HTTP2: Send remaining data and trailers together

[JamesNK]

Fixes #11270

The test checks that the data is correct, but it doesn't verify that data and trailers were flushed together. What is the best way to check this using the current HTTP/2 test pattern?

[jkotalik]

The test checks that the data is correct, but it doesn't verify that data and trailers were flushed together. What is the best way to check this using the current HTTP/2 test pattern?

I can't think of a great way here. You would need to be able to hang somewhere between WriteData and writing the response trailers to verify that the data wasn't flushed.

[Tratcher]

No, we don't have a great way to check for the absence of a gap between frames. Checking for the presence of a gap would be easier.

[JamesNK]

I've added a check for flow control and a test - ResponseTrailers_WithLargeUnflushedData_DataExceedsFlowControlAvailableAndNotSentWithTrailers - but the test hangs while reading the large body. 1 byte remains in the data frame but the server is not sending it.

I expected ExpectAsync to unblock flow control and allow the server to send more data. Is that not the case?

[Tratcher]

Flow control is unblocked by sending window updates frames (manually), not by calling ExpectAsync.

[JamesNK]

Thanks. Test now verifies flow control is respected.

[Tratcher]

Much better. I assume it shows up as expected in a wireshark trace?

[JamesNK]

app.Run(context =>
{
    context.Response.BodyWriter.GetMemory(1000);
    context.Response.BodyWriter.Advance(1000);
    context.Response.AppendTrailer("trailer", "trailer2");

    return Task.CompletedTask;
});

Wireshark of headers, data and headers (trailers) sent in a single packet:

[JamesNK]

@Tratcher Ping. Could you re-review and either approve or give feedback of issues to resolve.