Get NotSupportedException for a non-seekable stream when ResumeAsync is called after previous call on ResumeAsync timeout

[sparkinglu]

Not sure if this is a real issue.

When the resumable sync is used with a non-seekable stream, we got the NotSupportedException sometimes. We went through the codes and found there may be something wrong in the ResumableUpload.cs.

1. At the 374th line (StreamLength = ContentStream.CanSeek ? ContentStream.Length : UnknownSize;). the StreamLength is the UnknownSize if the stream is non-seekable.
2. So at the 517th-527th lines, it seems correct to use StreamLength to check if the stream is seekable. When it is seekable, it calls PrepareNextChunkKnownSize which calls set positions at 652th.
   if (StreamLength != UnknownSize)
   {
   PrepareNextChunkKnownSize(request, stream, cancellationToken);
   }
   else
   {
   PrepareNextChunkUnknownSize(request, stream, cancellationToken);
   }
3. However at the 627th (StreamLength = LastMediaLength + BytesServerReceived;), the StreamLength is assigned always even though it is non-seekable. So it could be wrong to use the StreamLength to check if it is seekable if the previous upload timeout and one retry is done on the same ResumableUpload instance.

[sparkinglu]

Here are the pseudo-codes to reproduce this issue when the uploaded file size is less than chunk size and the 1st call on ResumeAsync timeouts.

create an object of ResumableUpload.InsertMediaUpload
retry the below operations if timeout
calls ResumeAsync
return if complete

[peleyal]

Sorry for the late response....

1. So, your stream is non-seekable, right? So, StreamLength is set to unknown size.
   https://github.com/google/google-api-dotnet-client/blob/master/Src/GoogleApis/Apis/%5BMedia%5D/Upload/ResumableUpload.cs#L374
2. Why do you care about seekable in this case, I thought we said that the stream is NOT seekable. So, I would expect a call to PrepareNextChunkUnknownSize,
   https://github.com/google/google-api-dotnet-client/blob/master/Src/GoogleApis/Apis/%5BMedia%5D/Upload/ResumableUpload.cs#L523
3. PrepareNextChunkUnknownSize is defined in https://github.com/google/google-api-dotnet-client/blob/master/Src/GoogleApis/Apis/%5BMedia%5D/Upload/ResumableUpload.cs#L571.
   Are you suggesting that there is a bug in this function?
4. In your last comment you said that the file size is less than chunk size (but it's unknown, right?)
   So is it the use case where we have a unknown size stream and the first request fails?

Thanks,
Eyal

[chrisdunelm]

I'm fairly sure I've reproduced this bug in a test. I hope to have the new test-cases and a fix ready in the next few days.
It occurs, as you say, when the last chunk of a non-seekable stream fails to upload.

[chrisdunelm]

Finally fixed :)