/// <summary>
/// Method to create an index file if one does not exist.
/// </summary>
/// <param name="sourcefilename">Source filename.</param>
/// <param name="sequencePointers">List of sequences in the source</param>
/// <returns>IndexedSequenceProvider object</returns>
public static SidecarFileProvider CreateIndexFile(string sourcefilename, IList <SequencePointer> sequencePointers)
{
if (sequencePointers == null)
{
throw new ArgumentNullException("sequencePointers");
}
using (FileStream outputStream = new FileStream(sourcefilename + IndexFileExtension, FileMode.Create))
{
using (BinaryWriter writer = new BinaryWriter(outputStream))
{
// create a new master index file
IndexFileHeader header = new IndexFileHeader(sourcefilename, sequencePointers.Count);
// Spare space for writing filesize and date later on
outputStream.Seek(sizeof(long) * 2, SeekOrigin.Begin);
// serialize header information
BinaryFormatter headerWriter = new BinaryFormatter();
headerWriter.Serialize(outputStream, header);
// serialize sequence pointer objects
int index;
for (index = 0; index < sequencePointers.Count; index++)
{
WritePointer(outputStream, sequencePointers[index]);
}
outputStream.Seek(0, SeekOrigin.Begin);
// Write to the space left at top (File size and date)
writer.Write(outputStream.Length);
writer.Write(DateTime.Now.Date.ToFileTime());
}
}
return(new SidecarFileProvider(sourcefilename));
}
/// <summary>
/// Initializes a new instance of IndexedSequenceProvider class.
/// </summary>
/// <param name="sourceFilename">Full path to the source sequence file.
/// This method will search for the index file by itself</param>
private SidecarFileProvider(string sourceFilename)
{
try
{
_inputStream = new FileStream(sourceFilename + IndexFileExtension, FileMode.Open, FileAccess.Read);
_offsetReader = new BinaryReader(_inputStream);
_sidecarLength = _offsetReader.ReadInt64();
_sidecarLastWriteTime = _offsetReader.ReadInt64();
// read header info
BinaryFormatter headerFormatter = new BinaryFormatter();
_header = headerFormatter.Deserialize(_inputStream) as IndexFileHeader;
_contentsOffset = _inputStream.Position; // TOC starts just after the header
}
catch
{
// Dispose of streams if opened and later crashed
Dispose();
throw;
}
}
