public virtual IKeyAndValue GetSmallest(IBTreeNode node, bool delete)
{
if (!node.IsLeaf())
{
var childTreeNode = node.GetChildAt(0, true);
if (childTreeNode.GetNbKeys() == _degree - 1)
{
node = PrepareForDelete(node, childTreeNode, 0);
}
childTreeNode = node.GetChildAt(0, true);
return(GetSmallest(childTreeNode, delete));
}
var keyAndValue = node.GetKeyAndValueAt(0);
if (delete)
{
node.DeleteKeyAndValueAt(0, true);
_persister.SaveNode(node);
}
return(keyAndValue);
}
private T NextAsc()
{
// Try to go down till a leaf
while (!CurrentNode.IsLeaf())
{
CurrentNode = CurrentNode.GetChildAt(_currentKeyIndex, true);
_currentKeyIndex = 0;
}
// If leaf has more keys
if (_currentKeyIndex < CurrentNode.GetNbKeys())
{
NbReturnedElements++;
var nodeValue = GetValueAt(CurrentNode, _currentKeyIndex);
_currentKeyIndex++;
return((T)nodeValue);
}
// else go up till a node with keys
while (_currentKeyIndex >= CurrentNode.GetNbKeys())
{
var child = CurrentNode;
CurrentNode = CurrentNode.GetParent();
_currentKeyIndex = IndexOfChild(CurrentNode, child);
}
NbReturnedElements++;
var value = GetValueAt(CurrentNode, _currentKeyIndex);
_currentKeyIndex++;
return((T)value);
}
public virtual IKeyAndValue GetBiggest(IBTreeNode node, bool delete)
{
var lastKeyIndex = node.GetNbKeys() - 1;
var lastChildIndex = node.GetNbChildren() - 1;
if (lastChildIndex > lastKeyIndex)
{
var child = node.GetChildAt(lastChildIndex, true);
if (child.GetNbKeys() == _degree - 1)
{
node = PrepareForDelete(node, child, lastChildIndex);
}
lastChildIndex = node.GetNbChildren() - 1;
child = node.GetChildAt(lastChildIndex, true);
return(GetBiggest(child, delete));
}
var kav = node.GetKeyAndValueAt(lastKeyIndex);
if (delete)
{
node.DeleteKeyAndValueAt(lastKeyIndex, false);
_persister.SaveNode(node);
}
return(kav);
}
public static void ValidateNode(IBTreeNode node)
{
if (!OdbConfiguration.IsBTreeValidationEnabled())
return;
var nbKeys = node.GetNbKeys();
if (node.HasParent() && nbKeys < node.GetDegree() - 1)
{
var degree = (node.GetDegree() - 1).ToString();
throw new BTreeNodeValidationException("Node with less than " + degree + " keys");
}
var maxNbKeys = node.GetDegree() * 2 - 1;
var nbChildren = node.GetNbChildren();
var maxNbChildren = node.GetDegree() * 2;
if (nbChildren != 0 && nbKeys == 0)
throw new BTreeNodeValidationException("Node with no key but with children : " + node);
for (var i = 0; i < nbKeys; i++)
{
if (node.GetKeyAndValueAt(i) == null)
{
var keyIndex = i.ToString();
throw new BTreeNodeValidationException("Null key at " + keyIndex + " on node " + node);
}
CheckValuesOfChild(node.GetKeyAndValueAt(i), node.GetChildAt(i, false));
}
for (var 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 (var 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 (var 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));
}
}
public override void SetChildAt(IBTreeNode node, int childIndex, int
index, bool throwExceptionIfDoesNotExist)
{
var childTreeNode = node.GetChildAt(childIndex, throwExceptionIfDoesNotExist);
_children[index] = childTreeNode;
if (childTreeNode != null)
childTreeNode.SetParent(this);
}
private void BuildDisplay(IBTreeNode node, int currentHeight, object parentId, bool withIds)
{
if (currentHeight > _lines.Length - 1)
{
return;
}
// get string buffer of this line
var line = _lines[currentHeight];
if (withIds)
{
line.Append(node.GetId()).Append(":[");
}
else
{
line.Append("[");
}
for (var i = 0; i < node.GetNbKeys(); i++)
{
if (i > 0)
{
line.Append(" , ");
}
var keyAndValue = node.GetKeyAndValueAt(i);
line.Append(keyAndValue.GetKey());
}
if (withIds)
{
line.Append("]:").Append(node.GetParentId()).Append("/").Append(parentId).Append(" ");
}
else
{
line.Append("] ");
}
for (var i = 0; i < node.GetNbChildren(); i++)
{
var child = node.GetChildAt(i, false);
if (child != null)
{
BuildDisplay(child, currentHeight + 1, node.GetId(), withIds);
}
else
{
_lines[currentHeight + 1].Append(string.Concat("[Child {0} null!] ", (i + 1).ToString()));
}
}
}
public override void SetChildAt(IBTreeNode node, int childIndex, int
index, bool throwExceptionIfDoesNotExist)
{
var childTreeNode = node.GetChildAt(childIndex, throwExceptionIfDoesNotExist);
_children[index] = childTreeNode;
if (childTreeNode != null)
{
childTreeNode.SetParent(this);
}
}
private static int IndexOfChild(IBTreeNode parent, IBTreeNode child)
{
for (var i = 0; i < parent.GetNbChildren(); i++)
{
if (parent.GetChildAt(i, true).GetId().Equals(child.GetId()))
{
return(i);
}
}
var errorMessage = string.Format("parent {0} does not have the specified child : {1}", parent, child);
throw new OdbRuntimeException(NDatabaseError.InternalError.AddParameter(errorMessage));
}
private void InsertNonFull(IBTreeNode node, IComparable key, object value)
{
if (node.IsLeaf())
{
node.InsertKeyAndValue(key, value);
_persister.SaveNode(node);
return;
}
var position = node.GetPositionOfKey(key);
// return an index starting
// from 1 instead of 0
var realPosition = -position - 1;
// If position is positive, the key must be inserted in this node
if (position >= 0)
{
node.InsertKeyAndValue(key, value);
_persister.SaveNode(node);
return;
}
// descend
var nodeToDescend = node.GetChildAt(realPosition, true);
if (nodeToDescend.IsFull())
{
Split(node, nodeToDescend, realPosition);
if (node.GetKeyAt(realPosition).CompareTo(key) < 0)
{
nodeToDescend = node.GetChildAt(realPosition + 1, true);
}
}
InsertNonFull(nodeToDescend, key, value);
}
public static void CheckDuplicateChildren(IBTreeNode node1, IBTreeNode node2)
{
if (!OdbConfiguration.IsBTreeValidationEnabled())
return;
for (var i = 0; i < node1.GetNbChildren(); i++)
{
var child1 = node1.GetChildAt(i, true);
for (var j = 0; j < node2.GetNbChildren(); j++)
{
if (child1 == node2.GetChildAt(j, true))
throw new BTreeNodeValidationException("Duplicated node : " + child1);
}
}
}
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 void BuildDisplay(IBTreeNode node, int currentHeight, object parentId, bool withIds)
{
if (currentHeight > _lines.Length - 1)
return;
// get string buffer of this line
var line = _lines[currentHeight];
if (withIds)
line.Append(node.GetId()).Append(":[");
else
line.Append("[");
for (var i = 0; i < node.GetNbKeys(); i++)
{
if (i > 0)
line.Append(" , ");
var keyAndValue = node.GetKeyAndValueAt(i);
line.Append(keyAndValue.GetKey());
}
if (withIds)
line.Append("]:").Append(node.GetParentId()).Append("/").Append(parentId).Append(" ");
else
line.Append("] ");
for (var i = 0; i < node.GetNbChildren(); i++)
{
var child = node.GetChildAt(i, false);
if (child != null)
BuildDisplay(child, currentHeight + 1, node.GetId(), withIds);
else
_lines[currentHeight + 1].Append(string.Concat("[Child {0} null!] ", (i + 1).ToString()));
}
}
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");
}
/// <summary>
/// Returns the value of the deleted key
/// </summary>
/// <param name="node"> </param>
/// <param name="keyAndValue"> </param>
/// <returns> </returns>
/// <exception cref="System.Exception">System.Exception</exception>
private object InternalDelete(IBTreeNode node, IKeyAndValue keyAndValue)
{
var positionOfKey = node.GetPositionOfKey(keyAndValue.GetKey());
var keyIsHere = positionOfKey > 0;
if (node.IsLeaf())
{
if (keyIsHere)
{
var deletedValue = node.DeleteKeyForLeafNode(keyAndValue);
GetPersister().SaveNode(node);
return(deletedValue);
}
// key does not exist
return(null);
}
int realPosition;
if (!keyIsHere)
{
// descend
realPosition = -positionOfKey - 1;
var childTreeNode = node.GetChildAt(realPosition, true);
if (childTreeNode.GetNbKeys() == _degree - 1)
{
node = PrepareForDelete(node, childTreeNode, realPosition);
return(InternalDelete(node, keyAndValue));
}
return(InternalDelete(childTreeNode, keyAndValue));
}
// Here,the node is not a leaf and contains the key
realPosition = positionOfKey - 1;
var currentKey = node.GetKeyAt(realPosition);
var currentValue = node.GetValueAsObjectAt(realPosition);
// case 2a
var leftNode = node.GetChildAt(realPosition, true);
if (leftNode.GetNbKeys() >= _degree)
{
var prevKeyAndValue = GetBiggest(leftNode, true);
node.SetKeyAndValueAt(prevKeyAndValue, realPosition);
BTreeValidator.ValidateNode(node, node == _root);
GetPersister().SaveNode(node);
return(currentValue);
}
// case 2b
var rightNode = node.GetChildAt(realPosition + 1, true);
if (rightNode.GetNbKeys() >= _degree)
{
var nextKeyAndValue = GetSmallest(rightNode, true);
node.SetKeyAndValueAt(nextKeyAndValue, realPosition);
BTreeValidator.ValidateNode(node, node == _root);
GetPersister().SaveNode(node);
return(currentValue);
}
// case 2c
// Here, both left and right part have degree-1 keys
// remove the element to be deleted from node (shifting left all
// right
// elements, link to right link does not exist anymore)
// insert the key to be deleted in left child and merge the 2 nodes.
// rightNode should be deleted
// if node is root, then leftNode becomes the new root and node
// should be deleted
//
node.DeleteKeyAndValueAt(realPosition, true);
leftNode.InsertKeyAndValue(currentKey, currentValue);
leftNode.MergeWith(rightNode);
// If node is the root and is empty
if (!node.HasParent() && node.GetNbKeys() == 0)
{
_persister.DeleteNode(node);
_root = leftNode;
leftNode.SetParent(null);
// The height has been decreased. No need to save btree here.
// The calling delete method will save it.
_height--;
}
else
{
node.SetChildAt(leftNode, realPosition);
// Node must only be validated if it is not the root
BTreeValidator.ValidateNode(node, node == _root);
}
_persister.DeleteNode(rightNode);
BTreeValidator.ValidateNode(leftNode, leftNode == _root);
GetPersister().SaveNode(node);
GetPersister().SaveNode(leftNode);
return(InternalDelete(leftNode, keyAndValue));
}
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));
}
}
}
