Re: My -short- lock-free sequencer class, I want to see your comments

Hi,

Recently I needed a sequencer for my IOCP based socket server and
developed one. I try to implement it in lock-free manner. Your comments
will bee appreciated.

The class is very small and all it do is to maintain two numbers in thread
safe manner. Before every WSARecv call I get next available sequence
number from sequencer and put that number into my PerIoContext object.
When a recv completion occured then I check the sequence number to decide
if the completion occured in order. So one of the two numbers
(m_lCurrentSequence) represents call sequence and the other
(m_lRunningOrder) represents completion sequence. Here is the class :

class Sequencer
{
public:
    Sequencer (LONG lMaxSequence) : m_lCurrentSequence (0),
m_lRunningOrder (0), m_lMaxSequence (lMaxSequence)
    {
    }

    LONG getNextSequence ()
    {
         LONG lCurrentSequence, lNextSequence;
         while (true)
         {
              InterlockedExchange (&lCurrentSequence, m_lCurrentSequence);
              lNextSequence = (lCurrentSequence == m_lMaxSequence ? 0 :
lCurrentSequence + 1);
              if (lCurrentSequence == InterlockedCompareExchange
(&m_lCurrentSequence, lNextSequence, lCurrentSequence))
              {
                   break;
              }
       }
       return lNextSequence;
}

bool isInOrder (const LONG lSequence)
{
     return (lSequence == m_lRunningOrder);
}

bool updateRunningOrder (const LONG lSequence)
{
     if (isInOrder (lSequence))
     {
          // Safe region...
          LONG lNewRunningOrder = (lSequence + 1) > m_lMaxSequence ? 0 :
(lSequence + 1);
          InterlockedExchange (&m_lRunningOrder, lNewRunningOrder);
          return true;
     }
     return false;
}

private:
LONG m_lMaxSequence;
LONG m_lCurrentSequence;
LONG m_lRunningOrder;
};

Thanks in advance for your comments.