public bool Contains(long studentId, long courseId)
{
Monitor.Enter(head);
OffsetNode pred = head;
Monitor.Enter(head.Next);
OffsetNode curr = head.Next;
while (curr != tail || curr.Value != new Offset(studentId, courseId))
{
Monitor.Exit(pred);
pred = curr;
curr = curr.Next;
Monitor.Enter(curr);
}
if (curr == tail)
{
Monitor.Exit(pred);
Monitor.Exit(tail);
return(false);
}
else
{
Monitor.Exit(pred);
Monitor.Exit(curr);
return(true);
}
}
public void Remove(long studentId, long courseId)
{
Monitor.Enter(head);
OffsetNode pred = head;
Monitor.Enter(head.Next);
OffsetNode curr = head.Next;
while (curr != tail || curr.Value != new Offset(studentId, courseId))
{
Monitor.Exit(pred);
pred = curr;
curr = curr.Next;
Monitor.Enter(curr);
}
if (curr == tail)
{
Monitor.Exit(pred);
Monitor.Exit(tail);
}
else
{
pred.Next = curr.Next;
Length--;
Monitor.Exit(pred);
Monitor.Exit(curr);
}
}
public int EnumerateElems()
{
int result = 0;
OffsetNode tmp = head.Next;
while (tmp != tail)
{
result++;
tmp = tmp.Next;
}
return(result);
}
public void Add(long studentId, long courseId)
{
Monitor.Enter(head);
OffsetNode pred = head;
Monitor.Enter(head.Next);
OffsetNode curr = head.Next;
while (curr != tail)
{
Monitor.Exit(pred);
pred = curr;
curr = curr.Next;
Monitor.Enter(curr);
}
curr = new OffsetNode(new Offset(studentId, courseId), tail);
pred.Next = curr;
Length++;
Monitor.Exit(pred);
Monitor.Exit(tail);
}
public ExamList()
{
tail = new OffsetNode(new Offset(-1, -1));
head = new OffsetNode(new Offset(-1, -1), tail);
Length = 0;
}