private boolean calculateQuorum() {
    // quorum check
    int weight = getWeight(lastView.getMembers(), lastView.getLeadMember());
    int ackedWeight = getWeight(receivedAcks, lastView.getLeadMember());
    int lossThreshold = (int) Math.round((weight * partitionThreshold) / 100.0);
    if (isInfoEnabled) {
      logger.info(
          "quorum check: contacted {} processes with {} member weight units.  Threshold for a quorum is {}",
          receivedAcks.size(), ackedWeight, lossThreshold);
    }
    return (ackedWeight >= lossThreshold);
  }
GMSQuorumChecker is the implementation of QuorumChecker and can be used to determine
whether a quorum of membership is accessible.
geode-membership/src/main/java/org/apache/geode/distributed/internal/membership/gms/messenger/GMSQuorumChecker.java