private void TryCleanupExistingDownloadWebClient()
{
if (downloadWebClient == null)
{
return;
}
try
{
lock (this)
{
if (downloadWebClient != null)
{
downloadWebClient.DownloadFileCompleted -= OnDownloadCompleted;
downloadWebClient.DownloadProgressChanged -= OnDownloadProgressChanged;
downloadWebClient.OpenReadCompleted -= OnOpenReadCompleted;
downloadWebClient.CancelAsync();
downloadWebClient.Dispose();
downloadWebClient = null;
}
}
}
catch (Exception e)
{
logger.Warn("Error while cleaning up web client : {0}", e.Message);
}
}
private void TriggerWebClientDownloadFileAsync()
{
logger.Debug("Falling back to legacy DownloadFileAsync.");
try
{
isFallback = true;
string destinationDirectory = Path.GetDirectoryName(localFileName);
if (destinationDirectory != null && !Directory.Exists(destinationDirectory))
{
Directory.CreateDirectory(destinationDirectory);
}
TryCleanupExistingDownloadWebClient();
downloadWebClient = CreateWebClient();
downloadWebClient.DownloadFileAsync(fileSource, localFileName);
logger.Debug("Download async started. Source: {0} Destination: {1}", fileSource, localFileName);
}
catch (Exception ex)
{
logger.Warn("Failed to download Source:{0}, Destination:{1}, Error:{2}.", fileSource, localFileName, ex.Message);
if (!AttemptDownload())
{
InvokeDownloadCompleted(CompletedState.Failed, localFileName, ex);
}
}
}
private DownloadWebClient CreateWebClient()
{
DownloadWebClient webClient = new DownloadWebClient();
webClient.DownloadFileCompleted += OnDownloadCompleted;
webClient.DownloadProgressChanged += OnDownloadProgressChanged;
webClient.OpenReadCompleted += OnOpenReadCompleted;
return(webClient);
}
private void Download(Uri source, string fileDestination, long totalBytesToReceive)
{
try
{
long seekPosition;
FileHelpers.TryGetFileSize(fileDestination, out seekPosition);
TryCleanupExistingDownloadWebClient();
downloadWebClient = CreateWebClient();
downloadWebClient.OpenReadAsync(source, seekPosition);
logger.Debug("Download started. Source: {0} Destination: {1} Size: {2}", source, fileDestination, totalBytesToReceive);
}
catch (Exception e)
{
logger.Debug("Download failed: {0}", e.Message);
if (!AttemptDownload())
{
InvokeDownloadCompleted(CompletedState.Failed, localFileName, e);
}
}
}
private void OnOpenReadCompleted(object sender, OpenReadCompletedEventArgs args)
{
DownloadWebClient webClient = sender as DownloadWebClient;
if (webClient == null)
{
logger.Warn("Wrong sender in OnOpenReadCompleted: Actual:{0} Expected:{1}", sender.GetType(), typeof(DownloadWebClient));
return;
}
lock (cancelSync)
{
if (isCancelled)
{
logger.Debug("Download was cancelled.");
return;
}
if (!webClient.HasResponse)
{
logger.Debug("DownloadWebClient returned no response.");
TriggerWebClientDownloadFileAsync();
return;
}
bool appendExistingChunk = webClient.IsPartialResponse;
Stream destinationStream = CreateDestinationStream(appendExistingChunk);
if (destinationStream != null)
{
TrySetStreamReadTimeout(args.Result, (int)SourceStreamReadTimeout.TotalMilliseconds);
worker = new StreamCopyWorker();
worker.Completed += OnWorkerCompleted;
worker.ProgressChanged += OnWorkerProgressChanged;
worker.CopyAsync(args.Result, destinationStream, TotalBytesToReceive);
}
}
}
/// <summary>
/// OnDownloadCompleted event handler
/// </summary>
/// <param name="sender">Sender object</param>
/// <param name="args">AsyncCompletedEventArgs instance</param>
protected void OnDownloadCompleted(object sender, AsyncCompletedEventArgs args)
{
DownloadWebClient webClient = sender as DownloadWebClient;
if (webClient == null)
{
logger.Warn("Wrong sender in OnDownloadCompleted: Actual:{0} Expected:{1}", sender.GetType(), typeof(DownloadWebClient));
InvokeDownloadCompleted(CompletedState.Failed, localFileName);
return;
}
if (args.Cancelled)
{
logger.Debug("Download cancelled. Source: {0} Destination: {1}", fileSource, localFileName);
if (!isPaused)
{
DeleteDownloadedFile();
}
InvokeDownloadCompleted(CompletedState.Canceled, localFileName);
readyToDownload.Set();
}
else if (args.Error != null)
{
if (isFallback)
{
DeleteDownloadedFile();
}
////We may have NameResolutionFailure on internet connectivity problem.
////We don't use DnsFallbackResolver if we successfully started downloading, and then got internet problem.
////If we change [this.fileSource] here - we lose downloaded chunk in Cache (i.e. we create a new Cache item for new [this.fileSource]
if (attemptNumber == 1 && DnsFallbackResolver != null && IsNameResolutionFailure(args.Error))
{
Uri newFileSource = DnsFallbackResolver.Resolve(fileSource);
if (newFileSource != null)
{
fileSource = newFileSource;
logger.Debug("Download failed in case of DNS resolve error. Retry downloading with new source: {0}.", fileSource);
AttemptDownload();
return;
}
}
logger.Debug("Download failed. Source: {0} Destination: {1} Error: {2}", fileSource, localFileName, args.Error);
if (!AttemptDownload())
{
InvokeDownloadCompleted(CompletedState.Failed, null, args.Error);
readyToDownload.Set();
}
}
else
{
if (useFileNameFromServer)
{
localFileName = ApplyNewFileName(localFileName, webClient.GetOriginalFileNameFromDownload());
}
logger.Debug("Download completed. Source: {0} Destination: {1}", fileSource, localFileName);
if (UseCaching)
{
downloadCache.Add(fileSource, localFileName, webClient.ResponseHeaders);
}
////we may have the destination file not immediately closed after downloading
WaitFileClosed(localFileName, TimeSpan.FromSeconds(3));
InvokeDownloadCompleted(CompletedState.Succeeded, localFileName, null);
readyToDownload.Set();
}
}
