void updateLagInfo(ReplicaId peerReplica, long lagInBytes) {
      if (peerReplica.getDataNodeId().getDatacenterName().equals(localDcName)) {
        localDcPeerReplicaAndLag.put(peerReplica, lagInBytes);
        if (lagInBytes <= acceptableThreshold) {
          logger.trace("LocalReplicaLagInfo: local peer {} caught up with {}", peerReplica, replicaOnCurrentNode);
          localDcCaughtUpReplicas.add(peerReplica);
        } else {
          localDcCaughtUpReplicas.remove(peerReplica);
        }
      } else {
        remoteDcPeerReplicaAndLag.put(peerReplica, lagInBytes);
        if (lagInBytes <= acceptableThreshold) {
          remoteDcCaughtUpReplicas.add(peerReplica);
        } else {
          remoteDcCaughtUpReplicas.remove(peerReplica);
        }
      }
    }
Update replication lag in bytes between current replica and specified peer.
@param peerReplica the peer replica that the current replica is lagging behind
@param lagInBytes the bytes of current replica's lag from peer replica
ambry-clustermap/src/main/java/com/github/ambry/clustermap/AmbryReplicaSyncUpManager.java