private static async Task <IActionResult> OnCompleted(OnCompleteEnum OnComplete, CloudBlockBlob inputBlob, string thisGUID)
{
switch (OnComplete)
{
case OnCompleteEnum.Redirect:
{
// Redirect to the SAS URI to blob storage
return((ActionResult) new RedirectResult(inputBlob.GenerateSASURI()));
}
case OnCompleteEnum.Stream:
{
// Download the file and return it directly to the caller.
// For larger files, use a stream to minimize RAM usage.
return((ActionResult) new OkObjectResult(await inputBlob.DownloadTextAsync()));
}
default:
{
throw new InvalidOperationException($"Unexpected value: {OnComplete}");
}
}
}
public static async Task <IActionResult> Run(
[HttpTrigger(AuthorizationLevel.Anonymous, "get", Route = "RequestStatus/{thisGUID}")] HttpRequest req,
[Blob("data/{thisGuid}.blobdata", FileAccess.Read, Connection = "StorageConnectionAppSetting")] CloudBlockBlob inputBlob, string thisGUID,
ILogger log)
{
OnCompleteEnum OnComplete = Enum.Parse <OnCompleteEnum>(req.Query["OnComplete"].FirstOrDefault() ?? "Redirect");
OnPendingEnum OnPending = Enum.Parse <OnPendingEnum>(req.Query["OnPending"].FirstOrDefault() ?? "Accepted");
log.LogInformation($"C# HTTP trigger function processed a request for status on {thisGUID} - OnComplete {OnComplete} - OnPending {OnPending}");
// ** Check to see if the blob is present **
if (await inputBlob.ExistsAsync())
{
// ** If it's present, depending on the value of the optional "OnComplete" parameter choose what to do. **
return(await OnCompleted(OnComplete, inputBlob, thisGUID));
}
else
{
// ** If it's NOT present, then we need to back off, so depending on the value of the optional "OnPending" parameter choose what to do. **
string rqs = $"http://{Environment.GetEnvironmentVariable("WEBSITE_HOSTNAME")}/api/RequestStatus/{thisGUID}";
switch (OnPending)
{
case OnPendingEnum.Accepted:
{
// Return an HTTP 202 status code with the
return((ActionResult) new AcceptedResult()
{
Location = rqs
});
}
case OnPendingEnum.Synchronous:
{
// Back off and retry. Time out if the backoff period hits one minute
int backoff = 250;
while (!await inputBlob.ExistsAsync() && backoff < 64000)
{
log.LogInformation($"Synchronous mode {thisGUID}.blob - retrying in {backoff} ms");
backoff = backoff * 2;
await Task.Delay(backoff);
}
if (await inputBlob.ExistsAsync())
{
log.LogInformation($"Synchronous Redirect mode {thisGUID}.blob - completed after {backoff} ms");
return(await OnCompleted(OnComplete, inputBlob, thisGUID));
}
else
{
log.LogInformation($"Synchronous mode {thisGUID}.blob - NOT FOUND after timeout {backoff} ms");
return((ActionResult) new NotFoundResult());
}
}
default:
{
throw new InvalidOperationException($"Unexpected value: {OnPending}");
}
}
}
}
