vtkThreadedTaskQueue.h

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/*=========================================================================

  Program:   Visualization Toolkit
  Module:    vtkThreadedTaskQueue.h

  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
  All rights reserved.
  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notice for more information.

=========================================================================*/
#ifndef vtkThreadedTaskQueue_h
#define vtkThreadedTaskQueue_h

#include "vtkObject.h"
#include <atomic>
#include <condition_variable>
#include <cstdint>
#include <functional>
#include <memory>
#include <mutex>
#include <thread>

#if !defined(__WRAP__)
namespace vtkThreadedTaskQueueInternals
{
template <typename R>
class TaskQueue;

template <typename R>
class ResultQueue;
};

template <typename R, typename... Args>
class vtkThreadedTaskQueue
{
public:
  vtkThreadedTaskQueue(std::function<R(Args...)> worker, bool strict_ordering = true,
    int buffer_size = -1, int max_concurrent_tasks = -1);
  ~vtkThreadedTaskQueue();

  void Push(Args&&... args);

  bool Pop(R& result);

  bool TryPop(R& result);

  bool IsEmpty() const;

  void Flush();

private:
  vtkThreadedTaskQueue(const vtkThreadedTaskQueue&) = delete;
  void operator=(const vtkThreadedTaskQueue&) = delete;

  std::function<R(Args...)> Worker;

  std::unique_ptr<vtkThreadedTaskQueueInternals::TaskQueue<R> > Tasks;
  std::unique_ptr<vtkThreadedTaskQueueInternals::ResultQueue<R> > Results;

  int NumberOfThreads;
  std::unique_ptr<std::thread[]> Threads;
};

template <typename... Args>
class vtkThreadedTaskQueue<void, Args...>
{
public:
  vtkThreadedTaskQueue(std::function<void(Args...)> worker, bool strict_ordering = true,
    int buffer_size = -1, int max_concurrent_tasks = -1);
  ~vtkThreadedTaskQueue();

  void Push(Args&&... args);

  bool IsEmpty() const;

  void Flush();

private:
  vtkThreadedTaskQueue(const vtkThreadedTaskQueue&) = delete;
  void operator=(const vtkThreadedTaskQueue&) = delete;

  std::function<void(Args...)> Worker;

  std::unique_ptr<vtkThreadedTaskQueueInternals::TaskQueue<void> > Tasks;

  std::condition_variable ResultsCV;
  std::mutex NextResultIdMutex;
  std::atomic<std::uint64_t> NextResultId;

  int NumberOfThreads;
  std::unique_ptr<std::thread[]> Threads;
};

#include "vtkThreadedTaskQueue.txx"

#endif // !defined(__WRAP__)

#endif
// VTK-HeaderTest-Exclude: vtkThreadedTaskQueue.h