internal BPlusTreeNode(BPlusTree <TKey, TValue> tree, BPlusTreeIndexNode <TKey, TValue> parent)
{
Tree = tree;
Keywords = new List <TKey>();
Parent = parent;
IsLeaf = false;
}
public BPlusTreeIndexNode <TKey, TValue> PromoteToIndexNode()
{
BPlusTreeIndexNode <TKey, TValue> indexNode = null;
try {
BPlusTree <TKey, TValue> .LogInfo("Begin promoting leaf node to index node: " + this.ToString());
indexNode = new BPlusTreeIndexNode <TKey, TValue>(this.Tree, this.Parent, null);
indexNode.Location = this.Location;
indexNode.SlotSize = this.SlotSize;
} finally {
BPlusTree <TKey, TValue> .LogInfo("End promoting leaf node to index node: " + this.ToString());
}
return(indexNode);
}
protected internal BPlusTreeIndexNode(BPlusTree <TKey, TValue> tree, BPlusTreeIndexNode <TKey, TValue> parent, BinaryReader rdr)
: base(tree, parent)
{
IsLeaf = false;
ChildLocations = new List <long>();
if (rdr != null)
{
// index nodes store only children locations (which are always longs)
short childCount = rdr.ReadInt16();
for (int i = 0; i < childCount; i++)
{
ChildLocations.Add(rdr.ReadInt64());
}
}
}
private static BPlusTreeNode <TKey, TValue> processRead(BPlusTree <TKey, TValue> tree, BPlusTreeIndexNode <TKey, TValue> parent, BinaryReader rdr, object[] args)
{
// stream has been positioned appropriately.
// just read from it.
BPlusTreeNode <TKey, TValue> node = null;
tree.Lock(delegate() {
long startLocation = rdr.BaseStream.Position;
int slotSize = rdr.ReadInt32();
bool leaf = rdr.ReadBoolean();
short keywordCount = rdr.ReadInt16();
if (leaf)
{
node = new BPlusTreeLeafNode <TKey, TValue>(tree, parent, rdr);
}
else
{
node = new BPlusTreeIndexNode <TKey, TValue>(tree, parent, rdr);
}
node.Location = startLocation;
// now we must read in all the keywords (they're always at the end of the stream)
for (short i = 0; i < keywordCount; i++)
{
TKey keyManager = new TKey();
keyManager.Read(rdr);
node.Keywords.Add(keyManager);
}
node.SlotSize = slotSize;
// orient the stream pointer to the end of the node (which may be past the current data in it)
rdr.BaseStream.Position = startLocation + node.SlotSize;
});
return(node);
}
protected internal BPlusTreeLeafNode(BPlusTree <TKey, TValue> tree, BPlusTreeIndexNode <TKey, TValue> parent, BinaryReader rdr)
: base(tree, parent)
{
IsLeaf = true;
// LeftSiblingLocation = -1;
RightSiblingLocation = -1;
Values = new List <TValue>();
// leaves store only sibling locations and values (keywords are handled by the base, since they're in every kind of node)
if (rdr != null)
{
// LeftSiblingLocation = rdr.ReadInt64();
RightSiblingLocation = rdr.ReadInt64();
short valueCount = rdr.ReadInt16();
for (int i = 0; i < valueCount; i++)
{
TValue val = new TValue();
val.Read(rdr);
Values.Add(val);
}
}
}
internal BPlusTreeNode <TKey, TValue> SplitChild(BPlusTreeNode <TKey, TValue> originalChild, out int keywordIndex)
{
// Split the current node into two nodes:
// a. Left node contains all pointers/keywords to the left of the median
// b. Right node contains all pointers/keywords to the right of the median
// c. Parent node gets median keyword pushed into it
//
// Disk-wise: the originalChild is always written back to its original position (since we're splitting it, it's guaranteed to get smaller)
// the newChild is placed into either an available abandoned node or tacked on the end of the file.
// the parent node is written back to its original position IF IT FITS. Since we're coyping a keyword
// up into the parent node, it may cause it to outgrow its allocated size in the file. If this occurs,
// the call to this.Write() implicitly calls relocate(). relocate() will then either write the parent to
// an abandoned node or tack it onto the end of the file.
// first, determine the offset of the current originalchild in this (the parent)
keywordIndex = 0;
try {
BPlusTree <TKey, TValue> .LogInfo("Begin splitting node=" + this.ToString() + ", child=" + originalChild.ToString());
if (ChildLocations.Count > 0)
{
// TODO: troubleshoot this -- after several thousand splits, originalChild.Location is no longer found in the ChildLocations array!!!
//if (LastChildLocation == originalChild.Location) {
// // rightmost child, on a full node.
//} else {
while (keywordIndex < ChildLocations.Count && ChildLocations[keywordIndex] != originalChild.Location)
{
keywordIndex++;
}
//}
}
// assign the median keyword to the parent's Keywords list (inserts just before the current one)
//if (keywordIndex > this.Keywords.Count) {
// // rightmost keyword, add to the end of the list
// this.Keywords.Add(originalChild.MedianKeyword);
//} else {
// not rightmost keyword, insert it at the proper position
this.Keywords.Insert(keywordIndex, originalChild.MedianKeyword);
//}
if (originalChild.IsLeaf)
{
// since this is a leaf, we will copy up the median keyword to the parent (as opposed to push up for index nodes)
// create a leaf node
BPlusTreeLeafNode <TKey, TValue> origNode = (BPlusTreeLeafNode <TKey, TValue>)originalChild;
BPlusTreeLeafNode <TKey, TValue> newNode = new BPlusTreeLeafNode <TKey, TValue>(this.Tree, (BPlusTreeIndexNode <TKey, TValue>) this, null);
// copy right half of keywords + values from originalChild to newChild
newNode.Keywords.AddRange(origNode.Keywords.Skip(this.Tree.Median - 1));
newNode.Values.AddRange(origNode.Values.Skip(this.Tree.Median - 1));
// remove right half of keywords + values from originalChild
origNode.Keywords = origNode.Keywords.Take(this.Tree.Median - 1).ToList();
origNode.Values = origNode.Values.Take(this.Tree.Median - 1).ToList();
var nextKeywordIndex = keywordIndex + 1;
Tree.Lock(delegate() {
// write out nodes so sibling locations can be set properly
// note: orig node should never relocate on write since we're making it smaller (moving 1/2 of its keywords to a new node)
if (origNode.Write())
{
BPlusTree <TKey, TValue> .LogInfo("orig leaf node relocated during split child: " + origNode.ToString());
}
if (newNode.Write())
{
BPlusTree <TKey, TValue> .LogInfo("new leaf node relocated during split child: " + newNode.ToString());
}
// adjust sibling locations (we always add the new child to the right of the original one)
newNode.RightSiblingLocation = origNode.RightSiblingLocation;
// newNode.LeftSiblingLocation = origNode.Location;
origNode.RightSiblingLocation = newNode.Location;
ChildLocations.Insert(nextKeywordIndex, newNode.Location);
// write them out again so we save sibling locations
if (origNode.Write())
{
BPlusTree <TKey, TValue> .LogInfo("orig leaf node relocated on 2nd write during split child: " + origNode.ToString());
}
if (newNode.Write())
{
BPlusTree <TKey, TValue> .LogInfo("new leaf node relocated on 2nd write during split child: " + newNode.ToString());
}
// and write out the parent since it changed as well
if (Write())
{
BPlusTree <TKey, TValue> .LogInfo("parent of leaf node relocated during split child: " + this.ToString());
}
});
return(newNode);
}
else
{
// since this is an index node, we push up the keyword to the parent (as opposed to copy up for leaves)
// this means the median keyword will be removed from the original child but not moved to the new child
// create an index node
BPlusTreeIndexNode <TKey, TValue> origNode = (BPlusTreeIndexNode <TKey, TValue>)originalChild;
BPlusTreeIndexNode <TKey, TValue> newNode = new BPlusTreeIndexNode <TKey, TValue>(this.Tree, (BPlusTreeIndexNode <TKey, TValue>) this, null);
// copy right half of keywords + childlocations from originalChild to newChild
// (since this is an index node, skip the median keyword
newNode.Keywords.AddRange(origNode.Keywords.Skip(this.Tree.Median));
newNode.ChildLocations.AddRange(origNode.ChildLocations.Skip(this.Tree.Median));
// remove right half of keywords + childlocations from originalChild
// (note we stop one shy of the median keyword -- this is because the median keyword needs to be "pushed up"
// on an index node split. However, we don't drop the corresponding ChildLocation)
origNode.Keywords = origNode.Keywords.Take(this.Tree.Median - 1).ToList();
origNode.ChildLocations = origNode.ChildLocations.Take(this.Tree.Median).ToList();
var ki = keywordIndex;
Tree.Lock(delegate() {
if (origNode.Write())
{
BPlusTree <TKey, TValue> .LogInfo("orig index node relocated during split child: " + origNode.ToString());
}
if (newNode.Write())
{
BPlusTree <TKey, TValue> .LogInfo("new index node relocated during split child: " + newNode.ToString());
}
// original node may have relocated on write...
ChildLocations[ki] = origNode.Location;
ChildLocations.Insert(ki + 1, newNode.Location);
// and write out the parent since it changed as well
if (Write())
{
BPlusTree <TKey, TValue> .LogInfo("parent of index node relocated during split child: " + this.ToString());
}
});
return(newNode);
}
} finally {
BPlusTree <TKey, TValue> .LogInfo("End splitting node=" + this.ToString() + ", child=" + originalChild.ToString());
}
}
protected BPlusTreeNode <TKey, TValue> GetRightSibling(bool mustHaveSameParent)
{
if (this.IsLeaf)
{
// use the rightsibling pointer
BPlusTreeLeafNode <TKey, TValue> leaf = this as BPlusTreeLeafNode <TKey, TValue>;
return(BPlusTreeNode <TKey, TValue> .Read(this.Tree, this.Parent, leaf.RightSiblingLocation));
}
else
{
// look in parent for our smallest keyword, grab childlocation to the left of it
int parentChildCount;
int childLocationIndex = GetIndexInParent(out parentChildCount);
if (childLocationIndex == -1)
{
// never found the index, or no parent (aka root). No sibling to return.
return(null);
}
else
{
if (childLocationIndex < parentChildCount - 1)
{
// we know the right sibling is attached to the same parent.
BPlusTreeNode <TKey, TValue> node = BPlusTreeNode <TKey, TValue> .Read(this.Tree, this.Parent, Parent.ChildLocations[childLocationIndex + 1]);
return(node);
}
else
{
// we are the rightmost child, as we're at the location that's 1 past the fanout size
if (mustHaveSameParent)
{
// caller wants the sibling only if it's from the same parent, and it's not.
return(null);
}
else
{
// we have to find the common ancestor between this and its right sibling.
// spin up until we find the first node whose child index is <= Fanoutsize
// then drill down the leftmost path until we're at the same depth as we started at
int i = 0;
int nodeChildLocationIndex = -1;
BPlusTreeNode <TKey, TValue> node = this;
while (node.Parent != null)
{
i++;
// keep bubbling up until we're at a node whose parent has at least one child to our right.
nodeChildLocationIndex = node.GetIndexInParent(out parentChildCount);
if (nodeChildLocationIndex < parentChildCount - 1)
{
// this node is not the rightmost child of its parent.
// we're done bubbling (node contains the ancestor node, nodeChildLocationIndex can tell us the subtree to search down)
break;
}
else
{
node = node.Parent;
}
}
if (nodeChildLocationIndex == parentChildCount - 1)
{
// the only common ancestor has our node being the rightmost node in the tree (at this depth).
return(null);
}
// ok, node contains the ancestor somehwere up the tree that has the node we're looking for as its
// leftmost descendent at the same depth.
// So we just keep drilling down the leftmost path until we're at the same depth.
node = BPlusTreeNode <TKey, TValue> .Read(this.Tree, node as BPlusTreeIndexNode <TKey, TValue>, nodeChildLocationIndex + 1);
while (i > 0)
{
BPlusTreeIndexNode <TKey, TValue> indexNode = node as BPlusTreeIndexNode <TKey, TValue>;
node = BPlusTreeNode <TKey, TValue> .Read(this.Tree, indexNode, indexNode.ChildLocations[0]);
i--;
}
// node now contains the right sibling!
return(node);
}
}
}
//// bounce up to the parent
//if (Parent != null) {
// TKey ourKey = FirstKeyword;
// for (int i=0; i < Parent.Keywords.Count; i++) {
// TKey parentKeyword = Parent.Keywords[i];
// if (parentKeyword.CompareTo(ourKey, KeywordMatchMode.ExactMatch, false) == 0) {
// // follow right child
// BPlusTreeNode<TKey, TValue> node = BPlusTreeNode<TKey, TValue>.Read(this.Tree, this.Parent, Parent.ChildLocations[i+1]);
// return node;
// }
// }
//}
//return null;
}
}
protected BPlusTreeNode <TKey, TValue> GetLeftSibling(bool mustHaveSameParent)
{
// look in parent for our smallest keyword, grab childlocation to the left of it
int parentChildCount;
int childLocationIndex = GetIndexInParent(out parentChildCount);
if (childLocationIndex == -1)
{
// never found the index, or no parent (aka root). No sibling to return.
return(null);
}
else
{
if (childLocationIndex == 0)
{
if (mustHaveSameParent)
{
// caller wants the sibling only if it's from the same parent, and it's not.
return(null);
}
else
{
// we have to find the parent of our left sibling.
// spin up until we find the first node whose child index is > 0
// then drill down the rightmost path until we're at the same depth as we started at
int i = 0;
int nodeChildLocationIndex = -1;
BPlusTreeNode <TKey, TValue> node = this;
while (node.Parent != null)
{
i++;
// keep bubbling up until we're at a node whose parent has at least one child to our left.
nodeChildLocationIndex = node.GetIndexInParent(out parentChildCount);
if (nodeChildLocationIndex > 0)
{
// this node is not the leftmost child of its parent.
// we're done bubbling (node contains the ancestor node, nodeChildLocationIndex can tell us the subtree to search down)
break;
}
else
{
node = node.Parent;
}
}
if (nodeChildLocationIndex == 0)
{
// the only common ancestor has our node being the leftmost node in the tree (at this depth).
return(null);
}
// ok, node contains the ancestor somehwere up the tree that has the node we're looking for as its
// rightmost descendent at the same depth.
// So we just keep drilling down until we're at the same depth.
node = BPlusTreeNode <TKey, TValue> .Read(this.Tree, node as BPlusTreeIndexNode <TKey, TValue>, nodeChildLocationIndex - 1);
while (i > 0)
{
BPlusTreeIndexNode <TKey, TValue> indexNode = node as BPlusTreeIndexNode <TKey, TValue>;
node = BPlusTreeNode <TKey, TValue> .Read(this.Tree, indexNode, indexNode.LastChildLocation);
i--;
}
// node now contains the left sibling!
return(node);
}
}
else
{
// we know the left sibling is attached to the same parent.
BPlusTreeNode <TKey, TValue> node = BPlusTreeNode <TKey, TValue> .Read(this.Tree, this.Parent, Parent.ChildLocations[childLocationIndex - 1]);
return(node);
}
}
}
/// <summary>
/// Factory method for reading data from the tree's stream and returning either a BPlusTreeIndexNode or BPlusTreeLeafNode object
/// </summary>
/// <param name="tree"></param>
/// <param name="location"></param>
/// <returns></returns>
internal static BPlusTreeNode <TKey, TValue> Read(BPlusTree <TKey, TValue> tree, BPlusTreeIndexNode <TKey, TValue> parent, long location)
{
if (location < 1)
{
return(null);
}
BPlusTreeNode <TKey, TValue> node = null;
if (!tree.NodeCache.TryGetValue(location, out node))
{
node = tree.ReadNodeFromDisk(parent, processRead, location, null);
}
return(node);
}