public EnumWriter(IStreamProvider streamProvider, string columnPath, Type columnType, IColumnWriter valueWriter)
{
_streamProvider = streamProvider;
_columnPath = columnPath;
_valueWriter = valueWriter;
_dictionary = (IEnumColumnDictionary)Allocator.ConstructGenericOf(typeof(EnumColumnDictionary <>), columnType);
_rowIndexWriter = new PrimitiveArrayWriter <byte>(streamProvider.OpenWrite(Path.Combine(_columnPath, RowIndexFileName)));
}
public void Dispose()
{
// If we're still an enum column, write the distinct values out
if (_dictionary != null)
{
_valueWriter.Append(_dictionary.Values());
_dictionary = null;
}
if (_valueWriter != null)
{
_valueWriter.Dispose();
_valueWriter = null;
}
if (_rowIndexWriter != null)
{
_rowIndexWriter.Dispose();
_rowIndexWriter = null;
}
}
private void Convert()
{
// Close the row index writer
_rowIndexWriter.Dispose();
_rowIndexWriter = null;
// If we wrote any rows we need to convert...
if (_rowCountWritten > 0)
{
// Get the set of unique values and get rid of the value dictionary
XArray values = _dictionary.Values();
// Convert the indices previously written into raw values
Func <XArray, XArray> converter = TypeConverterFactory.GetConverter(typeof(byte), typeof(int));
using (IColumnReader rowIndexReader = new PrimitiveArrayReader <byte>(_streamProvider.OpenRead(Path.Combine(_columnPath, RowIndexFileName))))
{
int rowCount = rowIndexReader.Count;
ArraySelector page = ArraySelector.All(0).NextPage(rowCount, 10240);
while (page.Count > 0)
{
// Read an XArray of indices and convert to int[]
XArray rowIndices = converter(rowIndexReader.Read(page));
// Write the corresponding values
// Reselect is safe because 'values' are converted to a contiguous array
_valueWriter.Append(values.Reselect(ArraySelector.Map((int[])rowIndices.Array, rowIndices.Count)));
page = page.NextPage(rowCount, 10240);
}
}
}
// Remove the Dictionary (so future rows are streamed out as-is)
_dictionary = null;
// Delete the row index file
_streamProvider.Delete(Path.Combine(_columnPath, RowIndexFileName));
}
