public override async Task <Stream> LoadAsync(CancellationToken cancellationToken)
{
var result = await _storageBlob.GetAsync(Options.ModelName, Options.ModelFileName, cancellationToken);
if (result == null)
{
throw new ApplicationException("No Model was retrieved");
}
return(result);
}
internal async Task RunAsync()
{
var sw = ValueStopwatch.StartNew();
CancellationTokenSource?cancellation = null;
try
{
cancellation = CancellationTokenSource.CreateLinkedTokenSource(_stopping.Token);
cancellation.CancelAfter(TimeoutMilliseconds);
var blob = await _storageBlob.GetBlobAsync(_modelName, _fileName, cancellation.Token);
var etag = string.Empty;
if (blob != null)
{
await blob.FetchAttributesAsync();
etag = blob.Properties.ETag;
}
if (_eTag != etag)
{
var stream = await _storageBlob.GetAsync(_modelName, _fileName, cancellation.Token);
if (stream != null)
{
var previousToken = Interlocked.Exchange(ref _reloadToken, new ModelReloadToken());
_model = _mlContext.Model.Load(stream, out _);
_logger.LogInformation("[{loader}][Reloaded] {modelName} Elapsed {time}ms", nameof(AzureStorageMSModelLoader), _modelName, sw.GetElapsedTime().TotalMilliseconds);
previousToken.OnReload();
}
}
}
catch (OperationCanceledException) when(!_stopping.IsCancellationRequested)
{
// This is a cancellation - if the app is shutting down we want to ignore it.
}
catch (Exception ex)
{
_logger.LogError("Azure Storage Model Loader failed", ex);
}
finally
{
cancellation?.Dispose();
}
// schedule a polling task only if none exists and a valid delay is specified
if (_pollingTask == null)
{
_pollingTask = PollForChangesAsync();
}
}