public override T?Find(T targetValue)
{
SafeNode <T> current = Root;
current?.Mtx.WaitOne();
if (current?.Value.CompareTo(targetValue) == 0)
{
current.Mtx.ReleaseMutex();
return(targetValue);
}
while (current != null)
{
if (current.Value.CompareTo(targetValue) < 0)
{
current.Right?.Mtx.WaitOne();
current.Mtx.ReleaseMutex();
current = current.Right;
}
else if (current.Value.CompareTo(targetValue) > 0)
{
current.Left?.Mtx.WaitOne();
current.Mtx.ReleaseMutex();
current = current.Left;
}
else
{
current.Mtx.ReleaseMutex();
return(targetValue);
}
}
return(null);
}
public override void Insert(T value)
{
SafeNode <T> current = Root;
SafeNode <T> newNode = new SafeNode <T>(value);
_mtxRoot.WaitOne();
if (Root == null)
{
Root = newNode;
_mtxRoot.ReleaseMutex();
return;
}
_mtxRoot.ReleaseMutex();
current?.Mtx.WaitOne();
while (true)
{
if (current?.Value.CompareTo(newNode.Value) < 0)
{
if (current.Right == null)
{
current.Right = newNode;
current.Mtx.ReleaseMutex();
break;
}
current.Right?.Mtx.WaitOne();
current.Mtx.ReleaseMutex();
current = current.Right;
}
else if (current?.Value.CompareTo(newNode.Value) > 0)
{
if (current.Left == null)
{
current.Left = newNode;
current.Mtx.ReleaseMutex();
break;
}
current.Left?.Mtx.WaitOne();
current.Mtx.ReleaseMutex();
current = current.Left;
}
else
{
current?.Mtx.ReleaseMutex();
break;
}
}
}
public override void Remove(T targetValue)
{
// Find target node to remove
SafeNode <T> current = Root;
SafeNode <T> target = null;
SafeNode <T> parentOfTarget = null;
current?.Mtx.WaitOne();
if (current?.Value.CompareTo(targetValue) == 0)
{
target = current;
}
else
{
while (current != null)
{
if (current.Value.CompareTo(targetValue) < 0)
{
current.Right?.Mtx.WaitOne();
current.Mtx.ReleaseMutex();
parentOfTarget = current;
current = current.Right;
}
else if (current.Value.CompareTo(targetValue) > 0)
{
current.Left?.Mtx.WaitOne();
current.Mtx.ReleaseMutex();
parentOfTarget = current;
current = current.Left;
}
else
{
target = current;
break;
}
}
}
if (target == null)
{
return;
}
// Find nearest neighbors from left and right subtrees
SafeNode <T> leftNeighbor = target.Left;
SafeNode <T> prevOfLeftNeighbor = target;
leftNeighbor?.Mtx.WaitOne();
SafeNode <T> rightNeighbor = target.Right;
SafeNode <T> prevOfRightNeighbor = target;
rightNeighbor?.Mtx.WaitOne();
while (leftNeighbor?.Right != null || rightNeighbor?.Left != null)
{
leftNeighbor?.Right?.Mtx.WaitOne();
if (leftNeighbor?.Right != null)
{
leftNeighbor?.Mtx.ReleaseMutex();
prevOfLeftNeighbor = leftNeighbor;
leftNeighbor = leftNeighbor?.Right;
}
rightNeighbor?.Left?.Mtx.WaitOne();
if (rightNeighbor?.Left != null)
{
rightNeighbor?.Mtx.ReleaseMutex();
prevOfRightNeighbor = rightNeighbor;
rightNeighbor = rightNeighbor?.Left;
}
}
// Target node is leaf, just delete it
if (leftNeighbor == null && rightNeighbor == null)
{
if (parentOfTarget?.Left?.Equals(target) == true)
{
parentOfTarget.Left = null;
}
else if (parentOfTarget?.Right?.Equals(target) == true)
{
parentOfTarget.Right = null;
}
else
{
Root = null;
}
target.Mtx.ReleaseMutex();
return;
}
// Otherwise, swap values with one of nearest neighbors in subtrees
if (leftNeighbor != null)
{
target.Value = leftNeighbor.Value;
if (prevOfLeftNeighbor.Equals(target))
{
target.Left = leftNeighbor.Left;
}
else
{
prevOfLeftNeighbor.Right = leftNeighbor.Left;
}
}
else
{
target.Value = rightNeighbor.Value;
if (prevOfRightNeighbor.Equals(target))
{
target.Right = rightNeighbor.Right;
}
else
{
prevOfRightNeighbor.Left = rightNeighbor.Right;
}
}
leftNeighbor?.Mtx.ReleaseMutex();
rightNeighbor?.Mtx.ReleaseMutex();
target.Mtx.ReleaseMutex();
}
public SafeNode(T value) : base(value)
{
Mtx = new Mutex();
Left = null;
Right = null;
}