// Commented by Olivier 05/11/2007
// persister.flush();
/// <summary>
/// <pre>1 take median element
/// 2 insert the median in the parent (shifting necessary elements)
/// 3 create a new node with right part elements (moving keys and values and children)
/// 4 set this new node as a child of parent</pre>
/// </summary>
public virtual void Split(IBTreeNode parent, IBTreeNode node2Split, int childIndex)
{
// BTreeValidator.validateNode(parent, parent == root);
// BTreeValidator.validateNode(node2Split, false);
// 1
var medianValue = node2Split.GetMedian();
// 2
parent.SetKeyAndValueAt(medianValue, childIndex, true, true);
// 3
var rightPartTreeNode = node2Split.ExtractRightPart();
// 4
parent.SetChildAt(rightPartTreeNode, childIndex + 1);
parent.SetChildAt(node2Split, childIndex);
parent.IncrementNbChildren();
_persister.SaveNode(parent);
_persister.SaveNode(rightPartTreeNode);
_persister.SaveNode(node2Split);
if (!OdbConfiguration.IsBTreeValidationEnabled())
{
return;
}
BTreeValidator.ValidateNode(parent, parent == _root);
BTreeValidator.ValidateNode(rightPartTreeNode, false);
BTreeValidator.ValidateNode(node2Split, false);
}
public void Check_turning_on_the_btree_validation()
{
Assert.That(OdbConfiguration.IsBTreeValidationEnabled(), Is.False);
OdbConfiguration.EnableBTreeValidation();
Assert.That(OdbConfiguration.IsBTreeValidationEnabled(), Is.True);
OdbConfiguration.DisableBTreeValidation();
Assert.That(OdbConfiguration.IsBTreeValidationEnabled(), Is.False);
}
public static void ValidateNode(IBTreeNode node, bool isRoot)
{
if (!OdbConfiguration.IsBTreeValidationEnabled())
{
return;
}
ValidateNode(node);
if (isRoot && node.HasParent())
{
throw new BTreeNodeValidationException("Root node with a parent: " + node);
}
if (!isRoot && !node.HasParent())
{
throw new BTreeNodeValidationException("Internal node without parent: " + node);
}
}
public static void CheckDuplicateChildren(IBTreeNode node1, IBTreeNode node2)
{
if (!OdbConfiguration.IsBTreeValidationEnabled())
{
return;
}
for (int i = 0; i < node1.GetNbChildren(); i++)
{
IBTreeNode child1 = node1.GetChildAt(i, true);
for (int j = 0; j < node2.GetNbChildren(); j++)
{
if (child1 == node2.GetChildAt(j, true))
{
throw new BTreeNodeValidationException("Duplicated node : " + child1);
}
}
}
}
private static void CheckValuesOfChild(IKeyAndValue key, IBTreeNode node)
{
if (!OdbConfiguration.IsBTreeValidationEnabled())
{
return;
}
if (node == null)
{
return;
}
for (int i = 0; i < node.GetNbKeys(); i++)
{
if (node.GetKeyAndValueAt(i).GetKey().CompareTo(key.GetKey()) >= 0)
{
throw new BTreeNodeValidationException("Left child with values bigger than pivot " + key + " : " +
node);
}
}
}
private IBTreeNode PrepareForDelete(IBTreeNode parent, IBTreeNode child, int childIndex)
{
BTreeValidator.ValidateNode(parent);
BTreeValidator.ValidateNode(child);
// case 3a
IBTreeNode leftSibling = null;
IBTreeNode rightSibling = null;
if (childIndex > 0 && parent.GetNbChildren() > 0)
{
leftSibling = parent.GetChildAt(childIndex - 1, false);
}
if (childIndex < parent.GetNbChildren() - 1)
{
rightSibling = parent.GetChildAt(childIndex + 1, false);
}
// case 3a left
if (leftSibling != null && leftSibling.GetNbKeys() >= _degree)
{
var elementToMoveDown = parent.GetKeyAndValueAt(childIndex - 1);
var elementToMoveUp = leftSibling.GetLastKeyAndValue();
parent.SetKeyAndValueAt(elementToMoveUp, childIndex - 1);
child.InsertKeyAndValue(elementToMoveDown.GetKey(), elementToMoveDown.GetValue());
if (leftSibling.GetNbChildren() > leftSibling.GetNbKeys())
{
// Take the last child of the left sibling and set it the
// first child of the 'child' (incoming parameter)
// child.setChildAt(leftSibling.getChildAt(leftSibling.getNbChildren()
// - 1, true), 0);
child.SetChildAt(leftSibling, leftSibling.GetNbChildren() - 1, 0, true);
child.IncrementNbChildren();
}
leftSibling.DeleteKeyAndValueAt(leftSibling.GetNbKeys() - 1, false);
if (!leftSibling.IsLeaf())
{
leftSibling.DeleteChildAt(leftSibling.GetNbChildren() - 1);
}
_persister.SaveNode(parent);
_persister.SaveNode(child);
_persister.SaveNode(leftSibling);
if (OdbConfiguration.IsBTreeValidationEnabled())
{
BTreeValidator.ValidateNode(parent, parent == _root);
BTreeValidator.ValidateNode(child, false);
BTreeValidator.ValidateNode(leftSibling, false);
BTreeValidator.CheckDuplicateChildren(leftSibling, child);
}
return(parent);
}
// case 3a right
if (rightSibling != null && rightSibling.GetNbKeys() >= _degree)
{
var elementToMoveDown = parent.GetKeyAndValueAt(childIndex);
var elementToMoveUp = rightSibling.GetKeyAndValueAt(0);
parent.SetKeyAndValueAt(elementToMoveUp, childIndex);
child.InsertKeyAndValue(elementToMoveDown.GetKey(), elementToMoveDown.GetValue());
if (rightSibling.GetNbChildren() > 0)
{
// Take the first child of the right sibling and set it the
// last child of the 'child' (incoming parameter)
child.SetChildAt(rightSibling, 0, child.GetNbChildren(), true);
child.IncrementNbChildren();
}
rightSibling.DeleteKeyAndValueAt(0, true);
_persister.SaveNode(parent);
_persister.SaveNode(child);
_persister.SaveNode(rightSibling);
if (OdbConfiguration.IsBTreeValidationEnabled())
{
BTreeValidator.ValidateNode(parent, parent == _root);
BTreeValidator.ValidateNode(child, false);
BTreeValidator.ValidateNode(rightSibling, false);
BTreeValidator.CheckDuplicateChildren(rightSibling, child);
}
return(parent);
}
// case 3b
var isCase3B = (leftSibling != null && leftSibling.GetNbKeys() == _degree - 1) ||
(rightSibling != null && rightSibling.GetNbKeys() >= _degree - 1);
var parentWasSetToNull = false;
if (isCase3B)
{
// choose left sibling to execute merge
if (leftSibling != null)
{
var elementToMoveDown = parent.GetKeyAndValueAt(childIndex - 1);
leftSibling.InsertKeyAndValue(elementToMoveDown.GetKey(), elementToMoveDown.GetValue());
leftSibling.MergeWith(child);
parent.DeleteKeyAndValueAt(childIndex - 1, true);
if (parent.GetNbKeys() == 0)
{
// this is the root
if (!parent.HasParent())
{
_root = leftSibling;
_root.SetParent(null);
_height--;
parentWasSetToNull = true;
}
else
{
const string errorMessage = "Unexpected empty node that is node the root!";
throw new BTreeNodeValidationException(errorMessage);
}
}
else
{
parent.SetChildAt(leftSibling, childIndex - 1);
}
if (parentWasSetToNull)
{
_persister.DeleteNode(parent);
}
else
{
_persister.SaveNode(parent);
BTreeValidator.ValidateNode(parent, parent == _root);
}
// child was merged with another node it must be deleted
_persister.DeleteNode(child);
_persister.SaveNode(leftSibling);
// Validator.validateNode(child, child == root);
BTreeValidator.ValidateNode(leftSibling, leftSibling == _root);
// Validator.checkDuplicateChildren(leftSibling, child);
return(parentWasSetToNull
? _root
: parent);
}
// choose right sibling to execute merge
{
var elementToMoveDown = parent.GetKeyAndValueAt(childIndex);
child.InsertKeyAndValue(elementToMoveDown.GetKey(), elementToMoveDown.GetValue());
child.MergeWith(rightSibling);
parent.DeleteKeyAndValueAt(childIndex, true);
if (parent.GetNbKeys() == 0)
{
// this is the root
if (!parent.HasParent())
{
_root = child;
_root.SetParent(null);
_height--;
parentWasSetToNull = true;
}
else
{
throw new BTreeNodeValidationException("Unexpected empty root node!");
}
}
else
{
parent.SetChildAt(child, childIndex);
}
if (parentWasSetToNull)
{
_persister.DeleteNode(parent);
}
else
{
_persister.SaveNode(parent);
BTreeValidator.ValidateNode(parent, parent == _root);
}
_persister.DeleteNode(rightSibling);
_persister.SaveNode(child);
BTreeValidator.ValidateNode(child, child == _root);
// Validator.validateNode(rightSibling, rightSibling ==
// root);
// Validator.checkDuplicateChildren(rightSibling, child);
return(parentWasSetToNull
? _root
: parent);
}
}
throw new BTreeNodeValidationException("Unexpected case in executing prepare for delete");
}
public static void ValidateNode(IBTreeNode node)
{
if (!OdbConfiguration.IsBTreeValidationEnabled())
{
return;
}
int nbKeys = node.GetNbKeys();
if (node.HasParent() && nbKeys < node.GetDegree() - 1)
{
string degree = (node.GetDegree() - 1).ToString();
throw new BTreeNodeValidationException("Node with less than " + degree + " keys");
}
int maxNbKeys = node.GetDegree() * 2 - 1;
int nbChildren = node.GetNbChildren();
int maxNbChildren = node.GetDegree() * 2;
if (nbChildren != 0 && nbKeys == 0)
{
throw new BTreeNodeValidationException("Node with no key but with children : " + node);
}
for (int i = 0; i < nbKeys; i++)
{
if (node.GetKeyAndValueAt(i) == null)
{
string keyIndex = i.ToString();
throw new BTreeNodeValidationException("Null key at " + keyIndex + " on node " + node);
}
CheckValuesOfChild(node.GetKeyAndValueAt(i), node.GetChildAt(i, false));
}
for (int i = nbKeys; i < maxNbKeys; i++)
{
if (node.GetKeyAndValueAt(i) != null)
{
throw new BTreeNodeValidationException(string.Concat("Not Null key at ", i.ToString(),
" on node " + node));
}
}
IBTreeNode previousNode = null;
for (int i = 0; i < nbChildren; i++)
{
if (node.GetChildAt(i, false) == null)
{
throw new BTreeNodeValidationException(string.Concat("Null child at index ", i.ToString(),
" on node " + node));
}
if (previousNode != null && previousNode == node.GetChildAt(i, false))
{
throw new BTreeNodeValidationException(string.Concat("Two equals children at index ", i.ToString(),
" : " + previousNode));
}
previousNode = node.GetChildAt(i, false);
}
for (int i = nbChildren; i < maxNbChildren; i++)
{
if (node.GetChildAt(i, false) != null)
{
throw new BTreeNodeValidationException(string.Concat("Not Null child at ", i.ToString(),
" on node " + node));
}
}
}