/// <summary>
/// insert key/position entry in self
/// </summary>
/// <param name="key">Key to associate with the leaf</param>
/// <param name="position">position associated with key in external structur</param>
/// <param name="splitString">if not null then the smallest key in the new split leaf</param>
/// <param name="splitNode">if not null then the node was split and this is the leaf to the right.</param>
/// <returns>null unless the smallest key under this node has changed, in which case it returns the smallest key.</returns>
public string Insert(string key, long position, out string splitString, out BplusNode splitNode)
{
if (this.isLeaf)
{
return this.InsertLeaf(key, position, out splitString, out splitNode);
}
splitString = null;
splitNode = null;
int insertposition = this.FindAtOrNextPosition(key, false, true);
long insertBufferNumber = this.ChildBufferNumbers[insertposition];
if (insertBufferNumber==BplusTreeLong.NULLBUFFERNUMBER)
{
throw new BplusTreeException("key not followed by buffer number in non-leaf");
}
// insert in subtree
BplusNode InsertChild = this.MaterializeNodeAtIndex(insertposition);
BplusNode childSplit;
string childSplitString;
string childInsert = InsertChild.Insert(key, position, out childSplitString, out childSplit);
// if there was a split the node must expand
if (childSplit!=null)
{
// insert the child
this.Soil(); // redundant -- a child will have a change so this node will need to be copied
int newChildPosition = insertposition+1;
bool dosplit = false;
// if there is no free space we must do a split
if (this.ChildBufferNumbers[this.Size]!=BplusTreeLong.NULLBUFFERNUMBER)
{
dosplit = true;
this.PrepareForSplit();
}
// bubble over the current values to make space for new child
for (int i=this.ChildKeys.Length-2; i>=newChildPosition-1; i--)
{
int i1 = i+1;
int i2 = i1+1;
this.ChildKeys[i1] = this.ChildKeys[i];
this.ChildBufferNumbers[i2] = this.ChildBufferNumbers[i1];
BplusNode childNode = this.MaterializedChildNodes[i2] = this.MaterializedChildNodes[i1];
}
// record the new child
this.ChildKeys[newChildPosition-1] = childSplitString;
//this.MaterializedChildNodes[newChildPosition] = childSplit;
//this.ChildBufferNumbers[newChildPosition] = childSplit.myBufferNumber;
childSplit.Reparent(this, newChildPosition);
// split, if needed
if (dosplit)
{
int splitpoint = this.MaterializedChildNodes.Length/2-1;
splitString = this.ChildKeys[splitpoint];
splitNode = new BplusNode(this.owner, this.parent, -1, this.isLeaf);
// make copy of expanded node structure
BplusNode[] materialized = this.MaterializedChildNodes;
long[] buffernumbers = this.ChildBufferNumbers;
string[] keys = this.ChildKeys;
// repair the expanded node
this.ChildKeys = new string[this.Size];
this.MaterializedChildNodes = new BplusNode[this.Size+1];
this.ChildBufferNumbers = new long[this.Size+1];
this.Clear();
Array.Copy(materialized, 0, this.MaterializedChildNodes, 0, splitpoint+1);
Array.Copy(buffernumbers, 0, this.ChildBufferNumbers, 0, splitpoint+1);
Array.Copy(keys, 0, this.ChildKeys, 0, splitpoint);
// initialize the new node
splitNode.Clear(); // redundant.
int remainingKeys = this.Size-splitpoint;
Array.Copy(materialized, splitpoint+1, splitNode.MaterializedChildNodes, 0, remainingKeys+1);
Array.Copy(buffernumbers, splitpoint+1, splitNode.ChildBufferNumbers, 0, remainingKeys+1);
Array.Copy(keys, splitpoint+1, splitNode.ChildKeys, 0, remainingKeys);
// fix pointers in materialized children of splitnode
splitNode.reParentAllChildren();
// store the new node
splitNode.DumpToFreshBuffer();
splitNode.CheckIfTerminal();
splitNode.Soil();
this.CheckIfTerminal();
}
// fix pointers in children
this.reParentAllChildren();
}
if (insertposition==0)
{
// the smallest key may have changed
return childInsert;
}
return null; // no change in smallest key
}
public static void Merge(BplusNode left, string KeyBetween, BplusNode right, out string rightLeastKey,
out bool DeleteRight)
{
//System.Diagnostics.Debug.WriteLine("\r\n<br> merging "+right.myBufferNumber+" ("+KeyBetween+") "+left.myBufferNumber);
//System.Diagnostics.Debug.WriteLine(left.owner.toHtml());
rightLeastKey = null; // only if DeleteRight
if (left.isLeaf || right.isLeaf)
{
if (!(left.isLeaf&&right.isLeaf))
{
throw new BplusTreeException("can't merge leaf with non-leaf");
}
MergeLeaves(left, right, out DeleteRight);
rightLeastKey = right.ChildKeys[0];
return;
}
// merge non-leaves
DeleteRight = false;
string[] allkeys = new string[left.Size*2+1];
long[] allseeks = new long[left.Size*2+2];
BplusNode[] allMaterialized = new BplusNode[left.Size*2+2];
if (left.ChildBufferNumbers[0]==BplusTreeLong.NULLBUFFERNUMBER ||
right.ChildBufferNumbers[0]==BplusTreeLong.NULLBUFFERNUMBER)
{
throw new BplusTreeException("cannot merge empty non-leaf with non-leaf");
}
int index = 0;
allseeks[0] = left.ChildBufferNumbers[0];
allMaterialized[0] = left.MaterializedChildNodes[0];
for (int i=0; i<left.Size; i++)
{
if (left.ChildKeys[i]==null)
{
break;
}
allkeys[index] = left.ChildKeys[i];
allseeks[index+1] = left.ChildBufferNumbers[i+1];
allMaterialized[index+1] = left.MaterializedChildNodes[i+1];
index++;
}
allkeys[index] = KeyBetween;
index++;
allseeks[index] = right.ChildBufferNumbers[0];
allMaterialized[index] = right.MaterializedChildNodes[0];
int rightcount = 0;
for (int i=0; i<right.Size; i++)
{
if (right.ChildKeys[i]==null)
{
break;
}
allkeys[index] = right.ChildKeys[i];
allseeks[index+1] = right.ChildBufferNumbers[i+1];
allMaterialized[index+1] = right.MaterializedChildNodes[i+1];
index++;
rightcount++;
}
if (index<=left.Size)
{
// it will all fit in one node
//System.Diagnostics.Debug.WriteLine("deciding to forget "+right.myBufferNumber+" into "+left.myBufferNumber);
DeleteRight = true;
for (int i=0; i<index; i++)
{
left.ChildKeys[i] = allkeys[i];
left.ChildBufferNumbers[i] = allseeks[i];
left.MaterializedChildNodes[i] = allMaterialized[i];
}
left.ChildBufferNumbers[index] = allseeks[index];
left.MaterializedChildNodes[index] = allMaterialized[index];
left.reParentAllChildren();
left.Soil();
right.Free();
return;
}
// otherwise split the content between the nodes
left.Clear();
right.Clear();
left.Soil();
right.Soil();
int leftcontent = index/2;
int rightcontent = index-leftcontent-1;
rightLeastKey = allkeys[leftcontent];
int outputindex = 0;
for (int i=0; i<leftcontent; i++)
{
left.ChildKeys[i] = allkeys[outputindex];
left.ChildBufferNumbers[i] = allseeks[outputindex];
left.MaterializedChildNodes[i] = allMaterialized[outputindex];
outputindex++;
}
rightLeastKey = allkeys[outputindex];
left.ChildBufferNumbers[outputindex] = allseeks[outputindex];
left.MaterializedChildNodes[outputindex] = allMaterialized[outputindex];
outputindex++;
rightcount = 0;
for (int i=0; i<rightcontent; i++)
{
right.ChildKeys[i] = allkeys[outputindex];
right.ChildBufferNumbers[i] = allseeks[outputindex];
right.MaterializedChildNodes[i] = allMaterialized[outputindex];
outputindex++;
rightcount++;
}
right.ChildBufferNumbers[rightcount] = allseeks[outputindex];
right.MaterializedChildNodes[rightcount] = allMaterialized[outputindex];
left.reParentAllChildren();
right.reParentAllChildren();
}
