/// <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 BPlusTree SetupFromExistingStream(Stream fromFile, long seekStart)
{
if (fromFile == null)
{
throw new ArgumentNullException("fromFile");
}
BPlusTree tree = new BPlusTree(fromFile, seekStart, 100, 7, (byte)1);
tree.ReadHeader();
tree.BlockFile = BlockFile.SetupFromExistingStream(
fromFile, seekStart + HeaderSize, StorageConstants.BlockFileHeaderPrefix);
if (tree.BlockFile.BlockSize != tree.BlockSize)
{
throw new BPlusTreeException("Inner and outer block sizes should match.");
}
if (tree.RootNodeBlockNumber != StorageConstants.NullBlockNumber)
{
tree.RootNode = BPlusTreeNode.MakeRoot(tree, true);
tree.RootNode.LoadFromBlock(tree.RootNodeBlockNumber);
}
return(tree);
}
/// <summary>
/// 从指定的流初始化块文件
/// </summary>
/// <param name="fromFile">指定的流</param>
/// <param name="seekStart">流起始索引点</param>
/// <param name="blockFileHeaderPrefix">块存储头部前缀</param>
/// <returns>块文件</returns>
public static BlockFile SetupFromExistingStream(Stream fromFile, long seekStart, byte[] blockFileHeaderPrefix)
{
BlockFile file = new BlockFile(fromFile, seekStart, blockFileHeaderPrefix, 100); // dummy block size for now
file.ReadFileHeader();
return(file);
}
/// <summary>
/// 从指定的流初始化块文件
/// </summary>
/// <param name="fromFile">指定的流</param>
/// <param name="seekStart">流起始索引点</param>
/// <param name="blockFileHeaderPrefix">块存储头部前缀</param>
/// <param name="blockSize">块的大小</param>
/// <returns>块文件</returns>
public static BlockFile InitializeInStream(Stream fromFile, long seekStart, byte[] blockFileHeaderPrefix, int blockSize)
{
BlockFile file = new BlockFile(fromFile, seekStart, blockFileHeaderPrefix, blockSize);
file.WriteFileHeader();
return(file);
}
/// <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 BPlusTree InitializeInStream(Stream fromFile, long seekStart, int keyLength, int nodeCapacity)
{
if (fromFile == null)
{
throw new ArgumentNullException("fromFile");
}
if (fromFile.Length > seekStart)
{
throw new BPlusTreeException("Cannot initialize tree inside written area of stream.");
}
BPlusTree tree = new BPlusTree(fromFile, seekStart, keyLength, nodeCapacity, (byte)1);
tree.WriteHeader();
tree.BlockFile = BlockFile.InitializeInStream(
fromFile, seekStart + HeaderSize, StorageConstants.BlockFileHeaderPrefix, tree.BlockSize);
return(tree);
}