public ConcurrentListBasedMap(IComparer <K> comparer)
{
Guarder.CheckNull(comparer, "comparer");
this.comparer = comparer;
head = new LockableNode();
tail = new LockableNode();
head.Next = tail;
}
private void Find(K key, out LockableNode pred, out LockableNode curr)
{
pred = head;
curr = head.Next;
while (!ReferenceEquals(curr, tail) && comparer.Compare(curr.Key, key) < 0)
{
pred = curr;
curr = curr.Next;
}
}
public bool TryAdd(K key, V value)
{
Guarder.CheckNull(key, "key");
Guarder.CheckNull(value, "value");
while (true)
{
LockableNode pred, curr;
Find(key, out pred, out curr);
pred.Lock();
try
{
curr.Lock();
try
{
if (Validate(pred, curr))
{
if ((ReferenceEquals(pred.Next, tail) && ReferenceEquals(curr, tail)) || (comparer.Compare(curr.Key, key) != 0))
{
var entry = new LockableNode {
Key = key, Value = value, Marked = false, Next = curr
};
pred.Next = entry;
return(true);
}
else
{
return(false);
}
}
}
finally
{
curr.Unlock();
}
}
finally
{
pred.Unlock();
}
}
}
private bool Validate(LockableNode pred, LockableNode curr)
{
return(!pred.Marked && !curr.Marked && pred.Next == curr);
}
private bool IsNotFound(LockableNode pred, LockableNode curr)
{
return(ReferenceEquals(pred.Next, tail) && ReferenceEquals(curr, tail));
}