/** @return a good secondary or null if can't find one */
ServerAddress getASecondary() {
_checkClosed();
Node best = null;
double badBeforeBest = 0;
int start = _random.nextInt(_all.size());
double mybad = 0;
for (int i = 0; i < _all.size(); i++) {
Node n = _all.get((start + i) % _all.size());
if (!n.secondary()) {
mybad++;
continue;
}
if (best == null) {
best = n;
badBeforeBest = mybad;
mybad = 0;
continue;
}
long diff = best._pingTime - n._pingTime;
if (diff > slaveAcceptableLatencyMS
||
// this is a complex way to make sure we get a random distribution of slaves
((badBeforeBest - mybad) / (_all.size() - 1)) > _random.nextDouble()) {
best = n;
badBeforeBest = mybad;
mybad = 0;
}
}
if (best == null) return null;
return best._addr;
}
