public IEnumerable<PartitionedFileStream> GetStreams()
{
_fileStream.Seek(0, SeekOrigin.Begin);
var header = new PartitionedFileHeader(0);
header.Read(_fileStream);
var currentIndex = PartitionedFileHeader.DataOffset;
var dataStart = currentIndex;
var allOffsets = new List<long>();
while (currentIndex + sizeof(long) < dataStart + header.LengthOfCurrentBuffer)
{
var partitionedFileStreamOffset = Serializer.DeserializeLong(_fileStream);
allOffsets.Add(partitionedFileStreamOffset);
}
var allStreams = new List<PartitionedFileStream>();
foreach (var offset in allOffsets)
{
header = new PartitionedFileHeader(offset);
_fileStream.Seek(offset, SeekOrigin.Begin);
header.Read(_fileStream);
allStreams.Add(new PartitionedFileStream(_fileStream, header, AddNewHeaderSection));
}
return allStreams;
}
public PartitionedFileStreamFactory(string fileName)
{
_fileStream = new FileStream(fileName, FileMode.OpenOrCreate);
if (_fileStream.Length == 0)
{
_header = new PartitionedFileHeader(0);
_dataStart = _newStreamOffset = PartitionedFileHeader.DataOffset;
_header.Write(_fileStream);
}
}
public PartitionedFileStream(FileStream fileStream, PartitionedFileHeader header, Func<PartitionedFileHeader> getNewHeader)
{
_fileStream = fileStream;
_header = header;
_getNewHeader = getNewHeader;
UpdateLength();
SeekFromBegin(0);
_position = 0;
}
public PartitionedFileStream GetNewStream()
{
var bufferOverrun = (_newStreamOffset + sizeof (long)) - (_dataStart + _header.LengthOfCurrentBuffer);
if (bufferOverrun > 0)
{
_header.OffsetOfNextHeader = _fileStream.Length;
_fileStream.Seek(_currentHeaderOffset, SeekOrigin.Begin);
_header.Write(_fileStream);
_currentHeaderOffset = _header.OffsetOfHeader;
_header = AddNewHeaderSection();
_header.OffsetOfPrevHeader = _currentHeaderOffset;
_fileStream.Seek(_header.OffsetOfHeader, SeekOrigin.Begin);
_header.Write(_fileStream);
}
_fileStream.Seek(_newStreamOffset, SeekOrigin.Begin);
var newHeader = AddNewHeaderSection();
Serializer.Serialize(_fileStream, _fileStream.Length);
_newStreamOffset += sizeof (long);
return new PartitionedFileStream(_fileStream, newHeader, AddNewHeaderSection);
}
public PartitionedFileHeader AddNewHeaderSection()
{
var header = new PartitionedFileHeader(_fileStream.Length) { LengthOfCurrentBuffer = _bufferSize };
_fileStream.Seek(0, SeekOrigin.End);
header.Write(_fileStream);
var buffer = new byte[_bufferSize];
_fileStream.Write(buffer, 0, buffer.Length);
_fileStream.Seek(PartitionedFileHeader.DataOffset, SeekOrigin.Begin);
return header;
}
private void MoveToPreviousHeader()
{
if (_header.OffsetOfPrevHeader == null)
throw new InvalidOperationException("Already at the beginning of the Stream");
var oldPosition = _fileStream.Position;
_fileStream.Seek(_header.OffsetOfPrevHeader.Value, SeekOrigin.Begin);
_header = new PartitionedFileHeader(_header.OffsetOfPrevHeader.Value);
_header.Read(_fileStream);
_fileStream.Seek(oldPosition, SeekOrigin.Begin);
}
private void MoveToNextHeader()
{
var oldPosition = _fileStream.Position;
if (_header.OffsetOfNextHeader == null)
{
var nextHeader = _getNewHeader();
_header.OffsetOfNextHeader = nextHeader.OffsetOfHeader;
_fileStream.Seek(_header.OffsetOfHeader, SeekOrigin.Begin);
_header.Write(_fileStream);
nextHeader.OffsetOfPrevHeader = _header.OffsetOfHeader;
_fileStream.Seek(nextHeader.OffsetOfHeader, SeekOrigin.Begin);
nextHeader.Write(_fileStream);
_header = nextHeader;
}
else
{
_fileStream.Seek(_header.OffsetOfNextHeader.Value, SeekOrigin.Begin);
_header = new PartitionedFileHeader(_header.OffsetOfNextHeader.Value);
_header.Read(_fileStream);
}
_fileStream.Seek(oldPosition, SeekOrigin.Begin);
}
private PartitionedFileHeader AddNewHeaderSection()
{
const int bufferSize = 4096;
var header = new PartitionedFileHeader(_fileStream.Length) {LengthOfCurrentBuffer = bufferSize};
_fileStream.Seek(0, SeekOrigin.End);
header.Write(_fileStream);
var buffer = new byte[bufferSize];
_fileStream.Write(buffer, 0, buffer.Length);
return header;
}