static public IEnumerable <(string filename, string content)> ReadFromFileStreamBackwards(string fileName,
Func <string, FileStream> OpenFile, long maxLines = long.MaxValue)
{
FileSeeker f = new FileSeeker();
using var fileStream = new FileStreamWrapper(OpenFile(fileName));
fileStream.Seek(0, SeekOrigin.End); // We want to read backwards - so start at the end
for (; ;)
{
string line = null;
try
{
line = f.SeekLastLineFromCurrentAndPositionOnStartOfItAndReturnReadLine(fileStream);
}
catch (Exception)
{
}
if (line != null && --maxLines > 0)
{
yield return(Path.GetFileNameWithoutExtension(fileName), line);
}
else
{
break;
}
}
}
public int ReadPageData(FileStreamWrapper stream, int pageIdx)
{
if (null == stream)
{
throw new ArgumentNullException();
}
byte[] dataBuffer = new byte[PageSize];
// read from the file stream
if (0 > pageIdx ||
stream.Length < (pageIdx + 1) * PageSize)
{
throw new InvalidPageException();
}
stream.Seek(pageIdx * PageSize, SeekOrigin.Begin);
stream.Read(dataBuffer, 0, dataBuffer.Length);
// initialize members
this.recordList = new List <byte[]>();
this.ReadPageData(dataBuffer);
return(pageIdx);
}
public void SPT_TestReadWriteTable()
{
int entryCount = 40;
int physicalPageDistance = 5;
string dataFile = "SPT_TestData1.tpdb";
if (File.Exists(dataFile))
{
File.Delete(dataFile);
}
List <int> freedPages = null;
StoragePageManager spaceMgr = new StoragePageManager();
StoragePageTable pageTable2 = new StoragePageTable();
StoragePageTable pageTable = new StoragePageTable();
for (int idx = 0; idx < entryCount; idx++)
{
pageTable.SetLogicalPage(idx + physicalPageDistance);
}
using (FileStreamWrapper dataFileStream = FileStreamWrapper.CreateObject(dataFile))
{
int root = pageTable.WritePageTableData(dataFileStream, spaceMgr, out freedPages);
dataFileStream.Seek(0, SeekOrigin.Begin);
pageTable2.ReadPageTableData(dataFileStream, root);
}
for (int idx = 0; idx < entryCount; idx++)
{
int physicalAddress = pageTable2.GetPhysicalPage(idx);
Assert.AreEqual(idx + physicalPageDistance, physicalAddress);
}
}
public int WritePageData(FileStreamWrapper stream, int pageIdx)
{
if (null == stream)
{
throw new ArgumentNullException();
}
// get the page data
byte[] dataBuffer = new byte[PageSize];
this.WritePageData(dataBuffer);
// write to the file stream
if (0 > pageIdx ||
stream.Length < pageIdx * PageSize)
{
pageIdx = (int)(stream.Length / PageSize);
}
stream.Seek(pageIdx * PageSize, SeekOrigin.Begin);
stream.Write(dataBuffer, 0, dataBuffer.Length);
return(pageIdx);
}
public int ReadPageData(FileStreamWrapper stream, int pageIdx)
{
if (null == stream)
{
throw new ArgumentNullException();
}
byte[] dataBuffer = new byte[PageSize];
// read from the file stream
if (0 > pageIdx
|| stream.Length < (pageIdx + 1) * PageSize)
{
throw new InvalidPageException();
}
stream.Seek(pageIdx * PageSize, SeekOrigin.Begin);
stream.Read(dataBuffer, 0, dataBuffer.Length);
// initialize members
this.recordList = new List<byte[]>();
this.ReadPageData(dataBuffer);
return pageIdx;
}
public int WritePageData(FileStreamWrapper stream, int pageIdx)
{
if (null == stream)
{
throw new ArgumentNullException();
}
// get the page data
byte[] dataBuffer = new byte[PageSize];
this.WritePageData(dataBuffer);
// write to the file stream
if (0 > pageIdx
|| stream.Length < pageIdx * PageSize)
{
pageIdx = (int)(stream.Length / PageSize);
}
stream.Seek(pageIdx * PageSize, SeekOrigin.Begin);
stream.Write(dataBuffer, 0, dataBuffer.Length);
return pageIdx;
}
