private async ValueTask <(PacketHeaders, int, bool)> TransmissionControl(Memory <byte> output, CancellationToken token)
{
MessageType responseType;
int count;
bool isContinueReceiving;
var resultTask = Cast <Task <Result <bool> > >(task);
var stateTask = transmissionStateTrigger.WaitAsync(this, IsValidStateForResponsePredicate, token);
// wait for result or state transition
if (ReferenceEquals(resultTask, await Task.WhenAny(resultTask, stateTask).ConfigureAwait(false)))
{
// result obtained, finalize transmission
task = null;
state = State.ReceivingEntriesFinished;
remainingCount = 0;
count = IExchange.WriteResult(resultTask.Result, output.Span);
isContinueReceiving = false;
responseType = MessageType.None;
}
else
{
// should be in sync with IsValidStateForResponse
switch (state)
{
case State.ReceivingEntriesFinished:
count = IExchange.WriteResult(await resultTask.ConfigureAwait(false), output.Span);
isContinueReceiving = false;
responseType = MessageType.None;
break;
case State.ReadyToReceiveEntry:
count = EntriesExchange.CreateNextEntryResponse(output.Span, lookupIndex);
isContinueReceiving = true;
responseType = MessageType.NextEntry;
break;
case State.ReceivingEntry:
count = 0;
isContinueReceiving = true;
responseType = MessageType.Continue;
break;
default:
throw new InvalidOperationException();
}
}
return(new PacketHeaders(responseType, FlowControl.Ack), count, isContinueReceiving);
}
