public IRadixTreeNode Fetch(DbItemReference reference)
{
if (DbItemReference.IsNull(reference))
{
return(null);
}
var page = _pageManager.FetchPage(reference.PageIndex);
if (page.BackingObject == null)
{
var obj1 = RadixTreePageBackingObject.FromPage(page);
page = new Page(_pageManager, page.Index, () => Serialize(obj1), obj1);
}
var backingObject = (RadixTreePageBackingObject)page.BackingObject;
var obj = backingObject.Items[reference.ItemIndex];
var result = obj as IRadixTreeNode;
if (result == null)
{
result = NodeFromBytes((byte[])obj);
result.Reference = (DbItemReference)reference.Clone();
backingObject.Items[reference.ItemIndex] = result;
}
return(result);
}
private IRadixTreeNode NodeFromBytes(byte[] nodeBytes)
{
var result = new RadixTreeNode(0);
using (var ms = new MemoryStream(nodeBytes, false))
{
var buffer = new byte[PageFormatter.OnPagePointerSize];
ms.Read(buffer, 0, PageFormatter.OnPagePointerSize); // overall size
ms.Read(buffer, 0, PageFormatter.OnPagePointerSize); // prefix length
short prefixLength = BitConverter.ToInt16(buffer, 0);
var prefix = new byte[prefixLength];
ms.Read(prefix, 0, prefixLength); // prefix itself
result.Prefix = prefix;
result.ValueReference = DbItemReference.Read(ms);
result.ParentNodeReference = DbItemReference.Read(ms);
if (DbItemReference.IsNull(result.ValueReference))
{
result.ValueReference = null;
}
if (DbItemReference.IsNull(result.ParentNodeReference))
{
result.ParentNodeReference = null;
}
ms.Read(buffer, 0, sizeof(short));
var nodeCount = BitConverter.ToInt16(buffer, 0);
for (int i = 0; i < nodeCount; i++)
{
var key = (byte)ms.ReadByte();
var value = DbItemReference.Read(ms);
result.Entries.Add(new KeyValuePair <byte, DbItemReference>(key, value));
}
return(result);
}
}
private TKey BuildKeyForNode(IRadixTreeNode node)
{
var prefixes = new List <byte[]>();
while (!DbItemReference.IsNull(node.ParentNodeReference))
{
prefixes.Add(node.Prefix);
node = _nodeStorage.Fetch(node.ParentNodeReference);
}
prefixes.Reverse();
using (var ms = new MemoryStream())
{
foreach (var prefix in prefixes.Where(p => p != null))
{
ms.Write(prefix, 0, prefix.Length);
}
return(_keySerializer.Deserialize(ms.ToArray()));
}
}
/// <summary>
/// Inserts or updates key value pair.
/// </summary>
/// <param name="key">The key</param>
/// <param name="value">The value</param>
public void Set(TKey key, TValue value)
{
var binaryKey = _keySerializer.Serialize(key);
int keyOffset;
int nodePrefixOffset;
bool isFullMatch;
IRadixTreeNode targetNode = FindMostSuitableNode(binaryKey, out keyOffset, out nodePrefixOffset, out isFullMatch);
if (isFullMatch)
{
// here we needn't any manipulation with key prefixes
// simply update the existing or allocate a new value
targetNode.ValueReference =
targetNode.ValueReference != null
? _valueStorage.Reallocate(targetNode.ValueReference, value)
: _valueStorage.AllocateNew(value);
UpdateOrFail(targetNode);
return;
}
// we have a partial match
var remainingKeyPart = new byte[binaryKey.Length - keyOffset];
var nodeChain = new List <IRadixTreeNode>();
if (remainingKeyPart.Length > 0)
{
Buffer.BlockCopy(binaryKey, keyOffset, remainingKeyPart, 0, remainingKeyPart.Length);
// the remaining prefix may exceed the _maxPrefixLength
// we must create a chain of nodes, where each node
// contain part of the prefix remaining
nodeChain = CreateNodeChain(remainingKeyPart);
}
if (targetNode.Prefix != null && nodePrefixOffset < targetNode.Prefix.Length)
{
// we got into splitting update:
// the targetNode is split into newParentNode and targetNode itself
// nodeChain (if has any items) is attached to newParentNode as a child
// split prefix
byte[] remainingPrefix;
byte[] prefixForNewParent;
SplitPrefix(targetNode.Prefix, nodePrefixOffset, out prefixForNewParent, out remainingPrefix);
targetNode.Prefix = remainingPrefix;
var newParentNode = _nodeStorage.Create(prefixForNewParent.Length, 2);
newParentNode.Prefix = prefixForNewParent;
newParentNode.ParentNodeReference = targetNode.ParentNodeReference;
targetNode.ParentNodeReference = newParentNode.Reference;
var valueReference = _valueStorage.AllocateNew(value);
if (nodeChain.Any())
{
nodeChain.First().ParentNodeReference = newParentNode.Reference;
nodeChain.Last().ValueReference = valueReference;
}
else
{
newParentNode.ValueReference = valueReference;
}
// add links to child nodes
foreach (var item in GetChildLinks(nodeChain.FirstOrDefault(), targetNode))
{
newParentNode.Entries.Add(item);
}
if (nodeChain.Any())
{
foreach (var node in nodeChain)
{
UpdateOrFail(node);
}
}
UpdateOrFail(newParentNode);
UpdateOrFail(targetNode);
// change link in parent node if needed
if (!DbItemReference.IsNull(newParentNode.ParentNodeReference))
{
AdjustParentNodeLink(newParentNode, true);
}
}
else
{
// here is keeping update
// all nodes above remain intact
byte b = remainingKeyPart[0];
int index;
FindSuitableEntry(targetNode.Entries, b, out index);
targetNode.Entries.Insert(index, new KeyValuePair <byte, DbItemReference>(b, (DbItemReference)(nodeChain.First().Reference.Clone())));
bool reallocated;
targetNode = UpdateOrReallocateNode(targetNode, out reallocated);
if (reallocated)
{
AdjustParentNodeLink(targetNode, true);
AdjustLinksInChildNodes(targetNode, true);
}
nodeChain.First().ParentNodeReference = targetNode.Reference;
nodeChain.Last().ValueReference = _valueStorage.AllocateNew(value);
foreach (var node in nodeChain)
{
UpdateOrFail(node);
}
}
}
/// <summary>
/// Removes key-value pair by key.
/// </summary>
/// <param name="key">The key</param>
public void Remove(TKey key)
{
var binaryKey = _keySerializer.Serialize(key);
int keyOffset;
int nodePrefixOffset;
bool isFullMatch;
IRadixTreeNode node = FindMostSuitableNode(binaryKey, out keyOffset, out nodePrefixOffset, out isFullMatch);
if (isFullMatch)
{
_valueStorage.Free(node.ValueReference);
node.ValueReference = null;
if (node.Entries.Any())
{
if (node.Prefix != null && node.Entries.Count == 1)
{
var child = _nodeStorage.Fetch(node.Entries[0].Value);
var newPrefixLength = node.Prefix.Length + child.Prefix.Length;
if (newPrefixLength <= MaxPrefixLength)
{
var newPrefix = new byte[newPrefixLength];
Buffer.BlockCopy(node.Prefix, 0, newPrefix, 0, node.Prefix.Length);
Buffer.BlockCopy(child.Prefix, 0, newPrefix, node.Prefix.Length, child.Prefix.Length);
child.Prefix = newPrefix;
child.ParentNodeReference = node.ParentNodeReference;
_nodeStorage.Remove(node.Reference);
bool reallocated;
child = UpdateOrReallocateNode(child, out reallocated);
var parent = _nodeStorage.Fetch(child.ParentNodeReference);
int index;
FindSuitableEntry(parent.Entries, child.Prefix[0], out index);
parent.Entries[index] = new KeyValuePair <byte, DbItemReference>(child.Prefix[0], child.Reference);
UpdateOrFail(parent);
}
else
{
UpdateOrFail(node);
}
}
else
{
UpdateOrFail(node);
}
}
else
{
while (!DbItemReference.IsNull(node.ParentNodeReference))
{
var parentNode = _nodeStorage.Fetch(node.ParentNodeReference);
int index;
FindSuitableEntry(parentNode.Entries, node.Prefix[0], out index);
parentNode.Entries.RemoveAt(index);
_nodeStorage.Remove(node.Reference);
if (parentNode.Entries.Any() || parentNode.ValueReference != null ||
DbItemReference.IsNull(parentNode.ParentNodeReference))
{
UpdateOrFail(parentNode);
break;
}
node = parentNode;
}
}
}
}
/// <summary>
/// Gets the key next to the specified key.
/// The existence of the specified key is not required.
/// </summary>
/// <returns>The key next to specified key</returns>
public TKey NextTo(TKey key)
{
var binaryKey = _keySerializer.Serialize(key);
int keyOffset;
int nodePrefixOffset;
bool isFullMatch;
IRadixTreeNode targetNode = FindMostSuitableNode(binaryKey, out keyOffset, out nodePrefixOffset, out isFullMatch);
if (isFullMatch || keyOffset == binaryKey.Length)
{
if (targetNode.Entries.Any())
{
targetNode = _nodeStorage.Fetch(targetNode.Entries.First().Value);
}
else
{
while (!DbItemReference.IsNull(targetNode.ParentNodeReference))
{
var parent = _nodeStorage.Fetch(targetNode.ParentNodeReference);
targetNode = GetChildNextTo(parent, targetNode.Prefix[0]);
if (targetNode != null)
{
break;
}
targetNode = parent;
}
}
}
else
{
byte b = binaryKey[keyOffset];
while (true)
{
var child = GetChildNextTo(targetNode, b);
if (child != null)
{
targetNode = child;
break;
}
if (DbItemReference.IsNull(targetNode.ParentNodeReference))
{
break;
}
b = targetNode.Prefix[0];
targetNode = _nodeStorage.Fetch(targetNode.ParentNodeReference);
}
}
if (DbItemReference.IsNull(targetNode.ParentNodeReference))
{
return(default(TKey));
}
while (DbItemReference.IsNull(targetNode.ValueReference) && targetNode.Entries.Any())
{
targetNode = _nodeStorage.Fetch(targetNode.Entries.First().Value);
}
return(BuildKeyForNode(targetNode));
}
