struct SEQ
{
  volatile __int64 value;
  volatile __int64 lock_owner;
};

__int64 volatile gen_id(const char * seqName, __int64 delta)
{
  SEQ * seq;
  __int64 value,
          oldOwner,
          newOwner = fb::getCurrentTransactionId();
  
  if (NULL == (seq = fb::getSequenceByName(seqName))) throw (int)1;
  while (true)
  {
    oldOwner = ::InterlockedCompareExchange64(&seq->lock_owner, newOwner, 0);
    if (!oldOwner || newOwner == oldOwner) break;
    if (fb::isTransactionTimedOut(newOwner)) throw (int)2;
  }
  value = seq->value;
  if (delta)
  {
    value += delta;
    ::InterlockedExchange64(&seq->value, value);
  }
  if (!oldOwner) ::InterlockedCompareExchange64(&seq->lock_owner, 0, newOwner);
  return value;
}


__int64 volatile gen_lock(const char * seqName)
{
  SEQ * seq;
  __int64 value,
          oldOwner,
          newOwner = fb::getCurrentTransactionId();
  
  if (NULL == (seq = fb::getSequenceByName(seqName))) throw (int)1;
  while (true)
  {
    oldOwner = ::InterlockedCompareExchange64(&seq->lock_owner, newOwner, 0);
    if (!oldOwner || newOwner == oldOwner) break;
    if (fb::isTransactionTimedOut(newOwner)) throw (int)2;
  }
  return seq->value;
}


void volatile gen_unlock(const char * seqName)
{
  SEQ * seq;
  __int64 owner = fb::getCurrentTransactionId();

  if (NULL == (seq = fb::getSequenceByName(seqName))) throw (int)1;
  ::InterlockedCompareExchange64(&seq->lock_owner, 0, owner);
}