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

  Program:   Visualization Toolkit
  Module:    vtkSMPTools.cxx

  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.

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

#include "vtkSMPTools.h"

#include "vtkSMP.h"

#include <mutex>

#ifdef _MSC_VER
#pragma push_macro("__TBB_NO_IMPLICIT_LINKAGE")
#define __TBB_NO_IMPLICIT_LINKAGE 1
#endif

#include <tbb/task_scheduler_init.h>

#ifdef _MSC_VER
#pragma pop_macro("__TBB_NO_IMPLICIT_LINKAGE")
#endif

struct vtkSMPToolsInit
{
  tbb::task_scheduler_init Init;

  vtkSMPToolsInit(int numThreads)
    : Init(numThreads)
  {
  }
};

static bool vtkSMPToolsInitialized = 0;
static int vtkTBBNumSpecifiedThreads = 0;
static std::mutex vtkSMPToolsCS;

//------------------------------------------------------------------------------
const char* vtkSMPTools::GetBackend()
{
  return VTK_SMP_BACKEND;
}

//------------------------------------------------------------------------------
void vtkSMPTools::Initialize(int numThreads)
{
  vtkSMPToolsCS.lock();
  if (!vtkSMPToolsInitialized)
  {
    // If numThreads <= 0, don't create a task_scheduler_init
    // and let TBB do the default thing.
    if (numThreads > 0)
    {
      static vtkSMPToolsInit aInit(numThreads);
      vtkTBBNumSpecifiedThreads = numThreads;
    }
    vtkSMPToolsInitialized = true;
  }
  vtkSMPToolsCS.unlock();
}

//------------------------------------------------------------------------------
int vtkSMPTools::GetEstimatedNumberOfThreads()
{
  return vtkTBBNumSpecifiedThreads ? vtkTBBNumSpecifiedThreads
                                   : tbb::task_scheduler_init::default_num_threads();
}
