/// <summary>
/// Pull out sorted batches from the RowSorter instance and save them using the IBatchHandler implementation.
/// Also return the first batch as an output.
/// </summary>
/// <param name="rowSorter">RowSorter instance.</param>
/// <returns>The first batch pulled from the RowSorter.</returns>
private Batch SaveBatchesAndReturnFirstBatch(RowSorter rowSorter)
{
// Get an enumerator over the batch list.
IEnumerable<RowSorter.SortedBatch> batchEnumerator = rowSorter.PullSortedBatches();
// Prepare a batch header instance. The BatchCode will be the folder name under which we will write files corresponding
// to each sorted batch. Every batch will have a knowledge that contains the information in the batch. So we have to combine
// the existing client knowledge with the batch knowledge before returning it back to the caller.
var header = new BatchHeader
{
BatchCode = Guid.NewGuid(), // New batch code.
BatchFileNames = new List<string>()
};
var batchList = new List<Batch>();
Guid batchName = Guid.NewGuid();
Guid nextBatchName = Guid.NewGuid();
foreach (var sortedBatch in batchEnumerator)
{
// Create a new batch instance.
var b = new Batch
{
BatchCode = header.BatchCode,
FileName = batchName.ToString(), // Random file name
LearnedKnowledge = sortedBatch.sortedDataSetKnowledge.Serialize(),
Data = sortedBatch.sortedDataSet,
ClientScopeName = _clientScopeName,
NextBatch = nextBatchName
};
header.BatchFileNames.Add(b.FileName);
batchList.Add(b);
// Set the batch names.
batchName = nextBatchName;
nextBatchName = Guid.NewGuid();
}
// If there are no batches, just return.
if (0 == batchList.Count)
{
return null;
}
// Set properties for the last batch.
batchList[batchList.Count - 1].IsLastBatch = true;
batchList[batchList.Count - 1].NextBatch = null;
// Only save if we have more than 1 batch.
if (batchList.Count > 1)
{
// Save all but the first batch, since we are sending that to the client as a response to the current request.
_batchHandler.SaveBatches(batchList.Skip(1).ToList(), header);
}
// Return the first batch.
return batchList[0];
}
/// <summary>
/// Gets the next batch in a sequence.
/// </summary>
/// <param name="batchCode">Batch code value</param>
/// <param name="nextBatchSequenceNumber">Sequence number of the next batch</param>
/// <returns>Batch information</returns>
public Batch GetNextBatch(Guid batchCode, Guid nextBatchSequenceNumber)
{
// Create the batch directory.
var path = Path.Combine(_batchSpoolDirectory, batchCode.ToString());
if (!Directory.Exists(path))
{
// no batch found.
return(null);
}
string headerFilePath = Path.Combine(path, BATCH_HEADER_FILENAME);
BatchHeader header = null;
if (File.Exists(headerFilePath))
{
var headerFormatter = new BinaryFormatter();
using (var fileStream = new FileStream(headerFilePath, FileMode.Open, FileAccess.Read))
{
header = headerFormatter.Deserialize(fileStream) as BatchHeader;
}
}
if (null == header)
{
// no header
return(null);
}
// Get the batch file name from the header.
string batchFile = header.BatchFileNames.Where(b => new Guid(b) == nextBatchSequenceNumber).FirstOrDefault();
if (String.IsNullOrEmpty(batchFile))
{
// missing batch file.
return(null);
}
string batchFilePath = Path.Combine(path, batchFile);
Batch batch = null;
if (File.Exists(batchFilePath))
{
var formatter = new BinaryFormatter();
using (var fileStream = new FileStream(batchFilePath, FileMode.Open, FileAccess.Read))
{
batch = formatter.Deserialize(fileStream) as Batch;
}
}
if (null != batch)
{
string filePath = Path.Combine(path, batch.FileName);
if (File.Exists(filePath))
{
File.Delete(filePath);
}
if (batch.IsLastBatch)
{
// If this is the last batch then try to cleanup the directory.
CleanupBatchDirectory(path, headerFilePath, header);
}
}
return(batch);
}