/// <summary>
/// Seek with position not loading data immediately.
/// </summary>
/// <param name="position">
/// The position to restore
/// </param>
/// <returns>
/// Success boolean flag; whether a data file to be read was found. It may not be exact match for the position, however.
/// </returns>
/// <remarks>
/// The position is saved and completely restored when <see cref="LoadNextFile"/> is called; issues are reported
/// via <see cref="IRepositoryReader.SeekStatusCallback"/>, success is not reported, only warnings
/// , <see cref="FolderSeekStatus.PositionStatus"/>.
/// Note that you cannot change reading direction after the call to this method until you load the file and restore
/// the reading position.
/// </remarks>
public bool SeekDataFile(IFolderReadingPosition position)
{
// save position copy
_position.FromSeek(position);
bool retval = null != _fileIterator.Seek(position.Time, Backwards);
if (position.IsExact && (!retval || !_fileIterator.Current.Name.IsCovering(position.Time)))
{
_log.WarnFormat("Seek on folder {0} have not found data file containing item referenced in the position: {1}"
, position.FolderKey
, position.Time);
MasterReader.SeekStatusCallback(new FolderSeekStatus(TargetFolder.FolderKey, FolderSeekStatus.PositionStatus.FileNotFound));
}
if (retval)
{
DateTime firstTimeInFile = _getFirstItemToReadFromFileName(NextDataFile.Name);
if (_timeComparison.Compare(position.Time, firstTimeInFile) > 0)
{
// file starts before the seek time, so will need to skip some items in it
firstTimeInFile = _position.Time;
}
NextFileFirstTimestampToRead = firstTimeInFile;
}
WasPositioned = true;
LastSeekTime = position.Time;
SoughtFileLoaded = false;
return(retval);
}
/// <summary>
/// Given first logical (according to direction) item timestamp in file and logical time comparison (again, according
/// to direction) determine whether the file is to be read in full when restoring this position
/// </summary>
/// <param name="firstItemTimestampInFile">
/// First logical item timestamp in the file (of either first or last item when going forward and backwards respectively)
/// </param>
/// <param name="comparison">
/// Time comparison implementation
/// </param>
/// <returns>
/// <see langword="true"/> if first item in the file represented by <paramref name="firstItemTimestampInFile"/> will have to be read
/// <see langword="false"/> otherwise, i.e. when at least 1 item will have to be skipped
/// </returns>
public bool IsFileToBeReadInFull(DateTime firstItemTimestampInFile, Util.IDirectedTimeComparison comparison)
{
int cmp = comparison.Compare(firstItemTimestampInFile, Time);
return cmp > 0 || (cmp == 0 && NumberOfItemsWithTheTimestampRead == 0);
}