/// <summary>
/// Update the data part of the key.
/// </summary>
/// <param name="keyWithNewData"></param>
/// <returns></returns>
public bool UpdateData(IKey keyWithNewData)
{
IKey result = null;
BNode n = m_top;
bool finished = false;
int pos = -1;
while (!finished)
{
if (n.Leaf)
{
result = n.SearchKey(keyWithNewData, ref pos);
if (result != null)
{
n.ReplaceData(pos, keyWithNewData);
finished = true;
}
else
{
finished = true;
}
}
else
{
result = n.SearchKey(keyWithNewData, ref pos);
if (result == null)
{
uint nextNodeId = n.GetChildAt(pos);
n = (BNode)m_sgManager.GetSegment(nextNodeId, m_nodeFactory, m_keyFactory);
}
else
{
n.ReplaceData(pos, keyWithNewData);
finished = true;
}
}
}
return(result != null);
}
/// <summary>
/// Search for target int this b-tree. target may have data field to be null, the result should have it non-null.
/// </summary>
/// <param name="target"></param>
/// <returns></returns>
public IKey Search(IKey target)
{
IKey result = null;
BNode n = m_top;
bool finished = false;
int pos = -1;
while (!finished)
{
if (n.Leaf)
{
result = n.SearchKey(target, ref pos); //if key is found, result is not null,
//otherwise, result is null and pos is the possible node where the key may be in
if (result != null)
{
return(result);
}
else
{
return(null);
}
}
else
{
result = n.SearchKey(target, ref pos);
if (result == null)
{
uint nextNodeId = n.GetChildAt(pos);
n = (BNode)m_sgManager.GetSegment(nextNodeId, m_nodeFactory, m_keyFactory);
}
else
{
return(result);
}
}
}
return(null);
}
/// <summary>
/// Given a key, search the node where the key is stored in the tree with root as the root node.
/// </summary>
/// <param name="root"></param>
/// <param name="key"></param>
/// <param name="pos">the location the key is stored in</param>
/// <param name="visisted">all the visisted parent is saved in the stack.</param>
/// <returns></returns>
public BNode FindNode(BNode root, IKey key, ref int pos, System.Collections.Stack visited, System.Collections.Stack via)
{
Debug.Assert(visited != null);
BNode n = root;
pos = -1;
IKey temp = null;
while (!n.Leaf)
{
temp = n.SearchKey(key, ref pos);
if (temp == null)
{
uint nextNodeId = n.GetChildAt(pos);
visited.Push(n);
via.Push(pos);
n = (BNode)m_sgManager.GetSegment(nextNodeId, m_nodeFactory, m_keyFactory);
}
else
{
return(n);
}
}
//n is leaf
temp = n.SearchKey(key, ref pos);
if (temp == null)
{
return(null);
}
else
{
return(n);
}
}
/// <summary>
/// Insert the newKey into this B-tree,
/// </summary>
/// <param name="newKey"></param>
/// <returns></returns>
public bool Insert(IKey newKey)
{
//find the leaf where the newKey should be in
BNode n = m_top;
System.Collections.Stack visited = new System.Collections.Stack();
int pos = -1;
while (!n.Leaf)
{
IKey temp = n.SearchKey(newKey, ref pos);
if (temp == null)
{
uint nextNodeId = n.GetChildAt(pos);
visited.Push(n);
n = (BNode)m_sgManager.GetSegment(nextNodeId, m_nodeFactory, m_keyFactory);
}
else
{
return(false);
}
}
//now BNode n is the leaf where insert should happen
IKey t_temp = n.SearchKey(newKey, ref pos);
if (t_temp == null)
{
//not exists, go ahead to insert the new key
if (!n.IsFull)
{
n.InsertAtLeaf(newKey, pos);
return(true);
}
else
{
//split needed for this node
BNode right = new BNode();
m_sgManager.GetNewSegment(right);
IKey median = null;
n.SplitAtLeaf(newKey, pos, ref median, ref right); //this split is at leaf
bool finished = false;
//now n holds the left half of the items,
//right holds the right half items, median is the middle key
while (!finished)
{
//parent is node middle key will be inserted
BNode parent = (visited.Count > 0 ? (BNode)visited.Pop() : null);
if (parent == null)
{
//new top node is needed
BNode new_top = new BNode();
m_sgManager.GetNewSegment(new_top);
new_top.SetOrder(m_top.Order);
new_top.Leaf = false;
new_top.InsertFirstKey(median, n.SegmentID, right.SegmentID);
this.m_top_sid = new_top.SegmentID;
return(true);
}
else
{
IKey tt = parent.SearchKey(median, ref pos);
if (tt != null)
{
return(false);
}
if (!parent.IsFull)
{
parent.InsertAtInternal(median, pos, right.SegmentID);
return(true);
}
else
{
//parent is full again
BNode newRight = new BNode();
m_sgManager.GetNewSegment(newRight);
newRight.SetOrder(parent.Order);
newRight.Leaf = parent.Leaf;
//this split will insert median into the parent, then split and new middle key is newMedian
IKey newMedian;
parent.SplitAtInternal(median, pos, right.SegmentID, out newMedian, newRight);
n = parent;
median = newMedian;
right = newRight;
}
}
}
}
}
else
{
return(false);
}
return(false);
}
