/// <summary>
/// Reads bytes for a specific document from the database.
/// </summary>
/// <param name="dataContext">The DataContext for the database.</param>
/// <param name="documentID">The ID of the document to read the content for.</param>
/// <param name="offset">The starting offset to read the content bytes from.</param>
/// <param name="length">The length of content bytes to read.</param>
/// <returns>A byte array containing the document content for the specified byte range.</returns>
public async Task <byte[]> ReadChunk(Data.DataContext dataContext, Guid documentID, int offset, int length)
{
string filename = Path.Combine(_uploadPath, documentID.ToString("D") + ".part");
if (!File.Exists(filename))
{
lock (_lock)
{
if (!File.Exists(filename))
{
string tempFileName = Path.Combine(_uploadPath, "temp_" + documentID.ToString("D") + ".part");
using (var fs = new FileStream(tempFileName, FileMode.Append, FileAccess.Write, FileShare.Write))
using (var dbStream = new Data.Documents.DocumentStream(dataContext, documentID))
{
dbStream.CopyTo(fs);
fs.Flush();
fs.Close();
}
File.Move(tempFileName, filename);
}
}
}
byte[] buffer = new byte[length];
using (var stream = new FileStream(filename, FileMode.Open, FileAccess.Read, FileShare.Read))
{
stream.Seek(offset, SeekOrigin.Begin);
await stream.ReadAsync(buffer, 0, buffer.Length);
}
return(buffer);
}
/// <summary>
/// Returns a readonly stream for the specified document from the local disk cache.
/// </summary>
/// <param name="dataContext">The current datacontext to use if the cache needs to be populated.</param>
/// <param name="documentID">The ID of the document.</param>
/// <returns></returns>
public Stream GetStream(Data.DataContext dataContext, Guid documentID)
{
string filename = Path.Combine(_uploadPath, documentID.ToString("D") + ".part");
if (!File.Exists(filename))
{
lock (_lock)
{
if (!File.Exists(filename))
{
string tempFileName = Path.Combine(_uploadPath, "temp_" + documentID.ToString("D") + ".part");
using (var fs = new FileStream(tempFileName, FileMode.Append, FileAccess.Write, FileShare.ReadWrite))
using (var dbStream = new Data.Documents.DocumentStream(dataContext, documentID))
{
dbStream.CopyTo(fs);
fs.Flush();
fs.Close();
}
File.Move(tempFileName, filename);
}
}
}
return(new FileStream(filename, FileMode.Open, FileAccess.Read, FileShare.ReadWrite));
}
public void DownloadDocument()
{
Guid documentID = new Guid("6F1D10BB-B3E2-4028-A1E5-A84D011E4249");
using (var db = new DataContext())
{
var document = db.Documents.Single(d => d.ID == documentID);
using (var writer = File.OpenWrite(document.FileName))
using (var reader = new Data.Documents.DocumentStream(db, documentID))
{
reader.CopyTo(writer);
reader.Flush();
writer.Flush();
writer.Close();
}
}
}
