MongoDB.GridFS.GridStream.LoadChunk C# (CSharp) Метод

        private void LoadChunk(int n)
        {
            Contract.Requires(n > -1);
              Contract.Requires(n <= _totalChunks);
              if (n == _currentIndex) return;

              if (n >= _totalChunks)
              {
            _currentChunk = CreateChunk(n);
            _totalChunks = n + 1;
              }
              else
              {
            _currentChunk = _chunks.FindOne(new Doc {{"files_id", _fileInfo.Id}, {"n", n}});
              }

              _currentIndex = n;
              var data = _currentChunk["data"] as byte[];
              if (!IsFull(_currentChunk)) //non-full chunk
              {
            _buffer = new MemoryStream(new byte[_fileInfo.ChunkSize]);
            _buffer.Write(data, 0, data.Length);
              }
              else
              {
            _buffer = new MemoryStream(data);
              }
        }