public DataPage GetDataPage(uint pageID)
{
if (pageID == Header.LastPageID) // Page does not exists in disk
{
var dataPage = new DataPage(pageID);
return dataPage;
}
else
{
return PageFactory.GetDataPage(pageID, Reader, false);
}
}
internal FileDBStream(Engine engine, Guid id)
{
_engine = engine;
var indexNode = _engine.Search(id);
if (indexNode != null)
{
_streamLength = indexNode.FileLength;
_currentPage = PageFactory.GetDataPage(indexNode.DataPageID, engine.Reader, false);
_info = new EntryInfo(indexNode);
}
}
public static void ReadFromFile(DataPage dataPage, BinaryReader reader, bool onlyHeader)
{
// Seek the stream on first byte from data page
long initPos = reader.Seek(Header.HEADER_SIZE + ((long)dataPage.PageID * BasePage.PAGE_SIZE));
if (reader.ReadByte() != (byte)PageType.Data)
throw new FileDBException("PageID {0} is not a Data Page", dataPage.PageID);
dataPage.NextPageID = reader.ReadUInt32();
dataPage.IsEmpty = reader.ReadBoolean();
dataPage.DataBlockLength = reader.ReadInt16();
// If page is empty or onlyHeader parameter, I don't read data content
if (!dataPage.IsEmpty && !onlyHeader)
{
// Seek the stream at the end of page header
reader.Seek(initPos + DataPage.HEADER_SIZE);
// Read all bytes from page
dataPage.DataBlock = reader.ReadBytes(dataPage.DataBlockLength);
}
}
// Take a new data page on sequence and update the last
public static DataPage GetNewDataPage(DataPage basePage, Engine engine)
{
if (basePage.NextPageID != uint.MaxValue)
{
PageFactory.WriteToFile(basePage, engine.Writer); // Write last page on disk
var dataPage = PageFactory.GetDataPage(basePage.NextPageID, engine.Reader, false);
engine.Header.FreeDataPageID = dataPage.NextPageID;
if (engine.Header.FreeDataPageID == uint.MaxValue)
engine.Header.LastFreeDataPageID = uint.MaxValue;
return dataPage;
}
else
{
var pageID = ++engine.Header.LastPageID;
DataPage newPage = new DataPage(pageID);
basePage.NextPageID = newPage.PageID;
PageFactory.WriteToFile(basePage, engine.Writer); // Write last page on disk
return newPage;
}
}
public override int Read(byte[] buffer, int offset, int count)
{
int bytesLeft = count;
while (_currentPage != null && bytesLeft > 0)
{
int bytesToCopy = Math.Min(bytesLeft, _currentPage.DataBlockLength - _positionInPage);
Buffer.BlockCopy(_currentPage.DataBlock, _positionInPage, buffer, offset, bytesToCopy);
_positionInPage += bytesToCopy;
bytesLeft -= bytesToCopy;
offset += bytesToCopy;
_streamPosition += bytesToCopy;
if (_positionInPage >= _currentPage.DataBlockLength)
{
_positionInPage = 0;
if (_currentPage.NextPageID == uint.MaxValue)
_currentPage = null;
else
_currentPage = PageFactory.GetDataPage(_currentPage.NextPageID, _engine.Reader, false);
}
}
return count - bytesLeft;
}
public static DataPage GetDataPage(uint pageID, BinaryReader reader, bool onlyHeader)
{
var dataPage = new DataPage(pageID);
ReadFromFile(dataPage, reader, onlyHeader);
return dataPage;
}
public static void WriteToFile(DataPage dataPage, BinaryWriter writer)
{
// Seek the stream on first byte from data page
long initPos = writer.Seek(Header.HEADER_SIZE + ((long)dataPage.PageID * BasePage.PAGE_SIZE));
// Write data page header
writer.Write((byte)dataPage.Type);
writer.Write(dataPage.NextPageID);
writer.Write(dataPage.IsEmpty);
writer.Write(dataPage.DataBlockLength);
// I will only save data content if the page is not empty
if (!dataPage.IsEmpty)
{
// Seek the stream at the end of page header
writer.Seek(initPos + DataPage.HEADER_SIZE);
writer.Write(dataPage.DataBlock, 0, (int)dataPage.DataBlockLength);
}
}
public static void InsertFile(IndexNode node, EntryInfo enInfo, Stream stream, Engine engine)
{
var buffer = new byte[DataPage.DATA_PER_PAGE];
int dataFreeInPage = DataPage.DATA_PER_PAGE;
int writePos = 0;
int read = 0;
DataPage dataPage = engine.GetDataPage(node.DataPageID);
if (!dataPage.IsEmpty) // This is never to happend!!
{
throw new FileDBException("Page {0} is not empty", dataPage.PageID);
}
//-----------------------
//write metadata
//1. datetime of file
DateTime filedtm = enInfo.FileDateTime;
//--------------------------
writePos = WriteByte(dataPage.DataBlock, 0, 1); //marker - 1
writePos = WriteInt64(dataPage.DataBlock, writePos, filedtm.ToBinary()); //data part
//--------------------------
//2. long filename (if has long filename)
//-----------------------
if (enInfo.HasLongFileName)
{
//write full filename here
byte[] longFileNameBuff = System.Text.Encoding.UTF8.GetBytes(enInfo.FileUrl);
int buffLen = longFileNameBuff.Length;
if (buffLen > 512)
{
//for this version ***
throw new Exception("file name must not longer than 512 bytes");
}
writePos = WriteByte(dataPage.DataBlock, writePos, 2); //marker 2 long filename
//--------
writePos = WriteUInt16(dataPage.DataBlock, writePos, (ushort)buffLen); //2 bytes length of buffer
writePos = WriteBuffer(dataPage.DataBlock, writePos, longFileNameBuff); //buffer
//--------
}
dataPage.IsEmpty = false;
dataPage.DataBlockLength = (short)writePos;
dataFreeInPage -= writePos;
node.FileMetaDataLength = (ushort)writePos;
//-----------------------
bool isFirstRound = true;
uint fileLength = 0;
while ((read = stream.Read(buffer, 0, dataFreeInPage)) > 0)
{
//if we have some data to write
fileLength += (uint)read;
if (!isFirstRound)
{
dataPage = GetNewDataPage(dataPage, engine);
if (!dataPage.IsEmpty) // This is never to happend!!
{
throw new FileDBException("Page {0} is not empty", dataPage.PageID);
}
}
writePos = WriteBuffer(dataPage.DataBlock, writePos, buffer, read);
dataPage.IsEmpty = false;
dataPage.DataBlockLength = (short)writePos;
//----------------------------------------------
//reset for next
dataFreeInPage = DataPage.DATA_PER_PAGE;
writePos = 0;
isFirstRound = false;
//----------------------------------------------
}
// If the last page point to another one, i need to fix that
if (dataPage.NextPageID != uint.MaxValue)
{
engine.Header.FreeDataPageID = dataPage.NextPageID;
dataPage.NextPageID = uint.MaxValue;
}
// Save the last page on disk
PageFactory.WriteToFile(dataPage, engine.Writer);
// Save on node index that file length
node.FileLength = fileLength;
}
