public static void ReadFromFile(IndexPage indexPage, BinaryReader reader)
{
// Seek the stream to the first byte on page
long initPos = reader.SetReadPos(Header.FILE_START_HEADER_SIZE + (indexPage.PageID * BasePage.PAGE_SIZE));
if (reader.ReadByte() != (byte)PageType.Index)
throw new FileDBException("PageID {0} is not a Index Page", indexPage.PageID);
indexPage.NextPageID = reader.ReadUInt32();
indexPage.SetUsedNodeCount(reader.ReadByte());
// Seek the stream to end of header data page
reader.SetReadPos(initPos + IndexPage.INDEX_HEADER_SIZE);
//in this version
//each node uses buffer= 16+1+1+4+1+4+4+8+4+2+36 =81
//IndexPage.NODES_PER_PAGE = 50;
//so it use 81*50 = 4050
//IndexPage.INDEX_HEADER_SIZE =46
//so => 4050 +46 = 4096
//and each page has BasePage.PAGE_SIZE = 4096 => matched
for (int i = 0; i <= indexPage.UsedNodeCount; i++)
{
var node = indexPage.Nodes[i];
node.ID = reader.ReadGuid(); //16
node.IsDeleted = reader.ReadBoolean(); //1
node.Right.Index = reader.ReadByte(); //1
node.Right.PageID = reader.ReadUInt32(); //4
node.Left.Index = reader.ReadByte(); //1
node.Left.PageID = reader.ReadUInt32();//4
node.DataPageID = reader.ReadUInt32();//4
node.FileMetaDataLength = reader.ReadUInt16();//2
node.FileLength = reader.ReadUInt32();//4
int filenameCount = reader.ReadByte(); //1
if (filenameCount > IndexNode.FILENAME_SIZE)
{
node.FileUrl = reader.ReadUtf8String(IndexNode.FILENAME_SIZE);
}
else
{
string filename = reader.ReadUtf8String(IndexNode.FILENAME_SIZE);
node.FileUrl = filename.Substring(0, filenameCount);
}
}
}
public static BasePage GetBasePage(uint pageID, BinaryReader reader)
{
// Seek the stream at begin of page
long initPos = reader.SetReadPos(Header.FILE_START_HEADER_SIZE + (pageID * BasePage.PAGE_SIZE));
if (reader.ReadByte() == (byte)PageType.Index)
return GetIndexPage(pageID, reader);
else
return GetDataPage(pageID, reader, true);
}
public static void ReadFromFile(DataPage dataPage, BinaryReader reader, bool onlyHeader)
{
// Seek the stream on first byte from data page
long initPos = reader.SetReadPos(Header.FILE_START_HEADER_SIZE + (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.SetReadPos(initPos + DataPage.DATA_HEADER_SIZE);
// Read all bytes from page
dataPage.DataBlock = reader.ReadBytes(dataPage.DataBlockLength);
}
}
