/// <summary>
/// 从指定的流初始化树
/// </summary>
/// <param name="fromFile">指定的流</param>
/// <param name="seekStart">流起始查询点</param>
/// <returns>树</returns>
public static BPlusTreeLong SetupFromExistingStream(Stream fromFile, long seekStart)
{
if (fromFile == null)
{
throw new ArgumentNullException("fromFile");
}
BPlusTreeLong tree = new BPlusTreeLong(fromFile, seekStart, 100, 7, (byte)1); // dummy values for nodesize, keysize
tree.ReadHeader();
tree.BlockFile = BlockFile.SetupFromExistingStream(fromFile, seekStart + HeaderSize, StoredConstants.BlockFileHeaderPrefix);
if (tree.BlockFile.BlockSize != tree.BlockSize)
{
throw new BPlusTreeException("inner and outer block sizes should match");
}
if (tree.RootNodeBlockNumber != StoredConstants.NullBlockNumber)
{
tree.RootNode = BPlusTreeNode.MakeRoot(tree, true);
tree.RootNode.LoadFromBlock(tree.RootNodeBlockNumber);
}
return(tree);
}
/// <summary>
/// 创建B+树
/// </summary>
/// <param name="treeFileStream">指定树文件的文件流</param>
/// <param name="blockFileStream">指定块文件的文件流</param>
/// <param name="keyLength">树允许的键的长度</param>
/// <param name="nodeCapacity">树允许的各子节点的最大容量</param>
/// <param name="blockSize">块大小</param>
/// <returns>B+树</returns>
public static BPlusTreeBytes Create(Stream treeFileStream, Stream blockFileStream, int keyLength, int nodeCapacity, int blockSize)
{
BPlusTreeLong tree = BPlusTreeLong.InitializeInStream(treeFileStream, (long)0, keyLength, nodeCapacity);
LinkedFile archive = LinkedFile.InitializeInStream(blockFileStream, (long)0, blockSize);
return(new BPlusTreeBytes(tree, archive));
}
/// <summary>
/// 从文件打开B+树
/// </summary>
/// <param name="treeFileStream">指定树文件的文件流</param>
/// <param name="blockFileStream">指定块文件的文件流</param>
/// <returns>B+树</returns>
public static BPlusTreeBytes Open(Stream treeFileStream, Stream blockFileStream)
{
BPlusTreeLong tree = BPlusTreeLong.SetupFromExistingStream(treeFileStream, (long)0);
LinkedFile archive = LinkedFile.SetupFromExistingStream(blockFileStream, (long)0);
return(new BPlusTreeBytes(tree, archive));
}
/// <summary>
/// 检测给定的键是否符合树要求键的长度
/// </summary>
/// <param name="key">给定的键</param>
/// <param name="tree">给定的树</param>
/// <returns>是否符合树要求键的长度</returns>
public static bool ValidateKey(string key, BPlusTreeLong tree)
{
if (tree == null)
{
throw new ArgumentNullException("tree");
}
if (string.IsNullOrEmpty(key))
{
return(false);
}
int maxKeyLength = tree.KeyLength;
int maxKeyPayload = maxKeyLength - StoredConstants.ShortLength;
char[] keyChars = key.ToCharArray();
int charCount = Encoding.UTF8.GetEncoder().GetByteCount(keyChars, 0, keyChars.Length, true);
if (charCount > maxKeyPayload)
{
return(false);
}
return(true);
}
/// <summary>
/// 从指定的流初始化树
/// </summary>
/// <param name="fromFile">指定的流</param>
/// <param name="seekStart">流起始查询点</param>
/// <param name="keyLength">键长度</param>
/// <param name="nodeCapacity">节点容量</param>
/// <returns>树</returns>
public static BPlusTreeLong InitializeInStream(Stream fromFile, long seekStart, int keyLength, int nodeCapacity)
{
if (fromFile == null)
{
throw new ArgumentNullException("fromFile");
}
if (fromFile.Length > seekStart)
{
throw new BPlusTreeException("can't initialize tree inside written area of stream");
}
BPlusTreeLong tree = new BPlusTreeLong(fromFile, seekStart, keyLength, nodeCapacity, (byte)1);
tree.WriteHeader();
tree.BlockFile = BlockFile.InitializeInStream(fromFile, seekStart + HeaderSize, StoredConstants.BlockFileHeaderPrefix, tree.BlockSize);
return(tree);
}
public static void Check(BPlusTreeLong bpt)
{
Console.WriteLine(bpt.ToText());
bpt.CheckFreeBlock();
ArrayList allkeys = new ArrayList();
foreach (DictionaryEntry d in AllInsertHashtable)
{
allkeys.Add(d.Key);
}
allkeys.Sort();
allkeys.Reverse();
foreach (object thing in allkeys)
{
string thekey = (string)thing;
long thevalue = (long)AllInsertHashtable[thing];
if (thevalue != bpt[thekey])
{
throw new ApplicationException("no match on retrieval " + thekey + " --> " + bpt[thekey] + " not " + thevalue);
}
}
allkeys.Reverse();
string currentkey = bpt.FirstKey();
foreach (object thing in allkeys)
{
string testkey = (string)thing;
if (currentkey == null)
{
throw new ApplicationException("end of keys found when expecting " + testkey);
}
if (!testkey.Equals(currentkey))
{
throw new ApplicationException("when walking found " + currentkey + " when expecting " + testkey);
}
currentkey = bpt.NextKey(testkey);
}
}
/// <summary>
/// B+树，固定长度字符串为键，映射至Byte数组。
/// </summary>
/// <param name="tree">B+树</param>
/// <param name="archive">链式块文件</param>
internal BPlusTreeBytes(BPlusTreeLong tree, LinkedFile archive)
{
this.tree = tree;
this.archive = archive;
}
/// <summary>
/// B+树，固定长度字符串为键，映射至Byte数组。
/// </summary>
/// <param name="tree">B+树</param>
/// <param name="archive">链式块文件</param>
internal BPlusTreeBytes(BPlusTreeLong tree, LinkedFile archive)
{
this.tree = tree;
this.archive = archive;
}
/// <summary>
/// B+树节点
/// </summary>
/// <param name="tree">包含该节点的树</param>
/// <param name="parent">节点的父节点</param>
/// <param name="indexInParent">在父节点中的索引</param>
/// <param name="isLeaf">是否为叶子节点</param>
public BPlusTreeNode(BPlusTreeLong tree, BPlusTreeNode parent, int indexInParent, bool isLeaf)
{
if(tree == null)
throw new ArgumentNullException("tree");
this.Tree = tree;
this.Parent = parent;
this.IsLeaf = isLeaf;
this.IndexInParent = -1;
this.BlockNumber = StoredConstants.NullBlockNumber;
this.Capacity = tree.NodeCapacity;
this.Dirty = true;
this.Clear();
// 存在父节点
if (parent != null && indexInParent >= 0)
{
// B+树 父节点中键值数与子节点数量相等
if (indexInParent > this.Capacity)
{
throw new BPlusTreeException("parent index too large");
}
// 建立与父节点关系
this.Parent.ChildNodes[indexInParent] = this;
this.BlockNumber = this.Parent.ChildValues[indexInParent];
this.IndexInParent = indexInParent;
}
}
/// <summary>
/// 从指定的流初始化树
/// </summary>
/// <param name="fromFile">指定的流</param>
/// <param name="seekStart">流起始查询点</param>
/// <param name="keyLength">键长度</param>
/// <param name="nodeCapacity">节点容量</param>
/// <returns>树</returns>
public static BPlusTreeLong InitializeInStream(Stream fromFile, long seekStart, int keyLength, int nodeCapacity)
{
if (fromFile == null)
throw new ArgumentNullException("fromFile");
if (fromFile.Length > seekStart)
{
throw new BPlusTreeException("can't initialize tree inside written area of stream");
}
BPlusTreeLong tree = new BPlusTreeLong(fromFile, seekStart, keyLength, nodeCapacity, (byte)1);
tree.WriteHeader();
tree.BlockFile = BlockFile.InitializeInStream(fromFile, seekStart + HeaderSize, StoredConstants.BlockFileHeaderPrefix, tree.BlockSize);
return tree;
}
/// <summary>
/// 为指定树构造一个根节点
/// </summary>
/// <param name="tree">指定树</param>
/// <param name="isLeaf">是否为叶子节点</param>
/// <returns>根节点</returns>
public static BPlusTreeNode MakeRoot(BPlusTreeLong tree, bool isLeaf)
{
return new BPlusTreeNode(tree, null, -1, isLeaf);
}
/// <summary>
/// 重新组织分割树，新的根节点将有两个子节点
/// </summary>
/// <param name="oldRoot">原根节点</param>
/// <param name="splitFirstKey">新根节点的第一个Key</param>
/// <param name="splitNode">新分割出的节点</param>
/// <param name="tree">指定的树</param>
/// <returns>新根节点</returns>
public static BPlusTreeNode BinaryRoot(BPlusTreeNode oldRoot, string splitFirstKey, BPlusTreeNode splitNode, BPlusTreeLong tree)
{
if (oldRoot == null)
throw new ArgumentNullException("oldRoot");
if (splitNode == null)
throw new ArgumentNullException("splitNode");
// 已不是叶子节点
BPlusTreeNode newRoot = MakeRoot(tree, false);
// 新的跟记录分割节点的第一个Key
newRoot.ChildKeys[0] = splitFirstKey;
// 新旧节点分别为新的根节点的索引 0 1 位置
oldRoot.ResetParent(newRoot, 0);
splitNode.ResetParent(newRoot, 1);
// new root is stored elsewhere
return newRoot;
}
public static void Delete(BPlusTreeLong bpt, string key)
{
bpt.RemoveKey(key);
AllInsertHashtable.Remove(key);
Check(bpt);
}
public static void Commit(BPlusTreeLong bpt)
{
bpt.Commit();
LastCommittedInsertHashtable = (Hashtable)AllInsertHashtable.Clone();
Check(bpt);
}
/// <summary>
/// 从指定的流初始化树
/// </summary>
/// <param name="fromFile">指定的流</param>
/// <param name="seekStart">流起始查询点</param>
/// <returns>树</returns>
public static BPlusTreeLong SetupFromExistingStream(Stream fromFile, long seekStart)
{
if (fromFile == null)
throw new ArgumentNullException("fromFile");
BPlusTreeLong tree = new BPlusTreeLong(fromFile, seekStart, 100, 7, (byte)1); // dummy values for nodesize, keysize
tree.ReadHeader();
tree.BlockFile = BlockFile.SetupFromExistingStream(fromFile, seekStart + HeaderSize, StoredConstants.BlockFileHeaderPrefix);
if (tree.BlockFile.BlockSize != tree.BlockSize)
{
throw new BPlusTreeException("inner and outer block sizes should match");
}
if (tree.RootNodeBlockNumber != StoredConstants.NullBlockNumber)
{
tree.RootNode = BPlusTreeNode.MakeRoot(tree, true);
tree.RootNode.LoadFromBlock(tree.RootNodeBlockNumber);
}
return tree;
}
public static void Insert(BPlusTreeLong bpt, string key, long map)
{
bpt.Set(key, map);
AllInsertHashtable[key] = map;
Check(bpt);
}
/// <summary>
/// 检测给定的键是否符合树要求键的长度
/// </summary>
/// <param name="key">给定的键</param>
/// <param name="tree">给定的树</param>
/// <returns>是否符合树要求键的长度</returns>
public static bool ValidateKey(string key, BPlusTreeLong tree)
{
if (tree == null)
throw new ArgumentNullException("tree");
if (string.IsNullOrEmpty(key))
{
return false;
}
int maxKeyLength = tree.KeyLength;
int maxKeyPayload = maxKeyLength - StoredConstants.ShortLength;
char[] keyChars = key.ToCharArray();
int charCount = Encoding.UTF8.GetEncoder().GetByteCount(keyChars, 0, keyChars.Length, true);
if (charCount > maxKeyPayload)
{
return false;
}
return true;
}