/// <summary>
/// Executes the upload as defined by the input parameters.
/// </summary>
public void Execute()
{
//load up existing metadata or create a fresh one
var metadata = GetMetadata();
if (metadata.SegmentCount < this.Parameters.ThreadCount)
{
// reducing the thread count to make it equal to the segment count
// if it is larger, since those extra threads will not be used.
this.Parameters.ThreadCount = metadata.SegmentCount;
}
//begin (or resume) uploading the file
UploadFile(metadata);
if (_frontEnd.StreamExists(metadata.SegmentStreamDirectory))
{
// delete the folder that contained the intermediate segments, if there was one (for single segment uploads there will not be)
_frontEnd.DeleteStream(metadata.SegmentStreamDirectory, true);
}
//clean up metadata after a successful upload
metadata.DeleteFile();
}
/// <summary>
/// Downloads the portion of the InputFilePath to the given TargetStreamPath, starting at the given StartOffset.
/// The segment is further divided into equally-sized blocks which are downloaded in sequence.
/// Each such block is attempted a certain number of times; if after that it still cannot be downloaded, the entire segment is aborted (in which case no cleanup is performed on the server).
/// </summary>
/// <returns></returns>
public void Download()
{
if (!_frontEnd.StreamExists(_metadata.InputFilePath, !_metadata.IsDownload))
{
throw new FileNotFoundException("Unable to locate input file", _metadata.InputFilePath);
}
if (_token.IsCancellationRequested)
{
_token.ThrowIfCancellationRequested();
}
//open a file stream (truncate it if it already exists) for the target segment
// we always truncate here because overwrite validation should have already been done.
// always create the directory as well
Directory.CreateDirectory(Path.GetDirectoryName(_segmentMetadata.Path));
// download the data
DownloadSegmentContents();
VerifyDownloadedStream();
//any exceptions are (re)thrown to be handled by the caller; we do not handle retries or other recovery techniques here
}