private async Task DownloadItemImplAsync(
SemaphoreSlim downloadThrottle,
ContainerItem ticketedItem,
string downloadPath,
CancellationToken cancellationToken)
{
try
{
await downloadThrottle.WaitAsync().ConfigureAwait(false);
if (cancellationToken.IsCancellationRequested)
{
return;
}
// Download the file content to a temp file on the same drive.
// Assumption: the build won't produce files ending in .download.
string tmpDownloadPath = downloadPath + ".download";
FileSystemManager.EnsureParentDirectory(tmpDownloadPath);
FileSystemManager.DeleteFile(downloadPath);
await GetFileAsync(ticketedItem, tmpDownloadPath, cancellationToken).ConfigureAwait(false);
if (cancellationToken.IsCancellationRequested)
{
return;
}
// With the content successfully downloaded, move the tmp file to its permanent location.
FileSystemManager.MoveFile(tmpDownloadPath, downloadPath);
}
finally
{
downloadThrottle.Release();
}
}
// Wraps our use of the proxy client library
private async Task GetFileAsync(ContainerItem ticketedItem, string tmpDownloadPath, CancellationToken cancellationToken)
{
// Will get doubled on each attempt.
TimeSpan timeBetweenRetries = ContainerFetchEngineOptions.RetryInterval;
for (int triesRemaining = ContainerFetchEngineOptions.RetryLimit; ; triesRemaining--)
{
bool lastAttempt = (triesRemaining == 0);
timeBetweenRetries += timeBetweenRetries;
// Delete the tmp file inbetween attempts
FileSystemManager.DeleteFile(tmpDownloadPath);
try
{
Task <Stream> getFileTask = Provider.GetFileTask(ticketedItem, cancellationToken);
Task timeoutTask = Task.Delay(ContainerFetchEngineOptions.GetFileAsyncTimeout, cancellationToken);
ExecutionLogger.Debug(StringUtil.Format("Fetching contents of file {0}", tmpDownloadPath));
// Wait for GetFileAsync or the timeout to elapse.
await Task.WhenAny(getFileTask, timeoutTask).ConfigureAwait(false);
if (cancellationToken.IsCancellationRequested)
{
return;
}
if (!getFileTask.IsCompleted)
{
throw new TimeoutException(StringUtil.Loc("RMGetFileAsyncTimedOut", GetFileAsyncTimeoutMinutes));
}
ExecutionLogger.Debug(StringUtil.Format("Writing contents of file {0} to disk", tmpDownloadPath));
using (Stream stream = await getFileTask.ConfigureAwait(false))
{
await FileSystemManager.WriteStreamToFile(stream, tmpDownloadPath, ContainerFetchEngineOptions.DownloadBufferSize, cancellationToken);
}
ExecutionLogger.Debug(StringUtil.Format("Finished writing contents of file {0} to disk", tmpDownloadPath));
break;
}
catch (Exception exception)
{
if (exception is AggregateException)
{
exception = ((AggregateException)exception).Flatten().InnerException;
}
if (lastAttempt)
{
throw new Exception(StringUtil.Loc("RMErrorDownloadingContainerItem", tmpDownloadPath, exception));
}
lock (_lock)
{
ExecutionLogger.Warning(StringUtil.Loc("RMReAttemptingDownloadOfContainerItem", tmpDownloadPath, exception));
}
}
// "Sleep" in between attempts. (Can't await inside a catch clause.)
await Task.Delay(timeBetweenRetries);
}
}
private Task DownloadItemAsync(SemaphoreSlim downloadThrottle, ContainerItem ticketedItem)
{
string downloadPath = ConvertToLocalPath(ticketedItem);
return(DownloadItemImplAsync(downloadThrottle, ticketedItem, downloadPath));
}
