protected override bool SubscribeProgressAndContinueLoop(ref IProgressListener progressListener, out Promise previous)
{
// This is guaranteed to be pending.
bool firstSubscribe = _progressListeners.IsEmpty;
progressListener.Retain();
_progressListeners.Push(progressListener);
previous = _valueOrPrevious as Promise;
if (_secondPrevious)
{
if (!firstSubscribe)
{
return(false);
}
// Subscribe this to the returned promise.
progressListener = this;
}
return(previous != null);
}