SlopeLimitingBase.C

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//* This file is part of the MOOSE framework
//* https://www.mooseframework.org
//*
//* All rights reserved, see COPYRIGHT for full restrictions
//* https://github.com/idaholab/moose/blob/master/COPYRIGHT
//*
//* Licensed under LGPL 2.1, please see LICENSE for details
//* https://www.gnu.org/licenses/lgpl-2.1.html

#include "SlopeLimitingBase.h"
#include <unistd.h>
#include "libmesh/parallel.h"
#include "libmesh/parallel_algebra.h"

// Static mutex definition
Threads::spin_mutex SlopeLimitingBase::_mutex;

InputParameters
SlopeLimitingBase::validParams()
{
  InputParameters params = ElementLoopUserObject::validParams();
  params += TransientInterface::validParams();

  params.addClassDescription(
      "Base class for slope limiting to limit the slopes of cell average variables.");

  params.addParam<bool>("include_bc", true, "Indicate whether to include bc, default = true");

  return params;
}

SlopeLimitingBase::SlopeLimitingBase(const InputParameters & parameters)
  : ElementLoopUserObject(parameters),
    _lslope(
        declareRestartableData<std::map<dof_id_type, std::vector<RealGradient>>>("limited_slope")),
    _include_bc(getParam<bool>("include_bc")),
    _q_point_face(_assembly.qPointsFace()),
    _qrule_face(_assembly.qRuleFace()),
    _JxW_face(_assembly.JxWFace()),
    _normals_face(_assembly.normals()),
    _side(_assembly.side()),
    _side_elem(_assembly.sideElem()),
    _side_volume(_assembly.sideElemVolume()),
    _neighbor_elem(_assembly.neighbor())
{
}

void
SlopeLimitingBase::initialize()
{
  ElementLoopUserObject::initialize();

  _lslope.clear();
}

const std::vector<RealGradient> &
SlopeLimitingBase::getElementSlope(dof_id_type elementid) const
{
  Threads::spin_mutex::scoped_lock lock(_mutex);
  std::map<dof_id_type, std::vector<RealGradient>>::const_iterator pos = _lslope.find(elementid);

  if (pos == _lslope.end())
    mooseError("Limited slope is not cached for element id '", elementid, "' in ", __FUNCTION__);

  return pos->second;
}

void
SlopeLimitingBase::computeElement()
{
  dof_id_type _elementID = _current_elem->id();

  _lslope[_elementID] = limitElementSlope();
}

void
SlopeLimitingBase::serialize(std::string & serialized_buffer)
{
  std::ostringstream oss;

  // First store the number of elements to send
  unsigned int size = _interface_elem_ids.size();
  oss.write((char *)&size, sizeof(size));

  for (auto it = _interface_elem_ids.begin(); it != _interface_elem_ids.end(); ++it)
  {
    storeHelper(oss, *it, this);
    storeHelper(oss, _lslope[*it], this);
  }

  // Populate the passed in string pointer with the string stream's buffer contents
  serialized_buffer.assign(oss.str());
}

void
SlopeLimitingBase::deserialize(std::vector<std::string> & serialized_buffers)
{
  // The input string stream used for deserialization
  std::istringstream iss;

  mooseAssert(serialized_buffers.size() == _app.n_processors(),
              "Unexpected size of serialized_buffers: " << serialized_buffers.size());

  for (auto rank = decltype(_app.n_processors())(0); rank < serialized_buffers.size(); ++rank)
  {
    if (rank == processor_id())
      continue;

    iss.str(serialized_buffers[rank]); // populate the stream with a new buffer
    iss.clear();                       // reset the string stream state

    // Load the communicated data into all of the other processors' slots

    unsigned int size = 0;
    iss.read((char *)&size, sizeof(size));

    for (unsigned int i = 0; i < size; i++)
    {
      dof_id_type key;
      loadHelper(iss, key, this);

      std::vector<RealGradient> value;
      loadHelper(iss, value, this);

      // merge the data we received from other procs
      _lslope.insert(std::pair<dof_id_type, std::vector<RealGradient>>(key, value));
    }
  }
}

void
SlopeLimitingBase::finalize()
{
  ElementLoopUserObject::finalize();

  if (_app.n_processors() > 1)
  {
    std::vector<std::string> send_buffers(1);
    std::vector<std::string> recv_buffers;

    recv_buffers.reserve(_app.n_processors());
    serialize(send_buffers[0]);
    comm().allgather_packed_range((void *)(nullptr),
                                  send_buffers.begin(),
                                  send_buffers.end(),
                                  std::back_inserter(recv_buffers));
    deserialize(recv_buffers);
  }
}