why is send_trailers()/finish needed before waiting for response ?

[gopakumarce]

All the examples and documentation says that after send_request() and send_data(), one has to call send_trailers() or finish() before waiting to read response - but why is that, I mean its upto the server right ? The server can choose to respond with a response as soon as it gets a request, and then process the body after that.

The reason I ask is, on the client if I try a sequence like below

1. send_request()
2. recv_response()
3. send_data()

And on the server I when I get a request, I do

1. send_response()
2. recv_data()

After step3 on client, I do not do any send_trailer or finish(). What I see is that server gets the request, sends the response, client gets the response all right, client says send_data() is successful, but the recv_data() on server just waits for ever - if I close the connection, then suddenly recv_data() on server gets the data sent by the client, which kind of points into the direction of needing to call a finish()

But ive been going through the h3 code and I just cant figure out why the server would not immediately get the data in recv_data() that was sent by client in send_data() regardless of finish()/send_trailer() being called. I cant see where is that dependency - but it seems to be there somewhere because my server recv_data() hangs .. Any pointers to where in the code that dependency is there would be really appreciated (and some context on why that is the case)

[gopakumarce]

I am guessing this is because on the client side, after calling send_data(), I don't see what really kick starts the quinn layer to go send that data. The example talks about the driver.poll_close(), but that just seems to be listening for control frames, isnt there some form of driver activity that should also keep checking for data to send and trigger a quinn conn.wakeup() and all that ?

[gopakumarce]

And by that token, calling send_trailers() doesnt seem like it will do the job of waking up the driver to go send out all the accumulated data so far, it looks like it has to be a finish() call that will get all the data to the other side. So I guess all I am missing / not understanding is how do I send_data() and "do something" so that the quinn connection driver will send it to the other end

[gopakumarce]

Looking through the code more, I guess the answer is just that such a mode is not supported yet (a body/send_data() that stays alive for long, without needing a finish()). I will try to send a PR across for the same

[gopakumarce]

hmm .. well, thats not the case, I see quinn Connecting::new() spawn a driver poll task automatically

[gopakumarce]

Closing this query - it looks like its a bug, raised #219 for that