Method SendReceiveParticles

Filters/FlowPaths/vtkParticleTracerBase.cxx:488–592

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//------------------------------------------------------------------------------
bool vtkParticleTracerBase::SendReceiveParticles(
  std::vector<vtkIdType>& newReceivedInjectedPointIds)
{
  int numParticles = static_cast<int>(this->MPISendList.size());

  std::vector<int> allNumParticles(this->Controller->GetNumberOfProcesses(), 0);
  // Broadcast and receive size to/from all other processes.
  this->Controller->AllGather(&numParticles, allNumParticles.data(), 1);

  // write the message
  constexpr int typeSize = sizeof(ParticleInformation);

  vtkIdType messageSize = numParticles * typeSize;
  std::vector<char> sendMessage(messageSize, 0);
  for (int i = 0; i < numParticles; i++)
  {
    memcpy(&sendMessage[i * typeSize], &this->MPISendList[i], typeSize);
    auto it = this->MPIRecvList.find(this->MPISendList[i].InjectedPointId);
    if (it != this->MPIRecvList.end())
    {
      this->MPIRecvList.erase(it);
    }
  }

  std::vector<vtkIdType> messageLength(this->Controller->GetNumberOfProcesses(), 0);
  std::vector<vtkIdType> messageOffset(this->Controller->GetNumberOfProcesses() + 1, 0);
  int allMessageSize(0);
  int numAllParticles(0);
  for (int i = 0; i < this->Controller->GetNumberOfProcesses(); ++i)
  {
    numAllParticles += allNumParticles[i];
    messageLength[i] = allNumParticles[i] * typeSize;
    messageOffset[i] = allMessageSize;
    allMessageSize += messageLength[i];
  }
  messageOffset.back() = allMessageSize;

  // receive the message
  std::vector<char> recvMessage(allMessageSize, 0);
  this->Controller->AllGatherV(messageSize > 0 ? sendMessage.data() : nullptr,
    allMessageSize > 0 ? recvMessage.data() : nullptr, messageSize, messageLength.data(),
    messageOffset.data());

  int myRank = this->Controller->GetLocalProcessId();

  // owningProcess is used to make sure that particles that are sent aren't added
  // on multiple processes
  std::vector<vtkIdType> owningProcess(numAllParticles, -1);
  // we automatically ignore particles that we sent
  int ignoreBegin = messageOffset[myRank] / typeSize;
  int ignoreEnd = ignoreBegin + messageLength[myRank] / typeSize;
  for (int i = 0; i < numAllParticles; i++)
  {
    if (i < ignoreBegin || i >= ignoreEnd)
    {
      ParticleInformation tmpParticle;
      memcpy(&tmpParticle, &recvMessage[i * typeSize], typeSize);
      // since this is first test, avoid bad cache tests