
}
void addTask(std::unique_ptr<Task> task)
{
m_tasks.push(std::move(task));
}
void process()
{
// main loop
while (m_tasks.size() > 0 || m_workingThreadsCount > 0)
{
// assign tasks
while (!(m_tasks.empty() || m_freeThreads.empty()))
{
auto task = std::move(m_tasks.front());
m_tasks.pop();
Thread* freeThread = m_freeThreads.front();
m_freeThreads.pop();
freeThread->processTask(std::move(task));
m_workingThreadsCount++;
}
m_completionSemaphore.wait();
// check for completion
for (std::unique_ptr<Thread>& thread : m_threads)
{
if (thread->isTaskFinished())
{
std::unique_ptr<Task> task;
thread->collectTask(task);
m_onTaskFinished(*this, std::move(task));
m_freeThreads.push(thread.get());
m_workingThreadsCount--;
break;
}
}
}
}
private:
class Semaphore
{
public:
Semaphore(int count_ = 0)
: m_count(count_) {}
inline void notify()
{
std::unique_lock<std::mutex> lock(m_mutex);
m_count++;
m_cv.notify_one();
}
inline void wait()
{
std::unique_lock<std::mutex> lock(m_mutex);
while (m_count == 0){
m_cv.wait(lock);
}
m_count--;
}
private:
std::mutex m_mutex;
std::condition_variable m_cv;
int m_count;
};
class Thread
{
public:
Thread(uint32_t id_, Semaphore& completionSemaphore) : m_id(id_), m_completionSemaphore(completionSemaphore), m_running(false), m_taskFinished(false) {}
virtual ~Thread() { stop(); }
void start()
{
if (!m_running)
{
m_running = true;
m_thread = std::thread(&Thread::body, this);
}
}
void stop()
{
if (m_running)
{
m_running = false;
m_newTaskSemaphore.notify();
m_thread.join();
}
}
void processTask(std::unique_ptr<Task> task)
{
m_task = std::move(task);
m_taskFinished = false;
m_newTaskSemaphore.notify();
}
void collectTask(std::unique_ptr<Task>& task)
{
task = std::move(m_task);
m_task = nullptr;
m_taskFinished = false;
}
bool hasTask() const { return m_task != nullptr; }
bool isTaskFinished() const { return m_taskFinished; }
private:
void body()
{
while (1)
{
m_newTaskSemaphore.wait();
if (!m_running)
return;
m_task->process();
m_taskFinished = true;
m_completionSemaphore.notify();
}
}
uint32_t m_id;
Semaphore& m_completionSemaphore;
std::thread m_thread;
bool m_running;
std::unique_ptr<Task> m_task;
std::atomic<bool> m_taskFinished;
Semaphore m_newTaskSemaphore;
};
private:
uint32_t m_workingThreadsCount;
std::queue<std::unique_ptr<Task>> m_tasks;
OnTaskFinishedFunction m_onTaskFinished;
std::vector<std::unique_ptr<Thread>> m_threads;
std::queue<Thread*> m_freeThreads;
Semaphore m_completionSemaphore;
};
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