public bool Delete(Key k)
{
if (k == Inf1 || k == Inf2)
{
return(false); //or throw new Exception("Wrong key");
}
Internal gp = null, p = null;
Leaf l = null;
Update pupdate = null, gpupdate = null, result = null;
DInfo op = null;
while (true)
{
(gp, p, l, pupdate, gpupdate) = Search(k);
if (l.key != k)
{
return(false);
}
if (gpupdate.state != States.Clean)
{
Help(gpupdate);
}
else if (pupdate.state != States.Clean)
{
Help(pupdate);
}
else
{
op = new DInfo(gp, p, l, pupdate, null);
op.myUpdate = new Update(States.DFlag, op);
result = Interlocked.CompareExchange(ref gp.update, op.myUpdate, gpupdate);
if (result == gpupdate)
{
if (HelpDelete(op))
{
return(true);
}
}
else
{
Help(result);
}
}
}
}
private void HelpMarked(DInfo op)
{
Node other;
if (op.p.right == op.l)
{
other = op.p.left;
}
else
{
other = op.p.right;
}
CAS_Child(ref op.gp, op.p, other);
Interlocked.CompareExchange(ref op.gp.update, new Update(States.Clean, op), op.myUpdate);
}
private bool HelpDelete(DInfo op)
{
Update result = null;
result = Interlocked.CompareExchange(ref op.p.update, new Update(States.Mark, op), op.pupdate);
if (result == op.pupdate || (result.state == States.Mark && result.info == op))
{
HelpMarked(op);
return(true);
}
else
{
Help(result);
Interlocked.CompareExchange(ref op.gp.update, new Update(States.Clean, op), op.myUpdate);
return(false);
}
}
