private Page DiskReadPage(string tableName, int pageIndex, int fileId)
{
string filename = DatabaseName + "." + tableName + ".data." + fileId;
DataFileHeader tableDataFileHeader = ReadDataFileHeader(tableName, fileId);
if (pageIndex >= tableDataFileHeader.TotalPageNum)
{
throw new ApplicationException("pageIndex");
}
var p = new Page(tableDataFileHeader)
{
FileId = fileId,
PageIndex = pageIndex,
PageSize = tableDataFileHeader.PageSize,
TableName = tableName,
DataFileName = filename,
};
using (var fileStream = new FileStream(filename, FileMode.Open))
{
fileStream.Seek(DataFileHeaderSize + pageIndex * p.PageSize, SeekOrigin.Begin);
var pageData = new byte[p.PageSize];
fileStream.Read(pageData, 0, p.PageSize);
p.Decode(pageData);
}
return(p);
}
private void CreateTableFile(string tableName, int rowSize, int pageSize = DefaultPageSize, int pageNum = DefaultTotalPages)
{
for (int j = 0; j <= 1; j++)
{
string filename = DatabaseName + "." + tableName + ".data." + j;
if (File.Exists(filename))
{
continue;
}
var databaseHeader = new DataFileHeader
{
TotalPageNum = pageNum,
PageSize = pageSize,
RowSize = rowSize,
RowsPerPage = (pageSize - Page.PageHeadSize) / rowSize
};
var databaseHeaderBuffer = new byte[DataFileHeaderSize];
byte[] binaryHeader = SerializationHelper.ObjectToByteArray(databaseHeader);
Array.Copy(binaryHeader, databaseHeaderBuffer, binaryHeader.Length);
//Mark Database data file header
using (var fileStream = new FileStream(filename, FileMode.OpenOrCreate))
{
fileStream.Seek(0, SeekOrigin.Begin);
fileStream.Write(databaseHeaderBuffer, 0, DataFileHeaderSize);
fileStream.Flush();
}
using (var fileStream = new FileStream(filename, FileMode.OpenOrCreate))
{
for (int i = 0; i < pageNum; i++)
{
fileStream.Seek(DataFileHeaderSize + i * pageSize, SeekOrigin.Begin);
//Mark Page Header - {P$}{Page Index}{NextFreeRowIndex}
var encoder = new UTF8Encoding();
byte[] byteArray = encoder.GetBytes("P$");
fileStream.Write(byteArray, 0, byteArray.Length);
byteArray = BitConverter.GetBytes(i);
fileStream.Write(byteArray, 0, byteArray.Length);
byteArray = BitConverter.GetBytes(0);
fileStream.Write(byteArray, 0, byteArray.Length);
fileStream.Flush();
}
}
}
}
private void DiskWritePage(string tableName, Page page, int fileId)
{
string filename = DatabaseName + "." + page.TableName + ".data." + fileId;
DataFileHeader tableDataFileHeader = ReadDataFileHeader(tableName, page.FileId);
if (page.PageIndex >= tableDataFileHeader.TotalPageNum)
{
throw new ApplicationException("pageIndex");
}
page.FileId = fileId;
using (var fileStream = new FileStream(filename, FileMode.Open))
{
fileStream.Seek(DataFileHeaderSize + page.PageIndex * page.PageSize, SeekOrigin.Begin);
byte[] pageData = page.Encode();
fileStream.Write(pageData, 0, page.PageSize);
fileStream.Flush();
}
}
private void CreateTableFile(string tableName, int rowSize, int pageSize = DefaultPageSize, int pageNum = DefaultTotalPages)
{
for (int j = 0; j <= 1; j++)
{
string filename = DatabaseName + "." + tableName + ".data." + j;
if (File.Exists(filename))
continue;
var databaseHeader = new DataFileHeader
{
TotalPageNum = pageNum,
PageSize = pageSize,
RowSize = rowSize,
RowsPerPage = (pageSize - Page.PageHeadSize) / rowSize
};
var databaseHeaderBuffer = new byte[DataFileHeaderSize];
byte[] binaryHeader = SerializationHelper.ObjectToByteArray(databaseHeader);
Array.Copy(binaryHeader, databaseHeaderBuffer, binaryHeader.Length);
//Mark Database data file header
using (var fileStream = new FileStream(filename, FileMode.OpenOrCreate))
{
fileStream.Seek(0, SeekOrigin.Begin);
fileStream.Write(databaseHeaderBuffer, 0, DataFileHeaderSize);
fileStream.Flush();
}
using (var fileStream = new FileStream(filename, FileMode.OpenOrCreate))
{
for (int i = 0; i < pageNum; i++)
{
fileStream.Seek(DataFileHeaderSize + i * pageSize, SeekOrigin.Begin);
//Mark Page Header - {P$}{Page Index}{NextFreeRowIndex}
var encoder = new UTF8Encoding();
byte[] byteArray = encoder.GetBytes("P$");
fileStream.Write(byteArray, 0, byteArray.Length);
byteArray = BitConverter.GetBytes(i);
fileStream.Write(byteArray, 0, byteArray.Length);
byteArray = BitConverter.GetBytes(0);
fileStream.Write(byteArray, 0, byteArray.Length);
fileStream.Flush();
}
}
}
}
public Page(DataFileHeader dataFileHeader)
{
this.RowSize = dataFileHeader.RowSize;
this.RowsPerPage = dataFileHeader.RowsPerPage;
}
public const int PageHeadSize = SimpleDatabase.PageHeaderSize; // {P$}{Page Index}{NextFreeRowIndex}
public Page(DataFileHeader dataFileHeader)
{
this.RowSize = dataFileHeader.RowSize;
this.RowsPerPage = dataFileHeader.RowsPerPage;
}
