public void Callback(bool success, Edge e, Exception x) {
_success = success;
_edge = e;
_exception = x;
if(!success) {
if(System.Threading.Interlocked.Exchange(ref _called, 1) == 1) {
return;
}
ExternalECB(false, e, x);
} else {
Parent.AddEdge(this);
}
}