/// <summary>
/// Fetches a range of items.
/// </summary>
/// <param name="startIndex">The start index.</param>
/// <param name="count">The number of items to fetch.</param>
/// <returns></returns>
public override IList <BigFileLine> FetchRange(int startIndex, int pageCount, out int overallCount)
{
//Trace.WriteLine("FetchRangeBigText: " + startIndex + "," + pageCount);
lock (_inputStream)
{
if (_disposed || (startIndex / 100 >= _100LineIndex.Count))
{
overallCount = _lastFetchCount;
return(new List <BigFileLine>());
}
int pos100BoundaryIndex = startIndex / 100;
long pos100Boundary = _100LineIndex[startIndex / 100];
_inputStream.Seek(pos100Boundary, SeekOrigin.Begin);
List <BigFileLine> list = _lineConverter.GetLines(_inputStream, startIndex - pos100BoundaryIndex * 100, Math.Min(startIndex + pageCount, Count) - startIndex);
BlockingCollection <BigFileLine> columnCounter = StartCountingColumns();
foreach (var line in list)
{
columnCounter.Add(line);
}
columnCounter.CompleteAdding();
overallCount = _lastFetchCount;
return(list);
}
}
/// <summary>
/// Initializes a new instance of the <see cref="DemoCustomerProvider"/> class.
/// </summary>
/// <param name="count">The count.</param>
/// <param name="fetchDelay">The fetch delay.</param>
public FileLinesProvider(string inputFilename, int maxRows, BigFileLine lineConverter)
{
_maxRows = maxRows;
_lineConverter = lineConverter;
_inputFilename = inputFilename;
_inputStream = new FileStream(inputFilename, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
var firstLine = _lineConverter.GetLines(_inputStream, 0, 1).FirstOrDefault();
if (firstLine != null)
{
Header = firstLine.Columns.Aggregate((a, b) => a + "," + b);
}
_lineCountTask = Task.Run(() => CountLines(inputFilename, maxRows));
}
