private void relocate(BPlusTreeNode parentNode)
{
// this node has outgrown its allotted space.
// we need to move it to the end of the file and update everybody who points to it
// so have to update the following:
// 1. Parent node's pointer
// 2. Left sibling's pointer
// 3. Right sibling's pointer
// 4. All children's parent pointer (which points at this node)
_tree.Log("------------ BEGIN Relocating node ------------");
_tree.Log("BEGIN Relocating node -> ".PadRight(50) + ToString());
// get an abandoned node (or the end of the file, whichever comes first)
BPlusAbandonedNode abandonedNode = _tree.GetNextAvailableNodeLocation(this);
// mark this node as abandoned in the file (and remove from cache)
_tree.AbandonNode(this);
//if (this.IsRoot) {
// // we're relocating the root.
// _tree.Log("TODO: what to do here, if anything?");
//}
if (!IsLeaf)
{
// only leaf nodes should track left/right siblings.
LeftSiblingFileOffset = -1;
RightSiblingFileOffset = -1;
}
if (LeftSiblingFileOffset > -1)
{
BPlusTreeNode originalLeftSibling = BPlusTreeNode.Read(_tree, this.LeftSiblingFileOffset, true);
originalLeftSibling.RightSiblingFileOffset = originalLeftSibling.IsLeaf ? abandonedNode.FileOffset : -1;
_tree.Log(("Updating left sibling node @ " + originalLeftSibling.FileOffset + " -> ").PadRight(50) + originalLeftSibling.ToString());
originalLeftSibling.Write(null);
}
if (RightSiblingFileOffset > -1)
{
BPlusTreeNode originalRightSibling = BPlusTreeNode.Read(_tree, this.RightSiblingFileOffset, true);
originalRightSibling.LeftSiblingFileOffset = originalRightSibling.IsLeaf ? abandonedNode.FileOffset : -1;
_tree.Log(("Updating right sibling node @ " + originalRightSibling.FileOffset + " -> ").PadRight(50) + originalRightSibling.ToString());
originalRightSibling.Write(null);
}
if (this.IsRoot)
{
// special case! no parent means this is the root node.
// update the int at the very beginning of the file to point at the new root node
_tree.WriteRootNodeOffset(abandonedNode.FileOffset);
}
else
{
if (parentNode != null)
{
for (int i = 0; i < parentNode.KeywordCount + 1; i++)
{
if (parentNode.ChildrenByteOffsets[i] == FileOffset)
{
parentNode.ChildrenByteOffsets[i] = abandonedNode.FileOffset;
_tree.Log(("Updating parent node @ " + parentNode.FileOffset + " -> ").PadRight(50) + parentNode.ToString());
parentNode.Write(null);
// the Root node is cached in the tree object -- udpate it if need be
if (parentNode.IsRoot)
{
_tree.Root = parentNode;
}
break;
}
}
}
}
_tree.Writer.BaseStream.Position = abandonedNode.FileOffset;
FileOffset = abandonedNode.FileOffset;
//_chunkSize = abandonedNode.ByteCount;
_tree.Log("END Relocating node (not written yet) -> ".PadRight(50) + ToString());
_tree.Log("------------ END Relocating node ------------");
}