High level implementation

SPSC_Interface.cpp

// This is an idealized pseudo-implementation. Details are omitted for clarity
SMDataQueueBase::SMDataQueueBase(bool initializeMemory)
{
  CreateSharedMemoryRegion();

  if(initializeMemory)
  {
    new(m_SharedData) SharedData;
    // Allocate an empty node
    m_SharedData->m_Head = *AllocateNode(sizeof(size_t));
    m_SharedData->m_Tail = m_SharedData->m_Head;
  }
}

// Producer interface
void* SMDataQueueProducer::RequestNode(size_t sz)
{
  m_SharedData->m_NodeInProduction = *AllocateNode(sz);
  return m_SharedData->m_NodeInProduction;
}

void* SMDataQueueProducer::EnqueueMore(size_t sz)
{
  m_SharedData->m_NodeInProduction = *ExpandNode(m_SharedData->m_NodeInProduction, sz);
  return m_SharedData->m_NodeInProduction;
}

void SMDataQueueProducer::CommitNode()
{
  m_SharedData->m_Tail = m_SharedData->m_NodeInProduction;

  m_SharedData->m_NodeInProduction = Node();
}

//Consumer interface
void* SMDataQueueConsumer::Consume(size_t& size)
{
  // operator!= and operator= must be atomic to each other for the implementation to work
  // changing the identity of the object (so that operator!= start returning true) must be done atomically
  if(m_SharedData->m_Head != m_SharedData->m_Tail)
  {
    m_SharedData->m_Head = m_SharedData->m_Head->Successor;
    return GetNodeData(m_SharedData->m_Head);
  }
  else
  {
    return nullptr;
  }
}