Clarify what sending "completed" means e.g. wrt. flow control

[jan-ivar]

The SendStream write algorithm says: "Send bytes on stream.[[InternalStream]] and wait for the operation to complete."

But what does "complete" mean?

1. it's been buffered for sending?
2. it's been put on the wire?

3. the receiver has acked it?

   A non-normative note suggests it's "not necessarily" 3 and "may just" be 1:

I think we more strongly need to say it's not 3. I think we more strongly need to say it's not 2.

This avoids blocking on the network process, which would be great.

At minimum, "complete" must be beyond the last point of local failure, because the write promise has been resolved. I.e. 1.

Flow control

But atomic writes in #551 fail if blocked on flow control, putting the last point of local failure past flow control. IOW:

• a resolved promise from atomicWrite means sending passed flow control

Does the same invariant hold for non-atomic writes?

• Yes, a resolved promise from write means sending passed flow control
• No, write and atomicWrite have different guarantees

I think it needs to be 1 and yes for symmetry and sanity. I.e. "complete" means

1. it's been buffered for sending and has passed flow control

We should clarify that.

[aboba]

This seems like a duplicate of #426.

[jan-ivar]

Meeting:

• No